Add structures for exposing thread events and operations.

Summary:
Add structures for exposing events and operations.  Event describes
high-level action about a thread such as doing compaciton or
doing flush, while an operation describes lower-level action
of a thread such as reading / writing a SST table, waiting for
mutex.  Events and operations are designed to be independent.
One thread would typically involve in one event and one operation.

Code instrument will be in a separate diff.

Test Plan:
Add unit-tests in thread_list_test
make dbg -j32
./thread_list_test
export ROCKSDB_TESTS=ThreadList
./db_test

Reviewers: ljin, igor, sdong

Reviewed By: sdong

Subscribers: rven, jonahcohen, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D29781

db/db_test.cc

@@ -9435,10 +9435,10 @@ TEST(DBTest, GetThreadList) {
       env_->SleepForMicroseconds(100000);
       s = env_->GetThreadList(&thread_list);
       ASSERT_OK(s);
-      unsigned int thread_type_counts[ThreadStatus::ThreadType::TOTAL];
+      unsigned int thread_type_counts[ThreadStatus::NUM_THREAD_TYPES];
       memset(thread_type_counts, 0, sizeof(thread_type_counts));
       for (auto thread : thread_list) {
-        ASSERT_LT(thread.thread_type, ThreadStatus::ThreadType::TOTAL);
+        ASSERT_LT(thread.thread_type, ThreadStatus::NUM_THREAD_TYPES);
         thread_type_counts[thread.thread_type]++;
       }
       // Verify the total number of threades
@@ -9447,11 +9447,11 @@ TEST(DBTest, GetThreadList) {
           kHighPriCounts[test] + kLowPriCounts[test]);
       // Verify the number of high-priority threads
       ASSERT_EQ(
-          thread_type_counts[ThreadStatus::ThreadType::ROCKSDB_HIGH_PRIORITY],
+          thread_type_counts[ThreadStatus::HIGH_PRIORITY],
           kHighPriCounts[test]);
       // Verify the number of low-priority threads
       ASSERT_EQ(
-          thread_type_counts[ThreadStatus::ThreadType::ROCKSDB_LOW_PRIORITY],
+          thread_type_counts[ThreadStatus::LOW_PRIORITY],
           kLowPriCounts[test]);
     }
     if (i == 0) {

include/rocksdb/thread_status.h

@@ -2,6 +2,14 @@
 // This source code is licensed under the BSD-style license found in the
 // LICENSE file in the root directory of this source tree. An additional grant
 // of patent rights can be found in the PATENTS file in the same directory.
+//
+// This file defines the structures for exposing run-time status of any
+// rocksdb-related thread.  Such run-time status can be obtained via
+// GetThreadList() API.
+//
+// Note that all thread-status features are still under-development, and
+// thus APIs and class definitions might subject to change at this point.
+// Will remove this comment once the APIs have been finalized.
 
 #pragma once
 
@@ -22,29 +30,48 @@ namespace rocksdb {
 // The status of active threads can be fetched using
 // rocksdb::GetThreadList().
 struct ThreadStatus {
-  enum ThreadType {
+  // The type of a thread.
-    ROCKSDB_HIGH_PRIORITY = 0x0,
+  enum ThreadType : int {
-    ROCKSDB_LOW_PRIORITY = 0x1,
+    HIGH_PRIORITY = 0,  // RocksDB BG thread in high-pri thread pool
-    USER_THREAD = 0x2,
+    LOW_PRIORITY,  // RocksDB BG thread in low-pri thread pool
-    TOTAL = 0x3
+    USER,  // User thread (Non-RocksDB BG thread)
+    NUM_THREAD_TYPES
+  };
+
+  // The type used to refer to a thread operation.
+  // A thread operation describes high-level action of a thread.
+  // Examples include compaction and flush.
+  enum OperationType : int {
+    OP_UNKNOWN = 0,
+    OP_COMPACTION,
+    OP_FLUSH,
+    NUM_OP_TYPES
+  };
+
+  // The type used to refer to a thread state.
+  // A state describes lower-level action of a thread
+  // such as reading / writing a file or waiting for a mutex.
+  enum StateType : int {
+    STATE_UNKNOWN = 0,
+    NUM_STATE_TYPES
   };
 
