Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

26 files changed, 3773 insertions, 0 deletions

diff --git a/src/rocksdb/monitoring/file_read_sample.h b/src/rocksdb/monitoring/file_read_sample.h
new file mode 100644
index 00000000..9ad7d2f5
--- /dev/null
+++ b/src/rocksdb/monitoring/file_read_sample.h
@@ -0,0 +1,23 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+#pragma once
+#include "db/version_edit.h"
+#include "util/random.h"
+
+namespace rocksdb {
+static const uint32_t kFileReadSampleRate = 1024;
+extern bool should_sample_file_read();
+extern void sample_file_read_inc(FileMetaData*);
+
+inline bool should_sample_file_read() {
+  return (Random::GetTLSInstance()->Next() % kFileReadSampleRate == 307);
+}
+
+inline void sample_file_read_inc(FileMetaData* meta) {
+  meta->stats.num_reads_sampled.fetch_add(kFileReadSampleRate,
+                                          std::memory_order_relaxed);
+}
+}
diff --git a/src/rocksdb/monitoring/histogram.cc b/src/rocksdb/monitoring/histogram.cc
new file mode 100644
index 00000000..4bc7139d
--- /dev/null
+++ b/src/rocksdb/monitoring/histogram.cc
@@ -0,0 +1,292 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef __STDC_FORMAT_MACROS
+#define __STDC_FORMAT_MACROS
+#endif
+
+#include "monitoring/histogram.h"
+
+#include <inttypes.h>
+#include <cassert>
+#include <math.h>
+#include <stdio.h>
+
+#include "port/port.h"
+#include "util/cast_util.h"
+
+namespace rocksdb {
+
+HistogramBucketMapper::HistogramBucketMapper() {
+  // If you change this, you also need to change
+  // size of array buckets_ in HistogramImpl
+  bucketValues_ = {1, 2};
+  valueIndexMap_ = {{1, 0}, {2, 1}};
+  double bucket_val = static_cast<double>(bucketValues_.back());
+  while ((bucket_val = 1.5 * bucket_val) <= static_cast<double>(port::kMaxUint64)) {
+    bucketValues_.push_back(static_cast<uint64_t>(bucket_val));
+    // Extracts two most significant digits to make histogram buckets more
+    // human-readable. E.g., 172 becomes 170.
+    uint64_t pow_of_ten = 1;
+    while (bucketValues_.back() / 10 > 10) {
+      bucketValues_.back() /= 10;
+      pow_of_ten *= 10;
+    }
+    bucketValues_.back() *= pow_of_ten;
+    valueIndexMap_[bucketValues_.back()] = bucketValues_.size() - 1;
+  }
+  maxBucketValue_ = bucketValues_.back();
+  minBucketValue_ = bucketValues_.front();
+}
+
+size_t HistogramBucketMapper::IndexForValue(const uint64_t value) const {
+  if (value >= maxBucketValue_) {
+    return bucketValues_.size() - 1;
+  } else if ( value >= minBucketValue_ ) {
+    std::map<uint64_t, uint64_t>::const_iterator lowerBound =
+      valueIndexMap_.lower_bound(value);
+    if (lowerBound != valueIndexMap_.end()) {
+      return static_cast<size_t>(lowerBound->second);
+    } else {
+      return 0;
+    }
+  } else {
+    return 0;
+  }
+}
+
+namespace {
+  const HistogramBucketMapper bucketMapper;
+}
+
+HistogramStat::HistogramStat()
+  : num_buckets_(bucketMapper.BucketCount()) {
+  assert(num_buckets_ == sizeof(buckets_) / sizeof(*buckets_));
+  Clear();
+}
+
+void HistogramStat::Clear() {
+  min_.store(bucketMapper.LastValue(), std::memory_order_relaxed);
+  max_.store(0, std::memory_order_relaxed);
+  num_.store(0, std::memory_order_relaxed);
+  sum_.store(0, std::memory_order_relaxed);
+  sum_squares_.store(0, std::memory_order_relaxed);
+  for (unsigned int b = 0; b < num_buckets_; b++) {
+    buckets_[b].store(0, std::memory_order_relaxed);
+  }
+};
+
+bool HistogramStat::Empty() const { return num() == 0; }
+
+void HistogramStat::Add(uint64_t value) {
+  // This function is designed to be lock free, as it's in the critical path
+  // of any operation. Each individual value is atomic and the order of updates
+  // by concurrent threads is tolerable.
+  const size_t index = bucketMapper.IndexForValue(value);
+  assert(index < num_buckets_);
+  buckets_[index].store(buckets_[index].load(std::memory_order_relaxed) + 1,
+                        std::memory_order_relaxed);
+
+  uint64_t old_min = min();
+  if (value < old_min) {
+    min_.store(value, std::memory_order_relaxed);
+  }
+
+  uint64_t old_max = max();
+  if (value > old_max) {
+    max_.store(value, std::memory_order_relaxed);
+  }
+
+  num_.store(num_.load(std::memory_order_relaxed) + 1,
+             std::memory_order_relaxed);
+  sum_.store(sum_.load(std::memory_order_relaxed) + value,
+             std::memory_order_relaxed);
+  sum_squares_.store(
+      sum_squares_.load(std::memory_order_relaxed) + value * value,
+      std::memory_order_relaxed);
+}
+
+void HistogramStat::Merge(const HistogramStat& other) {
+  // This function needs to be performned with the outer lock acquired
+  // However, atomic operation on every member is still need, since Add()
+  // requires no lock and value update can still happen concurrently
+  uint64_t old_min = min();
+  uint64_t other_min = other.min();
+  while (other_min < old_min &&
+         !min_.compare_exchange_weak(old_min, other_min)) {}
+
+  uint64_t old_max = max();
+  uint64_t other_max = other.max();
+  while (other_max > old_max &&
+         !max_.compare_exchange_weak(old_max, other_max)) {}
+
+  num_.fetch_add(other.num(), std::memory_order_relaxed);
+  sum_.fetch_add(other.sum(), std::memory_order_relaxed);
+  sum_squares_.fetch_add(other.sum_squares(), std::memory_order_relaxed);
+  for (unsigned int b = 0; b < num_buckets_; b++) {
+    buckets_[b].fetch_add(other.bucket_at(b), std::memory_order_relaxed);
+  }
+}
+
+double HistogramStat::Median() const {
+  return Percentile(50.0);
+}
+
+double HistogramStat::Percentile(double p) const {
+  double threshold = num() * (p / 100.0);
+  uint64_t cumulative_sum = 0;
+  for (unsigned int b = 0; b < num_buckets_; b++) {
+    uint64_t bucket_value = bucket_at(b);
+    cumulative_sum += bucket_value;
+    if (cumulative_sum >= threshold) {
+      // Scale linearly within this bucket
+      uint64_t left_point = (b == 0) ? 0 : bucketMapper.BucketLimit(b-1);
+      uint64_t right_point = bucketMapper.BucketLimit(b);
+      uint64_t left_sum = cumulative_sum - bucket_value;
+      uint64_t right_sum = cumulative_sum;
+      double pos = 0;
+      uint64_t right_left_diff = right_sum - left_sum;
+      if (right_left_diff != 0) {
+       pos = (threshold - left_sum) / right_left_diff;
+      }
+      double r = left_point + (right_point - left_point) * pos;
+      uint64_t cur_min = min();
+      uint64_t cur_max = max();
+      if (r < cur_min) r = static_cast<double>(cur_min);
+      if (r > cur_max) r = static_cast<double>(cur_max);
+      return r;
+    }
+  }
+  return static_cast<double>(max());
+}
+
+double HistogramStat::Average() const {
+  uint64_t cur_num = num();
+  uint64_t cur_sum = sum();
+  if (cur_num == 0) return 0;
+  return static_cast<double>(cur_sum) / static_cast<double>(cur_num);
+}
+
+double HistogramStat::StandardDeviation() const {
+  uint64_t cur_num = num();
+  uint64_t cur_sum = sum();
+  uint64_t cur_sum_squares = sum_squares();
+  if (cur_num == 0) return 0;
+  double variance =
+      static_cast<double>(cur_sum_squares * cur_num - cur_sum * cur_sum) /
+      static_cast<double>(cur_num * cur_num);
+  return sqrt(variance);
+}
+std::string HistogramStat::ToString() const {
+  uint64_t cur_num = num();
+  std::string r;
+  char buf[1650];
+  snprintf(buf, sizeof(buf),
+           "Count: %" PRIu64 " Average: %.4f  StdDev: %.2f\n",
+           cur_num, Average(), StandardDeviation());
+  r.append(buf);
+  snprintf(buf, sizeof(buf),
+           "Min: %" PRIu64 "  Median: %.4f  Max: %" PRIu64 "\n",
+           (cur_num == 0 ? 0 : min()), Median(), (cur_num == 0 ? 0 : max()));
+  r.append(buf);
+  snprintf(buf, sizeof(buf),
+           "Percentiles: "
+           "P50: %.2f P75: %.2f P99: %.2f P99.9: %.2f P99.99: %.2f\n",
+           Percentile(50), Percentile(75), Percentile(99), Percentile(99.9),
+           Percentile(99.99));
+  r.append(buf);
+  r.append("------------------------------------------------------\n");
+  if (cur_num == 0) return r;   // all buckets are empty
+  const double mult = 100.0 / cur_num;
+  uint64_t cumulative_sum = 0;
+  for (unsigned int b = 0; b < num_buckets_; b++) {
+    uint64_t bucket_value = bucket_at(b);
+    if (bucket_value <= 0.0) continue;
+    cumulative_sum += bucket_value;
+    snprintf(buf, sizeof(buf),
+             "%c %7" PRIu64 ", %7" PRIu64 " ] %8" PRIu64 " %7.3f%% %7.3f%% ",
+             (b == 0) ? '[' : '(',
+             (b == 0) ? 0 : bucketMapper.BucketLimit(b-1),  // left
+              bucketMapper.BucketLimit(b),  // right
+              bucket_value,                   // count
+             (mult * bucket_value),           // percentage
+             (mult * cumulative_sum));       // cumulative percentage
+    r.append(buf);
+
+    // Add hash marks based on percentage; 20 marks for 100%.
+    size_t marks = static_cast<size_t>(mult * bucket_value / 5 + 0.5);
+    r.append(marks, '#');
+    r.push_back('\n');
+  }
+  return r;
+}
+
+void HistogramStat::Data(HistogramData * const data) const {
+  assert(data);
+  data->median = Median();
+  data->percentile95 = Percentile(95);
+  data->percentile99 = Percentile(99);
+  data->max = static_cast<double>(max());
+  data->average = Average();
+  data->standard_deviation = StandardDeviation();
+  data->count = num();
+  data->sum = sum();
+  data->min = static_cast<double>(min());
+}
+
+void HistogramImpl::Clear() {
+  std::lock_guard<std::mutex> lock(mutex_);
+  stats_.Clear();
+}
+
+bool HistogramImpl::Empty() const {
+  return stats_.Empty();
+}
+
+void HistogramImpl::Add(uint64_t value) {
+  stats_.Add(value);
+}
+
+void HistogramImpl::Merge(const Histogram& other) {
+  if (strcmp(Name(), other.Name()) == 0) {
+    Merge(
+        *static_cast_with_check<const HistogramImpl, const Histogram>(&other));
+  }
+}
+
+void HistogramImpl::Merge(const HistogramImpl& other) {
+  std::lock_guard<std::mutex> lock(mutex_);
+  stats_.Merge(other.stats_);
+}
+
+double HistogramImpl::Median() const {
+  return stats_.Median();
+}
+
+double HistogramImpl::Percentile(double p) const {
+  return stats_.Percentile(p);
+}
+
+double HistogramImpl::Average() const {
+  return stats_.Average();
+}
+
+double HistogramImpl::StandardDeviation() const {
+ return stats_.StandardDeviation();
+}
+
+std::string HistogramImpl::ToString() const {
+  return stats_.ToString();
+}
+
+void HistogramImpl::Data(HistogramData * const data) const {
+  stats_.Data(data);
+}
+
+} // namespace levedb
diff --git a/src/rocksdb/monitoring/histogram.h b/src/rocksdb/monitoring/histogram.h
new file mode 100644
index 00000000..6bf2e9e9
--- /dev/null
+++ b/src/rocksdb/monitoring/histogram.h
@@ -0,0 +1,149 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+#include "rocksdb/statistics.h"
+
+#include <cassert>
+#include <string>
+#include <vector>
+#include <map>
+#include <mutex>
+
+namespace rocksdb {
+
+class HistogramBucketMapper {
+ public:
+
+  HistogramBucketMapper();
+
+  // converts a value to the bucket index.
+  size_t IndexForValue(uint64_t value) const;
+  // number of buckets required.
+
+  size_t BucketCount() const {
+    return bucketValues_.size();
+  }
+
+  uint64_t LastValue() const {
+    return maxBucketValue_;
+  }
+
+  uint64_t FirstValue() const {
+    return minBucketValue_;
+  }
+
+  uint64_t BucketLimit(const size_t bucketNumber) const {
+    assert(bucketNumber < BucketCount());
+    return bucketValues_[bucketNumber];
+  }
+
+ private:
+  std::vector<uint64_t> bucketValues_;
+  uint64_t maxBucketValue_;
+  uint64_t minBucketValue_;
+  std::map<uint64_t, uint64_t> valueIndexMap_;
+};
+
+struct HistogramStat {
+  HistogramStat();
+  ~HistogramStat() {}
+
+  HistogramStat(const HistogramStat&) = delete;
+  HistogramStat& operator=(const HistogramStat&) = delete;
+
+  void Clear();
+  bool Empty() const;
+  void Add(uint64_t value);
+  void Merge(const HistogramStat& other);
+
+  inline uint64_t min() const { return min_.load(std::memory_order_relaxed); }
+  inline uint64_t max() const { return max_.load(std::memory_order_relaxed); }
+  inline uint64_t num() const { return num_.load(std::memory_order_relaxed); }
+  inline uint64_t sum() const { return sum_.load(std::memory_order_relaxed); }
+  inline uint64_t sum_squares() const {
+    return sum_squares_.load(std::memory_order_relaxed);
+  }
+  inline uint64_t bucket_at(size_t b) const {
+    return buckets_[b].load(std::memory_order_relaxed);
+  }
+
+  double Median() const;
+  double Percentile(double p) const;
+  double Average() const;
+  double StandardDeviation() const;
+  void Data(HistogramData* const data) const;
+  std::string ToString() const;
+
+  // To be able to use HistogramStat as thread local variable, it
+  // cannot have dynamic allocated member. That's why we're
+  // using manually values from BucketMapper
+  std::atomic_uint_fast64_t min_;
+  std::atomic_uint_fast64_t max_;
+  std::atomic_uint_fast64_t num_;
+  std::atomic_uint_fast64_t sum_;
+  std::atomic_uint_fast64_t sum_squares_;
+  std::atomic_uint_fast64_t buckets_[109]; // 109==BucketMapper::BucketCount()
+  const uint64_t num_buckets_;
+};
+
+class Histogram {
+public:
+  Histogram() {}
+  virtual ~Histogram() {};
+
+  virtual void Clear() = 0;
+  virtual bool Empty() const = 0;
+  virtual void Add(uint64_t value) = 0;
+  virtual void Merge(const Histogram&) = 0;
+
+  virtual std::string ToString() const = 0;
+  virtual const char* Name() const = 0;
+  virtual uint64_t min() const = 0;
+  virtual uint64_t max() const = 0;
+  virtual uint64_t num() const = 0;
+  virtual double Median() const = 0;
+  virtual double Percentile(double p) const = 0;
+  virtual double Average() const = 0;
+  virtual double StandardDeviation() const = 0;
+  virtual void Data(HistogramData* const data) const = 0;
+};
+
+class HistogramImpl : public Histogram {
+ public:
+  HistogramImpl() { Clear(); }
+
+  HistogramImpl(const HistogramImpl&) = delete;
+  HistogramImpl& operator=(const HistogramImpl&) = delete;
+
+  virtual void Clear() override;
+  virtual bool Empty() const override;
+  virtual void Add(uint64_t value) override;
+  virtual void Merge(const Histogram& other) override;
+  void Merge(const HistogramImpl& other);
+
+  virtual std::string ToString() const override;
+  virtual const char* Name() const override { return "HistogramImpl"; }
+  virtual uint64_t min() const override { return stats_.min(); }
+  virtual uint64_t max() const override { return stats_.max(); }
+  virtual uint64_t num() const override { return stats_.num(); }
+  virtual double Median() const override;
+  virtual double Percentile(double p) const override;
+  virtual double Average() const override;
+  virtual double StandardDeviation() const override;
+  virtual void Data(HistogramData* const data) const override;
+
+  virtual ~HistogramImpl() {}
+
+ private:
+  HistogramStat stats_;
+  std::mutex mutex_;
+};
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/histogram_test.cc b/src/rocksdb/monitoring/histogram_test.cc
new file mode 100644
index 00000000..df58822f
--- /dev/null
+++ b/src/rocksdb/monitoring/histogram_test.cc
@@ -0,0 +1,221 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+#include <cmath>
+
+#include "monitoring/histogram.h"
+#include "monitoring/histogram_windowing.h"
+#include "util/testharness.h"
+
+namespace rocksdb {
+
+class HistogramTest : public testing::Test {};
+
+namespace {
+  const double kIota = 0.1;
+  const HistogramBucketMapper bucketMapper;
+  Env* env = Env::Default();
+}
+
+void PopulateHistogram(Histogram& histogram,
+             uint64_t low, uint64_t high, uint64_t loop = 1) {
+  for (; loop > 0; loop--) {
+    for (uint64_t i = low; i <= high; i++) {
+      histogram.Add(i);
+    }
+  }
+}
+
+void BasicOperation(Histogram& histogram) {
+  PopulateHistogram(histogram, 1, 110, 10); // fill up to bucket [70, 110)
+
+  HistogramData data;
+  histogram.Data(&data);
+
+  ASSERT_LE(fabs(histogram.Percentile(100.0) - 110.0), kIota);
+  ASSERT_LE(fabs(data.percentile99 - 108.9), kIota);  // 99 * 110 / 100
+  ASSERT_LE(fabs(data.percentile95 - 104.5), kIota);  // 95 * 110 / 100
+  ASSERT_LE(fabs(data.median - 55.0), kIota);  // 50 * 110 / 100
+  ASSERT_EQ(data.average, 55.5);  // (1 + 110) / 2
+}
+
+void MergeHistogram(Histogram& histogram, Histogram& other) {
+  PopulateHistogram(histogram, 1, 100);
+  PopulateHistogram(other, 101, 250);
+  histogram.Merge(other);
+
+  HistogramData data;
+  histogram.Data(&data);
+
+  ASSERT_LE(fabs(histogram.Percentile(100.0) - 250.0), kIota);
+  ASSERT_LE(fabs(data.percentile99 - 247.5), kIota);  // 99 * 250 / 100
+  ASSERT_LE(fabs(data.percentile95 - 237.5), kIota);  // 95 * 250 / 100
+  ASSERT_LE(fabs(data.median - 125.0), kIota);  // 50 * 250 / 100
+  ASSERT_EQ(data.average, 125.5);  // (1 + 250) / 2
+}
+
+void EmptyHistogram(Histogram& histogram) {
+  ASSERT_EQ(histogram.min(), bucketMapper.LastValue());
+  ASSERT_EQ(histogram.max(), 0);
+  ASSERT_EQ(histogram.num(), 0);
+  ASSERT_EQ(histogram.Median(), 0.0);
+  ASSERT_EQ(histogram.Percentile(85.0), 0.0);
+  ASSERT_EQ(histogram.Average(), 0.0);
+  ASSERT_EQ(histogram.StandardDeviation(), 0.0);
+}
+
+void ClearHistogram(Histogram& histogram) {
+  for (uint64_t i = 1; i <= 100; i++) {
+    histogram.Add(i);
+  }
+  histogram.Clear();
+  ASSERT_TRUE(histogram.Empty());
+  ASSERT_EQ(histogram.Median(), 0);
+  ASSERT_EQ(histogram.Percentile(85.0), 0);
+  ASSERT_EQ(histogram.Average(), 0);
+}
+
+TEST_F(HistogramTest, BasicOperation) {
+  HistogramImpl histogram;
+  BasicOperation(histogram);
+
+  HistogramWindowingImpl histogramWindowing;
+  BasicOperation(histogramWindowing);
+}
+
+TEST_F(HistogramTest, BoundaryValue) {
+  HistogramImpl histogram;
+  // - both should be in [0, 1] bucket because we place values on bucket
+  //   boundaries in the lower bucket.
+  // - all points are in [0, 1] bucket, so p50 will be 0.5
+  // - the test cannot be written with a single point since histogram won't
+  //   report percentiles lower than the min or greater than the max.
