Adding upstream version 14.2.21.upstream/14.2.21upstream

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

1 files changed, 1774 insertions, 0 deletions

diff --git a/src/rocksdb/env/env_test.cc b/src/rocksdb/env/env_test.cc
new file mode 100644
index 00000000..47800928
--- /dev/null
+++ b/src/rocksdb/env/env_test.cc
@@ -0,0 +1,1774 @@
+//  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 OS_WIN
+#include <sys/ioctl.h>
+#endif
+
+#ifdef ROCKSDB_MALLOC_USABLE_SIZE
+#ifdef OS_FREEBSD
+#include <malloc_np.h>
+#else
+#include <malloc.h>
+#endif
+#endif
+#include <sys/types.h>
+
+#include <iostream>
+#include <unordered_set>
+#include <atomic>
+#include <list>
+
+#ifdef OS_LINUX
+#include <fcntl.h>
+#include <linux/fs.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#endif
+
+#ifdef ROCKSDB_FALLOCATE_PRESENT
+#include <errno.h>
+#endif
+
+#include "env/env_chroot.h"
+#include "port/port.h"
+#include "rocksdb/env.h"
+#include "util/coding.h"
+#include "util/log_buffer.h"
+#include "util/mutexlock.h"
+#include "util/string_util.h"
+#include "util/sync_point.h"
+#include "util/testharness.h"
+#include "util/testutil.h"
+
+#ifdef OS_LINUX
+static const size_t kPageSize = sysconf(_SC_PAGESIZE);
+#else
+static const size_t kPageSize = 4 * 1024;
+#endif
+
+namespace rocksdb {
+
+static const int kDelayMicros = 100000;
+
+struct Deleter {
+  explicit Deleter(void (*fn)(void*)) : fn_(fn) {}
+
+  void operator()(void* ptr) {
+    assert(fn_);
+    assert(ptr);
+    (*fn_)(ptr);
+  }
+
+  void (*fn_)(void*);
+};
+
+std::unique_ptr<char, Deleter> NewAligned(const size_t size, const char ch) {
+  char* ptr = nullptr;
+#ifdef OS_WIN
+  if (nullptr == (ptr = reinterpret_cast<char*>(_aligned_malloc(size, kPageSize)))) {
+    return std::unique_ptr<char, Deleter>(nullptr, Deleter(_aligned_free));
+  }
+  std::unique_ptr<char, Deleter> uptr(ptr, Deleter(_aligned_free));
+#else
+  if (posix_memalign(reinterpret_cast<void**>(&ptr), kPageSize, size) != 0) {
+    return std::unique_ptr<char, Deleter>(nullptr, Deleter(free));
+  }
+  std::unique_ptr<char, Deleter> uptr(ptr, Deleter(free));
+#endif
+  memset(uptr.get(), ch, size);
+  return uptr;
+}
+
+class EnvPosixTest : public testing::Test {
+ private:
+  port::Mutex mu_;
+  std::string events_;
+
+ public:
+  Env* env_;
+  bool direct_io_;
+  EnvPosixTest() : env_(Env::Default()), direct_io_(false) {}
+};
+
+class EnvPosixTestWithParam
+    : public EnvPosixTest,
+      public ::testing::WithParamInterface<std::pair<Env*, bool>> {
+ public:
+  EnvPosixTestWithParam() {
+    std::pair<Env*, bool> param_pair = GetParam();
+    env_ = param_pair.first;
+    direct_io_ = param_pair.second;
+  }
+
+  void WaitThreadPoolsEmpty() {
+    // Wait until the thread pools are empty.
+    while (env_->GetThreadPoolQueueLen(Env::Priority::LOW) != 0) {
+      Env::Default()->SleepForMicroseconds(kDelayMicros);
+    }
+    while (env_->GetThreadPoolQueueLen(Env::Priority::HIGH) != 0) {
+      Env::Default()->SleepForMicroseconds(kDelayMicros);
+    }
+  }
+
+  ~EnvPosixTestWithParam() override { WaitThreadPoolsEmpty(); }
+};
+
+static void SetBool(void* ptr) {
+  reinterpret_cast<std::atomic<bool>*>(ptr)->store(true);
+}
+
+TEST_F(EnvPosixTest, DISABLED_RunImmediately) {
+  for (int pri = Env::BOTTOM; pri < Env::TOTAL; ++pri) {
+    std::atomic<bool> called(false);
+    env_->SetBackgroundThreads(1, static_cast<Env::Priority>(pri));
+    env_->Schedule(&SetBool, &called, static_cast<Env::Priority>(pri));
+    Env::Default()->SleepForMicroseconds(kDelayMicros);
+    ASSERT_TRUE(called.load());
+  }
+}
+
+TEST_F(EnvPosixTest, RunEventually) {
+  std::atomic<bool> called(false);
+  env_->StartThread(&SetBool, &called);
+  env_->WaitForJoin();
+  ASSERT_TRUE(called.load());
+}
+
+#ifdef OS_WIN
+TEST_F(EnvPosixTest, AreFilesSame) {
+  {
+    bool tmp;
+    if (env_->AreFilesSame("", "", &tmp).IsNotSupported()) {
+      fprintf(stderr,
+              "skipping EnvBasicTestWithParam.AreFilesSame due to "
+              "unsupported Env::AreFilesSame\n");
+      return;
+    }
+  }
+
+  const EnvOptions soptions;
+  auto* env = Env::Default();
+  std::string same_file_name = test::PerThreadDBPath(env, "same_file");
+  std::string same_file_link_name = same_file_name + "_link";
+
+  std::unique_ptr<WritableFile> same_file;
+  ASSERT_OK(env->NewWritableFile(same_file_name,
+    &same_file, soptions));
+  same_file->Append("random_data");
+  ASSERT_OK(same_file->Flush());
+  same_file.reset();
+
+  ASSERT_OK(env->LinkFile(same_file_name, same_file_link_name));
+  bool result = false;
+  ASSERT_OK(env->AreFilesSame(same_file_name, same_file_link_name, &result));
+  ASSERT_TRUE(result);
+}
+#endif
+
+#ifdef OS_LINUX
+TEST_F(EnvPosixTest, DISABLED_FilePermission) {
+  // Only works for Linux environment
+  if (env_ == Env::Default()) {
+    EnvOptions soptions;
+    std::vector<std::string> fileNames{
+        test::PerThreadDBPath(env_, "testfile"),
+        test::PerThreadDBPath(env_, "testfile1")};
+    std::unique_ptr<WritableFile> wfile;
+    ASSERT_OK(env_->NewWritableFile(fileNames[0], &wfile, soptions));
+    ASSERT_OK(env_->NewWritableFile(fileNames[1], &wfile, soptions));
+    wfile.reset();
+    std::unique_ptr<RandomRWFile> rwfile;
+    ASSERT_OK(env_->NewRandomRWFile(fileNames[1], &rwfile, soptions));
+
+    struct stat sb;
+    for (const auto& filename : fileNames) {
+      if (::stat(filename.c_str(), &sb) == 0) {
+        ASSERT_EQ(sb.st_mode & 0777, 0644);
+      }
+      env_->DeleteFile(filename);
+    }
+
+    env_->SetAllowNonOwnerAccess(false);
+    ASSERT_OK(env_->NewWritableFile(fileNames[0], &wfile, soptions));
+    ASSERT_OK(env_->NewWritableFile(fileNames[1], &wfile, soptions));
+    wfile.reset();
+    ASSERT_OK(env_->NewRandomRWFile(fileNames[1], &rwfile, soptions));
+
+    for (const auto& filename : fileNames) {
+      if (::stat(filename.c_str(), &sb) == 0) {
+        ASSERT_EQ(sb.st_mode & 0777, 0600);
+      }
+      env_->DeleteFile(filename);
+    }
+  }
+}
+#endif
+
+TEST_F(EnvPosixTest, MemoryMappedFileBuffer) {
+  const int kFileBytes = 1 << 15;  // 32 KB
+  std::string expected_data;
+  std::string fname = test::PerThreadDBPath(env_, "testfile");
+  {
+    std::unique_ptr<WritableFile> wfile;
+    const EnvOptions soptions;
+    ASSERT_OK(env_->NewWritableFile(fname, &wfile, soptions));
+
+    Random rnd(301);
+    test::RandomString(&rnd, kFileBytes, &expected_data);
+    ASSERT_OK(wfile->Append(expected_data));
+  }
+
+  std::unique_ptr<MemoryMappedFileBuffer> mmap_buffer;
+  Status status = env_->NewMemoryMappedFileBuffer(fname, &mmap_buffer);
+  // it should be supported at least on linux
+#if !defined(OS_LINUX)
+  if (status.IsNotSupported()) {
+    fprintf(stderr,
+            "skipping EnvPosixTest.MemoryMappedFileBuffer due to "
+            "unsupported Env::NewMemoryMappedFileBuffer\n");
+    return;
+  }
+#endif  // !defined(OS_LINUX)
+
+  ASSERT_OK(status);
+  ASSERT_NE(nullptr, mmap_buffer.get());
+  ASSERT_NE(nullptr, mmap_buffer->GetBase());
+  ASSERT_EQ(kFileBytes, mmap_buffer->GetLen());
+  std::string actual_data(reinterpret_cast<const char*>(mmap_buffer->GetBase()),
+                          mmap_buffer->GetLen());
+  ASSERT_EQ(expected_data, actual_data);
+}
+
+TEST_P(EnvPosixTestWithParam, UnSchedule) {
+  std::atomic<bool> called(false);
+  env_->SetBackgroundThreads(1, Env::LOW);
+
+  /* Block the low priority queue */
+  test::SleepingBackgroundTask sleeping_task, sleeping_task1;
+  env_->Schedule(&test::SleepingBackgroundTask::DoSleepTask, &sleeping_task,
+                 Env::Priority::LOW);
+
+  /* Schedule another task */
+  env_->Schedule(&test::SleepingBackgroundTask::DoSleepTask, &sleeping_task1,
+                 Env::Priority::LOW, &sleeping_task1);
+
+  /* Remove it with a different tag  */
+  ASSERT_EQ(0, env_->UnSchedule(&called, Env::Priority::LOW));
+
+  /* Remove it from the queue with the right tag */
+  ASSERT_EQ(1, env_->UnSchedule(&sleeping_task1, Env::Priority::LOW));
+
+  // Unblock background thread
+  sleeping_task.WakeUp();
+
+  /* Schedule another task */
+  env_->Schedule(&SetBool, &called);
+  for (int i = 0; i < kDelayMicros; i++) {
+    if (called.load()) {
+      break;
+    }
+    Env::Default()->SleepForMicroseconds(1);
+  }
+  ASSERT_TRUE(called.load());
+
+  ASSERT_TRUE(!sleeping_task.IsSleeping() && !sleeping_task1.IsSleeping());
+  WaitThreadPoolsEmpty();
+}
+
+// This tests assumes that the last scheduled
+// task will run last. In fact, in the allotted
+// sleeping time nothing may actually run or they may
+// run in any order. The purpose of the test is unclear.