-#if ROCKSDB_USING_THREAD_STATUS
   ThreadStatus(const uint64_t _id,
                const ThreadType _thread_type,
                const std::string& _db_name,
                const std::string& _cf_name,
-               const std::string& _event) :
+               const OperationType _operation_type,
+               const StateType _state_type) :
       thread_id(_id), thread_type(_thread_type),
       db_name(_db_name),
       cf_name(_cf_name),
-      event(_event) {}
+      operation_type(_operation_type), state_type(_state_type) {}
 
   // An unique ID for the thread.
   const uint64_t thread_id;
 
-  // The type of the thread, it could be ROCKSDB_HIGH_PRIORITY,
+  // The type of the thread, it could be HIGH_PRIORITY,
-  // ROCKSDB_LOW_PRIORITY, and USER_THREAD
+  // LOW_PRIORITY, and USER
   const ThreadType thread_type;
 
   // The name of the DB instance where the thread is currently
@@ -57,11 +84,11 @@ struct ThreadStatus {
   // in any column family.
   const std::string cf_name;
 
-  // The event that the current thread is involved.
+  // The operation (high-level action) that the current thread is involved.
-  // It would be set to empty string if the information about event
+  const OperationType operation_type;
-  // is not currently available.
+
-  const std::string event;
+  // The state (lower-level action) that the current thread is involved.
-#endif  // ROCKSDB_USING_THREAD_STATUS
+  const StateType state_type;
 };
 
 }  // namespace rocksdb

util/env_posix.cc

@@ -1694,8 +1694,8 @@ class PosixEnv : public Env {
       // for thread-status
       ThreadStatusUtil::SetThreadType(tp->env_,
           (tp->GetThreadPriority() == Env::Priority::HIGH ?
-              ThreadStatus::ThreadType::ROCKSDB_HIGH_PRIORITY :
+              ThreadStatus::HIGH_PRIORITY :
-              ThreadStatus::ThreadType::ROCKSDB_LOW_PRIORITY));
+              ThreadStatus::LOW_PRIORITY));
 #endif
       delete meta;
       tp->BGThread(thread_id);

util/thread_list_test.cc

@@ -14,46 +14,65 @@
 
 namespace rocksdb {
 
-class SleepingBackgroundTask {
+class SimulatedBackgroundTask {
  public:
-  SleepingBackgroundTask(const void* db_key, const std::string& db_name,
+  SimulatedBackgroundTask(
-                         const void* cf_key, const std::string& cf_name)
+      const void* db_key, const std::string& db_name,
+      const void* cf_key, const std::string& cf_name,
+      const ThreadStatus::OperationType operation_type =
+          ThreadStatus::OP_UNKNOWN,
+      const ThreadStatus::StateType state_type =
+          ThreadStatus::STATE_UNKNOWN)
       : db_key_(db_key), db_name_(db_name),
         cf_key_(cf_key), cf_name_(cf_name),
-        should_sleep_(true), sleeping_count_(0) {
+        operation_type_(operation_type), state_type_(state_type),
+        should_run_(true), running_count_(0) {
     Env::Default()->GetThreadStatusUpdater()->NewColumnFamilyInfo(
         db_key_, db_name_, cf_key_, cf_name_);
   }
 
-  ~SleepingBackgroundTask() {
+  ~SimulatedBackgroundTask() {
     Env::Default()->GetThreadStatusUpdater()->EraseDatabaseInfo(db_key_);
   }
 