+  histogram.Add(0);
+  histogram.Add(1);
+
+  ASSERT_LE(fabs(histogram.Percentile(50.0) - 0.5), kIota);
+}
+
+TEST_F(HistogramTest, MergeHistogram) {
+  HistogramImpl histogram;
+  HistogramImpl other;
+  MergeHistogram(histogram, other);
+
+  HistogramWindowingImpl histogramWindowing;
+  HistogramWindowingImpl otherWindowing;
+  MergeHistogram(histogramWindowing, otherWindowing);
+}
+
+TEST_F(HistogramTest, EmptyHistogram) {
+  HistogramImpl histogram;
+  EmptyHistogram(histogram);
+
+  HistogramWindowingImpl histogramWindowing;
+  EmptyHistogram(histogramWindowing);
+}
+
+TEST_F(HistogramTest, ClearHistogram) {
+  HistogramImpl histogram;
+  ClearHistogram(histogram);
+
+  HistogramWindowingImpl histogramWindowing;
+  ClearHistogram(histogramWindowing);
+}
+
+TEST_F(HistogramTest, HistogramWindowingExpire) {
+  uint64_t num_windows = 3;
+  int micros_per_window = 1000000;
+  uint64_t min_num_per_window = 0;
+
+  HistogramWindowingImpl
+      histogramWindowing(num_windows, micros_per_window, min_num_per_window);
+
+  PopulateHistogram(histogramWindowing, 1, 1, 100);
+  env->SleepForMicroseconds(micros_per_window);
+  ASSERT_EQ(histogramWindowing.num(), 100);
+  ASSERT_EQ(histogramWindowing.min(), 1);
+  ASSERT_EQ(histogramWindowing.max(), 1);
+  ASSERT_EQ(histogramWindowing.Average(), 1);
+
+  PopulateHistogram(histogramWindowing, 2, 2, 100);
+  env->SleepForMicroseconds(micros_per_window);
+  ASSERT_EQ(histogramWindowing.num(), 200);
+  ASSERT_EQ(histogramWindowing.min(), 1);
+  ASSERT_EQ(histogramWindowing.max(), 2);
+  ASSERT_EQ(histogramWindowing.Average(), 1.5);
+
+  PopulateHistogram(histogramWindowing, 3, 3, 100);
+  env->SleepForMicroseconds(micros_per_window);
+  ASSERT_EQ(histogramWindowing.num(), 300);
+  ASSERT_EQ(histogramWindowing.min(), 1);
+  ASSERT_EQ(histogramWindowing.max(), 3);
+  ASSERT_EQ(histogramWindowing.Average(), 2.0);
+
+  // dropping oldest window with value 1, remaining 2 ~ 4
+  PopulateHistogram(histogramWindowing, 4, 4, 100);
+  env->SleepForMicroseconds(micros_per_window);
+  ASSERT_EQ(histogramWindowing.num(), 300);
+  ASSERT_EQ(histogramWindowing.min(), 2);
+  ASSERT_EQ(histogramWindowing.max(), 4);
+  ASSERT_EQ(histogramWindowing.Average(), 3.0);
+
+  // dropping oldest window with value 2, remaining 3 ~ 5
+  PopulateHistogram(histogramWindowing, 5, 5, 100);
+  env->SleepForMicroseconds(micros_per_window);
+  ASSERT_EQ(histogramWindowing.num(), 300);
+  ASSERT_EQ(histogramWindowing.min(), 3);
+  ASSERT_EQ(histogramWindowing.max(), 5);
+  ASSERT_EQ(histogramWindowing.Average(), 4.0);
+}
+
+TEST_F(HistogramTest, HistogramWindowingMerge) {
+  uint64_t num_windows = 3;
+  int micros_per_window = 1000000;
+  uint64_t min_num_per_window = 0;
+
+  HistogramWindowingImpl
+      histogramWindowing(num_windows, micros_per_window, min_num_per_window);
+  HistogramWindowingImpl
+      otherWindowing(num_windows, micros_per_window, min_num_per_window);
+
+  PopulateHistogram(histogramWindowing, 1, 1, 100);
+  PopulateHistogram(otherWindowing, 1, 1, 100);
+  env->SleepForMicroseconds(micros_per_window);
+
+  PopulateHistogram(histogramWindowing, 2, 2, 100);
+  PopulateHistogram(otherWindowing, 2, 2, 100);
+  env->SleepForMicroseconds(micros_per_window);
+
+  PopulateHistogram(histogramWindowing, 3, 3, 100);
+  PopulateHistogram(otherWindowing, 3, 3, 100);
+  env->SleepForMicroseconds(micros_per_window);
+
+  histogramWindowing.Merge(otherWindowing);
+  ASSERT_EQ(histogramWindowing.num(), 600);
+  ASSERT_EQ(histogramWindowing.min(), 1);
+  ASSERT_EQ(histogramWindowing.max(), 3);
+  ASSERT_EQ(histogramWindowing.Average(), 2.0);
+
+  // dropping oldest window with value 1, remaining 2 ~ 4
+  PopulateHistogram(histogramWindowing, 4, 4, 100);
+  env->SleepForMicroseconds(micros_per_window);
+  ASSERT_EQ(histogramWindowing.num(), 500);
+  ASSERT_EQ(histogramWindowing.min(), 2);
+  ASSERT_EQ(histogramWindowing.max(), 4);
+
+  // dropping oldest window with value 2, remaining 3 ~ 5
+  PopulateHistogram(histogramWindowing, 5, 5, 100);
+  env->SleepForMicroseconds(micros_per_window);
+  ASSERT_EQ(histogramWindowing.num(), 400);
+  ASSERT_EQ(histogramWindowing.min(), 3);
+  ASSERT_EQ(histogramWindowing.max(), 5);
+}
+
+}  // namespace rocksdb
+
+int main(int argc, char** argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}
diff --git a/src/rocksdb/monitoring/histogram_windowing.cc b/src/rocksdb/monitoring/histogram_windowing.cc
new file mode 100644
index 00000000..ecd6f090
--- /dev/null
+++ b/src/rocksdb/monitoring/histogram_windowing.cc
@@ -0,0 +1,202 @@
+//  Copyright (c) 2013, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "monitoring/histogram_windowing.h"
+#include "monitoring/histogram.h"
+#include "util/cast_util.h"
+
+#include <algorithm>
+
+namespace rocksdb {
+
+HistogramWindowingImpl::HistogramWindowingImpl() {
+  env_ = Env::Default();
+  window_stats_.reset(new HistogramStat[static_cast<size_t>(num_windows_)]);
+  Clear();
+}
+
+HistogramWindowingImpl::HistogramWindowingImpl(
+    uint64_t num_windows,
+    uint64_t micros_per_window,
+    uint64_t min_num_per_window) :
+      num_windows_(num_windows),
+      micros_per_window_(micros_per_window),
+      min_num_per_window_(min_num_per_window) {
+  env_ = Env::Default();
+  window_stats_.reset(new HistogramStat[static_cast<size_t>(num_windows_)]);
+  Clear();
+}
+
+HistogramWindowingImpl::~HistogramWindowingImpl() {
+}
+
+void HistogramWindowingImpl::Clear() {
+  std::lock_guard<std::mutex> lock(mutex_);
+
+  stats_.Clear();
+  for (size_t i = 0; i < num_windows_; i++) {
+    window_stats_[i].Clear();
+  }
+  current_window_.store(0, std::memory_order_relaxed);
+  last_swap_time_.store(env_->NowMicros(), std::memory_order_relaxed);
+}
+
+bool HistogramWindowingImpl::Empty() const { return stats_.Empty(); }
+
+// This function is designed to be lock free, as it's in the critical path
+// of any operation.
+// Each individual value is atomic, it is just that some samples can go
+// in the older bucket which is tolerable.
+void HistogramWindowingImpl::Add(uint64_t value){
+  TimerTick();
+
+  // Parent (global) member update
+  stats_.Add(value);
+
+  // Current window update
+  window_stats_[static_cast<size_t>(current_window())].Add(value);
+}
+
+void HistogramWindowingImpl::Merge(const Histogram& other) {
+  if (strcmp(Name(), other.Name()) == 0) {
+    Merge(
+        *static_cast_with_check<const HistogramWindowingImpl, const Histogram>(
+            &other));
+  }
+}
+
+void HistogramWindowingImpl::Merge(const HistogramWindowingImpl& other) {
+  std::lock_guard<std::mutex> lock(mutex_);
+  stats_.Merge(other.stats_);
+
+  if (stats_.num_buckets_ != other.stats_.num_buckets_ ||
+      micros_per_window_ != other.micros_per_window_) {
+    return;
+  }
+
+  uint64_t cur_window = current_window();
+  uint64_t other_cur_window = other.current_window();
+  // going backwards for alignment
+  for (unsigned int i = 0;
+                    i < std::min(num_windows_, other.num_windows_); i++) {
+    uint64_t window_index =
+        (cur_window + num_windows_ - i) % num_windows_;
+    uint64_t other_window_index =
+        (other_cur_window + other.num_windows_ - i) % other.num_windows_;
+    size_t windex = static_cast<size_t>(window_index);
+    size_t other_windex = static_cast<size_t>(other_window_index);
+
+    window_stats_[windex].Merge(
+      other.window_stats_[other_windex]);
+  }
+}
+
+std::string HistogramWindowingImpl::ToString() const {
+  return stats_.ToString();
+}
+
+double HistogramWindowingImpl::Median() const {
+  return Percentile(50.0);
+}
+
+double HistogramWindowingImpl::Percentile(double p) const {
+  // Retry 3 times in total
+  for (int retry = 0; retry < 3; retry++) {
+    uint64_t start_num = stats_.num();
+    double result = stats_.Percentile(p);
+    // Detect if swap buckets or Clear() was called during calculation
+    if (stats_.num() >= start_num) {
+      return result;
+    }
+  }
+  return 0.0;
+}
+
+double HistogramWindowingImpl::Average() const {
+  return stats_.Average();
+}
+
+double HistogramWindowingImpl::StandardDeviation() const {
+  return stats_.StandardDeviation();
+}
+
+void HistogramWindowingImpl::Data(HistogramData * const data) const {
+  stats_.Data(data);
+}
+
+void HistogramWindowingImpl::TimerTick() {
+  uint64_t curr_time = env_->NowMicros();
+  size_t curr_window_ = static_cast<size_t>(current_window());
+  if (curr_time - last_swap_time() > micros_per_window_ &&
+      window_stats_[curr_window_].num() >= min_num_per_window_) {
+    SwapHistoryBucket();
+  }
+}
+
+void HistogramWindowingImpl::SwapHistoryBucket() {
+  // Threads executing Add() would be competing for this mutex, the first one
+  // who got the metex would take care of the bucket swap, other threads
+  // can skip this.
+  // If mutex is held by Merge() or Clear(), next Add() will take care of the
+  // swap, if needed.
+  if (mutex_.try_lock()) {
+    last_swap_time_.store(env_->NowMicros(), std::memory_order_relaxed);
+
+    uint64_t curr_window = current_window();
+    uint64_t next_window = (curr_window == num_windows_ - 1) ?
+                                                    0 : curr_window + 1;
+
+    // subtract next buckets from totals and swap to next buckets
+    HistogramStat& stats_to_drop = 
+      window_stats_[static_cast<size_t>(next_window)];
+
+    if (!stats_to_drop.Empty()) {
+      for (size_t b = 0; b < stats_.num_buckets_; b++){
+        stats_.buckets_[b].fetch_sub(
+            stats_to_drop.bucket_at(b), std::memory_order_relaxed);
+      }
+
+      if (stats_.min() == stats_to_drop.min()) {
+        uint64_t new_min = std::numeric_limits<uint64_t>::max();
+        for (unsigned int i = 0; i < num_windows_; i++) {
+          if (i != next_window) {
+            uint64_t m = window_stats_[i].min();
+            if (m < new_min) new_min = m;
+          }
+        }
+        stats_.min_.store(new_min, std::memory_order_relaxed);
+      }
+
+      if (stats_.max() == stats_to_drop.max()) {
+        uint64_t new_max = 0;
+        for (unsigned int i = 0; i < num_windows_; i++) {
+          if (i != next_window) {
+            uint64_t m = window_stats_[i].max();
+            if (m > new_max) new_max = m;
+          }
+        }
+        stats_.max_.store(new_max, std::memory_order_relaxed);
+      }
+
+      stats_.num_.fetch_sub(stats_to_drop.num(), std::memory_order_relaxed);
+      stats_.sum_.fetch_sub(stats_to_drop.sum(), std::memory_order_relaxed);
+      stats_.sum_squares_.fetch_sub(
+                  stats_to_drop.sum_squares(), std::memory_order_relaxed);
+
+      stats_to_drop.Clear();
+    }
+
+    // advance to next window bucket
+    current_window_.store(next_window, std::memory_order_relaxed);
+
+    mutex_.unlock();
+  }
+}
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/histogram_windowing.h b/src/rocksdb/monitoring/histogram_windowing.h
new file mode 100644
index 00000000..6532aa24
--- /dev/null
+++ b/src/rocksdb/monitoring/histogram_windowing.h
@@ -0,0 +1,80 @@
+//  Copyright (c) 2013, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+
+#include "monitoring/histogram.h"
+#include "rocksdb/env.h"
+
+namespace rocksdb {
+
+class HistogramWindowingImpl : public Histogram
+{
+public:
+  HistogramWindowingImpl();
+  HistogramWindowingImpl(uint64_t num_windows,
+                         uint64_t micros_per_window,
+                         uint64_t min_num_per_window);
+
+  HistogramWindowingImpl(const HistogramWindowingImpl&) = delete;
+  HistogramWindowingImpl& operator=(const HistogramWindowingImpl&) = delete;
+
+  ~HistogramWindowingImpl();
+
+  virtual void Clear() override;
+  virtual bool Empty() const override;
+  virtual void Add(uint64_t value) override;
+  virtual void Merge(const Histogram& other) override;
+  void Merge(const HistogramWindowingImpl& other);
+
+  virtual std::string ToString() const override;
+  virtual const char* Name() const override { return "HistogramWindowingImpl"; }
+  virtual uint64_t min() const override { return stats_.min(); }
+  virtual uint64_t max() const override { return stats_.max(); }
+  virtual uint64_t num() const override { return stats_.num(); }
+  virtual double Median() const override;
+  virtual double Percentile(double p) const override;
+  virtual double Average() const override;
+  virtual double StandardDeviation() const override;
+  virtual void Data(HistogramData* const data) const override;
+
+private:
+  void TimerTick();
+  void SwapHistoryBucket();
+  inline uint64_t current_window() const {
+    return current_window_.load(std::memory_order_relaxed);
+  }
+  inline uint64_t last_swap_time() const{
+    return last_swap_time_.load(std::memory_order_relaxed);
+  }
+
+  Env* env_;
+  std::mutex mutex_;
+
+  // Aggregated stats over windows_stats_, all the computation is done
+  // upon aggregated values
+  HistogramStat stats_;
+
+  // This is a circular array representing the latest N time-windows.
+  // Each entry stores a time-window of data. Expiration is done
+  // on window-based.
+  std::unique_ptr<HistogramStat[]> window_stats_;
+
+  std::atomic_uint_fast64_t current_window_;
+  std::atomic_uint_fast64_t last_swap_time_;
+
+  // Following parameters are configuable
+  uint64_t num_windows_ = 5;
+  uint64_t micros_per_window_ = 60000000;
+  // By default, don't care about the number of values in current window
+  // when decide whether to swap windows or not.
+  uint64_t min_num_per_window_ = 0;
+};
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/instrumented_mutex.cc b/src/rocksdb/monitoring/instrumented_mutex.cc
new file mode 100644
index 00000000..7b61bcf4
--- /dev/null
+++ b/src/rocksdb/monitoring/instrumented_mutex.cc
@@ -0,0 +1,69 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include "monitoring/instrumented_mutex.h"
+#include "monitoring/perf_context_imp.h"
+#include "monitoring/thread_status_util.h"
+#include "util/sync_point.h"
+
+namespace rocksdb {
+namespace {
+Statistics* stats_for_report(Env* env, Statistics* stats) {
+  if (env != nullptr && stats != nullptr &&
+      stats->get_stats_level() > kExceptTimeForMutex) {
+    return stats;
+  } else {
+    return nullptr;
+  }
+}
+}  // namespace
+
+void InstrumentedMutex::Lock() {
+  PERF_CONDITIONAL_TIMER_FOR_MUTEX_GUARD(
+      db_mutex_lock_nanos, stats_code_ == DB_MUTEX_WAIT_MICROS,
+      stats_for_report(env_, stats_), stats_code_);
+  LockInternal();
+}
+
+void InstrumentedMutex::LockInternal() {
+#ifndef NDEBUG
+  ThreadStatusUtil::TEST_StateDelay(ThreadStatus::STATE_MUTEX_WAIT);
+#endif
+  mutex_.Lock();
+}
+
+void InstrumentedCondVar::Wait() {
+  PERF_CONDITIONAL_TIMER_FOR_MUTEX_GUARD(
+      db_condition_wait_nanos, stats_code_ == DB_MUTEX_WAIT_MICROS,
+      stats_for_report(env_, stats_), stats_code_);
+  WaitInternal();
+}
+
+void InstrumentedCondVar::WaitInternal() {
+#ifndef NDEBUG
+  ThreadStatusUtil::TEST_StateDelay(ThreadStatus::STATE_MUTEX_WAIT);
+#endif
+  cond_.Wait();
+}
+
+bool InstrumentedCondVar::TimedWait(uint64_t abs_time_us) {
+  PERF_CONDITIONAL_TIMER_FOR_MUTEX_GUARD(
+      db_condition_wait_nanos, stats_code_ == DB_MUTEX_WAIT_MICROS,
+      stats_for_report(env_, stats_), stats_code_);
+  return TimedWaitInternal(abs_time_us);
+}
+
+bool InstrumentedCondVar::TimedWaitInternal(uint64_t abs_time_us) {
+#ifndef NDEBUG
+  ThreadStatusUtil::TEST_StateDelay(ThreadStatus::STATE_MUTEX_WAIT);
+#endif
+
+  TEST_SYNC_POINT_CALLBACK("InstrumentedCondVar::TimedWaitInternal",
+                           &abs_time_us);
+
+  return cond_.TimedWait(abs_time_us);
+}
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/instrumented_mutex.h b/src/rocksdb/monitoring/instrumented_mutex.h
new file mode 100644
index 00000000..83d7523e
--- /dev/null
+++ b/src/rocksdb/monitoring/instrumented_mutex.h
@@ -0,0 +1,98 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include "monitoring/statistics.h"
+#include "port/port.h"
+#include "rocksdb/env.h"
+#include "rocksdb/statistics.h"
+#include "rocksdb/thread_status.h"
+#include "util/stop_watch.h"
+
+namespace rocksdb {
+class InstrumentedCondVar;
+
+// A wrapper class for port::Mutex that provides additional layer
+// for collecting stats and instrumentation.
+class InstrumentedMutex {
+ public:
+  explicit InstrumentedMutex(bool adaptive = false)
+      : mutex_(adaptive), stats_(nullptr), env_(nullptr),
+        stats_code_(0) {}
+
+  InstrumentedMutex(
+      Statistics* stats, Env* env,
+      int stats_code, bool adaptive = false)
+      : mutex_(adaptive), stats_(stats), env_(env),
+        stats_code_(stats_code) {}
+
+  void Lock();
+
+  void Unlock() {
+    mutex_.Unlock();
+  }
+
+  void AssertHeld() {
+    mutex_.AssertHeld();
+  }
+
+ private:
+  void LockInternal();
+  friend class InstrumentedCondVar;
+  port::Mutex mutex_;
+  Statistics* stats_;
+  Env* env_;
+  int stats_code_;
+};
+
+// A wrapper class for port::Mutex that provides additional layer
+// for collecting stats and instrumentation.