+#ifndef OS_WIN
+TEST_P(EnvPosixTestWithParam, RunMany) {
+  std::atomic<int> last_id(0);
+
+  struct CB {
+    std::atomic<int>* last_id_ptr;  // Pointer to shared slot
+    int id;                         // Order# for the execution of this callback
+
+    CB(std::atomic<int>* p, int i) : last_id_ptr(p), id(i) {}
+
+    static void Run(void* v) {
+      CB* cb = reinterpret_cast<CB*>(v);
+      int cur = cb->last_id_ptr->load();
+      ASSERT_EQ(cb->id - 1, cur);
+      cb->last_id_ptr->store(cb->id);
+    }
+  };
+
+  // Schedule in different order than start time
+  CB cb1(&last_id, 1);
+  CB cb2(&last_id, 2);
+  CB cb3(&last_id, 3);
+  CB cb4(&last_id, 4);
+  env_->Schedule(&CB::Run, &cb1);
+  env_->Schedule(&CB::Run, &cb2);
+  env_->Schedule(&CB::Run, &cb3);
+  env_->Schedule(&CB::Run, &cb4);
+
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  int cur = last_id.load(std::memory_order_acquire);
+  ASSERT_EQ(4, cur);
+  WaitThreadPoolsEmpty();
+}
+#endif
+
+struct State {
+  port::Mutex mu;
+  int val;
+  int num_running;
+};
+
+static void ThreadBody(void* arg) {
+  State* s = reinterpret_cast<State*>(arg);
+  s->mu.Lock();
+  s->val += 1;
+  s->num_running -= 1;
+  s->mu.Unlock();
+}
+
+TEST_P(EnvPosixTestWithParam, StartThread) {
+  State state;
+  state.val = 0;
+  state.num_running = 3;
+  for (int i = 0; i < 3; i++) {
+    env_->StartThread(&ThreadBody, &state);
+  }
+  while (true) {
+    state.mu.Lock();
+    int num = state.num_running;
+    state.mu.Unlock();
+    if (num == 0) {
+      break;
+    }
+    Env::Default()->SleepForMicroseconds(kDelayMicros);
+  }
+  ASSERT_EQ(state.val, 3);
+  WaitThreadPoolsEmpty();
+}
+
+TEST_P(EnvPosixTestWithParam, TwoPools) {
+  // Data structures to signal tasks to run.
+  port::Mutex mutex;
+  port::CondVar cv(&mutex);
+  bool should_start = false;
+
+  class CB {
+   public:
+    CB(const std::string& pool_name, int pool_size, port::Mutex* trigger_mu,
+       port::CondVar* trigger_cv, bool* _should_start)
+        : mu_(),
+          num_running_(0),
+          num_finished_(0),
+          pool_size_(pool_size),
+          pool_name_(pool_name),
+          trigger_mu_(trigger_mu),
+          trigger_cv_(trigger_cv),
+          should_start_(_should_start) {}
+
+    static void Run(void* v) {
+      CB* cb = reinterpret_cast<CB*>(v);
+      cb->Run();
+    }
+
+    void Run() {
+      {
+        MutexLock l(&mu_);
+        num_running_++;
+        // make sure we don't have more than pool_size_ jobs running.
+        ASSERT_LE(num_running_, pool_size_.load());
+      }
+
+      {
+        MutexLock l(trigger_mu_);
+        while (!(*should_start_)) {
+          trigger_cv_->Wait();
+        }
+      }
+
+      {
+        MutexLock l(&mu_);
+        num_running_--;
+        num_finished_++;
+      }
+    }
+
+    int NumFinished() {
+      MutexLock l(&mu_);
+      return num_finished_;
+    }
+
+    void Reset(int pool_size) {
+      pool_size_.store(pool_size);
+      num_finished_ = 0;
+    }
+
+   private:
+    port::Mutex mu_;
+    int num_running_;
+    int num_finished_;
+    std::atomic<int> pool_size_;
+    std::string pool_name_;
+    port::Mutex* trigger_mu_;
+    port::CondVar* trigger_cv_;
+    bool* should_start_;
+  };
+
+  const int kLowPoolSize = 2;
+  const int kHighPoolSize = 4;
+  const int kJobs = 8;
+
+  CB low_pool_job("low", kLowPoolSize, &mutex, &cv, &should_start);
+  CB high_pool_job("high", kHighPoolSize, &mutex, &cv, &should_start);
+
+  env_->SetBackgroundThreads(kLowPoolSize);
+  env_->SetBackgroundThreads(kHighPoolSize, Env::Priority::HIGH);
+
+  ASSERT_EQ(0U, env_->GetThreadPoolQueueLen(Env::Priority::LOW));
+  ASSERT_EQ(0U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+
+  // schedule same number of jobs in each pool
+  for (int i = 0; i < kJobs; i++) {
+    env_->Schedule(&CB::Run, &low_pool_job);
+    env_->Schedule(&CB::Run, &high_pool_job, Env::Priority::HIGH);
+  }
+  // Wait a short while for the jobs to be dispatched.
+  int sleep_count = 0;
+  while ((unsigned int)(kJobs - kLowPoolSize) !=
+             env_->GetThreadPoolQueueLen(Env::Priority::LOW) ||
+         (unsigned int)(kJobs - kHighPoolSize) !=
+             env_->GetThreadPoolQueueLen(Env::Priority::HIGH)) {
+    env_->SleepForMicroseconds(kDelayMicros);
+    if (++sleep_count > 100) {
+      break;
+    }
+  }
+
+  ASSERT_EQ((unsigned int)(kJobs - kLowPoolSize),
+            env_->GetThreadPoolQueueLen());
+  ASSERT_EQ((unsigned int)(kJobs - kLowPoolSize),
+            env_->GetThreadPoolQueueLen(Env::Priority::LOW));
+  ASSERT_EQ((unsigned int)(kJobs - kHighPoolSize),
+            env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+
+  // Trigger jobs to run.