-  void DoSleep() {
+  void Run() {
-    Env::Default()->GetThreadStatusUpdater()->SetColumnFamilyInfoKey(cf_key_);
     std::unique_lock<std::mutex> l(mutex_);
-    sleeping_count_++;
+    running_count_++;
-    while (should_sleep_) {
+    Env::Default()->GetThreadStatusUpdater()->SetColumnFamilyInfoKey(cf_key_);
+    Env::Default()->GetThreadStatusUpdater()->SetThreadOperation(
+        operation_type_);
+    Env::Default()->GetThreadStatusUpdater()->SetThreadState(state_type_);
+    while (should_run_) {
       bg_cv_.wait(l);
     }
-    sleeping_count_--;
+    Env::Default()->GetThreadStatusUpdater()->ClearThreadState();
-    bg_cv_.notify_all();
+    Env::Default()->GetThreadStatusUpdater()->ClearThreadOperation();
     Env::Default()->GetThreadStatusUpdater()->SetColumnFamilyInfoKey(0);
+    running_count_--;
+    bg_cv_.notify_all();
   }
-  void WakeUp() {
+
+  void FinishAllTasks() {
     std::unique_lock<std::mutex> l(mutex_);
-    should_sleep_ = false;
+    should_run_ = false;
     bg_cv_.notify_all();
   }
+
+  void WaitUntilScheduled(int job_count, Env* env) {
+    while (running_count_ < job_count) {
+      env->SleepForMicroseconds(1000);
+    }
+  }
+
   void WaitUntilDone() {
     std::unique_lock<std::mutex> l(mutex_);
-    while (sleeping_count_ > 0) {
+    while (running_count_ > 0) {
       bg_cv_.wait(l);
     }
   }
 
-  static void DoSleepTask(void* arg) {
+  static void DoSimulatedTask(void* arg) {
-    reinterpret_cast<SleepingBackgroundTask*>(arg)->DoSleep();
+    reinterpret_cast<SimulatedBackgroundTask*>(arg)->Run();
   }
 
  private:
@@ -61,10 +80,12 @@ class SleepingBackgroundTask {
   const std::string db_name_;
   const void* cf_key_;
   const std::string cf_name_;
+  const ThreadStatus::OperationType operation_type_;
+  const ThreadStatus::StateType state_type_;
   std::mutex mutex_;
   std::condition_variable bg_cv_;
-  bool should_sleep_;
+  bool should_run_;
-  std::atomic<int> sleeping_count_;
+  std::atomic<int> running_count_;
 };
 
 class ThreadListTest {
@@ -73,72 +94,232 @@ class ThreadListTest {
   }
 };
 
+TEST(ThreadListTest, EventTables) {
+  // verify the global tables for operations and states are properly indexed.
+  for (int type = 0; type != ThreadStatus::NUM_OP_TYPES; ++type) {
+    ASSERT_EQ(global_operation_table[type].type, type);
+  }
+
+  for (int type = 0; type != ThreadStatus::NUM_STATE_TYPES; ++type) {
+    ASSERT_EQ(global_state_table[type].type, type);
+  }
+}
+
 TEST(ThreadListTest, SimpleColumnFamilyInfoTest) {
   Env* env = Env::Default();
   const int kHighPriorityThreads = 3;
   const int kLowPriorityThreads = 5;
-  const int kSleepingHighPriThreads = kHighPriorityThreads - 1;
+  const int kSimulatedHighPriThreads = kHighPriorityThreads - 1;
-  const int kSleepingLowPriThreads = kLowPriorityThreads / 3;
+  const int kSimulatedLowPriThreads = kLowPriorityThreads / 3;
   env->SetBackgroundThreads(kHighPriorityThreads, Env::HIGH);
   env->SetBackgroundThreads(kLowPriorityThreads, Env::LOW);
 
-  SleepingBackgroundTask sleeping_task(
+  SimulatedBackgroundTask running_task(
-      reinterpret_cast<void*>(1234), "sleeping",
+      reinterpret_cast<void*>(1234), "running",
       reinterpret_cast<void*>(5678), "pikachu");
 