+class InstrumentedMutexLock {
+ public:
+  explicit InstrumentedMutexLock(InstrumentedMutex* mutex) : mutex_(mutex) {
+    mutex_->Lock();
+  }
+
+  ~InstrumentedMutexLock() {
+    mutex_->Unlock();
+  }
+
+ private:
+  InstrumentedMutex* const mutex_;
+  InstrumentedMutexLock(const InstrumentedMutexLock&) = delete;
+  void operator=(const InstrumentedMutexLock&) = delete;
+};
+
+class InstrumentedCondVar {
+ public:
+  explicit InstrumentedCondVar(InstrumentedMutex* instrumented_mutex)
+      : cond_(&(instrumented_mutex->mutex_)),
+        stats_(instrumented_mutex->stats_),
+        env_(instrumented_mutex->env_),
+        stats_code_(instrumented_mutex->stats_code_) {}
+
+  void Wait();
+
+  bool TimedWait(uint64_t abs_time_us);
+
+  void Signal() {
+    cond_.Signal();
+  }
+
+  void SignalAll() {
+    cond_.SignalAll();
+  }
+
+ private:
+  void WaitInternal();
+  bool TimedWaitInternal(uint64_t abs_time_us);
+  port::CondVar cond_;
+  Statistics* stats_;
+  Env* env_;
+  int stats_code_;
+};
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/iostats_context.cc b/src/rocksdb/monitoring/iostats_context.cc
new file mode 100644
index 00000000..3d102f91
--- /dev/null
+++ b/src/rocksdb/monitoring/iostats_context.cc
@@ -0,0 +1,60 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include <sstream>
+#include "monitoring/iostats_context_imp.h"
+#include "rocksdb/env.h"
+
+namespace rocksdb {
+
+#ifdef ROCKSDB_SUPPORT_THREAD_LOCAL
+__thread IOStatsContext iostats_context;
+#endif
+
+IOStatsContext* get_iostats_context() {
+#ifdef ROCKSDB_SUPPORT_THREAD_LOCAL
+  return &iostats_context;
+#else
+  return nullptr;
+#endif
+}
+
+void IOStatsContext::Reset() {
+  thread_pool_id = Env::Priority::TOTAL;
+  bytes_read = 0;
+  bytes_written = 0;
+  open_nanos = 0;
+  allocate_nanos = 0;
+  write_nanos = 0;
+  read_nanos = 0;
+  range_sync_nanos = 0;
+  prepare_write_nanos = 0;
+  fsync_nanos = 0;
+  logger_nanos = 0;
+}
+
+#define IOSTATS_CONTEXT_OUTPUT(counter)         \
+  if (!exclude_zero_counters || counter > 0) {  \
+    ss << #counter << " = " << counter << ", "; \
+  }
+
+std::string IOStatsContext::ToString(bool exclude_zero_counters) const {
+  std::ostringstream ss;
+  IOSTATS_CONTEXT_OUTPUT(thread_pool_id);
+  IOSTATS_CONTEXT_OUTPUT(bytes_read);
+  IOSTATS_CONTEXT_OUTPUT(bytes_written);
+  IOSTATS_CONTEXT_OUTPUT(open_nanos);
+  IOSTATS_CONTEXT_OUTPUT(allocate_nanos);
+  IOSTATS_CONTEXT_OUTPUT(write_nanos);
+  IOSTATS_CONTEXT_OUTPUT(read_nanos);
+  IOSTATS_CONTEXT_OUTPUT(range_sync_nanos);
+  IOSTATS_CONTEXT_OUTPUT(fsync_nanos);
+  IOSTATS_CONTEXT_OUTPUT(prepare_write_nanos);
+  IOSTATS_CONTEXT_OUTPUT(logger_nanos);
+
+  return ss.str();
+}
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/iostats_context_imp.h b/src/rocksdb/monitoring/iostats_context_imp.h
new file mode 100644
index 00000000..23c2088c
--- /dev/null
+++ b/src/rocksdb/monitoring/iostats_context_imp.h
@@ -0,0 +1,60 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+#pragma once
+#include "monitoring/perf_step_timer.h"
+#include "rocksdb/iostats_context.h"
+
+#ifdef ROCKSDB_SUPPORT_THREAD_LOCAL
+namespace rocksdb {
+extern __thread IOStatsContext iostats_context;
+}  // namespace rocksdb
+
+// increment a specific counter by the specified value
+#define IOSTATS_ADD(metric, value) (iostats_context.metric += value)
+
+// Increase metric value only when it is positive
+#define IOSTATS_ADD_IF_POSITIVE(metric, value)   \
+  if (value > 0) { IOSTATS_ADD(metric, value); }
+
+// reset a specific counter to zero
+#define IOSTATS_RESET(metric) (iostats_context.metric = 0)
+
+// reset all counters to zero
+#define IOSTATS_RESET_ALL() (iostats_context.Reset())
+
+#define IOSTATS_SET_THREAD_POOL_ID(value) \
+  (iostats_context.thread_pool_id = value)
+
+#define IOSTATS_THREAD_POOL_ID() (iostats_context.thread_pool_id)
+
+#define IOSTATS(metric) (iostats_context.metric)
+
+// Declare and set start time of the timer
+#define IOSTATS_TIMER_GUARD(metric)                                     \
+  PerfStepTimer iostats_step_timer_##metric(&(iostats_context.metric)); \
+  iostats_step_timer_##metric.Start();
+
+// Declare and set start time of the timer
+#define IOSTATS_CPU_TIMER_GUARD(metric, env)           \
+  PerfStepTimer iostats_step_timer_##metric(           \
+      &(iostats_context.metric), env, true,            \
+      PerfLevel::kEnableTimeAndCPUTimeExceptForMutex); \
+  iostats_step_timer_##metric.Start();
+
+#else  // ROCKSDB_SUPPORT_THREAD_LOCAL
+
+#define IOSTATS_ADD(metric, value)
+#define IOSTATS_ADD_IF_POSITIVE(metric, value)
+#define IOSTATS_RESET(metric)
+#define IOSTATS_RESET_ALL()
+#define IOSTATS_SET_THREAD_POOL_ID(value)
+#define IOSTATS_THREAD_POOL_ID()
+#define IOSTATS(metric) 0
+
+#define IOSTATS_TIMER_GUARD(metric)
+#define IOSTATS_CPU_TIMER_GUARD(metric, env)
+
+#endif  // ROCKSDB_SUPPORT_THREAD_LOCAL
diff --git a/src/rocksdb/monitoring/iostats_context_test.cc b/src/rocksdb/monitoring/iostats_context_test.cc
new file mode 100644
index 00000000..74d3e432
--- /dev/null
+++ b/src/rocksdb/monitoring/iostats_context_test.cc
@@ -0,0 +1,29 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include "rocksdb/iostats_context.h"
+#include "util/testharness.h"
+
+namespace rocksdb {
+
+TEST(IOStatsContextTest, ToString) {
+  get_iostats_context()->Reset();
+  get_iostats_context()->bytes_read = 12345;
+
+  std::string zero_included = get_iostats_context()->ToString();
+  ASSERT_NE(std::string::npos, zero_included.find("= 0"));
+  ASSERT_NE(std::string::npos, zero_included.find("= 12345"));
+
+  std::string zero_excluded = get_iostats_context()->ToString(true);
+  ASSERT_EQ(std::string::npos, zero_excluded.find("= 0"));
+  ASSERT_NE(std::string::npos, zero_excluded.find("= 12345"));
+}
+
+}  // namespace rocksdb
+
+int main(int argc, char** argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}
diff --git a/src/rocksdb/monitoring/perf_context.cc b/src/rocksdb/monitoring/perf_context.cc
new file mode 100644
index 00000000..40b0b215
--- /dev/null
+++ b/src/rocksdb/monitoring/perf_context.cc
@@ -0,0 +1,556 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+
+#include <sstream>
+#include "monitoring/perf_context_imp.h"
+
+namespace rocksdb {
+
+#if defined(NPERF_CONTEXT) || !defined(ROCKSDB_SUPPORT_THREAD_LOCAL)
+PerfContext perf_context;
+#else
+#if defined(OS_SOLARIS)
+__thread PerfContext perf_context_;
+#else
+thread_local PerfContext perf_context;
+#endif
+#endif
+
+PerfContext* get_perf_context() {
+#if defined(NPERF_CONTEXT) || !defined(ROCKSDB_SUPPORT_THREAD_LOCAL)
+  return &perf_context;
+#else
+#if defined(OS_SOLARIS)
+  return &perf_context_;
+#else
+  return &perf_context;
+#endif
+#endif
+}
+
+PerfContext::~PerfContext() {
+#if !defined(NPERF_CONTEXT) && defined(ROCKSDB_SUPPORT_THREAD_LOCAL) && !defined(OS_SOLARIS)
+  ClearPerLevelPerfContext();
+#endif
+}
+
+PerfContext::PerfContext(const PerfContext& other) {
+#ifndef NPERF_CONTEXT
+  user_key_comparison_count = other.user_key_comparison_count;
+  block_cache_hit_count = other.block_cache_hit_count;
+  block_read_count = other.block_read_count;
+  block_read_byte = other.block_read_byte;
+  block_read_time = other.block_read_time;
+  block_cache_index_hit_count = other.block_cache_index_hit_count;
+  index_block_read_count = other.index_block_read_count;
+  block_cache_filter_hit_count = other.block_cache_filter_hit_count;
+  filter_block_read_count = other.filter_block_read_count;
+  compression_dict_block_read_count = other.compression_dict_block_read_count;
+  block_checksum_time = other.block_checksum_time;
+  block_decompress_time = other.block_decompress_time;
+  get_read_bytes = other.get_read_bytes;
+  multiget_read_bytes = other.multiget_read_bytes;
+  iter_read_bytes = other.iter_read_bytes;
+  internal_key_skipped_count = other.internal_key_skipped_count;
+  internal_delete_skipped_count = other.internal_delete_skipped_count;
+  internal_recent_skipped_count = other.internal_recent_skipped_count;
+  internal_merge_count = other.internal_merge_count;
+  write_wal_time = other.write_wal_time;
+  get_snapshot_time = other.get_snapshot_time;
+  get_from_memtable_time = other.get_from_memtable_time;
+  get_from_memtable_count = other.get_from_memtable_count;
+  get_post_process_time = other.get_post_process_time;
+  get_from_output_files_time = other.get_from_output_files_time;
+  seek_on_memtable_time = other.seek_on_memtable_time;
+  seek_on_memtable_count = other.seek_on_memtable_count;
+  next_on_memtable_count = other.next_on_memtable_count;
+  prev_on_memtable_count = other.prev_on_memtable_count;
+  seek_child_seek_time = other.seek_child_seek_time;
+  seek_child_seek_count = other.seek_child_seek_count;
+  seek_min_heap_time = other.seek_min_heap_time;
+  seek_internal_seek_time = other.seek_internal_seek_time;
+  find_next_user_entry_time = other.find_next_user_entry_time;
+  write_pre_and_post_process_time = other.write_pre_and_post_process_time;
+  write_memtable_time = other.write_memtable_time;
+  write_delay_time = other.write_delay_time;
+  write_thread_wait_nanos = other.write_thread_wait_nanos;
+  write_scheduling_flushes_compactions_time =
+      other.write_scheduling_flushes_compactions_time;
+  db_mutex_lock_nanos = other.db_mutex_lock_nanos;
+  db_condition_wait_nanos = other.db_condition_wait_nanos;
+  merge_operator_time_nanos = other.merge_operator_time_nanos;
+  read_index_block_nanos = other.read_index_block_nanos;
+  read_filter_block_nanos = other.read_filter_block_nanos;
+  new_table_block_iter_nanos = other.new_table_block_iter_nanos;
+  new_table_iterator_nanos = other.new_table_iterator_nanos;
+  block_seek_nanos = other.block_seek_nanos;
+  find_table_nanos = other.find_table_nanos;
+  bloom_memtable_hit_count = other.bloom_memtable_hit_count;
+  bloom_memtable_miss_count = other.bloom_memtable_miss_count;
+  bloom_sst_hit_count = other.bloom_sst_hit_count;
+  bloom_sst_miss_count = other.bloom_sst_miss_count;
+  key_lock_wait_time = other.key_lock_wait_time;
+  key_lock_wait_count = other.key_lock_wait_count;
+
+  env_new_sequential_file_nanos = other.env_new_sequential_file_nanos;
+  env_new_random_access_file_nanos = other.env_new_random_access_file_nanos;
+  env_new_writable_file_nanos = other.env_new_writable_file_nanos;
+  env_reuse_writable_file_nanos = other.env_reuse_writable_file_nanos;
+  env_new_random_rw_file_nanos = other.env_new_random_rw_file_nanos;
+  env_new_directory_nanos = other.env_new_directory_nanos;
+  env_file_exists_nanos = other.env_file_exists_nanos;
+  env_get_children_nanos = other.env_get_children_nanos;
+  env_get_children_file_attributes_nanos =
+      other.env_get_children_file_attributes_nanos;
+  env_delete_file_nanos = other.env_delete_file_nanos;
+  env_create_dir_nanos = other.env_create_dir_nanos;
+  env_create_dir_if_missing_nanos = other.env_create_dir_if_missing_nanos;
+  env_delete_dir_nanos = other.env_delete_dir_nanos;
+  env_get_file_size_nanos = other.env_get_file_size_nanos;
+  env_get_file_modification_time_nanos =
+      other.env_get_file_modification_time_nanos;
+  env_rename_file_nanos = other.env_rename_file_nanos;
+  env_link_file_nanos = other.env_link_file_nanos;
+  env_lock_file_nanos = other.env_lock_file_nanos;
+  env_unlock_file_nanos = other.env_unlock_file_nanos;
+  env_new_logger_nanos = other.env_new_logger_nanos;
+  get_cpu_nanos = other.get_cpu_nanos;
+  iter_next_cpu_nanos = other.iter_next_cpu_nanos;
+  iter_prev_cpu_nanos = other.iter_prev_cpu_nanos;
+  iter_seek_cpu_nanos = other.iter_seek_cpu_nanos;
+  if (per_level_perf_context_enabled && level_to_perf_context != nullptr) {
+    ClearPerLevelPerfContext();
+  }
+  if (other.level_to_perf_context != nullptr) {
+    level_to_perf_context = new std::map<uint32_t, PerfContextByLevel>();
+    *level_to_perf_context = *other.level_to_perf_context;
+  }
+  per_level_perf_context_enabled = other.per_level_perf_context_enabled;
+#endif
+}
+
+PerfContext::PerfContext(PerfContext&& other) noexcept {
+#ifndef NPERF_CONTEXT
+  user_key_comparison_count = other.user_key_comparison_count;
+  block_cache_hit_count = other.block_cache_hit_count;
+  block_read_count = other.block_read_count;
+  block_read_byte = other.block_read_byte;
+  block_read_time = other.block_read_time;
+  block_cache_index_hit_count = other.block_cache_index_hit_count;
+  index_block_read_count = other.index_block_read_count;
+  block_cache_filter_hit_count = other.block_cache_filter_hit_count;
+  filter_block_read_count = other.filter_block_read_count;
+  compression_dict_block_read_count = other.compression_dict_block_read_count;
+  block_checksum_time = other.block_checksum_time;
+  block_decompress_time = other.block_decompress_time;
+  get_read_bytes = other.get_read_bytes;
+  multiget_read_bytes = other.multiget_read_bytes;
+  iter_read_bytes = other.iter_read_bytes;
+  internal_key_skipped_count = other.internal_key_skipped_count;
+  internal_delete_skipped_count = other.internal_delete_skipped_count;
+  internal_recent_skipped_count = other.internal_recent_skipped_count;
+  internal_merge_count = other.internal_merge_count;
+  write_wal_time = other.write_wal_time;
+  get_snapshot_time = other.get_snapshot_time;
+  get_from_memtable_time = other.get_from_memtable_time;
+  get_from_memtable_count = other.get_from_memtable_count;
+  get_post_process_time = other.get_post_process_time;
+  get_from_output_files_time = other.get_from_output_files_time;
+  seek_on_memtable_time = other.seek_on_memtable_time;
+  seek_on_memtable_count = other.seek_on_memtable_count;
+  next_on_memtable_count = other.next_on_memtable_count;
+  prev_on_memtable_count = other.prev_on_memtable_count;
+  seek_child_seek_time = other.seek_child_seek_time;
+  seek_child_seek_count = other.seek_child_seek_count;
+  seek_min_heap_time = other.seek_min_heap_time;
+  seek_internal_seek_time = other.seek_internal_seek_time;
+  find_next_user_entry_time = other.find_next_user_entry_time;
+  write_pre_and_post_process_time = other.write_pre_and_post_process_time;
+  write_memtable_time = other.write_memtable_time;
+  write_delay_time = other.write_delay_time;
+  write_thread_wait_nanos = other.write_thread_wait_nanos;
+  write_scheduling_flushes_compactions_time =
+      other.write_scheduling_flushes_compactions_time;
+  db_mutex_lock_nanos = other.db_mutex_lock_nanos;
+  db_condition_wait_nanos = other.db_condition_wait_nanos;
+  merge_operator_time_nanos = other.merge_operator_time_nanos;
+  read_index_block_nanos = other.read_index_block_nanos;
+  read_filter_block_nanos = other.read_filter_block_nanos;
+  new_table_block_iter_nanos = other.new_table_block_iter_nanos;
+  new_table_iterator_nanos = other.new_table_iterator_nanos;
+  block_seek_nanos = other.block_seek_nanos;
+  find_table_nanos = other.find_table_nanos;
+  bloom_memtable_hit_count = other.bloom_memtable_hit_count;
+  bloom_memtable_miss_count = other.bloom_memtable_miss_count;
+  bloom_sst_hit_count = other.bloom_sst_hit_count;
+  bloom_sst_miss_count = other.bloom_sst_miss_count;
+  key_lock_wait_time = other.key_lock_wait_time;
+  key_lock_wait_count = other.key_lock_wait_count;
+
+  env_new_sequential_file_nanos = other.env_new_sequential_file_nanos;
+  env_new_random_access_file_nanos = other.env_new_random_access_file_nanos;
+  env_new_writable_file_nanos = other.env_new_writable_file_nanos;
+  env_reuse_writable_file_nanos = other.env_reuse_writable_file_nanos;
+  env_new_random_rw_file_nanos = other.env_new_random_rw_file_nanos;
+  env_new_directory_nanos = other.env_new_directory_nanos;
+  env_file_exists_nanos = other.env_file_exists_nanos;
+  env_get_children_nanos = other.env_get_children_nanos;
+  env_get_children_file_attributes_nanos =
+      other.env_get_children_file_attributes_nanos;
+  env_delete_file_nanos = other.env_delete_file_nanos;
+  env_create_dir_nanos = other.env_create_dir_nanos;
+  env_create_dir_if_missing_nanos = other.env_create_dir_if_missing_nanos;
+  env_delete_dir_nanos = other.env_delete_dir_nanos;
+  env_get_file_size_nanos = other.env_get_file_size_nanos;
+  env_get_file_modification_time_nanos =
+      other.env_get_file_modification_time_nanos;
+  env_rename_file_nanos = other.env_rename_file_nanos;
+  env_link_file_nanos = other.env_link_file_nanos;
+  env_lock_file_nanos = other.env_lock_file_nanos;
+  env_unlock_file_nanos = other.env_unlock_file_nanos;
+  env_new_logger_nanos = other.env_new_logger_nanos;
+  get_cpu_nanos = other.get_cpu_nanos;
+  iter_next_cpu_nanos = other.iter_next_cpu_nanos;
+  iter_prev_cpu_nanos = other.iter_prev_cpu_nanos;
+  iter_seek_cpu_nanos = other.iter_seek_cpu_nanos;
+  if (per_level_perf_context_enabled && level_to_perf_context != nullptr) {