+  {
+    MutexLock l(&mutex);
+    should_start = true;
+    cv.SignalAll();
+  }
+
+  // wait for all jobs to finish
+  while (low_pool_job.NumFinished() < kJobs ||
+         high_pool_job.NumFinished() < kJobs) {
+    env_->SleepForMicroseconds(kDelayMicros);
+  }
+
+  ASSERT_EQ(0U, env_->GetThreadPoolQueueLen(Env::Priority::LOW));
+  ASSERT_EQ(0U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+
+  // Hold jobs to schedule;
+  should_start = false;
+
+  // call IncBackgroundThreadsIfNeeded to two pools. One increasing and
+  // the other decreasing
+  env_->IncBackgroundThreadsIfNeeded(kLowPoolSize - 1, Env::Priority::LOW);
+  env_->IncBackgroundThreadsIfNeeded(kHighPoolSize + 1, Env::Priority::HIGH);
+  high_pool_job.Reset(kHighPoolSize + 1);
+  low_pool_job.Reset(kLowPoolSize);
+
+  // schedule same number of jobs in each pool
+  for (int i = 0; i < kJobs; i++) {
+    env_->Schedule(&CB::Run, &low_pool_job);
+    env_->Schedule(&CB::Run, &high_pool_job, Env::Priority::HIGH);
+  }
+  // Wait a short while for the jobs to be dispatched.
+  sleep_count = 0;
+  while ((unsigned int)(kJobs - kLowPoolSize) !=
+             env_->GetThreadPoolQueueLen(Env::Priority::LOW) ||
+         (unsigned int)(kJobs - (kHighPoolSize + 1)) !=
+             env_->GetThreadPoolQueueLen(Env::Priority::HIGH)) {
+    env_->SleepForMicroseconds(kDelayMicros);
+    if (++sleep_count > 100) {
+      break;
+    }
+  }
+  ASSERT_EQ((unsigned int)(kJobs - kLowPoolSize),
+            env_->GetThreadPoolQueueLen());
+  ASSERT_EQ((unsigned int)(kJobs - kLowPoolSize),
+            env_->GetThreadPoolQueueLen(Env::Priority::LOW));
+  ASSERT_EQ((unsigned int)(kJobs - (kHighPoolSize + 1)),
+            env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+
+  // Trigger jobs to run.
+  {
+    MutexLock l(&mutex);
+    should_start = true;
+    cv.SignalAll();
+  }
+
+  // wait for all jobs to finish
+  while (low_pool_job.NumFinished() < kJobs ||
+         high_pool_job.NumFinished() < kJobs) {
+    env_->SleepForMicroseconds(kDelayMicros);
+  }
+
+  env_->SetBackgroundThreads(kHighPoolSize, Env::Priority::HIGH);
+  WaitThreadPoolsEmpty();
+}
+
+TEST_P(EnvPosixTestWithParam, DecreaseNumBgThreads) {
+  std::vector<test::SleepingBackgroundTask> tasks(10);
+
+  // Set number of thread to 1 first.
+  env_->SetBackgroundThreads(1, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+
+  // Schedule 3 tasks. 0 running; Task 1, 2 waiting.
+  for (size_t i = 0; i < 3; i++) {
+    env_->Schedule(&test::SleepingBackgroundTask::DoSleepTask, &tasks[i],
+                   Env::Priority::HIGH);
+    Env::Default()->SleepForMicroseconds(kDelayMicros);
+  }
+  ASSERT_EQ(2U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  ASSERT_TRUE(tasks[0].IsSleeping());
+  ASSERT_TRUE(!tasks[1].IsSleeping());
+  ASSERT_TRUE(!tasks[2].IsSleeping());
+
+  // Increase to 2 threads. Task 0, 1 running; 2 waiting
+  env_->SetBackgroundThreads(2, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ(1U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  ASSERT_TRUE(tasks[0].IsSleeping());
+  ASSERT_TRUE(tasks[1].IsSleeping());
+  ASSERT_TRUE(!tasks[2].IsSleeping());
+
+  // Shrink back to 1 thread. Still task 0, 1 running, 2 waiting
+  env_->SetBackgroundThreads(1, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ(1U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  ASSERT_TRUE(tasks[0].IsSleeping());
+  ASSERT_TRUE(tasks[1].IsSleeping());
+  ASSERT_TRUE(!tasks[2].IsSleeping());
+
+  // The last task finishes. Task 0 running, 2 waiting.
+  tasks[1].WakeUp();
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ(1U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  ASSERT_TRUE(tasks[0].IsSleeping());
+  ASSERT_TRUE(!tasks[1].IsSleeping());
+  ASSERT_TRUE(!tasks[2].IsSleeping());
+
+  // Increase to 5 threads. Task 0 and 2 running.
+  env_->SetBackgroundThreads(5, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ((unsigned int)0, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  ASSERT_TRUE(tasks[0].IsSleeping());
+  ASSERT_TRUE(tasks[2].IsSleeping());
+
+  // Change number of threads a couple of times while there is no sufficient
+  // tasks.
+  env_->SetBackgroundThreads(7, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  tasks[2].WakeUp();
+  ASSERT_EQ(0U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  env_->SetBackgroundThreads(3, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ(0U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  env_->SetBackgroundThreads(4, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ(0U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  env_->SetBackgroundThreads(5, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ(0U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  env_->SetBackgroundThreads(4, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ(0U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+
+  Env::Default()->SleepForMicroseconds(kDelayMicros * 50);
+
+  // Enqueue 5 more tasks. Thread pool size now is 4.
+  // Task 0, 3, 4, 5 running;6, 7 waiting.
+  for (size_t i = 3; i < 8; i++) {
+    env_->Schedule(&test::SleepingBackgroundTask::DoSleepTask, &tasks[i],
+                   Env::Priority::HIGH);
+  }
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ(2U, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  ASSERT_TRUE(tasks[3].IsSleeping());
+  ASSERT_TRUE(tasks[4].IsSleeping());
+  ASSERT_TRUE(tasks[5].IsSleeping());
+  ASSERT_TRUE(!tasks[6].IsSleeping());
+  ASSERT_TRUE(!tasks[7].IsSleeping());
+
+  // Wake up task 0, 3 and 4. Task 5, 6, 7 running.
+  tasks[0].WakeUp();
+  tasks[3].WakeUp();
+  tasks[4].WakeUp();
+
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ((unsigned int)0, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  for (size_t i = 5; i < 8; i++) {
+    ASSERT_TRUE(tasks[i].IsSleeping());
+  }
+
+  // Shrink back to 1 thread. Still task 5, 6, 7 running
+  env_->SetBackgroundThreads(1, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_TRUE(tasks[5].IsSleeping());
+  ASSERT_TRUE(tasks[6].IsSleeping());
+  ASSERT_TRUE(tasks[7].IsSleeping());
+
+  // Wake up task  6. Task 5, 7 running
+  tasks[6].WakeUp();
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_TRUE(tasks[5].IsSleeping());
+  ASSERT_TRUE(!tasks[6].IsSleeping());
+  ASSERT_TRUE(tasks[7].IsSleeping());
+
+  // Wake up threads 7. Task 5 running
+  tasks[7].WakeUp();
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_TRUE(!tasks[7].IsSleeping());
+
+  // Enqueue thread 8 and 9. Task 5 running; one of 8, 9 might be running.
+  env_->Schedule(&test::SleepingBackgroundTask::DoSleepTask, &tasks[8],
+                 Env::Priority::HIGH);
+  env_->Schedule(&test::SleepingBackgroundTask::DoSleepTask, &tasks[9],
+                 Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_GT(env_->GetThreadPoolQueueLen(Env::Priority::HIGH), (unsigned int)0);
+  ASSERT_TRUE(!tasks[8].IsSleeping() || !tasks[9].IsSleeping());
+
+  // Increase to 4 threads. Task 5, 8, 9 running.
+  env_->SetBackgroundThreads(4, Env::Priority::HIGH);
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_EQ((unsigned int)0, env_->GetThreadPoolQueueLen(Env::Priority::HIGH));
+  ASSERT_TRUE(tasks[8].IsSleeping());
+  ASSERT_TRUE(tasks[9].IsSleeping());
+
+  // Shrink to 1 thread
+  env_->SetBackgroundThreads(1, Env::Priority::HIGH);
+
+  // Wake up thread 9.
+  tasks[9].WakeUp();
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_TRUE(!tasks[9].IsSleeping());
+  ASSERT_TRUE(tasks[8].IsSleeping());
+
+  // Wake up thread 8
+  tasks[8].WakeUp();
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_TRUE(!tasks[8].IsSleeping());
+
+  // Wake up the last thread
+  tasks[5].WakeUp();
+
+  Env::Default()->SleepForMicroseconds(kDelayMicros);
+  ASSERT_TRUE(!tasks[5].IsSleeping());
+  WaitThreadPoolsEmpty();
+}
+
+#if (defined OS_LINUX || defined OS_WIN)
+// Travis doesn't support fallocate or getting unique ID from files for whatever
+// reason.