-  for (int test = 0; test < kSleepingHighPriThreads; ++test) {
+  for (int test = 0; test < kSimulatedHighPriThreads; ++test) {
-    env->Schedule(&SleepingBackgroundTask::DoSleepTask,
+    env->Schedule(&SimulatedBackgroundTask::DoSimulatedTask,
-        &sleeping_task, Env::Priority::HIGH);
+        &running_task, Env::Priority::HIGH);
   }
-  for (int test = 0; test < kSleepingLowPriThreads; ++test) {
+  for (int test = 0; test < kSimulatedLowPriThreads; ++test) {
-    env->Schedule(&SleepingBackgroundTask::DoSleepTask,
+    env->Schedule(&SimulatedBackgroundTask::DoSimulatedTask,
-        &sleeping_task, Env::Priority::LOW);
+        &running_task, Env::Priority::LOW);
   }
-
+  running_task.WaitUntilScheduled(
-  // make sure everything is scheduled.
+      kSimulatedHighPriThreads + kSimulatedLowPriThreads, env);
-  env->SleepForMicroseconds(10000);
 
   std::vector<ThreadStatus> thread_list;
 
-  // Verify the number of sleeping threads in each pool.
+  // Verify the number of running threads in each pool.
   env->GetThreadList(&thread_list);
-  int sleeping_count[ThreadStatus::ThreadType::TOTAL] = {0};
+  int running_count[ThreadStatus::NUM_THREAD_TYPES] = {0};
   for (auto thread_status : thread_list) {
     if (thread_status.cf_name == "pikachu" &&
-        thread_status.db_name == "sleeping") {
+        thread_status.db_name == "running") {
-      sleeping_count[thread_status.thread_type]++;
+      running_count[thread_status.thread_type]++;
     }
   }
   ASSERT_EQ(
-      sleeping_count[ThreadStatus::ThreadType::ROCKSDB_HIGH_PRIORITY],
+      running_count[ThreadStatus::HIGH_PRIORITY],
-      kSleepingHighPriThreads);
+      kSimulatedHighPriThreads);
   ASSERT_EQ(
-      sleeping_count[ThreadStatus::ThreadType::ROCKSDB_LOW_PRIORITY],
+      running_count[ThreadStatus::LOW_PRIORITY],
-      kSleepingLowPriThreads);
+      kSimulatedLowPriThreads);
   ASSERT_EQ(
-      sleeping_count[ThreadStatus::ThreadType::USER_THREAD], 0);
+      running_count[ThreadStatus::USER], 0);
 
-  sleeping_task.WakeUp();
+  running_task.FinishAllTasks();
-  sleeping_task.WaitUntilDone();
+  running_task.WaitUntilDone();
 
-  // Verify none of the threads are sleeping
+  // Verify none of the threads are running
   env->GetThreadList(&thread_list);
-  for (int i = 0; i < ThreadStatus::ThreadType::TOTAL; ++i) {
-    sleeping_count[i] = 0;
-  }
 