+    ClearPerLevelPerfContext();
+  }
+  if (other.level_to_perf_context != nullptr) {
+    level_to_perf_context = other.level_to_perf_context;
+    other.level_to_perf_context = nullptr;
+  }
+  per_level_perf_context_enabled = other.per_level_perf_context_enabled;
+#endif
+}
+
+// TODO(Zhongyi): reduce code duplication between copy constructor and
+// assignment operator
+PerfContext& PerfContext::operator=(const PerfContext& other) {
+#ifndef NPERF_CONTEXT
+  user_key_comparison_count = other.user_key_comparison_count;
+  block_cache_hit_count = other.block_cache_hit_count;
+  block_read_count = other.block_read_count;
+  block_read_byte = other.block_read_byte;
+  block_read_time = other.block_read_time;
+  block_cache_index_hit_count = other.block_cache_index_hit_count;
+  index_block_read_count = other.index_block_read_count;
+  block_cache_filter_hit_count = other.block_cache_filter_hit_count;
+  filter_block_read_count = other.filter_block_read_count;
+  compression_dict_block_read_count = other.compression_dict_block_read_count;
+  block_checksum_time = other.block_checksum_time;
+  block_decompress_time = other.block_decompress_time;
+  get_read_bytes = other.get_read_bytes;
+  multiget_read_bytes = other.multiget_read_bytes;
+  iter_read_bytes = other.iter_read_bytes;
+  internal_key_skipped_count = other.internal_key_skipped_count;
+  internal_delete_skipped_count = other.internal_delete_skipped_count;
+  internal_recent_skipped_count = other.internal_recent_skipped_count;
+  internal_merge_count = other.internal_merge_count;
+  write_wal_time = other.write_wal_time;
+  get_snapshot_time = other.get_snapshot_time;
+  get_from_memtable_time = other.get_from_memtable_time;
+  get_from_memtable_count = other.get_from_memtable_count;
+  get_post_process_time = other.get_post_process_time;
+  get_from_output_files_time = other.get_from_output_files_time;
+  seek_on_memtable_time = other.seek_on_memtable_time;
+  seek_on_memtable_count = other.seek_on_memtable_count;
+  next_on_memtable_count = other.next_on_memtable_count;
+  prev_on_memtable_count = other.prev_on_memtable_count;
+  seek_child_seek_time = other.seek_child_seek_time;
+  seek_child_seek_count = other.seek_child_seek_count;
+  seek_min_heap_time = other.seek_min_heap_time;
+  seek_internal_seek_time = other.seek_internal_seek_time;
+  find_next_user_entry_time = other.find_next_user_entry_time;
+  write_pre_and_post_process_time = other.write_pre_and_post_process_time;
+  write_memtable_time = other.write_memtable_time;
+  write_delay_time = other.write_delay_time;
+  write_thread_wait_nanos = other.write_thread_wait_nanos;
+  write_scheduling_flushes_compactions_time =
+      other.write_scheduling_flushes_compactions_time;
+  db_mutex_lock_nanos = other.db_mutex_lock_nanos;
+  db_condition_wait_nanos = other.db_condition_wait_nanos;
+  merge_operator_time_nanos = other.merge_operator_time_nanos;
+  read_index_block_nanos = other.read_index_block_nanos;
+  read_filter_block_nanos = other.read_filter_block_nanos;
+  new_table_block_iter_nanos = other.new_table_block_iter_nanos;
+  new_table_iterator_nanos = other.new_table_iterator_nanos;
+  block_seek_nanos = other.block_seek_nanos;
+  find_table_nanos = other.find_table_nanos;
+  bloom_memtable_hit_count = other.bloom_memtable_hit_count;
+  bloom_memtable_miss_count = other.bloom_memtable_miss_count;
+  bloom_sst_hit_count = other.bloom_sst_hit_count;
+  bloom_sst_miss_count = other.bloom_sst_miss_count;
+  key_lock_wait_time = other.key_lock_wait_time;
+  key_lock_wait_count = other.key_lock_wait_count;
+
+  env_new_sequential_file_nanos = other.env_new_sequential_file_nanos;
+  env_new_random_access_file_nanos = other.env_new_random_access_file_nanos;
+  env_new_writable_file_nanos = other.env_new_writable_file_nanos;
+  env_reuse_writable_file_nanos = other.env_reuse_writable_file_nanos;
+  env_new_random_rw_file_nanos = other.env_new_random_rw_file_nanos;
+  env_new_directory_nanos = other.env_new_directory_nanos;
+  env_file_exists_nanos = other.env_file_exists_nanos;
+  env_get_children_nanos = other.env_get_children_nanos;
+  env_get_children_file_attributes_nanos =
+      other.env_get_children_file_attributes_nanos;
+  env_delete_file_nanos = other.env_delete_file_nanos;
+  env_create_dir_nanos = other.env_create_dir_nanos;
+  env_create_dir_if_missing_nanos = other.env_create_dir_if_missing_nanos;
+  env_delete_dir_nanos = other.env_delete_dir_nanos;
+  env_get_file_size_nanos = other.env_get_file_size_nanos;
+  env_get_file_modification_time_nanos =
+      other.env_get_file_modification_time_nanos;
+  env_rename_file_nanos = other.env_rename_file_nanos;
+  env_link_file_nanos = other.env_link_file_nanos;
+  env_lock_file_nanos = other.env_lock_file_nanos;
+  env_unlock_file_nanos = other.env_unlock_file_nanos;
+  env_new_logger_nanos = other.env_new_logger_nanos;
+  get_cpu_nanos = other.get_cpu_nanos;
+  iter_next_cpu_nanos = other.iter_next_cpu_nanos;
+  iter_prev_cpu_nanos = other.iter_prev_cpu_nanos;
+  iter_seek_cpu_nanos = other.iter_seek_cpu_nanos;
+  if (per_level_perf_context_enabled && level_to_perf_context != nullptr) {
+    ClearPerLevelPerfContext();
+  }
+  if (other.level_to_perf_context != nullptr) {
+    level_to_perf_context = new std::map<uint32_t, PerfContextByLevel>();
+    *level_to_perf_context = *other.level_to_perf_context;
+  }
+  per_level_perf_context_enabled = other.per_level_perf_context_enabled;
+#endif
+  return *this;
+}
+
+void PerfContext::Reset() {
+#ifndef NPERF_CONTEXT
+  user_key_comparison_count = 0;
+  block_cache_hit_count = 0;
+  block_read_count = 0;
+  block_read_byte = 0;
+  block_read_time = 0;
+  block_cache_index_hit_count = 0;
+  index_block_read_count = 0;
+  block_cache_filter_hit_count = 0;
+  filter_block_read_count = 0;
+  compression_dict_block_read_count = 0;
+  block_checksum_time = 0;
+  block_decompress_time = 0;
+  get_read_bytes = 0;
+  multiget_read_bytes = 0;
+  iter_read_bytes = 0;
+  internal_key_skipped_count = 0;
+  internal_delete_skipped_count = 0;
+  internal_recent_skipped_count = 0;
+  internal_merge_count = 0;
+  write_wal_time = 0;
+
+  get_snapshot_time = 0;
+  get_from_memtable_time = 0;
+  get_from_memtable_count = 0;
+  get_post_process_time = 0;
+  get_from_output_files_time = 0;
+  seek_on_memtable_time = 0;
+  seek_on_memtable_count = 0;
+  next_on_memtable_count = 0;
+  prev_on_memtable_count = 0;
+  seek_child_seek_time = 0;
+  seek_child_seek_count = 0;
+  seek_min_heap_time = 0;
+  seek_internal_seek_time = 0;
+  find_next_user_entry_time = 0;
+  write_pre_and_post_process_time = 0;
+  write_memtable_time = 0;
+  write_delay_time = 0;
+  write_thread_wait_nanos = 0;
+  write_scheduling_flushes_compactions_time = 0;
+  db_mutex_lock_nanos = 0;
+  db_condition_wait_nanos = 0;
+  merge_operator_time_nanos = 0;
+  read_index_block_nanos = 0;
+  read_filter_block_nanos = 0;
+  new_table_block_iter_nanos = 0;
+  new_table_iterator_nanos = 0;
+  block_seek_nanos = 0;
+  find_table_nanos = 0;
+  bloom_memtable_hit_count = 0;
+  bloom_memtable_miss_count = 0;
+  bloom_sst_hit_count = 0;
+  bloom_sst_miss_count = 0;
+  key_lock_wait_time = 0;
+  key_lock_wait_count = 0;
+
+  env_new_sequential_file_nanos = 0;
+  env_new_random_access_file_nanos = 0;
+  env_new_writable_file_nanos = 0;
+  env_reuse_writable_file_nanos = 0;
+  env_new_random_rw_file_nanos = 0;
+  env_new_directory_nanos = 0;
+  env_file_exists_nanos = 0;
+  env_get_children_nanos = 0;
+  env_get_children_file_attributes_nanos = 0;
+  env_delete_file_nanos = 0;
+  env_create_dir_nanos = 0;
+  env_create_dir_if_missing_nanos = 0;
+  env_delete_dir_nanos = 0;
+  env_get_file_size_nanos = 0;
+  env_get_file_modification_time_nanos = 0;
+  env_rename_file_nanos = 0;
+  env_link_file_nanos = 0;
+  env_lock_file_nanos = 0;
+  env_unlock_file_nanos = 0;
+  env_new_logger_nanos = 0;
+  get_cpu_nanos = 0;
+  iter_next_cpu_nanos = 0;
+  iter_prev_cpu_nanos = 0;
+  iter_seek_cpu_nanos = 0;
+  if (per_level_perf_context_enabled && level_to_perf_context) {
+    for (auto& kv : *level_to_perf_context) {
+      kv.second.Reset();
+    }
+  }
+#endif
+}
+
+#define PERF_CONTEXT_OUTPUT(counter)             \
+  if (!exclude_zero_counters || (counter > 0)) { \
+    ss << #counter << " = " << counter << ", ";  \
+  }
+
+#define PERF_CONTEXT_BY_LEVEL_OUTPUT_ONE_COUNTER(counter)         \
+  if (per_level_perf_context_enabled && \
+      level_to_perf_context) {                                    \
+    ss << #counter << " = ";                                      \
+    for (auto& kv : *level_to_perf_context) {                     \
+      if (!exclude_zero_counters || (kv.second.counter > 0)) {    \
+        ss << kv.second.counter << "@level" << kv.first << ", ";  \
+      }                                                           \
+    }                                                             \
+  }
+
+void PerfContextByLevel::Reset() {
+#ifndef NPERF_CONTEXT
+  bloom_filter_useful = 0;
+  bloom_filter_full_positive = 0;
+  bloom_filter_full_true_positive = 0;
+  block_cache_hit_count = 0;
+  block_cache_miss_count = 0;
+#endif
+}
+
+std::string PerfContext::ToString(bool exclude_zero_counters) const {
+#ifdef NPERF_CONTEXT
+  return "";
+#else
+  std::ostringstream ss;
+  PERF_CONTEXT_OUTPUT(user_key_comparison_count);
+  PERF_CONTEXT_OUTPUT(block_cache_hit_count);
+  PERF_CONTEXT_OUTPUT(block_read_count);
+  PERF_CONTEXT_OUTPUT(block_read_byte);
+  PERF_CONTEXT_OUTPUT(block_read_time);
+  PERF_CONTEXT_OUTPUT(block_cache_index_hit_count);
+  PERF_CONTEXT_OUTPUT(index_block_read_count);
+  PERF_CONTEXT_OUTPUT(block_cache_filter_hit_count);
+  PERF_CONTEXT_OUTPUT(filter_block_read_count);
+  PERF_CONTEXT_OUTPUT(compression_dict_block_read_count);
+  PERF_CONTEXT_OUTPUT(block_checksum_time);
+  PERF_CONTEXT_OUTPUT(block_decompress_time);
+  PERF_CONTEXT_OUTPUT(get_read_bytes);
+  PERF_CONTEXT_OUTPUT(multiget_read_bytes);
+  PERF_CONTEXT_OUTPUT(iter_read_bytes);
+  PERF_CONTEXT_OUTPUT(internal_key_skipped_count);
+  PERF_CONTEXT_OUTPUT(internal_delete_skipped_count);
+  PERF_CONTEXT_OUTPUT(internal_recent_skipped_count);
+  PERF_CONTEXT_OUTPUT(internal_merge_count);
+  PERF_CONTEXT_OUTPUT(write_wal_time);
+  PERF_CONTEXT_OUTPUT(get_snapshot_time);
+  PERF_CONTEXT_OUTPUT(get_from_memtable_time);
+  PERF_CONTEXT_OUTPUT(get_from_memtable_count);
+  PERF_CONTEXT_OUTPUT(get_post_process_time);
+  PERF_CONTEXT_OUTPUT(get_from_output_files_time);
+  PERF_CONTEXT_OUTPUT(seek_on_memtable_time);
+  PERF_CONTEXT_OUTPUT(seek_on_memtable_count);
+  PERF_CONTEXT_OUTPUT(next_on_memtable_count);
+  PERF_CONTEXT_OUTPUT(prev_on_memtable_count);
+  PERF_CONTEXT_OUTPUT(seek_child_seek_time);
+  PERF_CONTEXT_OUTPUT(seek_child_seek_count);
+  PERF_CONTEXT_OUTPUT(seek_min_heap_time);
+  PERF_CONTEXT_OUTPUT(seek_internal_seek_time);
+  PERF_CONTEXT_OUTPUT(find_next_user_entry_time);
+  PERF_CONTEXT_OUTPUT(write_pre_and_post_process_time);
+  PERF_CONTEXT_OUTPUT(write_memtable_time);
+  PERF_CONTEXT_OUTPUT(write_thread_wait_nanos);
+  PERF_CONTEXT_OUTPUT(write_scheduling_flushes_compactions_time);
+  PERF_CONTEXT_OUTPUT(db_mutex_lock_nanos);
+  PERF_CONTEXT_OUTPUT(db_condition_wait_nanos);
+  PERF_CONTEXT_OUTPUT(merge_operator_time_nanos);
+  PERF_CONTEXT_OUTPUT(write_delay_time);
+  PERF_CONTEXT_OUTPUT(read_index_block_nanos);
+  PERF_CONTEXT_OUTPUT(read_filter_block_nanos);
+  PERF_CONTEXT_OUTPUT(new_table_block_iter_nanos);
+  PERF_CONTEXT_OUTPUT(new_table_iterator_nanos);
+  PERF_CONTEXT_OUTPUT(block_seek_nanos);
+  PERF_CONTEXT_OUTPUT(find_table_nanos);
+  PERF_CONTEXT_OUTPUT(bloom_memtable_hit_count);
+  PERF_CONTEXT_OUTPUT(bloom_memtable_miss_count);
+  PERF_CONTEXT_OUTPUT(bloom_sst_hit_count);
+  PERF_CONTEXT_OUTPUT(bloom_sst_miss_count);
+  PERF_CONTEXT_OUTPUT(key_lock_wait_time);
+  PERF_CONTEXT_OUTPUT(key_lock_wait_count);
+  PERF_CONTEXT_OUTPUT(env_new_sequential_file_nanos);
+  PERF_CONTEXT_OUTPUT(env_new_random_access_file_nanos);
+  PERF_CONTEXT_OUTPUT(env_new_writable_file_nanos);
+  PERF_CONTEXT_OUTPUT(env_reuse_writable_file_nanos);
+  PERF_CONTEXT_OUTPUT(env_new_random_rw_file_nanos);
+  PERF_CONTEXT_OUTPUT(env_new_directory_nanos);
+  PERF_CONTEXT_OUTPUT(env_file_exists_nanos);
+  PERF_CONTEXT_OUTPUT(env_get_children_nanos);
+  PERF_CONTEXT_OUTPUT(env_get_children_file_attributes_nanos);
+  PERF_CONTEXT_OUTPUT(env_delete_file_nanos);
+  PERF_CONTEXT_OUTPUT(env_create_dir_nanos);
+  PERF_CONTEXT_OUTPUT(env_create_dir_if_missing_nanos);
+  PERF_CONTEXT_OUTPUT(env_delete_dir_nanos);
+  PERF_CONTEXT_OUTPUT(env_get_file_size_nanos);
+  PERF_CONTEXT_OUTPUT(env_get_file_modification_time_nanos);
+  PERF_CONTEXT_OUTPUT(env_rename_file_nanos);
+  PERF_CONTEXT_OUTPUT(env_link_file_nanos);
+  PERF_CONTEXT_OUTPUT(env_lock_file_nanos);
+  PERF_CONTEXT_OUTPUT(env_unlock_file_nanos);
+  PERF_CONTEXT_OUTPUT(env_new_logger_nanos);
+  PERF_CONTEXT_OUTPUT(get_cpu_nanos);
+  PERF_CONTEXT_OUTPUT(iter_next_cpu_nanos);
+  PERF_CONTEXT_OUTPUT(iter_prev_cpu_nanos);
+  PERF_CONTEXT_OUTPUT(iter_seek_cpu_nanos);
+  PERF_CONTEXT_BY_LEVEL_OUTPUT_ONE_COUNTER(bloom_filter_useful);
+  PERF_CONTEXT_BY_LEVEL_OUTPUT_ONE_COUNTER(bloom_filter_full_positive);
+  PERF_CONTEXT_BY_LEVEL_OUTPUT_ONE_COUNTER(bloom_filter_full_true_positive);
+  PERF_CONTEXT_BY_LEVEL_OUTPUT_ONE_COUNTER(block_cache_hit_count);
+  PERF_CONTEXT_BY_LEVEL_OUTPUT_ONE_COUNTER(block_cache_miss_count);
+  return ss.str();
+#endif
+}
+
+void PerfContext::EnablePerLevelPerfContext() {
+  if (level_to_perf_context == nullptr) {
+    level_to_perf_context = new std::map<uint32_t, PerfContextByLevel>();
+  }
+  per_level_perf_context_enabled = true;
+}
+
+void PerfContext::DisablePerLevelPerfContext(){
+  per_level_perf_context_enabled = false;
+}
+
+void PerfContext::ClearPerLevelPerfContext(){
+  if (level_to_perf_context != nullptr) {
+    level_to_perf_context->clear();
+    delete level_to_perf_context;
+    level_to_perf_context = nullptr;
+  }
+  per_level_perf_context_enabled = false;
+}
+
+}
diff --git a/src/rocksdb/monitoring/perf_context_imp.h b/src/rocksdb/monitoring/perf_context_imp.h
new file mode 100644
index 00000000..e0ff8afc
--- /dev/null
+++ b/src/rocksdb/monitoring/perf_context_imp.h
@@ -0,0 +1,93 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+#pragma once
+#include "monitoring/perf_step_timer.h"
+#include "rocksdb/perf_context.h"
+#include "util/stop_watch.h"
+
+namespace rocksdb {
+#if defined(NPERF_CONTEXT) || !defined(ROCKSDB_SUPPORT_THREAD_LOCAL)
+extern PerfContext perf_context;
+#else
+#if defined(OS_SOLARIS)
+extern __thread PerfContext perf_context_;
+#define perf_context (*get_perf_context())
+#else
+extern thread_local PerfContext perf_context;
+#endif
+#endif
+
+#if defined(NPERF_CONTEXT)
+
+#define PERF_TIMER_GUARD(metric)
+#define PERF_CONDITIONAL_TIMER_FOR_MUTEX_GUARD(metric, condition)
+#define PERF_TIMER_MEASURE(metric)
+#define PERF_TIMER_STOP(metric)
+#define PERF_TIMER_START(metric)
+#define PERF_COUNTER_ADD(metric, value)
+
+#else
+
+// Stop the timer and update the metric
+#define PERF_TIMER_STOP(metric) perf_step_timer_##metric.Stop();
+
+#define PERF_TIMER_START(metric) perf_step_timer_##metric.Start();
+
+// Declare and set start time of the timer
+#define PERF_TIMER_GUARD(metric)                                  \
+  PerfStepTimer perf_step_timer_##metric(&(perf_context.metric)); \
+  perf_step_timer_##metric.Start();
+
+// Declare and set start time of the timer
+#define PERF_TIMER_GUARD_WITH_ENV(metric, env)                         \
+  PerfStepTimer perf_step_timer_##metric(&(perf_context.metric), env); \
+  perf_step_timer_##metric.Start();
+
+// Declare and set start time of the timer
+#define PERF_CPU_TIMER_GUARD(metric, env)              \
+  PerfStepTimer perf_step_timer_##metric(              \
+      &(perf_context.metric), env, true,               \
+      PerfLevel::kEnableTimeAndCPUTimeExceptForMutex); \
+  perf_step_timer_##metric.Start();
+
+#define PERF_CONDITIONAL_TIMER_FOR_MUTEX_GUARD(metric, condition, stats,       \
+                                               ticker_type)                    \
+  PerfStepTimer perf_step_timer_##metric(&(perf_context.metric), nullptr,      \
+                                         false, PerfLevel::kEnableTime, stats, \
+                                         ticker_type);                         \
+  if (condition) {                                                             \
+    perf_step_timer_##metric.Start();                                          \
+  }
+
+// Update metric with time elapsed since last START. start time is reset
+// to current timestamp.