+#ifndef TRAVIS
+
+namespace {
+bool IsSingleVarint(const std::string& s) {
+  Slice slice(s);
+
+  uint64_t v;
+  if (!GetVarint64(&slice, &v)) {
+    return false;
+  }
+
+  return slice.size() == 0;
+}
+
+bool IsUniqueIDValid(const std::string& s) {
+  return !s.empty() && !IsSingleVarint(s);
+}
+
+const size_t MAX_ID_SIZE = 100;
+char temp_id[MAX_ID_SIZE];
+
+
+}  // namespace
+
+// Determine whether we can use the FS_IOC_GETVERSION ioctl
+// on a file in directory DIR.  Create a temporary file therein,
+// try to apply the ioctl (save that result), cleanup and
+// return the result.  Return true if it is supported, and
+// false if anything fails.
+// Note that this function "knows" that dir has just been created
+// and is empty, so we create a simply-named test file: "f".
+bool ioctl_support__FS_IOC_GETVERSION(const std::string& dir) {
+#ifdef OS_WIN
+  return true;
+#else
+  const std::string file = dir + "/f";
+  int fd;
+  do {
+    fd = open(file.c_str(), O_CREAT | O_RDWR | O_TRUNC, 0644);
+  } while (fd < 0 && errno == EINTR);
+  long int version;
+  bool ok = (fd >= 0 && ioctl(fd, FS_IOC_GETVERSION, &version) >= 0);
+
+  close(fd);
+  unlink(file.c_str());
+
+  return ok;
+#endif
+}
+
+// To ensure that Env::GetUniqueId-related tests work correctly, the files
+// should be stored in regular storage like "hard disk" or "flash device",
+// and not on a tmpfs file system (like /dev/shm and /tmp on some systems).
+// Otherwise we cannot get the correct id.
+//
+// This function serves as the replacement for test::TmpDir(), which may be
+// customized to be on a file system that doesn't work with GetUniqueId().
+
+class IoctlFriendlyTmpdir {
+ public:
+  explicit IoctlFriendlyTmpdir() {
+    char dir_buf[100];
+
+    const char *fmt = "%s/rocksdb.XXXXXX";
+    const char *tmp = getenv("TEST_IOCTL_FRIENDLY_TMPDIR");
+
+#ifdef OS_WIN
+#define rmdir _rmdir
+    if(tmp == nullptr) {
+      tmp = getenv("TMP");
+    }
+
+    snprintf(dir_buf, sizeof dir_buf, fmt, tmp);
+    auto result = _mktemp(dir_buf);
+    assert(result != nullptr);
+    BOOL ret = CreateDirectory(dir_buf, NULL);
+    assert(ret == TRUE);
+    dir_ = dir_buf;
+#else
+    std::list<std::string> candidate_dir_list = {"/var/tmp", "/tmp"};
+
+    // If $TEST_IOCTL_FRIENDLY_TMPDIR/rocksdb.XXXXXX fits, use
+    // $TEST_IOCTL_FRIENDLY_TMPDIR; subtract 2 for the "%s", and
+    // add 1 for the trailing NUL byte.
+    if (tmp && strlen(tmp) + strlen(fmt) - 2 + 1 <= sizeof dir_buf) {
+      // use $TEST_IOCTL_FRIENDLY_TMPDIR value
+      candidate_dir_list.push_front(tmp);
+    }
+
+    for (const std::string& d : candidate_dir_list) {
+      snprintf(dir_buf, sizeof dir_buf, fmt, d.c_str());
+      if (mkdtemp(dir_buf)) {
+        if (ioctl_support__FS_IOC_GETVERSION(dir_buf)) {
+          dir_ = dir_buf;
+          return;
+        } else {
+          // Diagnose ioctl-related failure only if this is the
+          // directory specified via that envvar.
+          if (tmp && tmp == d) {
+            fprintf(stderr, "TEST_IOCTL_FRIENDLY_TMPDIR-specified directory is "
+                    "not suitable: %s\n", d.c_str());
+          }
+          rmdir(dir_buf);  // ignore failure
+        }
+      } else {
+        // mkdtemp failed: diagnose it, but don't give up.
+        fprintf(stderr, "mkdtemp(%s/...) failed: %s\n", d.c_str(),
+                strerror(errno));
+      }
+    }
+
+    fprintf(stderr, "failed to find an ioctl-friendly temporary directory;"
+            " specify one via the TEST_IOCTL_FRIENDLY_TMPDIR envvar\n");
+    std::abort();
+#endif
+}
+
+  ~IoctlFriendlyTmpdir() {
+    rmdir(dir_.c_str());
+  }
+
+  const std::string& name() const {
+    return dir_;
+  }
+
+ private:
+  std::string dir_;
+};
+
+#ifndef ROCKSDB_LITE
+TEST_F(EnvPosixTest, PositionedAppend) {
+  std::unique_ptr<WritableFile> writable_file;
+  EnvOptions options;
+  options.use_direct_writes = true;
+  options.use_mmap_writes = false;
+  IoctlFriendlyTmpdir ift;
+  ASSERT_OK(env_->NewWritableFile(ift.name() + "/f", &writable_file, options));
+  const size_t kBlockSize = 4096;
+  const size_t kDataSize = kPageSize;
+  // Write a page worth of 'a'
+  auto data_ptr = NewAligned(kDataSize, 'a');
+  Slice data_a(data_ptr.get(), kDataSize);
+  ASSERT_OK(writable_file->PositionedAppend(data_a, 0U));
+  // Write a page worth of 'b' right after the first sector
+  data_ptr = NewAligned(kDataSize, 'b');
+  Slice data_b(data_ptr.get(), kDataSize);
+  ASSERT_OK(writable_file->PositionedAppend(data_b, kBlockSize));
+  ASSERT_OK(writable_file->Close());
+  // The file now has 1 sector worth of a followed by a page worth of b
+
+  // Verify the above
+  std::unique_ptr<SequentialFile> seq_file;
+  ASSERT_OK(env_->NewSequentialFile(ift.name() + "/f", &seq_file, options));
+  char scratch[kPageSize * 2];
+  Slice result;
+  ASSERT_OK(seq_file->Read(sizeof(scratch), &result, scratch));
+  ASSERT_EQ(kPageSize + kBlockSize, result.size());
+  ASSERT_EQ('a', result[kBlockSize - 1]);
+  ASSERT_EQ('b', result[kBlockSize]);
+}
+#endif  // !ROCKSDB_LITE
+
+// Only works in linux platforms
+TEST_P(EnvPosixTestWithParam, RandomAccessUniqueID) {
+  // Create file.
+  if (env_ == Env::Default()) {
+    EnvOptions soptions;
+    soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
+    IoctlFriendlyTmpdir ift;
+    std::string fname = ift.name() + "/testfile";
+    std::unique_ptr<WritableFile> wfile;
+    ASSERT_OK(env_->NewWritableFile(fname, &wfile, soptions));
+
+    std::unique_ptr<RandomAccessFile> file;
+
+    // Get Unique ID
+    ASSERT_OK(env_->NewRandomAccessFile(fname, &file, soptions));
+    size_t id_size = file->GetUniqueId(temp_id, MAX_ID_SIZE);
+    ASSERT_TRUE(id_size > 0);
+    std::string unique_id1(temp_id, id_size);
+    ASSERT_TRUE(IsUniqueIDValid(unique_id1));
+
+    // Get Unique ID again
+    ASSERT_OK(env_->NewRandomAccessFile(fname, &file, soptions));
+    id_size = file->GetUniqueId(temp_id, MAX_ID_SIZE);
+    ASSERT_TRUE(id_size > 0);
+    std::string unique_id2(temp_id, id_size);
+    ASSERT_TRUE(IsUniqueIDValid(unique_id2));
+
+    // Get Unique ID again after waiting some time.
+    env_->SleepForMicroseconds(1000000);
+    ASSERT_OK(env_->NewRandomAccessFile(fname, &file, soptions));
+    id_size = file->GetUniqueId(temp_id, MAX_ID_SIZE);
+    ASSERT_TRUE(id_size > 0);
+    std::string unique_id3(temp_id, id_size);
+    ASSERT_TRUE(IsUniqueIDValid(unique_id3));
+
+    // Check IDs are the same.