+  for (int i = 0; i < ThreadStatus::NUM_THREAD_TYPES; ++i) {
+    running_count[i] = 0;
+  }
   for (auto thread_status : thread_list) {
     if (thread_status.cf_name == "pikachu" &&
-        thread_status.db_name == "sleeping") {
+        thread_status.db_name == "running") {
-      sleeping_count[thread_status.thread_type]++;
+      running_count[thread_status.thread_type]++;
     }
   }
+
   ASSERT_EQ(
-      sleeping_count[ThreadStatus::ThreadType::ROCKSDB_HIGH_PRIORITY], 0);
+      running_count[ThreadStatus::HIGH_PRIORITY], 0);
   ASSERT_EQ(
-      sleeping_count[ThreadStatus::ThreadType::ROCKSDB_LOW_PRIORITY], 0);
+      running_count[ThreadStatus::LOW_PRIORITY], 0);
   ASSERT_EQ(
-      sleeping_count[ThreadStatus::ThreadType::USER_THREAD], 0);
+      running_count[ThreadStatus::USER], 0);
+}
+
+namespace {
+  void UpdateStatusCounts(
+      const std::vector<ThreadStatus>& thread_list,
+      int operation_counts[], int state_counts[]) {
+    for (auto thread_status : thread_list) {
+      operation_counts[thread_status.operation_type]++;
+      state_counts[thread_status.state_type]++;
+    }
+  }
+
+  void VerifyAndResetCounts(
+      const int correct_counts[], int collected_counts[], int size) {
+    for (int i = 0; i < size; ++i) {
+      ASSERT_EQ(collected_counts[i], correct_counts[i]);
+      collected_counts[i] = 0;
+    }
+  }
+
+  void UpdateCount(
+      int operation_counts[], int from_event, int to_event, int amount) {
+    operation_counts[from_event] -= amount;
+    operation_counts[to_event] += amount;
+  }
+}  // namespace
+
+TEST(ThreadListTest, SimpleEventTest) {
+  Env* env = Env::Default();
+
+  // simulated tasks
+  const int kFlushWriteTasks = 3;
+  SimulatedBackgroundTask flush_write_task(
+      reinterpret_cast<void*>(1234), "running",
+      reinterpret_cast<void*>(5678), "pikachu",
+      ThreadStatus::OP_FLUSH);
+
+  const int kCompactionWriteTasks = 4;
+  SimulatedBackgroundTask compaction_write_task(
+      reinterpret_cast<void*>(1234), "running",
+      reinterpret_cast<void*>(5678), "pikachu",
+      ThreadStatus::OP_COMPACTION);
+
+  const int kCompactionReadTasks = 5;
+  SimulatedBackgroundTask compaction_read_task(
+      reinterpret_cast<void*>(1234), "running",
+      reinterpret_cast<void*>(5678), "pikachu",
+      ThreadStatus::OP_COMPACTION);
+
+  const int kCompactionWaitTasks = 6;
+  SimulatedBackgroundTask compaction_wait_task(
+      reinterpret_cast<void*>(1234), "running",
+      reinterpret_cast<void*>(5678), "pikachu",
+      ThreadStatus::OP_COMPACTION);
+
+  // setup right answers
+  int correct_operation_counts[ThreadStatus::NUM_OP_TYPES] = {0};
+  correct_operation_counts[ThreadStatus::OP_FLUSH] =
+      kFlushWriteTasks;
+  correct_operation_counts[ThreadStatus::OP_COMPACTION] =
+      kCompactionWriteTasks + kCompactionReadTasks + kCompactionWaitTasks;
+
+  env->SetBackgroundThreads(
+      correct_operation_counts[ThreadStatus::OP_FLUSH], Env::HIGH);
+  env->SetBackgroundThreads(
+      correct_operation_counts[ThreadStatus::OP_COMPACTION], Env::LOW);
+
+  // schedule the simulated tasks
+  for (int t = 0; t < kFlushWriteTasks; ++t) {
+    env->Schedule(&SimulatedBackgroundTask::DoSimulatedTask,
+        &flush_write_task, Env::Priority::HIGH);
+  }
+  flush_write_task.WaitUntilScheduled(kFlushWriteTasks, env);