+#define PERF_TIMER_MEASURE(metric) perf_step_timer_##metric.Measure();
+
+// Increase metric value
+#define PERF_COUNTER_ADD(metric, value)        \
+  if (perf_level >= PerfLevel::kEnableCount) { \
+    perf_context.metric += value;              \
+  }
+
+// Increase metric value
+#define PERF_COUNTER_BY_LEVEL_ADD(metric, value, level)                      \
+  if (perf_level >= PerfLevel::kEnableCount &&                               \
+      perf_context.per_level_perf_context_enabled &&                         \
+      perf_context.level_to_perf_context) {                                  \
+    if ((*(perf_context.level_to_perf_context)).find(level) !=               \
+        (*(perf_context.level_to_perf_context)).end()) {                     \
+      (*(perf_context.level_to_perf_context))[level].metric += value;        \
+    }                                                                        \
+    else {                                                                   \
+      PerfContextByLevel empty_context;                                      \
+      (*(perf_context.level_to_perf_context))[level] = empty_context;        \
+      (*(perf_context.level_to_perf_context))[level].metric += value;       \
+    }                                                                        \
+  }                                                                          \
+
+#endif
+
+}
diff --git a/src/rocksdb/monitoring/perf_level.cc b/src/rocksdb/monitoring/perf_level.cc
new file mode 100644
index 00000000..79c718cc
--- /dev/null
+++ b/src/rocksdb/monitoring/perf_level.cc
@@ -0,0 +1,28 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+
+#include <assert.h>
+#include "monitoring/perf_level_imp.h"
+
+namespace rocksdb {
+
+#ifdef ROCKSDB_SUPPORT_THREAD_LOCAL
+__thread PerfLevel perf_level = kEnableCount;
+#else
+PerfLevel perf_level = kEnableCount;
+#endif
+
+void SetPerfLevel(PerfLevel level) {
+  assert(level > kUninitialized);
+  assert(level < kOutOfBounds);
+  perf_level = level;
+}
+
+PerfLevel GetPerfLevel() {
+  return perf_level;
+}
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/perf_level_imp.h b/src/rocksdb/monitoring/perf_level_imp.h
new file mode 100644
index 00000000..2a3add19
--- /dev/null
+++ b/src/rocksdb/monitoring/perf_level_imp.h
@@ -0,0 +1,18 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+#pragma once
+#include "rocksdb/perf_level.h"
+#include "port/port.h"
+
+namespace rocksdb {
+
+#ifdef ROCKSDB_SUPPORT_THREAD_LOCAL
+extern __thread PerfLevel perf_level;
+#else
+extern PerfLevel perf_level;
+#endif
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/perf_step_timer.h b/src/rocksdb/monitoring/perf_step_timer.h
new file mode 100644
index 00000000..6501bd54
--- /dev/null
+++ b/src/rocksdb/monitoring/perf_step_timer.h
@@ -0,0 +1,79 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+#pragma once
+#include "monitoring/perf_level_imp.h"
+#include "rocksdb/env.h"
+#include "util/stop_watch.h"
+
+namespace rocksdb {
+
+class PerfStepTimer {
+ public:
+  explicit PerfStepTimer(
+      uint64_t* metric, Env* env = nullptr, bool use_cpu_time = false,
+      PerfLevel enable_level = PerfLevel::kEnableTimeExceptForMutex,
+      Statistics* statistics = nullptr, uint32_t ticker_type = 0)
+      : perf_counter_enabled_(perf_level >= enable_level),
+        use_cpu_time_(use_cpu_time),
+        env_((perf_counter_enabled_ || statistics != nullptr)
+                 ? ((env != nullptr) ? env : Env::Default())
+                 : nullptr),
+        start_(0),
+        metric_(metric),
+        statistics_(statistics),
+        ticker_type_(ticker_type) {}
+
+  ~PerfStepTimer() {
+    Stop();
+  }
+
+  void Start() {
+    if (perf_counter_enabled_ || statistics_ != nullptr) {
+      start_ = time_now();
+    }
+  }
+
+  uint64_t time_now() {
+    if (!use_cpu_time_) {
+      return env_->NowNanos();
+    } else {
+      return env_->NowCPUNanos();
+    }
+  }
+
+  void Measure() {
+    if (start_) {
+      uint64_t now = time_now();
+      *metric_ += now - start_;
+      start_ = now;
+    }
+  }
+
+  void Stop() {
+    if (start_) {
+      uint64_t duration = time_now() - start_;
+      if (perf_counter_enabled_) {
+        *metric_ += duration;
+      }
+
+      if (statistics_ != nullptr) {
+        RecordTick(statistics_, ticker_type_, duration);
+      }
+      start_ = 0;
+    }
+  }
+
+ private:
+  const bool perf_counter_enabled_;
+  const bool use_cpu_time_;
+  Env* const env_;
+  uint64_t start_;
+  uint64_t* metric_;
+  Statistics* statistics_;
+  uint32_t ticker_type_;
+};
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/statistics.cc b/src/rocksdb/monitoring/statistics.cc
new file mode 100644
index 00000000..adb8cbfe
--- /dev/null
+++ b/src/rocksdb/monitoring/statistics.cc
@@ -0,0 +1,407 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+#include "monitoring/statistics.h"
+
+#ifndef __STDC_FORMAT_MACROS
+#define __STDC_FORMAT_MACROS
+#endif
+
+#include <inttypes.h>
+#include "rocksdb/statistics.h"
+#include "port/likely.h"
+#include <algorithm>
+#include <cstdio>
+
+namespace rocksdb {
+
+// The order of items listed in  Tickers should be the same as
+// the order listed in TickersNameMap
+const std::vector<std::pair<Tickers, std::string>> TickersNameMap = {
+    {BLOCK_CACHE_MISS, "rocksdb.block.cache.miss"},
+    {BLOCK_CACHE_HIT, "rocksdb.block.cache.hit"},
+    {BLOCK_CACHE_ADD, "rocksdb.block.cache.add"},
+    {BLOCK_CACHE_ADD_FAILURES, "rocksdb.block.cache.add.failures"},
+    {BLOCK_CACHE_INDEX_MISS, "rocksdb.block.cache.index.miss"},
+    {BLOCK_CACHE_INDEX_HIT, "rocksdb.block.cache.index.hit"},
+    {BLOCK_CACHE_INDEX_ADD, "rocksdb.block.cache.index.add"},
+    {BLOCK_CACHE_INDEX_BYTES_INSERT, "rocksdb.block.cache.index.bytes.insert"},
+    {BLOCK_CACHE_INDEX_BYTES_EVICT, "rocksdb.block.cache.index.bytes.evict"},
+    {BLOCK_CACHE_FILTER_MISS, "rocksdb.block.cache.filter.miss"},
+    {BLOCK_CACHE_FILTER_HIT, "rocksdb.block.cache.filter.hit"},
+    {BLOCK_CACHE_FILTER_ADD, "rocksdb.block.cache.filter.add"},
+    {BLOCK_CACHE_FILTER_BYTES_INSERT,
+     "rocksdb.block.cache.filter.bytes.insert"},
+    {BLOCK_CACHE_FILTER_BYTES_EVICT, "rocksdb.block.cache.filter.bytes.evict"},
+    {BLOCK_CACHE_DATA_MISS, "rocksdb.block.cache.data.miss"},
+    {BLOCK_CACHE_DATA_HIT, "rocksdb.block.cache.data.hit"},
+    {BLOCK_CACHE_DATA_ADD, "rocksdb.block.cache.data.add"},
+    {BLOCK_CACHE_DATA_BYTES_INSERT, "rocksdb.block.cache.data.bytes.insert"},
+    {BLOCK_CACHE_BYTES_READ, "rocksdb.block.cache.bytes.read"},
+    {BLOCK_CACHE_BYTES_WRITE, "rocksdb.block.cache.bytes.write"},
+    {BLOOM_FILTER_USEFUL, "rocksdb.bloom.filter.useful"},
+    {BLOOM_FILTER_FULL_POSITIVE, "rocksdb.bloom.filter.full.positive"},
+    {BLOOM_FILTER_FULL_TRUE_POSITIVE,
+     "rocksdb.bloom.filter.full.true.positive"},
+    {PERSISTENT_CACHE_HIT, "rocksdb.persistent.cache.hit"},
+    {PERSISTENT_CACHE_MISS, "rocksdb.persistent.cache.miss"},
+    {SIM_BLOCK_CACHE_HIT, "rocksdb.sim.block.cache.hit"},
+    {SIM_BLOCK_CACHE_MISS, "rocksdb.sim.block.cache.miss"},
+    {MEMTABLE_HIT, "rocksdb.memtable.hit"},
+    {MEMTABLE_MISS, "rocksdb.memtable.miss"},
+    {GET_HIT_L0, "rocksdb.l0.hit"},
+    {GET_HIT_L1, "rocksdb.l1.hit"},
+    {GET_HIT_L2_AND_UP, "rocksdb.l2andup.hit"},
+    {COMPACTION_KEY_DROP_NEWER_ENTRY, "rocksdb.compaction.key.drop.new"},
+    {COMPACTION_KEY_DROP_OBSOLETE, "rocksdb.compaction.key.drop.obsolete"},
+    {COMPACTION_KEY_DROP_RANGE_DEL, "rocksdb.compaction.key.drop.range_del"},
+    {COMPACTION_KEY_DROP_USER, "rocksdb.compaction.key.drop.user"},
+    {COMPACTION_RANGE_DEL_DROP_OBSOLETE,
+     "rocksdb.compaction.range_del.drop.obsolete"},
+    {COMPACTION_OPTIMIZED_DEL_DROP_OBSOLETE,
+     "rocksdb.compaction.optimized.del.drop.obsolete"},
+    {COMPACTION_CANCELLED, "rocksdb.compaction.cancelled"},
+    {NUMBER_KEYS_WRITTEN, "rocksdb.number.keys.written"},
+    {NUMBER_KEYS_READ, "rocksdb.number.keys.read"},
+    {NUMBER_KEYS_UPDATED, "rocksdb.number.keys.updated"},
+    {BYTES_WRITTEN, "rocksdb.bytes.written"},
+    {BYTES_READ, "rocksdb.bytes.read"},
+    {NUMBER_DB_SEEK, "rocksdb.number.db.seek"},
+    {NUMBER_DB_NEXT, "rocksdb.number.db.next"},
+    {NUMBER_DB_PREV, "rocksdb.number.db.prev"},
+    {NUMBER_DB_SEEK_FOUND, "rocksdb.number.db.seek.found"},
+    {NUMBER_DB_NEXT_FOUND, "rocksdb.number.db.next.found"},
+    {NUMBER_DB_PREV_FOUND, "rocksdb.number.db.prev.found"},
+    {ITER_BYTES_READ, "rocksdb.db.iter.bytes.read"},
+    {NO_FILE_CLOSES, "rocksdb.no.file.closes"},
+    {NO_FILE_OPENS, "rocksdb.no.file.opens"},
+    {NO_FILE_ERRORS, "rocksdb.no.file.errors"},
+    {STALL_L0_SLOWDOWN_MICROS, "rocksdb.l0.slowdown.micros"},
+    {STALL_MEMTABLE_COMPACTION_MICROS, "rocksdb.memtable.compaction.micros"},
+    {STALL_L0_NUM_FILES_MICROS, "rocksdb.l0.num.files.stall.micros"},
+    {STALL_MICROS, "rocksdb.stall.micros"},
+    {DB_MUTEX_WAIT_MICROS, "rocksdb.db.mutex.wait.micros"},
+    {RATE_LIMIT_DELAY_MILLIS, "rocksdb.rate.limit.delay.millis"},
+    {NO_ITERATORS, "rocksdb.num.iterators"},
+    {NUMBER_MULTIGET_CALLS, "rocksdb.number.multiget.get"},
+    {NUMBER_MULTIGET_KEYS_READ, "rocksdb.number.multiget.keys.read"},
+    {NUMBER_MULTIGET_BYTES_READ, "rocksdb.number.multiget.bytes.read"},
+    {NUMBER_FILTERED_DELETES, "rocksdb.number.deletes.filtered"},
+    {NUMBER_MERGE_FAILURES, "rocksdb.number.merge.failures"},
+    {BLOOM_FILTER_PREFIX_CHECKED, "rocksdb.bloom.filter.prefix.checked"},
+    {BLOOM_FILTER_PREFIX_USEFUL, "rocksdb.bloom.filter.prefix.useful"},
+    {NUMBER_OF_RESEEKS_IN_ITERATION, "rocksdb.number.reseeks.iteration"},
+    {GET_UPDATES_SINCE_CALLS, "rocksdb.getupdatessince.calls"},
+    {BLOCK_CACHE_COMPRESSED_MISS, "rocksdb.block.cachecompressed.miss"},
+    {BLOCK_CACHE_COMPRESSED_HIT, "rocksdb.block.cachecompressed.hit"},
+    {BLOCK_CACHE_COMPRESSED_ADD, "rocksdb.block.cachecompressed.add"},
+    {BLOCK_CACHE_COMPRESSED_ADD_FAILURES,
+     "rocksdb.block.cachecompressed.add.failures"},
+    {WAL_FILE_SYNCED, "rocksdb.wal.synced"},
+    {WAL_FILE_BYTES, "rocksdb.wal.bytes"},
+    {WRITE_DONE_BY_SELF, "rocksdb.write.self"},
+    {WRITE_DONE_BY_OTHER, "rocksdb.write.other"},
+    {WRITE_TIMEDOUT, "rocksdb.write.timeout"},
+    {WRITE_WITH_WAL, "rocksdb.write.wal"},
+    {COMPACT_READ_BYTES, "rocksdb.compact.read.bytes"},
+    {COMPACT_WRITE_BYTES, "rocksdb.compact.write.bytes"},
+    {FLUSH_WRITE_BYTES, "rocksdb.flush.write.bytes"},
+    {NUMBER_DIRECT_LOAD_TABLE_PROPERTIES,
+     "rocksdb.number.direct.load.table.properties"},
+    {NUMBER_SUPERVERSION_ACQUIRES, "rocksdb.number.superversion_acquires"},
+    {NUMBER_SUPERVERSION_RELEASES, "rocksdb.number.superversion_releases"},
+    {NUMBER_SUPERVERSION_CLEANUPS, "rocksdb.number.superversion_cleanups"},
+    {NUMBER_BLOCK_COMPRESSED, "rocksdb.number.block.compressed"},
+    {NUMBER_BLOCK_DECOMPRESSED, "rocksdb.number.block.decompressed"},
+    {NUMBER_BLOCK_NOT_COMPRESSED, "rocksdb.number.block.not_compressed"},
+    {MERGE_OPERATION_TOTAL_TIME, "rocksdb.merge.operation.time.nanos"},
+    {FILTER_OPERATION_TOTAL_TIME, "rocksdb.filter.operation.time.nanos"},
+    {ROW_CACHE_HIT, "rocksdb.row.cache.hit"},
+    {ROW_CACHE_MISS, "rocksdb.row.cache.miss"},
+    {READ_AMP_ESTIMATE_USEFUL_BYTES, "rocksdb.read.amp.estimate.useful.bytes"},
+    {READ_AMP_TOTAL_READ_BYTES, "rocksdb.read.amp.total.read.bytes"},
+    {NUMBER_RATE_LIMITER_DRAINS, "rocksdb.number.rate_limiter.drains"},
+    {NUMBER_ITER_SKIP, "rocksdb.number.iter.skip"},
+    {BLOB_DB_NUM_PUT, "rocksdb.blobdb.num.put"},
+    {BLOB_DB_NUM_WRITE, "rocksdb.blobdb.num.write"},
+    {BLOB_DB_NUM_GET, "rocksdb.blobdb.num.get"},
+    {BLOB_DB_NUM_MULTIGET, "rocksdb.blobdb.num.multiget"},
+    {BLOB_DB_NUM_SEEK, "rocksdb.blobdb.num.seek"},
+    {BLOB_DB_NUM_NEXT, "rocksdb.blobdb.num.next"},
+    {BLOB_DB_NUM_PREV, "rocksdb.blobdb.num.prev"},
+    {BLOB_DB_NUM_KEYS_WRITTEN, "rocksdb.blobdb.num.keys.written"},
+    {BLOB_DB_NUM_KEYS_READ, "rocksdb.blobdb.num.keys.read"},
+    {BLOB_DB_BYTES_WRITTEN, "rocksdb.blobdb.bytes.written"},
+    {BLOB_DB_BYTES_READ, "rocksdb.blobdb.bytes.read"},
+    {BLOB_DB_WRITE_INLINED, "rocksdb.blobdb.write.inlined"},
+    {BLOB_DB_WRITE_INLINED_TTL, "rocksdb.blobdb.write.inlined.ttl"},
+    {BLOB_DB_WRITE_BLOB, "rocksdb.blobdb.write.blob"},
+    {BLOB_DB_WRITE_BLOB_TTL, "rocksdb.blobdb.write.blob.ttl"},
+    {BLOB_DB_BLOB_FILE_BYTES_WRITTEN, "rocksdb.blobdb.blob.file.bytes.written"},
+    {BLOB_DB_BLOB_FILE_BYTES_READ, "rocksdb.blobdb.blob.file.bytes.read"},
+    {BLOB_DB_BLOB_FILE_SYNCED, "rocksdb.blobdb.blob.file.synced"},
+    {BLOB_DB_BLOB_INDEX_EXPIRED_COUNT,
+     "rocksdb.blobdb.blob.index.expired.count"},
+    {BLOB_DB_BLOB_INDEX_EXPIRED_SIZE, "rocksdb.blobdb.blob.index.expired.size"},
+    {BLOB_DB_BLOB_INDEX_EVICTED_COUNT,
+     "rocksdb.blobdb.blob.index.evicted.count"},
+    {BLOB_DB_BLOB_INDEX_EVICTED_SIZE, "rocksdb.blobdb.blob.index.evicted.size"},
+    {BLOB_DB_GC_NUM_FILES, "rocksdb.blobdb.gc.num.files"},
+    {BLOB_DB_GC_NUM_NEW_FILES, "rocksdb.blobdb.gc.num.new.files"},
+    {BLOB_DB_GC_FAILURES, "rocksdb.blobdb.gc.failures"},
+    {BLOB_DB_GC_NUM_KEYS_OVERWRITTEN, "rocksdb.blobdb.gc.num.keys.overwritten"},
+    {BLOB_DB_GC_NUM_KEYS_EXPIRED, "rocksdb.blobdb.gc.num.keys.expired"},
+    {BLOB_DB_GC_NUM_KEYS_RELOCATED, "rocksdb.blobdb.gc.num.keys.relocated"},
+    {BLOB_DB_GC_BYTES_OVERWRITTEN, "rocksdb.blobdb.gc.bytes.overwritten"},
+    {BLOB_DB_GC_BYTES_EXPIRED, "rocksdb.blobdb.gc.bytes.expired"},
+    {BLOB_DB_GC_BYTES_RELOCATED, "rocksdb.blobdb.gc.bytes.relocated"},
+    {BLOB_DB_FIFO_NUM_FILES_EVICTED, "rocksdb.blobdb.fifo.num.files.evicted"},
+    {BLOB_DB_FIFO_NUM_KEYS_EVICTED, "rocksdb.blobdb.fifo.num.keys.evicted"},
+    {BLOB_DB_FIFO_BYTES_EVICTED, "rocksdb.blobdb.fifo.bytes.evicted"},
+    {TXN_PREPARE_MUTEX_OVERHEAD, "rocksdb.txn.overhead.mutex.prepare"},
+    {TXN_OLD_COMMIT_MAP_MUTEX_OVERHEAD,
+     "rocksdb.txn.overhead.mutex.old.commit.map"},
+    {TXN_DUPLICATE_KEY_OVERHEAD, "rocksdb.txn.overhead.duplicate.key"},
+    {TXN_SNAPSHOT_MUTEX_OVERHEAD, "rocksdb.txn.overhead.mutex.snapshot"},
+    {NUMBER_MULTIGET_KEYS_FOUND, "rocksdb.number.multiget.keys.found"},
+    {NO_ITERATOR_CREATED, "rocksdb.num.iterator.created"},
+    {NO_ITERATOR_DELETED, "rocksdb.num.iterator.deleted"},
+    {BLOCK_CACHE_COMPRESSION_DICT_MISS,
+     "rocksdb.block.cache.compression.dict.miss"},
+    {BLOCK_CACHE_COMPRESSION_DICT_HIT,
+     "rocksdb.block.cache.compression.dict.hit"},
+    {BLOCK_CACHE_COMPRESSION_DICT_ADD,
+     "rocksdb.block.cache.compression.dict.add"},
+    {BLOCK_CACHE_COMPRESSION_DICT_BYTES_INSERT,
+     "rocksdb.block.cache.compression.dict.bytes.insert"},
+    {BLOCK_CACHE_COMPRESSION_DICT_BYTES_EVICT,
+     "rocksdb.block.cache.compression.dict.bytes.evict"},
+};
+
+const std::vector<std::pair<Histograms, std::string>> HistogramsNameMap = {
+    {DB_GET, "rocksdb.db.get.micros"},
+    {DB_WRITE, "rocksdb.db.write.micros"},
+    {COMPACTION_TIME, "rocksdb.compaction.times.micros"},
+    {COMPACTION_CPU_TIME, "rocksdb.compaction.times.cpu_micros"},
+    {SUBCOMPACTION_SETUP_TIME, "rocksdb.subcompaction.setup.times.micros"},
+    {TABLE_SYNC_MICROS, "rocksdb.table.sync.micros"},
+    {COMPACTION_OUTFILE_SYNC_MICROS, "rocksdb.compaction.outfile.sync.micros"},
+    {WAL_FILE_SYNC_MICROS, "rocksdb.wal.file.sync.micros"},
+    {MANIFEST_FILE_SYNC_MICROS, "rocksdb.manifest.file.sync.micros"},
+    {TABLE_OPEN_IO_MICROS, "rocksdb.table.open.io.micros"},
+    {DB_MULTIGET, "rocksdb.db.multiget.micros"},
+    {READ_BLOCK_COMPACTION_MICROS, "rocksdb.read.block.compaction.micros"},
+    {READ_BLOCK_GET_MICROS, "rocksdb.read.block.get.micros"},
+    {WRITE_RAW_BLOCK_MICROS, "rocksdb.write.raw.block.micros"},
+    {STALL_L0_SLOWDOWN_COUNT, "rocksdb.l0.slowdown.count"},
+    {STALL_MEMTABLE_COMPACTION_COUNT, "rocksdb.memtable.compaction.count"},
+    {STALL_L0_NUM_FILES_COUNT, "rocksdb.num.files.stall.count"},
+    {HARD_RATE_LIMIT_DELAY_COUNT, "rocksdb.hard.rate.limit.delay.count"},
+    {SOFT_RATE_LIMIT_DELAY_COUNT, "rocksdb.soft.rate.limit.delay.count"},
+    {NUM_FILES_IN_SINGLE_COMPACTION, "rocksdb.numfiles.in.singlecompaction"},
+    {DB_SEEK, "rocksdb.db.seek.micros"},
+    {WRITE_STALL, "rocksdb.db.write.stall"},
+    {SST_READ_MICROS, "rocksdb.sst.read.micros"},
+    {NUM_SUBCOMPACTIONS_SCHEDULED, "rocksdb.num.subcompactions.scheduled"},
+    {BYTES_PER_READ, "rocksdb.bytes.per.read"},
+    {BYTES_PER_WRITE, "rocksdb.bytes.per.write"},
+    {BYTES_PER_MULTIGET, "rocksdb.bytes.per.multiget"},
+    {BYTES_COMPRESSED, "rocksdb.bytes.compressed"},
+    {BYTES_DECOMPRESSED, "rocksdb.bytes.decompressed"},
+    {COMPRESSION_TIMES_NANOS, "rocksdb.compression.times.nanos"},
+    {DECOMPRESSION_TIMES_NANOS, "rocksdb.decompression.times.nanos"},
+    {READ_NUM_MERGE_OPERANDS, "rocksdb.read.num.merge_operands"},
+    {BLOB_DB_KEY_SIZE, "rocksdb.blobdb.key.size"},
+    {BLOB_DB_VALUE_SIZE, "rocksdb.blobdb.value.size"},
+    {BLOB_DB_WRITE_MICROS, "rocksdb.blobdb.write.micros"},
+    {BLOB_DB_GET_MICROS, "rocksdb.blobdb.get.micros"},
+    {BLOB_DB_MULTIGET_MICROS, "rocksdb.blobdb.multiget.micros"},
+    {BLOB_DB_SEEK_MICROS, "rocksdb.blobdb.seek.micros"},
+    {BLOB_DB_NEXT_MICROS, "rocksdb.blobdb.next.micros"},
+    {BLOB_DB_PREV_MICROS, "rocksdb.blobdb.prev.micros"},
+    {BLOB_DB_BLOB_FILE_WRITE_MICROS, "rocksdb.blobdb.blob.file.write.micros"},
+    {BLOB_DB_BLOB_FILE_READ_MICROS, "rocksdb.blobdb.blob.file.read.micros"},
+    {BLOB_DB_BLOB_FILE_SYNC_MICROS, "rocksdb.blobdb.blob.file.sync.micros"},
+    {BLOB_DB_GC_MICROS, "rocksdb.blobdb.gc.micros"},
+    {BLOB_DB_COMPRESSION_MICROS, "rocksdb.blobdb.compression.micros"},
+    {BLOB_DB_DECOMPRESSION_MICROS, "rocksdb.blobdb.decompression.micros"},
+    {FLUSH_TIME, "rocksdb.db.flush.micros"},
+};
+
+std::shared_ptr<Statistics> CreateDBStatistics() {
+  return std::make_shared<StatisticsImpl>(nullptr);
+}
+
+StatisticsImpl::StatisticsImpl(std::shared_ptr<Statistics> stats)
+    : stats_(std::move(stats)) {}
+
+StatisticsImpl::~StatisticsImpl() {}
+
+uint64_t StatisticsImpl::getTickerCount(uint32_t tickerType) const {
+  MutexLock lock(&aggregate_lock_);
+  return getTickerCountLocked(tickerType);
+}
+
+uint64_t StatisticsImpl::getTickerCountLocked(uint32_t tickerType) const {
+  assert(tickerType < TICKER_ENUM_MAX);
+  uint64_t res = 0;
+  for (size_t core_idx = 0; core_idx < per_core_stats_.Size(); ++core_idx) {