+    ASSERT_EQ(unique_id1, unique_id2);
+    ASSERT_EQ(unique_id2, unique_id3);
+
+    // Delete the file
+    env_->DeleteFile(fname);
+  }
+}
+
+// only works in linux platforms
+#ifdef ROCKSDB_FALLOCATE_PRESENT
+TEST_P(EnvPosixTestWithParam, AllocateTest) {
+  if (env_ == Env::Default()) {
+    IoctlFriendlyTmpdir ift;
+    std::string fname = ift.name() + "/preallocate_testfile";
+
+    // Try fallocate in a file to see whether the target file system supports
+    // it.
+    // Skip the test if fallocate is not supported.
+    std::string fname_test_fallocate = ift.name() + "/preallocate_testfile_2";
+    int fd = -1;
+    do {
+      fd = open(fname_test_fallocate.c_str(), O_CREAT | O_RDWR | O_TRUNC, 0644);
+    } while (fd < 0 && errno == EINTR);
+    ASSERT_GT(fd, 0);
+
+    int alloc_status = fallocate(fd, 0, 0, 1);
+
+    int err_number = 0;
+    if (alloc_status != 0) {
+      err_number = errno;
+      fprintf(stderr, "Warning: fallocate() fails, %s\n", strerror(err_number));
+    }
+    close(fd);
+    ASSERT_OK(env_->DeleteFile(fname_test_fallocate));
+    if (alloc_status != 0 && err_number == EOPNOTSUPP) {
+      // The filesystem containing the file does not support fallocate
+      return;
+    }
+
+    EnvOptions soptions;
+    soptions.use_mmap_writes = false;
+    soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
+    std::unique_ptr<WritableFile> wfile;
+    ASSERT_OK(env_->NewWritableFile(fname, &wfile, soptions));
+
+    // allocate 100 MB
+    size_t kPreallocateSize = 100 * 1024 * 1024;
+    size_t kBlockSize = 512;
+    size_t kPageSize = 4096;
+    size_t kDataSize = 1024 * 1024;
+    auto data_ptr = NewAligned(kDataSize, 'A');
+    Slice data(data_ptr.get(), kDataSize);
+    wfile->SetPreallocationBlockSize(kPreallocateSize);
+    wfile->PrepareWrite(wfile->GetFileSize(), kDataSize);
+    ASSERT_OK(wfile->Append(data));
+    ASSERT_OK(wfile->Flush());
+
+    struct stat f_stat;
+    ASSERT_EQ(stat(fname.c_str(), &f_stat), 0);
+    ASSERT_EQ((unsigned int)kDataSize, f_stat.st_size);
+    // verify that blocks are preallocated
+    // Note here that we don't check the exact number of blocks preallocated --
+    // we only require that number of allocated blocks is at least what we
+    // expect.
+    // It looks like some FS give us more blocks that we asked for. That's fine.
+    // It might be worth investigating further.
+    ASSERT_LE((unsigned int)(kPreallocateSize / kBlockSize), f_stat.st_blocks);
+
+    // close the file, should deallocate the blocks
+    wfile.reset();
+
+    stat(fname.c_str(), &f_stat);
+    ASSERT_EQ((unsigned int)kDataSize, f_stat.st_size);
+    // verify that preallocated blocks were deallocated on file close
+    // Because the FS might give us more blocks, we add a full page to the size
+    // and expect the number of blocks to be less or equal to that.
+    ASSERT_GE((f_stat.st_size + kPageSize + kBlockSize - 1) / kBlockSize,
+              (unsigned int)f_stat.st_blocks);
+  }
+}
+#endif  // ROCKSDB_FALLOCATE_PRESENT
+
+// Returns true if any of the strings in ss are the prefix of another string.
+bool HasPrefix(const std::unordered_set<std::string>& ss) {
+  for (const std::string& s: ss) {
+    if (s.empty()) {
+      return true;
+    }
+    for (size_t i = 1; i < s.size(); ++i) {
+      if (ss.count(s.substr(0, i)) != 0) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+// Only works in linux and WIN platforms
+TEST_P(EnvPosixTestWithParam, RandomAccessUniqueIDConcurrent) {
+  if (env_ == Env::Default()) {
+    // Check whether a bunch of concurrently existing files have unique IDs.
+    EnvOptions soptions;
+    soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
+
+    // Create the files
+    IoctlFriendlyTmpdir ift;
+    std::vector<std::string> fnames;
+    for (int i = 0; i < 1000; ++i) {
+      fnames.push_back(ift.name() + "/" + "testfile" + ToString(i));
+
+      // Create file.
+      std::unique_ptr<WritableFile> wfile;
+      ASSERT_OK(env_->NewWritableFile(fnames[i], &wfile, soptions));
+    }
+
+    // Collect and check whether the IDs are unique.
+    std::unordered_set<std::string> ids;
+    for (const std::string fname : fnames) {
+      std::unique_ptr<RandomAccessFile> file;
+      std::string unique_id;
+      ASSERT_OK(env_->NewRandomAccessFile(fname, &file, soptions));
+      size_t id_size = file->GetUniqueId(temp_id, MAX_ID_SIZE);
+      ASSERT_TRUE(id_size > 0);
+      unique_id = std::string(temp_id, id_size);
+      ASSERT_TRUE(IsUniqueIDValid(unique_id));
+
+      ASSERT_TRUE(ids.count(unique_id) == 0);
+      ids.insert(unique_id);
+    }
+
+    // Delete the files
+    for (const std::string fname : fnames) {
+      ASSERT_OK(env_->DeleteFile(fname));
+    }
+
+    ASSERT_TRUE(!HasPrefix(ids));
+  }
+}
+
+// Only works in linux and WIN platforms
+TEST_P(EnvPosixTestWithParam, RandomAccessUniqueIDDeletes) {
+  if (env_ == Env::Default()) {
+    EnvOptions soptions;
+    soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
+
+    IoctlFriendlyTmpdir ift;
+    std::string fname = ift.name() + "/" + "testfile";
+
+    // Check that after file is deleted we don't get same ID again in a new
+    // file.
+    std::unordered_set<std::string> ids;
+    for (int i = 0; i < 1000; ++i) {
+      // Create file.
+      {
+        std::unique_ptr<WritableFile> wfile;
+        ASSERT_OK(env_->NewWritableFile(fname, &wfile, soptions));
+      }
+
+      // Get Unique ID
+      std::string unique_id;
+      {
+        std::unique_ptr<RandomAccessFile> file;
+        ASSERT_OK(env_->NewRandomAccessFile(fname, &file, soptions));
+        size_t id_size = file->GetUniqueId(temp_id, MAX_ID_SIZE);
+        ASSERT_TRUE(id_size > 0);
+        unique_id = std::string(temp_id, id_size);
+      }
+
+      ASSERT_TRUE(IsUniqueIDValid(unique_id));
+      ASSERT_TRUE(ids.count(unique_id) == 0);
+      ids.insert(unique_id);
+
+      // Delete the file
+      ASSERT_OK(env_->DeleteFile(fname));
+    }
+
+    ASSERT_TRUE(!HasPrefix(ids));
+  }
+}
+
+// Only works in linux platforms
+#ifdef OS_WIN
+TEST_P(EnvPosixTestWithParam, DISABLED_InvalidateCache) {
+#else
+TEST_P(EnvPosixTestWithParam, InvalidateCache) {
+#endif
+  rocksdb::SyncPoint::GetInstance()->EnableProcessing();
+    EnvOptions soptions;
+    soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
+    std::string fname = test::PerThreadDBPath(env_, "testfile");
+
+    const size_t kSectorSize = 512;
+    auto data = NewAligned(kSectorSize, 0);
+    Slice slice(data.get(), kSectorSize);
+
+    // Create file.