+
+  for (int t = 0; t < kCompactionWriteTasks; ++t) {
+    env->Schedule(&SimulatedBackgroundTask::DoSimulatedTask,
+        &compaction_write_task, Env::Priority::LOW);
+  }
+  compaction_write_task.WaitUntilScheduled(kCompactionWriteTasks, env);
+
+  for (int t = 0; t < kCompactionReadTasks; ++t) {
+    env->Schedule(&SimulatedBackgroundTask::DoSimulatedTask,
+        &compaction_read_task, Env::Priority::LOW);
+  }
+  compaction_read_task.WaitUntilScheduled(kCompactionReadTasks, env);
+
+  for (int t = 0; t < kCompactionWaitTasks; ++t) {
+    env->Schedule(&SimulatedBackgroundTask::DoSimulatedTask,
+        &compaction_wait_task, Env::Priority::LOW);
+  }
+  compaction_wait_task.WaitUntilScheduled(kCompactionWaitTasks, env);
+
+  // verify the thread-status
+  int operation_counts[ThreadStatus::NUM_OP_TYPES] = {0};
+  int state_counts[ThreadStatus::NUM_STATE_TYPES] = {0};
+
+  std::vector<ThreadStatus> thread_list;
+  env->GetThreadList(&thread_list);
+  UpdateStatusCounts(thread_list, operation_counts, state_counts);
+  VerifyAndResetCounts(correct_operation_counts, operation_counts,
+                       ThreadStatus::NUM_OP_TYPES);
+
+  // terminate compaction-wait tasks and see if the thread-status
+  // reflects this update
+  compaction_wait_task.FinishAllTasks();
+  compaction_wait_task.WaitUntilDone();
+  UpdateCount(correct_operation_counts, ThreadStatus::OP_COMPACTION,
+              ThreadStatus::OP_UNKNOWN, kCompactionWaitTasks);
+
+  env->GetThreadList(&thread_list);
+  UpdateStatusCounts(thread_list, operation_counts, state_counts);
+  VerifyAndResetCounts(correct_operation_counts, operation_counts,
+                       ThreadStatus::NUM_OP_TYPES);
+
+  // terminate flush-write tasks and see if the thread-status
+  // reflects this update
+  flush_write_task.FinishAllTasks();
+  flush_write_task.WaitUntilDone();
+  UpdateCount(correct_operation_counts, ThreadStatus::OP_FLUSH,
+              ThreadStatus::OP_UNKNOWN, kFlushWriteTasks);
+
+  env->GetThreadList(&thread_list);
+  UpdateStatusCounts(thread_list, operation_counts, state_counts);
+  VerifyAndResetCounts(correct_operation_counts, operation_counts,
+                       ThreadStatus::NUM_OP_TYPES);
+
+  // terminate compaction-write tasks and see if the thread-status
+  // reflects this update
+  compaction_write_task.FinishAllTasks();
+  compaction_write_task.WaitUntilDone();
+  UpdateCount(correct_operation_counts, ThreadStatus::OP_COMPACTION,
+              ThreadStatus::OP_UNKNOWN, kCompactionWriteTasks);
+
+  env->GetThreadList(&thread_list);
+  UpdateStatusCounts(thread_list, operation_counts, state_counts);
+  VerifyAndResetCounts(correct_operation_counts, operation_counts,
+                       ThreadStatus::NUM_OP_TYPES);
+
+  // terminate compaction-write tasks and see if the thread-status
+  // reflects this update
+  compaction_read_task.FinishAllTasks();
+  compaction_read_task.WaitUntilDone();
+  UpdateCount(correct_operation_counts, ThreadStatus::OP_COMPACTION,
+              ThreadStatus::OP_UNKNOWN, kCompactionReadTasks);
+
+  env->GetThreadList(&thread_list);
+  UpdateStatusCounts(thread_list, operation_counts, state_counts);
+  VerifyAndResetCounts(correct_operation_counts, operation_counts,
+                       ThreadStatus::NUM_OP_TYPES);
 }
 