+    res += per_core_stats_.AccessAtCore(core_idx)->tickers_[tickerType];
+  }
+  return res;
+}
+
+void StatisticsImpl::histogramData(uint32_t histogramType,
+                                   HistogramData* const data) const {
+  MutexLock lock(&aggregate_lock_);
+  getHistogramImplLocked(histogramType)->Data(data);
+}
+
+std::unique_ptr<HistogramImpl> StatisticsImpl::getHistogramImplLocked(
+    uint32_t histogramType) const {
+  assert(histogramType < HISTOGRAM_ENUM_MAX);
+  std::unique_ptr<HistogramImpl> res_hist(new HistogramImpl());
+  for (size_t core_idx = 0; core_idx < per_core_stats_.Size(); ++core_idx) {
+    res_hist->Merge(
+        per_core_stats_.AccessAtCore(core_idx)->histograms_[histogramType]);
+  }
+  return res_hist;
+}
+
+std::string StatisticsImpl::getHistogramString(uint32_t histogramType) const {
+  MutexLock lock(&aggregate_lock_);
+  return getHistogramImplLocked(histogramType)->ToString();
+}
+
+void StatisticsImpl::setTickerCount(uint32_t tickerType, uint64_t count) {
+  {
+    MutexLock lock(&aggregate_lock_);
+    setTickerCountLocked(tickerType, count);
+  }
+  if (stats_ && tickerType < TICKER_ENUM_MAX) {
+    stats_->setTickerCount(tickerType, count);
+  }
+}
+
+void StatisticsImpl::setTickerCountLocked(uint32_t tickerType, uint64_t count) {
+  assert(tickerType < TICKER_ENUM_MAX);
+  for (size_t core_idx = 0; core_idx < per_core_stats_.Size(); ++core_idx) {
+    if (core_idx == 0) {
+      per_core_stats_.AccessAtCore(core_idx)->tickers_[tickerType] = count;
+    } else {
+      per_core_stats_.AccessAtCore(core_idx)->tickers_[tickerType] = 0;
+    }
+  }
+}
+
+uint64_t StatisticsImpl::getAndResetTickerCount(uint32_t tickerType) {
+  uint64_t sum = 0;
+  {
+    MutexLock lock(&aggregate_lock_);
+    assert(tickerType < TICKER_ENUM_MAX);
+    for (size_t core_idx = 0; core_idx < per_core_stats_.Size(); ++core_idx) {
+      sum +=
+          per_core_stats_.AccessAtCore(core_idx)->tickers_[tickerType].exchange(
+              0, std::memory_order_relaxed);
+    }
+  }
+  if (stats_ && tickerType < TICKER_ENUM_MAX) {
+    stats_->setTickerCount(tickerType, 0);
+  }
+  return sum;
+}
+
+void StatisticsImpl::recordTick(uint32_t tickerType, uint64_t count) {
+  assert(tickerType < TICKER_ENUM_MAX);
+  per_core_stats_.Access()->tickers_[tickerType].fetch_add(
+      count, std::memory_order_relaxed);
+  if (stats_ && tickerType < TICKER_ENUM_MAX) {
+    stats_->recordTick(tickerType, count);
+  }
+}
+
+void StatisticsImpl::recordInHistogram(uint32_t histogramType, uint64_t value) {
+  assert(histogramType < HISTOGRAM_ENUM_MAX);
+  if (get_stats_level() <= StatsLevel::kExceptHistogramOrTimers) {
+    return;
+  }
+  per_core_stats_.Access()->histograms_[histogramType].Add(value);
+  if (stats_ && histogramType < HISTOGRAM_ENUM_MAX) {
+    stats_->recordInHistogram(histogramType, value);
+  }
+}
+
+Status StatisticsImpl::Reset() {
+  MutexLock lock(&aggregate_lock_);
+  for (uint32_t i = 0; i < TICKER_ENUM_MAX; ++i) {
+    setTickerCountLocked(i, 0);
+  }
+  for (uint32_t i = 0; i < HISTOGRAM_ENUM_MAX; ++i) {
+    for (size_t core_idx = 0; core_idx < per_core_stats_.Size(); ++core_idx) {
+      per_core_stats_.AccessAtCore(core_idx)->histograms_[i].Clear();
+    }
+  }
+  return Status::OK();
+}
+
+namespace {
+
+// a buffer size used for temp string buffers
+const int kTmpStrBufferSize = 200;
+
+} // namespace
+
+std::string StatisticsImpl::ToString() const {
+  MutexLock lock(&aggregate_lock_);
+  std::string res;
+  res.reserve(20000);
+  for (const auto& t : TickersNameMap) {
+    assert(t.first < TICKER_ENUM_MAX);
+    char buffer[kTmpStrBufferSize];
+    snprintf(buffer, kTmpStrBufferSize, "%s COUNT : %" PRIu64 "\n",
+             t.second.c_str(), getTickerCountLocked(t.first));
+    res.append(buffer);
+  }
+  for (const auto& h : HistogramsNameMap) {
+    assert(h.first < HISTOGRAM_ENUM_MAX);
+    char buffer[kTmpStrBufferSize];
+    HistogramData hData;
+    getHistogramImplLocked(h.first)->Data(&hData);
+    // don't handle failures - buffer should always be big enough and arguments
+    // should be provided correctly
+    int ret =
+        snprintf(buffer, kTmpStrBufferSize,
+                 "%s P50 : %f P95 : %f P99 : %f P100 : %f COUNT : %" PRIu64
+                 " SUM : %" PRIu64 "\n",
+                 h.second.c_str(), hData.median, hData.percentile95,
+                 hData.percentile99, hData.max, hData.count, hData.sum);
+    if (ret < 0 || ret >= kTmpStrBufferSize) {
+      assert(false);
+      continue;
+    }
+    res.append(buffer);
+  }
+  res.shrink_to_fit();
+  return res;
+}
+
+bool StatisticsImpl::getTickerMap(
+    std::map<std::string, uint64_t>* stats_map) const {
+  assert(stats_map);
+  if (!stats_map) return false;
+  stats_map->clear();
+  MutexLock lock(&aggregate_lock_);
+  for (const auto& t : TickersNameMap) {
+    assert(t.first < TICKER_ENUM_MAX);
+    (*stats_map)[t.second.c_str()] = getTickerCountLocked(t.first);
+  }
+  return true;
+}
+
+bool StatisticsImpl::HistEnabledForType(uint32_t type) const {
+  return type < HISTOGRAM_ENUM_MAX;
+}
+
+} // namespace rocksdb
diff --git a/src/rocksdb/monitoring/statistics.h b/src/rocksdb/monitoring/statistics.h
new file mode 100644
index 00000000..952bf8cb
--- /dev/null
+++ b/src/rocksdb/monitoring/statistics.h
@@ -0,0 +1,138 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+#pragma once
+#include "rocksdb/statistics.h"
+
+#include <atomic>
+#include <map>
+#include <string>
+#include <vector>
+
+#include "monitoring/histogram.h"
+#include "port/likely.h"
+#include "port/port.h"
+#include "util/core_local.h"
+#include "util/mutexlock.h"
+
+#ifdef __clang__
+#define ROCKSDB_FIELD_UNUSED __attribute__((__unused__))
+#else
+#define ROCKSDB_FIELD_UNUSED
+#endif  // __clang__
+
+#ifndef STRINGIFY
+#define STRINGIFY(x) #x
+#define TOSTRING(x) STRINGIFY(x)
+#endif
+
+namespace rocksdb {
+
+enum TickersInternal : uint32_t {
+  INTERNAL_TICKER_ENUM_START = TICKER_ENUM_MAX,
+  INTERNAL_TICKER_ENUM_MAX
+};
+
+enum HistogramsInternal : uint32_t {
+  INTERNAL_HISTOGRAM_START = HISTOGRAM_ENUM_MAX,
+  INTERNAL_HISTOGRAM_ENUM_MAX
+};
+
+class StatisticsImpl : public Statistics {
+ public:
+  StatisticsImpl(std::shared_ptr<Statistics> stats);
+  virtual ~StatisticsImpl();
+
+  virtual uint64_t getTickerCount(uint32_t ticker_type) const override;
+  virtual void histogramData(uint32_t histogram_type,
+                             HistogramData* const data) const override;
+  std::string getHistogramString(uint32_t histogram_type) const override;
+
+  virtual void setTickerCount(uint32_t ticker_type, uint64_t count) override;
+  virtual uint64_t getAndResetTickerCount(uint32_t ticker_type) override;
+  virtual void recordTick(uint32_t ticker_type, uint64_t count) override;
+  // The function is implemented for now for backward compatibility reason.
+  // In case a user explictly calls it, for example, they may have a wrapped
+  // Statistics object, passing the call to recordTick() into here, nothing
+  // will break.
+  void measureTime(uint32_t histogramType, uint64_t time) override {
+    recordInHistogram(histogramType, time);
+  }
+  virtual void recordInHistogram(uint32_t histogram_type,
+                                 uint64_t value) override;
+
+  virtual Status Reset() override;
+  virtual std::string ToString() const override;
+  virtual bool getTickerMap(std::map<std::string, uint64_t>*) const override;
+  virtual bool HistEnabledForType(uint32_t type) const override;
+
+ private:
+  // If non-nullptr, forwards updates to the object pointed to by `stats_`.
+  std::shared_ptr<Statistics> stats_;
+  // Synchronizes anything that operates across other cores' local data,
+  // such that operations like Reset() can be performed atomically.
+  mutable port::Mutex aggregate_lock_;
+
+  // The ticker/histogram data are stored in this structure, which we will store
+  // per-core. It is cache-aligned, so tickers/histograms belonging to different
+  // cores can never share the same cache line.
+  //
+  // Alignment attributes expand to nothing depending on the platform
+  struct ALIGN_AS(CACHE_LINE_SIZE) StatisticsData {
+    std::atomic_uint_fast64_t tickers_[INTERNAL_TICKER_ENUM_MAX] = {{0}};
+    HistogramImpl histograms_[INTERNAL_HISTOGRAM_ENUM_MAX];
+#ifndef HAVE_ALIGNED_NEW
+    char
+        padding[(CACHE_LINE_SIZE -
+                 (INTERNAL_TICKER_ENUM_MAX * sizeof(std::atomic_uint_fast64_t) +
+                  INTERNAL_HISTOGRAM_ENUM_MAX * sizeof(HistogramImpl)) %
+                     CACHE_LINE_SIZE)] ROCKSDB_FIELD_UNUSED;
+#endif
+    void *operator new(size_t s) { return port::cacheline_aligned_alloc(s); }
+    void *operator new[](size_t s) { return port::cacheline_aligned_alloc(s); }
+    void operator delete(void *p) { port::cacheline_aligned_free(p); }
+    void operator delete[](void *p) { port::cacheline_aligned_free(p); }
+  };
+
+  static_assert(sizeof(StatisticsData) % CACHE_LINE_SIZE == 0, "Expected " TOSTRING(CACHE_LINE_SIZE) "-byte aligned");
+
+  CoreLocalArray<StatisticsData> per_core_stats_;
+
+  uint64_t getTickerCountLocked(uint32_t ticker_type) const;
+  std::unique_ptr<HistogramImpl> getHistogramImplLocked(
+      uint32_t histogram_type) const;
+  void setTickerCountLocked(uint32_t ticker_type, uint64_t count);
+};
+
+// Utility functions
+inline void RecordInHistogram(Statistics* statistics, uint32_t histogram_type,
+                              uint64_t value) {
+  if (statistics) {
+    statistics->recordInHistogram(histogram_type, value);
+  }
+}
+
+inline void RecordTimeToHistogram(Statistics* statistics,
+                                  uint32_t histogram_type, uint64_t value) {
+  if (statistics) {
+    statistics->reportTimeToHistogram(histogram_type, value);
+  }
+}
+
+inline void RecordTick(Statistics* statistics, uint32_t ticker_type,
+                       uint64_t count = 1) {
+  if (statistics) {
+    statistics->recordTick(ticker_type, count);
+  }
+}
+
+inline void SetTickerCount(Statistics* statistics, uint32_t ticker_type,
+                           uint64_t count) {
+  if (statistics) {
+    statistics->setTickerCount(ticker_type, count);
+  }
+}
+
+}
diff --git a/src/rocksdb/monitoring/statistics_test.cc b/src/rocksdb/monitoring/statistics_test.cc
new file mode 100644
index 00000000..a77022bf
--- /dev/null
+++ b/src/rocksdb/monitoring/statistics_test.cc
@@ -0,0 +1,47 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+
+#include "port/stack_trace.h"
+#include "util/testharness.h"
+#include "util/testutil.h"
+
+#include "rocksdb/statistics.h"
+
+namespace rocksdb {
+
+class StatisticsTest : public testing::Test {};
+
+// Sanity check to make sure that contents and order of TickersNameMap
+// match Tickers enum
+TEST_F(StatisticsTest, SanityTickers) {
+  EXPECT_EQ(static_cast<size_t>(Tickers::TICKER_ENUM_MAX),
+            TickersNameMap.size());
+
+  for (uint32_t t = 0; t < Tickers::TICKER_ENUM_MAX; t++) {
+    auto pair = TickersNameMap[static_cast<size_t>(t)];
+    ASSERT_EQ(pair.first, t) << "Miss match at " << pair.second;
+  }
+}
+
+// Sanity check to make sure that contents and order of HistogramsNameMap
+// match Tickers enum
+TEST_F(StatisticsTest, SanityHistograms) {
+  EXPECT_EQ(static_cast<size_t>(Histograms::HISTOGRAM_ENUM_MAX),
+            HistogramsNameMap.size());
+
+  for (uint32_t h = 0; h < Histograms::HISTOGRAM_ENUM_MAX; h++) {
+    auto pair = HistogramsNameMap[static_cast<size_t>(h)];
+    ASSERT_EQ(pair.first, h) << "Miss match at " << pair.second;
+  }
+}
+
+}  // namespace rocksdb
+
+int main(int argc, char** argv) {
+  rocksdb::port::InstallStackTraceHandler();
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}
diff --git a/src/rocksdb/monitoring/thread_status_impl.cc b/src/rocksdb/monitoring/thread_status_impl.cc
new file mode 100644
index 00000000..f4531ce7
--- /dev/null
+++ b/src/rocksdb/monitoring/thread_status_impl.cc
@@ -0,0 +1,163 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+
+#include <sstream>
+
+#include "rocksdb/env.h"
+#include "rocksdb/thread_status.h"
+#include "util/string_util.h"
+#include "util/thread_operation.h"
+
+namespace rocksdb {
+
+#ifdef ROCKSDB_USING_THREAD_STATUS
+std::string ThreadStatus::GetThreadTypeName(
+    ThreadStatus::ThreadType thread_type) {
+  switch (thread_type) {
+    case ThreadStatus::ThreadType::HIGH_PRIORITY:
+      return "High Pri";
+    case ThreadStatus::ThreadType::LOW_PRIORITY:
+      return "Low Pri";
+    case ThreadStatus::ThreadType::USER:
+      return "User";
+    case ThreadStatus::ThreadType::BOTTOM_PRIORITY:
+      return "Bottom Pri";
+    case ThreadStatus::ThreadType::NUM_THREAD_TYPES:
+      assert(false);
+  }
+  return "Unknown";
+}
+
+const std::string& ThreadStatus::GetOperationName(
+    ThreadStatus::OperationType op_type) {
+  if (op_type < 0 || op_type >= NUM_OP_TYPES) {
+    return global_operation_table[OP_UNKNOWN].name;
+  }
+  return global_operation_table[op_type].name;
+}
+
+const std::string& ThreadStatus::GetOperationStageName(
+    ThreadStatus::OperationStage stage) {
+  if (stage < 0 || stage >= NUM_OP_STAGES) {
+    return global_op_stage_table[STAGE_UNKNOWN].name;
+  }
+  return global_op_stage_table[stage].name;
+}
+
+const std::string& ThreadStatus::GetStateName(
+    ThreadStatus::StateType state_type) {
+  if (state_type < 0 || state_type >= NUM_STATE_TYPES) {
+    return global_state_table[STATE_UNKNOWN].name;
+  }
+  return global_state_table[state_type].name;
+}
+
+const std::string ThreadStatus::MicrosToString(uint64_t micros) {
+  if (micros == 0) {
+    return "";
+  }
+  const int kBufferLen = 100;
+  char buffer[kBufferLen];
+  AppendHumanMicros(micros, buffer, kBufferLen, false);
+  return std::string(buffer);
+}
+
+const std::string& ThreadStatus::GetOperationPropertyName(
+    ThreadStatus::OperationType op_type, int i) {
+  static const std::string empty_str = "";
+  switch (op_type) {
+    case ThreadStatus::OP_COMPACTION:
+      if (i >= NUM_COMPACTION_PROPERTIES) {
+        return empty_str;
+      }
+      return compaction_operation_properties[i].name;
+    case ThreadStatus::OP_FLUSH:
+      if (i >= NUM_FLUSH_PROPERTIES) {
+        return empty_str;
+      }
+      return flush_operation_properties[i].name;
+    default:
+      return empty_str;
+  }
+}
+
+std::map<std::string, uint64_t> ThreadStatus::InterpretOperationProperties(
+    ThreadStatus::OperationType op_type, const uint64_t* op_properties) {
+  int num_properties;
+  switch (op_type) {
+    case OP_COMPACTION:
+      num_properties = NUM_COMPACTION_PROPERTIES;
+      break;
+    case OP_FLUSH:
+      num_properties = NUM_FLUSH_PROPERTIES;
+      break;
+    default:
+      num_properties = 0;
+  }
+
+  std::map<std::string, uint64_t> property_map;
+  for (int i = 0; i < num_properties; ++i) {
+    if (op_type == OP_COMPACTION && i == COMPACTION_INPUT_OUTPUT_LEVEL) {
+      property_map.insert({"BaseInputLevel", op_properties[i] >> 32});
+      property_map.insert(
+          {"OutputLevel", op_properties[i] % (uint64_t(1) << 32U)});
+    } else if (op_type == OP_COMPACTION && i == COMPACTION_PROP_FLAGS) {
+      property_map.insert({"IsManual", ((op_properties[i] & 2) >> 1)});
+      property_map.insert({"IsDeletion", ((op_properties[i] & 4) >> 2)});
+      property_map.insert({"IsTrivialMove", ((op_properties[i] & 8) >> 3)});
+    } else {
+      property_map.insert(
+          {GetOperationPropertyName(op_type, i), op_properties[i]});
+    }
+  }
+  return property_map;
+}
+
+#else
+
+std::string ThreadStatus::GetThreadTypeName(
+    ThreadStatus::ThreadType /*thread_type*/) {
+  static std::string dummy_str = "";
+  return dummy_str;
+}
+
+const std::string& ThreadStatus::GetOperationName(
+    ThreadStatus::OperationType /*op_type*/) {
+  static std::string dummy_str = "";
+  return dummy_str;
+}
+
+const std::string& ThreadStatus::GetOperationStageName(
+    ThreadStatus::OperationStage /*stage*/) {
+  static std::string dummy_str = "";
+  return dummy_str;
+}
+
+const std::string& ThreadStatus::GetStateName(
+    ThreadStatus::StateType /*state_type*/) {
+  static std::string dummy_str = "";
+  return dummy_str;
+}
+
+const std::string ThreadStatus::MicrosToString(uint64_t /*op_elapsed_time*/) {
+  static std::string dummy_str = "";
+  return dummy_str;
+}
+
+const std::string& ThreadStatus::GetOperationPropertyName(
+    ThreadStatus::OperationType /*op_type*/, int /*i*/) {
+  static std::string dummy_str = "";
+  return dummy_str;
+}
+
+std::map<std::string, uint64_t> ThreadStatus::InterpretOperationProperties(
+    ThreadStatus::OperationType /*op_type*/,
+    const uint64_t* /*op_properties*/) {
+  return std::map<std::string, uint64_t>();
+}
+
+#endif  // ROCKSDB_USING_THREAD_STATUS
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/thread_status_updater.cc b/src/rocksdb/monitoring/thread_status_updater.cc
new file mode 100644
index 00000000..cde44928
--- /dev/null
+++ b/src/rocksdb/monitoring/thread_status_updater.cc
@@ -0,0 +1,314 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include "monitoring/thread_status_updater.h"
+#include <memory>
+#include "port/likely.h"
+#include "rocksdb/env.h"
+#include "util/mutexlock.h"
+
+namespace rocksdb {
+
+#ifdef ROCKSDB_USING_THREAD_STATUS
+
+__thread ThreadStatusData* ThreadStatusUpdater::thread_status_data_ = nullptr;
+
+void ThreadStatusUpdater::RegisterThread(ThreadStatus::ThreadType ttype,
+                                         uint64_t thread_id) {
+  if (UNLIKELY(thread_status_data_ == nullptr)) {
+    thread_status_data_ = new ThreadStatusData();
+    thread_status_data_->thread_type = ttype;
+    thread_status_data_->thread_id = thread_id;
+    std::lock_guard<std::mutex> lck(thread_list_mutex_);
+    thread_data_set_.insert(thread_status_data_);
+  }
+
+  ClearThreadOperationProperties();
+}
+
+void ThreadStatusUpdater::UnregisterThread() {
+  if (thread_status_data_ != nullptr) {
+    std::lock_guard<std::mutex> lck(thread_list_mutex_);
+    thread_data_set_.erase(thread_status_data_);
+    delete thread_status_data_;
+    thread_status_data_ = nullptr;
+  }
+}
+
+void ThreadStatusUpdater::ResetThreadStatus() {
+  ClearThreadState();
+  ClearThreadOperation();
+  SetColumnFamilyInfoKey(nullptr);
+}
+
+void ThreadStatusUpdater::SetColumnFamilyInfoKey(const void* cf_key) {
+  auto* data = Get();
+  if (data == nullptr) {
+    return;
+  }
+  // set the tracking flag based on whether cf_key is non-null or not.