+    {
+      std::unique_ptr<WritableFile> wfile;
+#if !defined(OS_MACOSX) && !defined(OS_WIN) && !defined(OS_SOLARIS) && !defined(OS_AIX)
+      if (soptions.use_direct_writes) {
+        soptions.use_direct_writes = false;
+      }
+#endif
+      ASSERT_OK(env_->NewWritableFile(fname, &wfile, soptions));
+      ASSERT_OK(wfile->Append(slice));
+      ASSERT_OK(wfile->InvalidateCache(0, 0));
+      ASSERT_OK(wfile->Close());
+    }
+
+    // Random Read
+    {
+      std::unique_ptr<RandomAccessFile> file;
+      auto scratch = NewAligned(kSectorSize, 0);
+      Slice result;
+#if !defined(OS_MACOSX) && !defined(OS_WIN) && !defined(OS_SOLARIS) && !defined(OS_AIX)
+      if (soptions.use_direct_reads) {
+        soptions.use_direct_reads = false;
+      }
+#endif
+      ASSERT_OK(env_->NewRandomAccessFile(fname, &file, soptions));
+      ASSERT_OK(file->Read(0, kSectorSize, &result, scratch.get()));
+      ASSERT_EQ(memcmp(scratch.get(), data.get(), kSectorSize), 0);
+      ASSERT_OK(file->InvalidateCache(0, 11));
+      ASSERT_OK(file->InvalidateCache(0, 0));
+    }
+
+    // Sequential Read
+    {
+      std::unique_ptr<SequentialFile> file;
+      auto scratch = NewAligned(kSectorSize, 0);
+      Slice result;
+#if !defined(OS_MACOSX) && !defined(OS_WIN) && !defined(OS_SOLARIS) && !defined(OS_AIX)
+      if (soptions.use_direct_reads) {
+        soptions.use_direct_reads = false;
+      }
+#endif
+      ASSERT_OK(env_->NewSequentialFile(fname, &file, soptions));
+      if (file->use_direct_io()) {
+        ASSERT_OK(file->PositionedRead(0, kSectorSize, &result, scratch.get()));
+      } else {
+        ASSERT_OK(file->Read(kSectorSize, &result, scratch.get()));
+      }
+      ASSERT_EQ(memcmp(scratch.get(), data.get(), kSectorSize), 0);
+      ASSERT_OK(file->InvalidateCache(0, 11));
+      ASSERT_OK(file->InvalidateCache(0, 0));
+    }
+    // Delete the file
+    ASSERT_OK(env_->DeleteFile(fname));
+  rocksdb::SyncPoint::GetInstance()->ClearTrace();
+}
+#endif  // not TRAVIS
+#endif  // OS_LINUX || OS_WIN
+
+class TestLogger : public Logger {
+ public:
+  using Logger::Logv;
+  void Logv(const char* format, va_list ap) override {
+    log_count++;
+
+    char new_format[550];
+    std::fill_n(new_format, sizeof(new_format), '2');
+    {
+      va_list backup_ap;
+      va_copy(backup_ap, ap);
+      int n = vsnprintf(new_format, sizeof(new_format) - 1, format, backup_ap);
+      // 48 bytes for extra information + bytes allocated
+
+// When we have n == -1 there is not a terminating zero expected
+#ifdef OS_WIN
+      if (n < 0) {
+        char_0_count++;
+      }
+#endif
+
+      if (new_format[0] == '[') {
+        // "[DEBUG] "
+        ASSERT_TRUE(n <= 56 + (512 - static_cast<int>(sizeof(struct timeval))));
+      } else {
+        ASSERT_TRUE(n <= 48 + (512 - static_cast<int>(sizeof(struct timeval))));
+      }
+      va_end(backup_ap);
+    }
+
+    for (size_t i = 0; i < sizeof(new_format); i++) {
+      if (new_format[i] == 'x') {
+        char_x_count++;
+      } else if (new_format[i] == '\0') {
+        char_0_count++;
+      }
+    }
+  }
+  int log_count;
+  int char_x_count;
+  int char_0_count;
+};
+
+TEST_P(EnvPosixTestWithParam, LogBufferTest) {
+  TestLogger test_logger;
+  test_logger.SetInfoLogLevel(InfoLogLevel::INFO_LEVEL);
+  test_logger.log_count = 0;
+  test_logger.char_x_count = 0;
+  test_logger.char_0_count = 0;
+  LogBuffer log_buffer(InfoLogLevel::INFO_LEVEL, &test_logger);
+  LogBuffer log_buffer_debug(DEBUG_LEVEL, &test_logger);
+
+  char bytes200[200];
+  std::fill_n(bytes200, sizeof(bytes200), '1');
+  bytes200[sizeof(bytes200) - 1] = '\0';
+  char bytes600[600];
+  std::fill_n(bytes600, sizeof(bytes600), '1');
+  bytes600[sizeof(bytes600) - 1] = '\0';
+  char bytes9000[9000];
+  std::fill_n(bytes9000, sizeof(bytes9000), '1');
+  bytes9000[sizeof(bytes9000) - 1] = '\0';
+
+  ROCKS_LOG_BUFFER(&log_buffer, "x%sx", bytes200);
+  ROCKS_LOG_BUFFER(&log_buffer, "x%sx", bytes600);
+  ROCKS_LOG_BUFFER(&log_buffer, "x%sx%sx%sx", bytes200, bytes200, bytes200);
+  ROCKS_LOG_BUFFER(&log_buffer, "x%sx%sx", bytes200, bytes600);
+  ROCKS_LOG_BUFFER(&log_buffer, "x%sx%sx", bytes600, bytes9000);
+
+  ROCKS_LOG_BUFFER(&log_buffer_debug, "x%sx", bytes200);
+  test_logger.SetInfoLogLevel(DEBUG_LEVEL);
+  ROCKS_LOG_BUFFER(&log_buffer_debug, "x%sx%sx%sx", bytes600, bytes9000,
+                   bytes200);
+
+  ASSERT_EQ(0, test_logger.log_count);
+  log_buffer.FlushBufferToLog();
+  log_buffer_debug.FlushBufferToLog();
+  ASSERT_EQ(6, test_logger.log_count);
+  ASSERT_EQ(6, test_logger.char_0_count);
+  ASSERT_EQ(10, test_logger.char_x_count);
+}
+
+class TestLogger2 : public Logger {
+ public:
+  explicit TestLogger2(size_t max_log_size) : max_log_size_(max_log_size) {}
+  using Logger::Logv;
+  void Logv(const char* format, va_list ap) override {
+    char new_format[2000];
+    std::fill_n(new_format, sizeof(new_format), '2');
+    {
+      va_list backup_ap;
+      va_copy(backup_ap, ap);
+      int n = vsnprintf(new_format, sizeof(new_format) - 1, format, backup_ap);
+      // 48 bytes for extra information + bytes allocated
+      ASSERT_TRUE(
+          n <= 48 + static_cast<int>(max_log_size_ - sizeof(struct timeval)));
+      ASSERT_TRUE(n > static_cast<int>(max_log_size_ - sizeof(struct timeval)));
+      va_end(backup_ap);
+    }
+  }
+  size_t max_log_size_;
+};
+
+TEST_P(EnvPosixTestWithParam, LogBufferMaxSizeTest) {
+  char bytes9000[9000];
+  std::fill_n(bytes9000, sizeof(bytes9000), '1');
+  bytes9000[sizeof(bytes9000) - 1] = '\0';
+
+  for (size_t max_log_size = 256; max_log_size <= 1024;
+       max_log_size += 1024 - 256) {
+    TestLogger2 test_logger(max_log_size);
+    test_logger.SetInfoLogLevel(InfoLogLevel::INFO_LEVEL);
+    LogBuffer log_buffer(InfoLogLevel::INFO_LEVEL, &test_logger);
+    ROCKS_LOG_BUFFER_MAX_SZ(&log_buffer, max_log_size, "%s", bytes9000);
+    log_buffer.FlushBufferToLog();
+  }
+}
+
+TEST_P(EnvPosixTestWithParam, Preallocation) {
+  rocksdb::SyncPoint::GetInstance()->EnableProcessing();
+  const std::string src = test::PerThreadDBPath(env_, "testfile");
+  std::unique_ptr<WritableFile> srcfile;
+  EnvOptions soptions;
+  soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
+#if !defined(OS_MACOSX) && !defined(OS_WIN) && !defined(OS_SOLARIS) && !defined(OS_AIX) && !defined(OS_OPENBSD) && !defined(OS_FREEBSD)
+    if (soptions.use_direct_writes) {
+      rocksdb::SyncPoint::GetInstance()->SetCallBack(
+          "NewWritableFile:O_DIRECT", [&](void* arg) {
+            int* val = static_cast<int*>(arg);
+            *val &= ~O_DIRECT;
+          });
+    }
+#endif
+    ASSERT_OK(env_->NewWritableFile(src, &srcfile, soptions));
+    srcfile->SetPreallocationBlockSize(1024 * 1024);
+
+    // No writes should mean no preallocation
+    size_t block_size, last_allocated_block;
+    srcfile->GetPreallocationStatus(&block_size, &last_allocated_block);
+    ASSERT_EQ(last_allocated_block, 0UL);
+
+    // Small write should preallocate one block
+    size_t kStrSize = 4096;
+    auto data = NewAligned(kStrSize, 'A');
+    Slice str(data.get(), kStrSize);
+    srcfile->PrepareWrite(srcfile->GetFileSize(), kStrSize);
+    srcfile->Append(str);
+    srcfile->GetPreallocationStatus(&block_size, &last_allocated_block);
+    ASSERT_EQ(last_allocated_block, 1UL);
+
+    // Write an entire preallocation block, make sure we increased by two.