 }  // namespace rocksdb

util/thread_operation.h

@@ -0,0 +1,68 @@
+// Copyright (c) 2013, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+//
+// This file defines the structures for thread operation and state.
+// Thread operations are used to describe high level action of a
+// thread such as doing compaction or flush, while thread state
+// are used to describe lower-level action such as reading /
+// writing a file or waiting for a mutex.  Operations and states
+// are designed to be independent.  Typically, a thread usually involves
+// in one operation and one state at any specific point in time.
+
+#pragma once
+
+#include "include/rocksdb/thread_status.h"
+
+#include <string>
+
+namespace rocksdb {
+
+#if ROCKSDB_USING_THREAD_STATUS
+
+// The structure that describes a major thread operation.
+struct OperationInfo {
+  const ThreadStatus::OperationType type;
+  const std::string name;
+};
+
+// The global operation table.
+//
+// When updating a status of a thread, the pointer of the OperationInfo
+// of the current ThreadStatusData will be pointing to one of the
+// rows in this global table.
+//
+// Note that it's not designed to be constant as in the future we
+// might consider adding global count to the OperationInfo.
+static OperationInfo global_operation_table[] = {
+  {ThreadStatus::OP_UNKNOWN, ""},
+  {ThreadStatus::OP_COMPACTION, "Compaction"},
+  {ThreadStatus::OP_FLUSH, "Flush"}
+};
+
+// The structure that describes a state.
+struct StateInfo {
+  const ThreadStatus::StateType type;
+  const std::string name;
+};
+
+// The global state table.
+//
+// When updating a status of a thread, the pointer of the StateInfo
+// of the current ThreadStatusData will be pointing to one of the
+// rows in this global table.
+static StateInfo global_state_table[] = {
+  {ThreadStatus::STATE_UNKNOWN, ""},
+};
+
+#else
+
+struct OperationInfo {
+};
+
+struct StateInfo {
+};
+
+#endif  // ROCKSDB_USING_THREAD_STATUS
+}  // namespace rocksdb

util/thread_status_updater.cc

@@ -34,10 +34,28 @@ void ThreadStatusUpdater::SetColumnFamilyInfoKey(
   data->cf_key.store(cf_key, std::memory_order_relaxed);
 }
 
-void ThreadStatusUpdater::SetEventInfoPtr(
+void ThreadStatusUpdater::SetThreadOperation(
-    const ThreadEventInfo* event_info) {
+    const ThreadStatus::OperationType type) {
   auto* data = InitAndGet();
-  data->event_info.store(event_info, std::memory_order_relaxed);
+  data->operation_type.store(type, std::memory_order_relaxed);
+}
+
+void ThreadStatusUpdater::ClearThreadOperation() {
+  auto* data = InitAndGet();
+  data->operation_type.store(
+      ThreadStatus::OP_UNKNOWN, std::memory_order_relaxed);
+}
+
+void ThreadStatusUpdater::SetThreadState(
+    const ThreadStatus::StateType type) {
+  auto* data = InitAndGet();
+  data->state_type.store(type, std::memory_order_relaxed);
+}
+
+void ThreadStatusUpdater::ClearThreadState() {
+  auto* data = InitAndGet();
+  data->state_type.store(
+      ThreadStatus::STATE_UNKNOWN, std::memory_order_relaxed);
 }
 
 Status ThreadStatusUpdater::GetThreadList(
@@ -50,30 +68,35 @@ Status ThreadStatusUpdater::GetThreadList(
     assert(thread_data);
     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);
     auto iter = cf_info_map_.find(cf_key);
     assert(cf_key == 0 || iter != cf_info_map_.end());
     auto* cf_info = iter != cf_info_map_.end() ?
         iter->second.get() : nullptr;
-    auto* event_info = thread_data->event_info.load(
-        std::memory_order_relaxed);
     const std::string* db_name = nullptr;
     const std::string* cf_name = nullptr;
-    const std::string* event_name = nullptr;
+    ThreadStatus::OperationType op_type = ThreadStatus::OP_UNKNOWN;
+    ThreadStatus::StateType state_type = ThreadStatus::STATE_UNKNOWN;
     if (cf_info != nullptr) {
       db_name = &cf_info->db_name;
       cf_name = &cf_info->cf_name;
+      op_type = thread_data->operation_type.load(
+          std::memory_order_relaxed);
       // display lower-level info only when higher-level info is available.
-      if (event_info != nullptr) {
+      if (op_type != ThreadStatus::OP_UNKNOWN) {
-        event_name = &event_info->event_name;
+        state_type = thread_data->state_type.load(
+            std::memory_order_relaxed);
       }
     }
     thread_list->emplace_back(
         thread_data->thread_id, thread_type,
         db_name ? *db_name : "",
         cf_name ? *cf_name : "",
-        event_name ? *event_name : "");
+        op_type, state_type);
   }
 
   return Status::OK();
@@ -93,6 +116,8 @@ ThreadStatusData* ThreadStatusUpdater::InitAndGet() {
 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_[cf_key].reset(
@@ -101,6 +126,8 @@ void ThreadStatusUpdater::NewColumnFamilyInfo(
 }
 
