1 files changed, 118 insertions, 0 deletions
diff --git a/src/rocksdb/util/stop_watch.h b/src/rocksdb/util/stop_watch.h
new file mode 100644
index 000000000..e26380d97
--- /dev/null
+++ b/src/rocksdb/util/stop_watch.h
@@ -0,0 +1,118 @@
+//  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 "rocksdb/system_clock.h"
+
+namespace ROCKSDB_NAMESPACE {
+// Auto-scoped.
+// Records the measure time into the corresponding histogram if statistics
+// is not nullptr. It is also saved into *elapsed if the pointer is not nullptr
+// and overwrite is true, it will be added to *elapsed if overwrite is false.
+class StopWatch {
+ public:
+  StopWatch(SystemClock* clock, Statistics* statistics,
+            const uint32_t hist_type, uint64_t* elapsed = nullptr,
+            bool overwrite = true, bool delay_enabled = false)
+      : clock_(clock),
+        statistics_(statistics),
+        hist_type_(hist_type),
+        elapsed_(elapsed),
+        overwrite_(overwrite),
+        stats_enabled_(statistics &&
+                       statistics->get_stats_level() >=
+                           StatsLevel::kExceptTimers &&
+                       statistics->HistEnabledForType(hist_type)),
+        delay_enabled_(delay_enabled),
+        total_delay_(0),
+        delay_start_time_(0),
+        start_time_((stats_enabled_ || elapsed != nullptr) ? clock->NowMicros()
+                                                           : 0) {}
+
+  ~StopWatch() {
+    if (elapsed_) {
+      if (overwrite_) {
+        *elapsed_ = clock_->NowMicros() - start_time_;
+      } else {
+        *elapsed_ += clock_->NowMicros() - start_time_;
+      }
+    }
+    if (elapsed_ && delay_enabled_) {
+      *elapsed_ -= total_delay_;
+    }
+    if (stats_enabled_) {
+      statistics_->reportTimeToHistogram(
+          hist_type_, (elapsed_ != nullptr)
+                          ? *elapsed_
+                          : (clock_->NowMicros() - start_time_));
+    }
+  }
+
+  void DelayStart() {
+    // if delay_start_time_ is not 0, it means we are already tracking delay,
+    // so delay_start_time_ should not be overwritten
+    if (elapsed_ && delay_enabled_ && delay_start_time_ == 0) {
+      delay_start_time_ = clock_->NowMicros();
+    }
+  }
+
+  void DelayStop() {
+    if (elapsed_ && delay_enabled_ && delay_start_time_ != 0) {
+      total_delay_ += clock_->NowMicros() - delay_start_time_;
+    }
+    // reset to 0 means currently no delay is being tracked, so two consecutive
+    // calls to DelayStop will not increase total_delay_
+    delay_start_time_ = 0;
+  }
+
+  uint64_t GetDelay() const { return delay_enabled_ ? total_delay_ : 0; }
+
+  uint64_t start_time() const { return start_time_; }
+
+ private:
+  SystemClock* clock_;
+  Statistics* statistics_;
+  const uint32_t hist_type_;
+  uint64_t* elapsed_;
+  bool overwrite_;
+  bool stats_enabled_;
+  bool delay_enabled_;
+  uint64_t total_delay_;
+  uint64_t delay_start_time_;
+  const uint64_t start_time_;
+};
+
+// a nano second precision stopwatch
+class StopWatchNano {
+ public:
+  explicit StopWatchNano(SystemClock* clock, bool auto_start = false)
+      : clock_(clock), start_(0) {
+    if (auto_start) {
+      Start();
+    }
+  }
+
+  void Start() { start_ = clock_->NowNanos(); }
+
+  uint64_t ElapsedNanos(bool reset = false) {
+    auto now = clock_->NowNanos();
+    auto elapsed = now - start_;
+    if (reset) {
+      start_ = now;
+    }
+    return elapsed;
+  }
+
+  uint64_t ElapsedNanosSafe(bool reset = false) {
+    return (clock_ != nullptr) ? ElapsedNanos(reset) : 0U;
+  }
+
+ private:
+  SystemClock* clock_;
+  uint64_t start_;
+};
+
+}  // namespace ROCKSDB_NAMESPACE