+    {
+      auto buf_ptr = NewAligned(block_size, ' ');
+      Slice buf(buf_ptr.get(), block_size);
+      srcfile->PrepareWrite(srcfile->GetFileSize(), block_size);
+      srcfile->Append(buf);
+      srcfile->GetPreallocationStatus(&block_size, &last_allocated_block);
+      ASSERT_EQ(last_allocated_block, 2UL);
+    }
+
+    // Write five more blocks at once, ensure we're where we need to be.
+    {
+      auto buf_ptr = NewAligned(block_size * 5, ' ');
+      Slice buf = Slice(buf_ptr.get(), block_size * 5);
+      srcfile->PrepareWrite(srcfile->GetFileSize(), buf.size());
+      srcfile->Append(buf);
+      srcfile->GetPreallocationStatus(&block_size, &last_allocated_block);
+      ASSERT_EQ(last_allocated_block, 7UL);
+    }
+  rocksdb::SyncPoint::GetInstance()->ClearTrace();
+}
+
+// Test that the two ways to get children file attributes (in bulk or
+// individually) behave consistently.
+TEST_P(EnvPosixTestWithParam, ConsistentChildrenAttributes) {
+  rocksdb::SyncPoint::GetInstance()->EnableProcessing();
+    EnvOptions soptions;
+    soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
+    const int kNumChildren = 10;
+
+    std::string data;
+    for (int i = 0; i < kNumChildren; ++i) {
+      const std::string path =
+          test::TmpDir(env_) + "/" + "testfile_" + std::to_string(i);
+      std::unique_ptr<WritableFile> file;
+#if !defined(OS_MACOSX) && !defined(OS_WIN) && !defined(OS_SOLARIS) && !defined(OS_AIX) && !defined(OS_OPENBSD) && !defined(OS_FREEBSD)
+      if (soptions.use_direct_writes) {
+        rocksdb::SyncPoint::GetInstance()->SetCallBack(
+            "NewWritableFile:O_DIRECT", [&](void* arg) {
+              int* val = static_cast<int*>(arg);
+              *val &= ~O_DIRECT;
+            });
+      }
+#endif
+      ASSERT_OK(env_->NewWritableFile(path, &file, soptions));
+      auto buf_ptr = NewAligned(data.size(), 'T');
+      Slice buf(buf_ptr.get(), data.size());
+      file->Append(buf);
+      data.append(std::string(4096, 'T'));
+    }
+
+    std::vector<Env::FileAttributes> file_attrs;
+    ASSERT_OK(env_->GetChildrenFileAttributes(test::TmpDir(env_), &file_attrs));
+    for (int i = 0; i < kNumChildren; ++i) {
+      const std::string name = "testfile_" + std::to_string(i);
+      const std::string path = test::TmpDir(env_) + "/" + name;
+
+      auto file_attrs_iter = std::find_if(
+          file_attrs.begin(), file_attrs.end(),
+          [&name](const Env::FileAttributes& fm) { return fm.name == name; });
+      ASSERT_TRUE(file_attrs_iter != file_attrs.end());
+      uint64_t size;
+      ASSERT_OK(env_->GetFileSize(path, &size));
+      ASSERT_EQ(size, 4096 * i);
+      ASSERT_EQ(size, file_attrs_iter->size_bytes);
+    }
+    rocksdb::SyncPoint::GetInstance()->ClearTrace();
+}
+
+// Test that all WritableFileWrapper forwards all calls to WritableFile.
+TEST_P(EnvPosixTestWithParam, WritableFileWrapper) {
+  class Base : public WritableFile {
+   public:
+    mutable int *step_;
+
+    void inc(int x) const {
+      EXPECT_EQ(x, (*step_)++);
+    }
+
+    explicit Base(int* step) : step_(step) {
+      inc(0);
+    }
+
+    Status Append(const Slice& /*data*/) override {
+      inc(1);
+      return Status::OK();
+    }
+
+    Status PositionedAppend(const Slice& /*data*/,
+                            uint64_t /*offset*/) override {
+      inc(2);
+      return Status::OK();
+    }
+
+    Status Truncate(uint64_t /*size*/) override {
+      inc(3);
+      return Status::OK();
+    }
+
+    Status Close() override {
+      inc(4);
+      return Status::OK();
+    }
+
+    Status Flush() override {
+      inc(5);
+      return Status::OK();
+    }
+
+    Status Sync() override {
+      inc(6);
+      return Status::OK();
+    }
+
+    Status Fsync() override {
+      inc(7);
+      return Status::OK();
+    }
+
+    bool IsSyncThreadSafe() const override {
+      inc(8);
+      return true;
+    }
+
+    bool use_direct_io() const override {
+      inc(9);
+      return true;
+    }
+
+    size_t GetRequiredBufferAlignment() const override {
+      inc(10);
+      return 0;
+    }
+
+    void SetIOPriority(Env::IOPriority /*pri*/) override { inc(11); }
+
+    Env::IOPriority GetIOPriority() override {
+      inc(12);
+      return Env::IOPriority::IO_LOW;
+    }
+
+    void SetWriteLifeTimeHint(Env::WriteLifeTimeHint /*hint*/) override {
+      inc(13);
+    }
+
+    Env::WriteLifeTimeHint GetWriteLifeTimeHint() override {
+      inc(14);
+      return Env::WriteLifeTimeHint::WLTH_NOT_SET;
+    }
+
+    uint64_t GetFileSize() override {
+      inc(15);
+      return 0;
+    }
+
+    void SetPreallocationBlockSize(size_t /*size*/) override { inc(16); }
+
+    void GetPreallocationStatus(size_t* /*block_size*/,
+                                size_t* /*last_allocated_block*/) override {
+      inc(17);
+    }
+
+    size_t GetUniqueId(char* /*id*/, size_t /*max_size*/) const override {
+      inc(18);
+      return 0;
+    }
+
+    Status InvalidateCache(size_t /*offset*/, size_t /*length*/) override {
+      inc(19);
+      return Status::OK();
+    }
+
+    Status RangeSync(uint64_t /*offset*/, uint64_t /*nbytes*/) override {
+      inc(20);
+      return Status::OK();
+    }
+
+    void PrepareWrite(size_t /*offset*/, size_t /*len*/) override { inc(21); }
+
+    Status Allocate(uint64_t /*offset*/, uint64_t /*len*/) override {
+      inc(22);
+      return Status::OK();
+    }
+
+   public:
+    ~Base() override { inc(23); }
+  };
+
+  class Wrapper : public WritableFileWrapper {
+   public:
+    explicit Wrapper(WritableFile* target) : WritableFileWrapper(target) {}
+  };
+
+  int step = 0;
+
+  {
+    Base b(&step);
+    Wrapper w(&b);
+    w.Append(Slice());
+    w.PositionedAppend(Slice(), 0);
+    w.Truncate(0);
+    w.Close();
+    w.Flush();
+    w.Sync();
+    w.Fsync();
+    w.IsSyncThreadSafe();
+    w.use_direct_io();
+    w.GetRequiredBufferAlignment();
+    w.SetIOPriority(Env::IOPriority::IO_HIGH);
+    w.GetIOPriority();
+    w.SetWriteLifeTimeHint(Env::WriteLifeTimeHint::WLTH_NOT_SET);
+    w.GetWriteLifeTimeHint();
+    w.GetFileSize();
+    w.SetPreallocationBlockSize(0);
+    w.GetPreallocationStatus(nullptr, nullptr);
+    w.GetUniqueId(nullptr, 0);
+    w.InvalidateCache(0, 0);
+    w.RangeSync(0, 0);
+    w.PrepareWrite(0, 0);
+    w.Allocate(0, 0);
+  }
+
+  EXPECT_EQ(24, step);
+}
+
+TEST_P(EnvPosixTestWithParam, PosixRandomRWFile) {
+  const std::string path = test::PerThreadDBPath(env_, "random_rw_file");
+
+  env_->DeleteFile(path);
+
+  std::unique_ptr<RandomRWFile> file;
+
+  // Cannot open non-existing file.