+  // If enable_thread_tracking is set to false, the input cf_key
+  // would be nullptr.
+  data->enable_tracking = (cf_key != nullptr);
+  data->cf_key.store(const_cast<void*>(cf_key), std::memory_order_relaxed);
+}
+
+const void* ThreadStatusUpdater::GetColumnFamilyInfoKey() {
+  auto* data = GetLocalThreadStatus();
+  if (data == nullptr) {
+    return nullptr;
+  }
+  return data->cf_key.load(std::memory_order_relaxed);
+}
+
+void ThreadStatusUpdater::SetThreadOperation(
+    const ThreadStatus::OperationType type) {
+  auto* data = GetLocalThreadStatus();
+  if (data == nullptr) {
+    return;
+  }
+  // NOTE: Our practice here is to set all the thread operation properties
+  //       and stage before we set thread operation, and thread operation
+  //       will be set in std::memory_order_release.  This is to ensure
+  //       whenever a thread operation is not OP_UNKNOWN, we will always
+  //       have a consistent information on its properties.
+  data->operation_type.store(type, std::memory_order_release);
+  if (type == ThreadStatus::OP_UNKNOWN) {
+    data->operation_stage.store(ThreadStatus::STAGE_UNKNOWN,
+                                std::memory_order_relaxed);
+    ClearThreadOperationProperties();
+  }
+}
+
+void ThreadStatusUpdater::SetThreadOperationProperty(int i, uint64_t value) {
+  auto* data = GetLocalThreadStatus();
+  if (data == nullptr) {
+    return;
+  }
+  data->op_properties[i].store(value, std::memory_order_relaxed);
+}
+
+void ThreadStatusUpdater::IncreaseThreadOperationProperty(int i,
+                                                          uint64_t delta) {
+  auto* data = GetLocalThreadStatus();
+  if (data == nullptr) {
+    return;
+  }
+  data->op_properties[i].fetch_add(delta, std::memory_order_relaxed);
+}
+
+void ThreadStatusUpdater::SetOperationStartTime(const uint64_t start_time) {
+  auto* data = GetLocalThreadStatus();
+  if (data == nullptr) {
+    return;
+  }
+  data->op_start_time.store(start_time, std::memory_order_relaxed);
+}
+
+void ThreadStatusUpdater::ClearThreadOperation() {
+  auto* data = GetLocalThreadStatus();
+  if (data == nullptr) {
+    return;
+  }
+  data->operation_stage.store(ThreadStatus::STAGE_UNKNOWN,
+                              std::memory_order_relaxed);
+  data->operation_type.store(ThreadStatus::OP_UNKNOWN,
+                             std::memory_order_relaxed);
+  ClearThreadOperationProperties();
+}
+
+void ThreadStatusUpdater::ClearThreadOperationProperties() {
+  auto* data = GetLocalThreadStatus();
+  if (data == nullptr) {
+    return;
+  }
+  for (int i = 0; i < ThreadStatus::kNumOperationProperties; ++i) {
+    data->op_properties[i].store(0, std::memory_order_relaxed);
+  }
+}
+
+ThreadStatus::OperationStage ThreadStatusUpdater::SetThreadOperationStage(
+    ThreadStatus::OperationStage stage) {
+  auto* data = GetLocalThreadStatus();
+  if (data == nullptr) {
+    return ThreadStatus::STAGE_UNKNOWN;
+  }
+  return data->operation_stage.exchange(stage, std::memory_order_relaxed);
+}
+
+void ThreadStatusUpdater::SetThreadState(const ThreadStatus::StateType type) {
+  auto* data = GetLocalThreadStatus();
+  if (data == nullptr) {
+    return;
+  }
+  data->state_type.store(type, std::memory_order_relaxed);
+}
+
+void ThreadStatusUpdater::ClearThreadState() {
+  auto* data = GetLocalThreadStatus();
+  if (data == nullptr) {
+    return;
+  }
+  data->state_type.store(ThreadStatus::STATE_UNKNOWN,
+                         std::memory_order_relaxed);
+}
+
+Status ThreadStatusUpdater::GetThreadList(
+    std::vector<ThreadStatus>* thread_list) {
+  thread_list->clear();
+  std::vector<std::shared_ptr<ThreadStatusData>> valid_list;
+  uint64_t now_micros = Env::Default()->NowMicros();
+
+  std::lock_guard<std::mutex> lck(thread_list_mutex_);
+  for (auto* thread_data : thread_data_set_) {
+    assert(thread_data);
+    auto thread_id = thread_data->thread_id.load(std::memory_order_relaxed);
+    auto thread_type = thread_data->thread_type.load(std::memory_order_relaxed);
+    // Since any change to cf_info_map requires thread_list_mutex,
+    // which is currently held by GetThreadList(), here we can safely
+    // use "memory_order_relaxed" to load the cf_key.
+    auto cf_key = thread_data->cf_key.load(std::memory_order_relaxed);
+
+    ThreadStatus::OperationType op_type = ThreadStatus::OP_UNKNOWN;
+    ThreadStatus::OperationStage op_stage = ThreadStatus::STAGE_UNKNOWN;
+    ThreadStatus::StateType state_type = ThreadStatus::STATE_UNKNOWN;
+    uint64_t op_elapsed_micros = 0;
+    uint64_t op_props[ThreadStatus::kNumOperationProperties] = {0};
+
+    auto iter = cf_info_map_.find(cf_key);
+    if (iter != cf_info_map_.end()) {
+      op_type = thread_data->operation_type.load(std::memory_order_acquire);
+      // display lower-level info only when higher-level info is available.
+      if (op_type != ThreadStatus::OP_UNKNOWN) {
+        op_elapsed_micros = now_micros - thread_data->op_start_time.load(
+                                             std::memory_order_relaxed);
+        op_stage = thread_data->operation_stage.load(std::memory_order_relaxed);
+        state_type = thread_data->state_type.load(std::memory_order_relaxed);
+        for (int i = 0; i < ThreadStatus::kNumOperationProperties; ++i) {
+          op_props[i] =
+              thread_data->op_properties[i].load(std::memory_order_relaxed);
+        }
+      }
+    }
+
+    thread_list->emplace_back(
+        thread_id, thread_type,
+        iter != cf_info_map_.end() ? iter->second.db_name : "",
+        iter != cf_info_map_.end() ? iter->second.cf_name : "", op_type,
+        op_elapsed_micros, op_stage, op_props, state_type);
+  }
+
+  return Status::OK();
+}
+
+ThreadStatusData* ThreadStatusUpdater::GetLocalThreadStatus() {
+  if (thread_status_data_ == nullptr) {
+    return nullptr;
+  }
+  if (!thread_status_data_->enable_tracking) {
+    assert(thread_status_data_->cf_key.load(std::memory_order_relaxed) ==
+           nullptr);
+    return nullptr;
+  }
+  return thread_status_data_;
+}
+
+void ThreadStatusUpdater::NewColumnFamilyInfo(const void* db_key,
+                                              const std::string& db_name,
+                                              const void* cf_key,
+                                              const std::string& cf_name) {
+  // Acquiring same lock as GetThreadList() to guarantee
+  // a consistent view of global column family table (cf_info_map).
+  std::lock_guard<std::mutex> lck(thread_list_mutex_);
+
+  cf_info_map_.emplace(std::piecewise_construct, std::make_tuple(cf_key),
+                       std::make_tuple(db_key, db_name, cf_name));
+  db_key_map_[db_key].insert(cf_key);
+}
+
+void ThreadStatusUpdater::EraseColumnFamilyInfo(const void* cf_key) {
+  // Acquiring same lock as GetThreadList() to guarantee
+  // a consistent view of global column family table (cf_info_map).
+  std::lock_guard<std::mutex> lck(thread_list_mutex_);
+
+  auto cf_pair = cf_info_map_.find(cf_key);
+  if (cf_pair != cf_info_map_.end()) {
+    // Remove its entry from db_key_map_ by the following steps:
+    // 1. Obtain the entry in db_key_map_ whose set contains cf_key
+    // 2. Remove it from the set.
+    ConstantColumnFamilyInfo& cf_info = cf_pair->second;
+    auto db_pair = db_key_map_.find(cf_info.db_key);
+    assert(db_pair != db_key_map_.end());
+    size_t result __attribute__((__unused__));
+    result = db_pair->second.erase(cf_key);
+    assert(result);
+    cf_info_map_.erase(cf_pair);
+  }
+}
+
+void ThreadStatusUpdater::EraseDatabaseInfo(const void* db_key) {
+  // Acquiring same lock as GetThreadList() to guarantee
+  // a consistent view of global column family table (cf_info_map).
+  std::lock_guard<std::mutex> lck(thread_list_mutex_);
+  auto db_pair = db_key_map_.find(db_key);
+  if (UNLIKELY(db_pair == db_key_map_.end())) {
+    // In some occasional cases such as DB::Open fails, we won't
+    // register ColumnFamilyInfo for a db.
+    return;
+  }
+
+  for (auto cf_key : db_pair->second) {
+    auto cf_pair = cf_info_map_.find(cf_key);
+    if (cf_pair != cf_info_map_.end()) {
+      cf_info_map_.erase(cf_pair);
+    }
+  }
+  db_key_map_.erase(db_key);
+}
+
+#else
+
+void ThreadStatusUpdater::RegisterThread(ThreadStatus::ThreadType /*ttype*/,
+                                         uint64_t /*thread_id*/) {}
+
+void ThreadStatusUpdater::UnregisterThread() {}
+
+void ThreadStatusUpdater::ResetThreadStatus() {}
+
+void ThreadStatusUpdater::SetColumnFamilyInfoKey(const void* /*cf_key*/) {}
+
+void ThreadStatusUpdater::SetThreadOperation(
+    const ThreadStatus::OperationType /*type*/) {}
+
+void ThreadStatusUpdater::ClearThreadOperation() {}
+
+void ThreadStatusUpdater::SetThreadState(
+    const ThreadStatus::StateType /*type*/) {}
+
+void ThreadStatusUpdater::ClearThreadState() {}
+
+Status ThreadStatusUpdater::GetThreadList(
+    std::vector<ThreadStatus>* /*thread_list*/) {
+  return Status::NotSupported(
+      "GetThreadList is not supported in the current running environment.");
+}
+
+void ThreadStatusUpdater::NewColumnFamilyInfo(const void* /*db_key*/,
+                                              const std::string& /*db_name*/,
+                                              const void* /*cf_key*/,
+                                              const std::string& /*cf_name*/) {}
+
+void ThreadStatusUpdater::EraseColumnFamilyInfo(const void* /*cf_key*/) {}
+
+void ThreadStatusUpdater::EraseDatabaseInfo(const void* /*db_key*/) {}
+
+void ThreadStatusUpdater::SetThreadOperationProperty(int /*i*/,
+                                                     uint64_t /*value*/) {}
+
+void ThreadStatusUpdater::IncreaseThreadOperationProperty(int /*i*/,
+                                                          uint64_t /*delta*/) {}
+
+#endif  // ROCKSDB_USING_THREAD_STATUS
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/thread_status_updater.h b/src/rocksdb/monitoring/thread_status_updater.h
new file mode 100644
index 00000000..6706d159
--- /dev/null
+++ b/src/rocksdb/monitoring/thread_status_updater.h
@@ -0,0 +1,233 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// The implementation of ThreadStatus.
+//
+// Note that we make get and set access to ThreadStatusData lockless.
+// As a result, ThreadStatusData as a whole is not atomic.  However,
+// we guarantee consistent ThreadStatusData all the time whenever
+// user call GetThreadList().  This consistency guarantee is done
+// by having the following constraint in the internal implementation
+// of set and get order:
+//
+// 1. When reset any information in ThreadStatusData, always start from
+//    clearing up the lower-level information first.
+// 2. When setting any information in ThreadStatusData, always start from
+//    setting the higher-level information.
+// 3. When returning ThreadStatusData to the user, fields are fetched from
+//    higher-level to lower-level.  In addition, where there's a nullptr
+//    in one field, then all fields that has lower-level than that field
+//    should be ignored.
+//
+// The high to low level information would be:
+// thread_id > thread_type > db > cf > operation > state
+//
+// This means user might not always get full information, but whenever
+// returned by the GetThreadList() is guaranteed to be consistent.
+#pragma once
+#include <atomic>
+#include <list>
+#include <memory>
+#include <mutex>
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include "rocksdb/status.h"
+#include "rocksdb/thread_status.h"
+#include "port/port.h"
+#include "util/thread_operation.h"
+
+namespace rocksdb {
+
+class ColumnFamilyHandle;
+
+// The structure that keeps constant information about a column family.
+struct ConstantColumnFamilyInfo {
+#ifdef ROCKSDB_USING_THREAD_STATUS
+ public:
+  ConstantColumnFamilyInfo(
+      const void* _db_key,
+      const std::string& _db_name,
+      const std::string& _cf_name) :
+      db_key(_db_key), db_name(_db_name), cf_name(_cf_name) {}
+  const void* db_key;
+  const std::string db_name;
+  const std::string cf_name;
+#endif  // ROCKSDB_USING_THREAD_STATUS
+};
+
+// the internal data-structure that is used to reflect the current
+// status of a thread using a set of atomic pointers.
+struct ThreadStatusData {
+#ifdef ROCKSDB_USING_THREAD_STATUS
+  explicit ThreadStatusData() : enable_tracking(false) {
+    thread_id.store(0);
+    thread_type.store(ThreadStatus::USER);
+    cf_key.store(nullptr);
+    operation_type.store(ThreadStatus::OP_UNKNOWN);
+    op_start_time.store(0);
+    state_type.store(ThreadStatus::STATE_UNKNOWN);
+  }
+
+  // A flag to indicate whether the thread tracking is enabled
+  // in the current thread.  This value will be updated based on whether
+  // the associated Options::enable_thread_tracking is set to true
+  // in ThreadStatusUtil::SetColumnFamily().
+  //
+  // If set to false, then SetThreadOperation and SetThreadState
+  // will be no-op.
+  bool enable_tracking;
+
+  std::atomic<uint64_t> thread_id;
+  std::atomic<ThreadStatus::ThreadType> thread_type;
+  std::atomic<void*> cf_key;
+  std::atomic<ThreadStatus::OperationType> operation_type;
+  std::atomic<uint64_t> op_start_time;
+  std::atomic<ThreadStatus::OperationStage> operation_stage;
+  std::atomic<uint64_t> op_properties[ThreadStatus::kNumOperationProperties];
+  std::atomic<ThreadStatus::StateType> state_type;
+#endif  // ROCKSDB_USING_THREAD_STATUS
+};
+
+// The class that stores and updates the status of the current thread
+// using a thread-local ThreadStatusData.
+//
+// In most of the case, you should use ThreadStatusUtil to update
+// the status of the current thread instead of using ThreadSatusUpdater
+// directly.
+//
+// @see ThreadStatusUtil
+class ThreadStatusUpdater {
+ public:
+  ThreadStatusUpdater() {}
+
+  // Releases all ThreadStatusData of all active threads.
+  virtual ~ThreadStatusUpdater() {}
+
+  // Unregister the current thread.
+  void UnregisterThread();
+
+  // Reset the status of the current thread.  This includes resetting
+  // ColumnFamilyInfoKey, ThreadOperation, and ThreadState.
+  void ResetThreadStatus();
+
+  // Set the id of the current thread.
+  void SetThreadID(uint64_t thread_id);
+
+  // Register the current thread for tracking.