 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);
   assert(cf_pair != cf_info_map_.end());
@@ -122,6 +149,8 @@ void ThreadStatusUpdater::EraseColumnFamilyInfo(const void* cf_key) {
 }
 
 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())) {
@@ -154,8 +183,18 @@ void ThreadStatusUpdater::SetColumnFamilyInfoKey(
     const void* cf_key) {
 }
 
-void ThreadStatusUpdater::SetEventInfoPtr(
+void ThreadStatusUpdater::SetThreadOperation(
-    const ThreadEventInfo* event_info) {
+    const ThreadStatus::OperationType type) {
+}
+
+void ThreadStatusUpdater::ClearThreadOperation() {
+}
+
+void ThreadStatusUpdater::SetThreadState(
+    const ThreadStatus::StateType type) {
+}
+
+void ThreadStatusUpdater::ClearThreadState() {
 }
 
 Status ThreadStatusUpdater::GetThreadList(

util/thread_status_updater.h

@@ -22,7 +22,7 @@
 //    should be ignored.
 //
 // The high to low level information would be:
-// thread_id > thread_type > db > cf > event > event_count > event_details
+// 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.
@@ -37,6 +37,7 @@
 #include "rocksdb/status.h"
 #include "rocksdb/thread_status.h"
 #include "port/port_posix.h"
+#include "util/thread_operation.h"
 
 namespace rocksdb {
 
@@ -57,27 +58,21 @@ struct ConstantColumnFamilyInfo {
 #endif  // ROCKSDB_USING_THREAD_STATUS
 };
 
-// The structure that describes an event.
-struct ThreadEventInfo {
-#if ROCKSDB_USING_THREAD_STATUS
- public:
-  const std::string event_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 {
 #if ROCKSDB_USING_THREAD_STATUS
   explicit ThreadStatusData() : thread_id(0) {
-    thread_type.store(ThreadStatus::ThreadType::USER_THREAD);
+    thread_type.store(ThreadStatus::USER);
     cf_key.store(0);
-    event_info.store(nullptr);
+    operation_type.store(ThreadStatus::OP_UNKNOWN);
+    state_type.store(ThreadStatus::STATE_UNKNOWN);
   }
   uint64_t thread_id;
   std::atomic<ThreadStatus::ThreadType> thread_type;
   std::atomic<const void*> cf_key;
-  std::atomic<const ThreadEventInfo*> event_info;
+  std::atomic<ThreadStatus::OperationType> operation_type;
+  std::atomic<ThreadStatus::StateType> state_type;
 #endif  // ROCKSDB_USING_THREAD_STATUS
 };
 
@@ -103,12 +98,20 @@ class ThreadStatusUpdater {
   void SetThreadType(ThreadStatus::ThreadType ttype);
 
   // Update the column-family info of the current thread by setting
-  // its thread-local pointer of ThreadEventInfo to the correct entry.
+  // its thread-local pointer of ThreadStateInfo to the correct entry.
   void SetColumnFamilyInfoKey(const void* cf_key);
 
-  // Update the event info of the current thread by setting
+  // Update the thread operation of the current thread.
-  // its thread-local pointer of ThreadEventInfo to the correct entry.
+  void SetThreadOperation(const ThreadStatus::OperationType type);
-  void SetEventInfoPtr(const ThreadEventInfo* event_info);
+
+  // Clear thread operation of the current thread.
+  void ClearThreadOperation();
+
+  // 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(