+  ASSERT_NOK(env_->NewRandomRWFile(path, &file, EnvOptions()));
+
+  // Create the file using WriteableFile
+  {
+    std::unique_ptr<WritableFile> wf;
+    ASSERT_OK(env_->NewWritableFile(path, &wf, EnvOptions()));
+  }
+
+  ASSERT_OK(env_->NewRandomRWFile(path, &file, EnvOptions()));
+
+  char buf[10000];
+  Slice read_res;
+
+  ASSERT_OK(file->Write(0, "ABCD"));
+  ASSERT_OK(file->Read(0, 10, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "ABCD");
+
+  ASSERT_OK(file->Write(2, "XXXX"));
+  ASSERT_OK(file->Read(0, 10, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "ABXXXX");
+
+  ASSERT_OK(file->Write(10, "ZZZ"));
+  ASSERT_OK(file->Read(10, 10, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "ZZZ");
+
+  ASSERT_OK(file->Write(11, "Y"));
+  ASSERT_OK(file->Read(10, 10, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "ZYZ");
+
+  ASSERT_OK(file->Write(200, "FFFFF"));
+  ASSERT_OK(file->Read(200, 10, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "FFFFF");
+
+  ASSERT_OK(file->Write(205, "XXXX"));
+  ASSERT_OK(file->Read(200, 10, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "FFFFFXXXX");
+
+  ASSERT_OK(file->Write(5, "QQQQ"));
+  ASSERT_OK(file->Read(0, 9, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "ABXXXQQQQ");
+
+  ASSERT_OK(file->Read(2, 4, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "XXXQ");
+
+  // Close file and reopen it
+  file->Close();
+  ASSERT_OK(env_->NewRandomRWFile(path, &file, EnvOptions()));
+
+  ASSERT_OK(file->Read(0, 9, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "ABXXXQQQQ");
+
+  ASSERT_OK(file->Read(10, 3, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "ZYZ");
+
+  ASSERT_OK(file->Read(200, 9, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "FFFFFXXXX");
+
+  ASSERT_OK(file->Write(4, "TTTTTTTTTTTTTTTT"));
+  ASSERT_OK(file->Read(0, 10, &read_res, buf));
+  ASSERT_EQ(read_res.ToString(), "ABXXTTTTTT");
+
+  // Clean up
+  env_->DeleteFile(path);
+}
+
+class RandomRWFileWithMirrorString {
+ public:
+  explicit RandomRWFileWithMirrorString(RandomRWFile* _file) : file_(_file) {}
+
+  void Write(size_t offset, const std::string& data) {
+    // Write to mirror string
+    StringWrite(offset, data);
+
+    // Write to file
+    Status s = file_->Write(offset, data);
+    ASSERT_OK(s) << s.ToString();
+  }
+
+  void Read(size_t offset = 0, size_t n = 1000000) {
+    Slice str_res(nullptr, 0);
+    if (offset < file_mirror_.size()) {
+      size_t str_res_sz = std::min(file_mirror_.size() - offset, n);
+      str_res = Slice(file_mirror_.data() + offset, str_res_sz);
+      StopSliceAtNull(&str_res);
+    }
+
+    Slice file_res;
+    Status s = file_->Read(offset, n, &file_res, buf_);
+    ASSERT_OK(s) << s.ToString();
+    StopSliceAtNull(&file_res);
+
+    ASSERT_EQ(str_res.ToString(), file_res.ToString()) << offset << " " << n;
+  }
+
+  void SetFile(RandomRWFile* _file) { file_ = _file; }
+
+ private:
+  void StringWrite(size_t offset, const std::string& src) {
+    if (offset + src.size() > file_mirror_.size()) {
+      file_mirror_.resize(offset + src.size(), '\0');
+    }
+
+    char* pos = const_cast<char*>(file_mirror_.data() + offset);
+    memcpy(pos, src.data(), src.size());
+  }
+
+  void StopSliceAtNull(Slice* slc) {
+    for (size_t i = 0; i < slc->size(); i++) {
+      if ((*slc)[i] == '\0') {
+        *slc = Slice(slc->data(), i);
+        break;
+      }
+    }
+  }
+
+  char buf_[10000];
+  RandomRWFile* file_;
+  std::string file_mirror_;
+};
+
+TEST_P(EnvPosixTestWithParam, PosixRandomRWFileRandomized) {
+  const std::string path = test::PerThreadDBPath(env_, "random_rw_file_rand");
+  env_->DeleteFile(path);
+
+  std::unique_ptr<RandomRWFile> file;
+
+#ifdef OS_LINUX
+  // Cannot open non-existing file.
+  ASSERT_NOK(env_->NewRandomRWFile(path, &file, EnvOptions()));
+#endif
+
+  // Create the file using WriteableFile
+  {
+    std::unique_ptr<WritableFile> wf;
+    ASSERT_OK(env_->NewWritableFile(path, &wf, EnvOptions()));
+  }
+
+  ASSERT_OK(env_->NewRandomRWFile(path, &file, EnvOptions()));
+  RandomRWFileWithMirrorString file_with_mirror(file.get());
+
+  Random rnd(301);
+  std::string buf;
+  for (int i = 0; i < 10000; i++) {
+    // Genrate random data
+    test::RandomString(&rnd, 10, &buf);
+
+    // Pick random offset for write
+    size_t write_off = rnd.Next() % 1000;
+    file_with_mirror.Write(write_off, buf);
+
+    // Pick random offset for read
+    size_t read_off = rnd.Next() % 1000;
+    size_t read_sz = rnd.Next() % 20;
+    file_with_mirror.Read(read_off, read_sz);
+
+    if (i % 500 == 0) {
+      // Reopen the file every 500 iters
+      ASSERT_OK(env_->NewRandomRWFile(path, &file, EnvOptions()));
+      file_with_mirror.SetFile(file.get());
+    }
+  }
+
+  // clean up
+  env_->DeleteFile(path);
+}
+
+class TestEnv : public EnvWrapper {
+  public:
+    explicit TestEnv() : EnvWrapper(Env::Default()),
+                close_count(0) { }
+
+  class TestLogger : public Logger {
+   public:
+    using Logger::Logv;
+    TestLogger(TestEnv* env_ptr) : Logger() { env = env_ptr; }
+    ~TestLogger() override {
+      if (!closed_) {
+        CloseHelper();
+      }
+    }
+    void Logv(const char* /*format*/, va_list /*ap*/) override{};
+
+   protected:
+    Status CloseImpl() override { return CloseHelper(); }
+
+   private:
+    Status CloseHelper() {
+      env->CloseCountInc();;
+      return Status::OK();
+    }
+    TestEnv* env;
+  };
+
+  void CloseCountInc() { close_count++; }
+
+  int GetCloseCount() { return close_count; }
+
+  Status NewLogger(const std::string& /*fname*/,
+                   std::shared_ptr<Logger>* result) override {
+    result->reset(new TestLogger(this));
+    return Status::OK();
+  }
+
+ private:
+  int close_count;
+};
+
+class EnvTest : public testing::Test {};
+
+TEST_F(EnvTest, Close) {
+  TestEnv* env = new TestEnv();
+  std::shared_ptr<Logger> logger;
+  Status s;
+
+  s = env->NewLogger("", &logger);
+  ASSERT_EQ(s, Status::OK());
+  logger.get()->Close();
+  ASSERT_EQ(env->GetCloseCount(), 1);
+  // Call Close() again. CloseHelper() should not be called again
+  logger.get()->Close();
+  ASSERT_EQ(env->GetCloseCount(), 1);
+  logger.reset();
+  ASSERT_EQ(env->GetCloseCount(), 1);
+
+  s = env->NewLogger("", &logger);
+  ASSERT_EQ(s, Status::OK());
+  logger.reset();
+  ASSERT_EQ(env->GetCloseCount(), 2);
+
+  delete env;
+}
+
+INSTANTIATE_TEST_CASE_P(DefaultEnvWithoutDirectIO, EnvPosixTestWithParam,
+                        ::testing::Values(std::pair<Env*, bool>(Env::Default(),
+                                                                false)));
+#if !defined(ROCKSDB_LITE)
+INSTANTIATE_TEST_CASE_P(DefaultEnvWithDirectIO, EnvPosixTestWithParam,
+                        ::testing::Values(std::pair<Env*, bool>(Env::Default(),
+                                                                true)));
+#endif  // !defined(ROCKSDB_LITE)
+
+#if !defined(ROCKSDB_LITE) && !defined(OS_WIN)
+static std::unique_ptr<Env> chroot_env(
+    NewChrootEnv(Env::Default(), test::TmpDir(Env::Default())));
+INSTANTIATE_TEST_CASE_P(
+    ChrootEnvWithoutDirectIO, EnvPosixTestWithParam,
+    ::testing::Values(std::pair<Env*, bool>(chroot_env.get(), false)));
+INSTANTIATE_TEST_CASE_P(
+    ChrootEnvWithDirectIO, EnvPosixTestWithParam,
+    ::testing::Values(std::pair<Env*, bool>(chroot_env.get(), true)));
+#endif  // !defined(ROCKSDB_LITE) && !defined(OS_WIN)
+
+}  // namespace rocksdb
+
+int main(int argc, char** argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}