+  void RegisterThread(ThreadStatus::ThreadType ttype, uint64_t thread_id);
+
+  // Update the column-family info of the current thread by setting
+  // its thread-local pointer of ThreadStateInfo to the correct entry.
+  void SetColumnFamilyInfoKey(const void* cf_key);
+
+  // returns the column family info key.
+  const void* GetColumnFamilyInfoKey();
+
+  // Update the thread operation of the current thread.
+  void SetThreadOperation(const ThreadStatus::OperationType type);
+
+  // The start time of the current thread operation.  It is in the format
+  // of micro-seconds since some fixed point in time.
+  void SetOperationStartTime(const uint64_t start_time);
+
+  // Set the "i"th property of the current operation.
+  //
+  // NOTE: Our practice here is to set all the thread operation properties
+  //       and stage before we set thread operation, and thread operation
+  //       will be set in std::memory_order_release.  This is to ensure
+  //       whenever a thread operation is not OP_UNKNOWN, we will always
+  //       have a consistent information on its properties.
+  void SetThreadOperationProperty(
+      int i, uint64_t value);
+
+  // Increase the "i"th property of the current operation with
+  // the specified delta.
+  void IncreaseThreadOperationProperty(
+      int i, uint64_t delta);
+
+  // Update the thread operation stage of the current thread.
+  ThreadStatus::OperationStage SetThreadOperationStage(
+      const ThreadStatus::OperationStage stage);
+
+  // Clear thread operation of the current thread.
+  void ClearThreadOperation();
+
+  // Reset all thread-operation-properties to 0.
+  void ClearThreadOperationProperties();
+
+  // Update the thread state of the current thread.
+  void SetThreadState(const ThreadStatus::StateType type);
+
+  // Clear the thread state of the current thread.
+  void ClearThreadState();
+
+  // Obtain the status of all active registered threads.
+  Status GetThreadList(
+      std::vector<ThreadStatus>* thread_list);
+
+  // Create an entry in the global ColumnFamilyInfo table for the
+  // specified column family.  This function should be called only
+  // when the current thread does not hold db_mutex.
+  void NewColumnFamilyInfo(
+      const void* db_key, const std::string& db_name,
+      const void* cf_key, const std::string& cf_name);
+
+  // Erase all ConstantColumnFamilyInfo that is associated with the
+  // specified db instance.  This function should be called only when
+  // the current thread does not hold db_mutex.
+  void EraseDatabaseInfo(const void* db_key);
+
+  // Erase the ConstantColumnFamilyInfo that is associated with the
+  // specified ColumnFamilyData.  This function should be called only
+  // when the current thread does not hold db_mutex.
+  void EraseColumnFamilyInfo(const void* cf_key);
+
+  // Verifies whether the input ColumnFamilyHandles matches
+  // the information stored in the current cf_info_map.
+  void TEST_VerifyColumnFamilyInfoMap(
+      const std::vector<ColumnFamilyHandle*>& handles,
+      bool check_exist);
+
+ protected:
+#ifdef ROCKSDB_USING_THREAD_STATUS
+  // The thread-local variable for storing thread status.
+  static __thread ThreadStatusData* thread_status_data_;
+
+  // Returns the pointer to the thread status data only when the
+  // thread status data is non-null and has enable_tracking == true.
+  ThreadStatusData* GetLocalThreadStatus();
+
+  // Directly returns the pointer to thread_status_data_ without
+  // checking whether enabling_tracking is true of not.
+  ThreadStatusData* Get() {
+    return thread_status_data_;
+  }
+
+  // The mutex that protects cf_info_map and db_key_map.
+  std::mutex thread_list_mutex_;
+
+  // The current status data of all active threads.
+  std::unordered_set<ThreadStatusData*> thread_data_set_;
+
+  // A global map that keeps the column family information.  It is stored
+  // globally instead of inside DB is to avoid the situation where DB is
+  // closing while GetThreadList function already get the pointer to its
+  // CopnstantColumnFamilyInfo.
+  std::unordered_map<const void*, ConstantColumnFamilyInfo> cf_info_map_;
+
+  // A db_key to cf_key map that allows erasing elements in cf_info_map
+  // associated to the same db_key faster.
+  std::unordered_map<
+      const void*, std::unordered_set<const void*>> db_key_map_;
+
+#else
+  static ThreadStatusData* thread_status_data_;
+#endif  // ROCKSDB_USING_THREAD_STATUS
+};
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/thread_status_updater_debug.cc b/src/rocksdb/monitoring/thread_status_updater_debug.cc
new file mode 100644
index 00000000..8dc0fe6f
--- /dev/null
+++ b/src/rocksdb/monitoring/thread_status_updater_debug.cc
@@ -0,0 +1,42 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include <mutex>
+
+#include "db/column_family.h"
+#include "monitoring/thread_status_updater.h"
+
+namespace rocksdb {
+
+#ifndef NDEBUG
+#ifdef ROCKSDB_USING_THREAD_STATUS
+void ThreadStatusUpdater::TEST_VerifyColumnFamilyInfoMap(
+    const std::vector<ColumnFamilyHandle*>& handles, bool check_exist) {
+  std::unique_lock<std::mutex> lock(thread_list_mutex_);
+  if (check_exist) {
+    assert(cf_info_map_.size() == handles.size());
+  }
+  for (auto* handle : handles) {
+    auto* cfd = reinterpret_cast<ColumnFamilyHandleImpl*>(handle)->cfd();
+    auto iter __attribute__((__unused__)) = cf_info_map_.find(cfd);
+    if (check_exist) {
+      assert(iter != cf_info_map_.end());
+      assert(iter->second.cf_name == cfd->GetName());
+    } else {
+      assert(iter == cf_info_map_.end());
+    }
+  }
+}
+
+#else
+
+void ThreadStatusUpdater::TEST_VerifyColumnFamilyInfoMap(
+    const std::vector<ColumnFamilyHandle*>& /*handles*/, bool /*check_exist*/) {
+}
+
+#endif  // ROCKSDB_USING_THREAD_STATUS
+#endif  // !NDEBUG
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/thread_status_util.cc b/src/rocksdb/monitoring/thread_status_util.cc
new file mode 100644
index 00000000..c2af0a57
--- /dev/null
+++ b/src/rocksdb/monitoring/thread_status_util.cc
@@ -0,0 +1,206 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include "monitoring/thread_status_util.h"
+
+#include "monitoring/thread_status_updater.h"
+#include "rocksdb/env.h"
+
+namespace rocksdb {
+
+#ifdef ROCKSDB_USING_THREAD_STATUS
+__thread ThreadStatusUpdater* ThreadStatusUtil::thread_updater_local_cache_ =
+    nullptr;
+__thread bool ThreadStatusUtil::thread_updater_initialized_ = false;
+
+void ThreadStatusUtil::RegisterThread(const Env* env,
+                                      ThreadStatus::ThreadType thread_type) {
+  if (!MaybeInitThreadLocalUpdater(env)) {
+    return;
+  }
+  assert(thread_updater_local_cache_);
+  thread_updater_local_cache_->RegisterThread(thread_type, env->GetThreadID());
+}
+
+void ThreadStatusUtil::UnregisterThread() {
+  thread_updater_initialized_ = false;
+  if (thread_updater_local_cache_ != nullptr) {
+    thread_updater_local_cache_->UnregisterThread();
+    thread_updater_local_cache_ = nullptr;
+  }
+}
+
+void ThreadStatusUtil::SetColumnFamily(const ColumnFamilyData* cfd,
+                                       const Env* env,
+                                       bool enable_thread_tracking) {
+  if (!MaybeInitThreadLocalUpdater(env)) {
+    return;
+  }
+  assert(thread_updater_local_cache_);
+  if (cfd != nullptr && enable_thread_tracking) {
+    thread_updater_local_cache_->SetColumnFamilyInfoKey(cfd);
+  } else {
+    // When cfd == nullptr or enable_thread_tracking == false, we set
+    // ColumnFamilyInfoKey to nullptr, which makes SetThreadOperation
+    // and SetThreadState become no-op.
+    thread_updater_local_cache_->SetColumnFamilyInfoKey(nullptr);
+  }
+}
+
+void ThreadStatusUtil::SetThreadOperation(ThreadStatus::OperationType op) {
+  if (thread_updater_local_cache_ == nullptr) {
+    // thread_updater_local_cache_ must be set in SetColumnFamily
+    // or other ThreadStatusUtil functions.
+    return;
+  }
+
+  if (op != ThreadStatus::OP_UNKNOWN) {
+    uint64_t current_time = Env::Default()->NowMicros();
+    thread_updater_local_cache_->SetOperationStartTime(current_time);
+  } else {
+    // TDOO(yhchiang): we could report the time when we set operation to
+    // OP_UNKNOWN once the whole instrumentation has been done.
+    thread_updater_local_cache_->SetOperationStartTime(0);
+  }
+  thread_updater_local_cache_->SetThreadOperation(op);
+}
+
+ThreadStatus::OperationStage ThreadStatusUtil::SetThreadOperationStage(
+    ThreadStatus::OperationStage stage) {
+  if (thread_updater_local_cache_ == nullptr) {
+    // thread_updater_local_cache_ must be set in SetColumnFamily
+    // or other ThreadStatusUtil functions.
+    return ThreadStatus::STAGE_UNKNOWN;
+  }
+
+  return thread_updater_local_cache_->SetThreadOperationStage(stage);
+}
+
+void ThreadStatusUtil::SetThreadOperationProperty(int code, uint64_t value) {
+  if (thread_updater_local_cache_ == nullptr) {
+    // thread_updater_local_cache_ must be set in SetColumnFamily
+    // or other ThreadStatusUtil functions.
+    return;
+  }
+
+  thread_updater_local_cache_->SetThreadOperationProperty(code, value);
+}
+
+void ThreadStatusUtil::IncreaseThreadOperationProperty(int code,
+                                                       uint64_t delta) {
+  if (thread_updater_local_cache_ == nullptr) {
+    // thread_updater_local_cache_ must be set in SetColumnFamily
+    // or other ThreadStatusUtil functions.
+    return;
+  }
+
+  thread_updater_local_cache_->IncreaseThreadOperationProperty(code, delta);
+}
+
+void ThreadStatusUtil::SetThreadState(ThreadStatus::StateType state) {
+  if (thread_updater_local_cache_ == nullptr) {
+    // thread_updater_local_cache_ must be set in SetColumnFamily
+    // or other ThreadStatusUtil functions.
+    return;
+  }
+
+  thread_updater_local_cache_->SetThreadState(state);
+}
+
+void ThreadStatusUtil::ResetThreadStatus() {
+  if (thread_updater_local_cache_ == nullptr) {
+    return;
+  }
+  thread_updater_local_cache_->ResetThreadStatus();
+}
+
+void ThreadStatusUtil::NewColumnFamilyInfo(const DB* db,
+                                           const ColumnFamilyData* cfd,
+                                           const std::string& cf_name,
+                                           const Env* env) {
+  if (!MaybeInitThreadLocalUpdater(env)) {
+    return;
+  }
+  assert(thread_updater_local_cache_);
+  if (thread_updater_local_cache_) {
+    thread_updater_local_cache_->NewColumnFamilyInfo(db, db->GetName(), cfd,
+                                                     cf_name);
+  }
+}
+
+void ThreadStatusUtil::EraseColumnFamilyInfo(const ColumnFamilyData* cfd) {
+  if (thread_updater_local_cache_ == nullptr) {
+    return;
+  }
+  thread_updater_local_cache_->EraseColumnFamilyInfo(cfd);
+}
+
+void ThreadStatusUtil::EraseDatabaseInfo(const DB* db) {
+  ThreadStatusUpdater* thread_updater = db->GetEnv()->GetThreadStatusUpdater();
+  if (thread_updater == nullptr) {
+    return;
+  }
+  thread_updater->EraseDatabaseInfo(db);
+}
+
+bool ThreadStatusUtil::MaybeInitThreadLocalUpdater(const Env* env) {
+  if (!thread_updater_initialized_ && env != nullptr) {
+    thread_updater_initialized_ = true;
+    thread_updater_local_cache_ = env->GetThreadStatusUpdater();
+  }
+  return (thread_updater_local_cache_ != nullptr);
+}
+
+AutoThreadOperationStageUpdater::AutoThreadOperationStageUpdater(
+    ThreadStatus::OperationStage stage) {
+  prev_stage_ = ThreadStatusUtil::SetThreadOperationStage(stage);
+}
+
+AutoThreadOperationStageUpdater::~AutoThreadOperationStageUpdater() {
+  ThreadStatusUtil::SetThreadOperationStage(prev_stage_);
+}
+
+#else
+
+ThreadStatusUpdater* ThreadStatusUtil::thread_updater_local_cache_ = nullptr;
+bool ThreadStatusUtil::thread_updater_initialized_ = false;
+
+bool ThreadStatusUtil::MaybeInitThreadLocalUpdater(const Env* /*env*/) {
+  return false;
+}
+
+void ThreadStatusUtil::SetColumnFamily(const ColumnFamilyData* /*cfd*/,
+                                       const Env* /*env*/,
+                                       bool /*enable_thread_tracking*/) {}
+
+void ThreadStatusUtil::SetThreadOperation(ThreadStatus::OperationType /*op*/) {}
+
+void ThreadStatusUtil::SetThreadOperationProperty(int /*code*/,
+                                                  uint64_t /*value*/) {}
+
+void ThreadStatusUtil::IncreaseThreadOperationProperty(int /*code*/,
+                                                       uint64_t /*delta*/) {}
+
+void ThreadStatusUtil::SetThreadState(ThreadStatus::StateType /*state*/) {}
+
+void ThreadStatusUtil::NewColumnFamilyInfo(const DB* /*db*/,
+                                           const ColumnFamilyData* /*cfd*/,
+                                           const std::string& /*cf_name*/,
+                                           const Env* /*env*/) {}
+
+void ThreadStatusUtil::EraseColumnFamilyInfo(const ColumnFamilyData* /*cfd*/) {}
+
+void ThreadStatusUtil::EraseDatabaseInfo(const DB* /*db*/) {}
+
+void ThreadStatusUtil::ResetThreadStatus() {}
+
+AutoThreadOperationStageUpdater::AutoThreadOperationStageUpdater(
+    ThreadStatus::OperationStage /*stage*/) {}
+
+AutoThreadOperationStageUpdater::~AutoThreadOperationStageUpdater() {}
+
+#endif  // ROCKSDB_USING_THREAD_STATUS
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/thread_status_util.h b/src/rocksdb/monitoring/thread_status_util.h
new file mode 100644
index 00000000..a403435c
--- /dev/null
+++ b/src/rocksdb/monitoring/thread_status_util.h
@@ -0,0 +1,134 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include <string>
+
+#include "monitoring/thread_status_updater.h"
+#include "rocksdb/db.h"
+#include "rocksdb/env.h"
+#include "rocksdb/thread_status.h"
+
+namespace rocksdb {
+
+class ColumnFamilyData;
+
+// The static utility class for updating thread-local status.
+//
+// The thread-local status is updated via the thread-local cached
+// pointer thread_updater_local_cache_.  During each function call,
+// when ThreadStatusUtil finds thread_updater_local_cache_ is
+// left uninitialized (determined by thread_updater_initialized_),
+// it will tries to initialize it using the return value of
+// Env::GetThreadStatusUpdater().  When thread_updater_local_cache_
+// is initialized by a non-null pointer, each function call will
+// then update the status of the current thread.  Otherwise,
+// all function calls to ThreadStatusUtil will be no-op.
+class ThreadStatusUtil {
+ public:
+  // Register the current thread for tracking.
+  static void RegisterThread(
+      const Env* env, ThreadStatus::ThreadType thread_type);
+
+  // Unregister the current thread.
+  static void UnregisterThread();
+
+  // Create an entry in the global ColumnFamilyInfo table for the
+  // specified column family.  This function should be called only
+  // when the current thread does not hold db_mutex.
+  static void NewColumnFamilyInfo(const DB* db, const ColumnFamilyData* cfd,
+                                  const std::string& cf_name, const Env* env);
+
+  // Erase the ConstantColumnFamilyInfo that is associated with the
+  // specified ColumnFamilyData.  This function should be called only
+  // when the current thread does not hold db_mutex.
+  static void EraseColumnFamilyInfo(const ColumnFamilyData* cfd);
+
+  // Erase all ConstantColumnFamilyInfo that is associated with the
+  // specified db instance.  This function should be called only when
+  // the current thread does not hold db_mutex.
+  static void EraseDatabaseInfo(const DB* db);
+
+  // Update the thread status to indicate the current thread is doing
+  // something related to the specified column family.
+  static void SetColumnFamily(const ColumnFamilyData* cfd, const Env* env,
+                              bool enable_thread_tracking);
+
+  static void SetThreadOperation(ThreadStatus::OperationType type);
+
+  static ThreadStatus::OperationStage SetThreadOperationStage(
+      ThreadStatus::OperationStage stage);
+
+  static void SetThreadOperationProperty(
+      int code, uint64_t value);
+
+  static void IncreaseThreadOperationProperty(
+      int code, uint64_t delta);
+
+  static void SetThreadState(ThreadStatus::StateType type);
+
+  static void ResetThreadStatus();
+
+#ifndef NDEBUG
+  static void TEST_SetStateDelay(
+      const ThreadStatus::StateType state, int micro);
+  static void TEST_StateDelay(const ThreadStatus::StateType state);
+#endif
+
+ protected:
+  // Initialize the thread-local ThreadStatusUpdater when it finds
+  // the cached value is nullptr.  Returns true if it has cached
+  // a non-null pointer.
+  static bool MaybeInitThreadLocalUpdater(const Env* env);
+
+#ifdef ROCKSDB_USING_THREAD_STATUS
+  // A boolean flag indicating whether thread_updater_local_cache_
+  // is initialized.  It is set to true when an Env uses any
+  // ThreadStatusUtil functions using the current thread other
+  // than UnregisterThread().  It will be set to false when
+  // UnregisterThread() is called.
+  //
+  // When this variable is set to true, thread_updater_local_cache_
+  // will not be updated until this variable is again set to false
+  // in UnregisterThread().
+  static  __thread bool thread_updater_initialized_;
+
+  // The thread-local cached ThreadStatusUpdater that caches the
+  // thread_status_updater_ of the first Env that uses any ThreadStatusUtil
+  // function other than UnregisterThread().  This variable will
+  // be cleared when UnregisterThread() is called.
+  //
+  // When this variable is set to a non-null pointer, then the status
+  // of the current thread will be updated when a function of
+  // ThreadStatusUtil is called.  Otherwise, all functions of
+  // ThreadStatusUtil will be no-op.
+  //
+  // When thread_updater_initialized_ is set to true, this variable
+  // will not be updated until this thread_updater_initialized_ is
+  // again set to false in UnregisterThread().
+  static __thread ThreadStatusUpdater* thread_updater_local_cache_;
+#else
+  static bool thread_updater_initialized_;
+  static ThreadStatusUpdater* thread_updater_local_cache_;
+#endif
+};
+
+// A helper class for updating thread state.  It will set the
+// thread state according to the input parameter in its constructor
+// and set the thread state to the previous state in its destructor.
+class AutoThreadOperationStageUpdater {
+ public:
+  explicit AutoThreadOperationStageUpdater(
+      ThreadStatus::OperationStage stage);
+  ~AutoThreadOperationStageUpdater();
+
+#ifdef ROCKSDB_USING_THREAD_STATUS
+ private:
+  ThreadStatus::OperationStage prev_stage_;
+#endif
+};
+
+}  // namespace rocksdb
diff --git a/src/rocksdb/monitoring/thread_status_util_debug.cc b/src/rocksdb/monitoring/thread_status_util_debug.cc
new file mode 100644
index 00000000..b4fa5847
--- /dev/null
+++ b/src/rocksdb/monitoring/thread_status_util_debug.cc
@@ -0,0 +1,32 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include <atomic>
+
+#include "monitoring/thread_status_updater.h"
+#include "monitoring/thread_status_util.h"
+#include "rocksdb/env.h"
+
+namespace rocksdb {
+
+#ifndef NDEBUG
+// the delay for debugging purpose.
+static std::atomic<int> states_delay[ThreadStatus::NUM_STATE_TYPES];
+
+void ThreadStatusUtil::TEST_SetStateDelay(
+    const ThreadStatus::StateType state, int micro) {
+  states_delay[state].store(micro, std::memory_order_relaxed);
+}
+
+void ThreadStatusUtil::TEST_StateDelay(const ThreadStatus::StateType state) {
+  auto delay = states_delay[state].load(std::memory_order_relaxed);
+  if (delay > 0) {
+    Env::Default()->SleepForMicroseconds(delay);
+  }
+}
+
+#endif  // !NDEBUG
+
+}  // namespace rocksdb