Fix OnFlushCompleted fired before flush result write to MANIFEST (#5908)

Summary:
When there are concurrent flush job on the same CF, `OnFlushCompleted` can be called before the flush result being install to LSM. Fixing the issue by passing `FlushJobInfo` through `MemTable`, and the thread who commit the flush result can fetch the `FlushJobInfo` and fire `OnFlushCompleted` on behave of the thread actually writing the SST.

Fix https://github.com/facebook/rocksdb/issues/5892
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5908

Test Plan: Add new test. The test will fail without the fix.

Differential Revision: D17916144

Pulled By: riversand963

fbshipit-source-id: e18df67d9533b5baee52ae3605026cdeb05cbe10

HISTORY.md

@@ -9,6 +9,7 @@
 * Revert the feature "Merging iterator to avoid child iterator reseek for some cases (#5286)" since it might cause strong results when reseek happens with a different iterator upper bound.
 * Fix a bug causing a crash during ingest external file when background compaction cause severe error (file not found).
 * Fix a bug when partitioned filters and prefix search are used in conjunction, ::SeekForPrev could return invalid for an existing prefix. ::SeekForPrev might be called by the user, or internally on ::Prev, or within ::Seek if the return value involves Delete or a Merge operand.
+* Fix OnFlushCompleted fired before flush result persisted in MANIFEST when there's concurrent flush job. The bug exists since OnFlushCompleted was introduced in rocksdb 3.8.
 ### New Features
 * Introduced DBOptions::max_write_batch_group_size_bytes to configure maximum limit on number of bytes that are written in a single batch of WAL or memtable write. It is followed when the leader write size is larger than 1/8 of this limit.
 * VerifyChecksum() by default will issue readahead. Allow ReadOptions to be passed in to those functions to override the readhead size. For checksum verifying before external SST file ingestion, a new option IngestExternalFileOptions.verify_checksums_readahead_size, is added for this readahead setting.

db/db_flush_test.cc

@@ -7,10 +7,16 @@
 // 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 <atomic>
+
+#include "db/db_impl/db_impl.h"
 #include "db/db_test_util.h"
+#include "port/port.h"
 #include "port/stack_trace.h"
 #include "test_util/fault_injection_test_env.h"
 #include "test_util/sync_point.h"
+#include "util/cast_util.h"
+#include "util/mutexlock.h"
 
 namespace rocksdb {
 
@@ -323,6 +329,96 @@ TEST_F(DBFlushTest, CFDropRaceWithWaitForFlushMemTables) {
   SyncPoint::GetInstance()->DisableProcessing();
 }
 
+#ifndef ROCKSDB_LITE
+TEST_F(DBFlushTest, FireOnFlushCompletedAfterCommittedResult) {
+  class TestListener : public EventListener {
+   public:
+    void OnFlushCompleted(DB* db, const FlushJobInfo& info) override {
+      // There's only one key in each flush.
+      ASSERT_EQ(info.smallest_seqno, info.largest_seqno);
+      ASSERT_NE(0, info.smallest_seqno);
+      if (info.smallest_seqno == seq1) {
+        // First flush completed
+        ASSERT_FALSE(completed1);
+        completed1 = true;
+        CheckFlushResultCommitted(db, seq1);
+      } else {
+        // Second flush completed
+        ASSERT_FALSE(completed2);
+        completed2 = true;
+        ASSERT_EQ(info.smallest_seqno, seq2);
+        CheckFlushResultCommitted(db, seq2);
+      }
+    }
+
+    void CheckFlushResultCommitted(DB* db, SequenceNumber seq) {
+      DBImpl* db_impl = static_cast_with_check<DBImpl>(db);
+      InstrumentedMutex* mutex = db_impl->mutex();
+      mutex->Lock();
+      auto* cfd =
+          reinterpret_cast<ColumnFamilyHandleImpl*>(db->DefaultColumnFamily())
+              ->cfd();
+      ASSERT_LT(seq, cfd->imm()->current()->GetEarliestSequenceNumber());
+      mutex->Unlock();
+    }
+
+    std::atomic<SequenceNumber> seq1{0};
+    std::atomic<SequenceNumber> seq2{0};
+    std::atomic<bool> completed1{false};
+    std::atomic<bool> completed2{false};
+  };
+  std::shared_ptr<TestListener> listener = std::make_shared<TestListener>();
+
+  SyncPoint::GetInstance()->LoadDependency(
+      {{"DBImpl::FlushMemTable:AfterScheduleFlush",
+        "DBFlushTest::FireOnFlushCompletedAfterCommittedResult:WaitFirst"},
+       {"DBImpl::FlushMemTableToOutputFile:Finish",
+        "DBFlushTest::FireOnFlushCompletedAfterCommittedResult:WaitSecond"}});
+  SyncPoint::GetInstance()->SetCallBack(
+      "FlushJob::WriteLevel0Table", [&listener](void* arg) {
+        // Wait for the second flush finished, out of mutex.
+        auto* mems = reinterpret_cast<autovector<MemTable*>*>(arg);
+        if (mems->front()->GetEarliestSequenceNumber() == listener->seq1 - 1) {
+          TEST_SYNC_POINT(
+              "DBFlushTest::FireOnFlushCompletedAfterCommittedResult:"
+              "WaitSecond");
+        }
+      });
+
+  Options options = CurrentOptions();
+  options.create_if_missing = true;
+  options.listeners.push_back(listener);
+  // Setting max_flush_jobs = max_background_jobs / 4 = 2.
+  options.max_background_jobs = 8;
+  // Allow 2 immutable memtables.
+  options.max_write_buffer_number = 3;
+  Reopen(options);
+  SyncPoint::GetInstance()->EnableProcessing();
+  ASSERT_OK(Put("foo", "v"));
+  listener->seq1 = db_->GetLatestSequenceNumber();
+  // t1 will wait for the second flush complete before committing flush result.
+  auto t1 = port::Thread([&]() {
+    // flush_opts.wait = true
+    ASSERT_OK(db_->Flush(FlushOptions()));
+  });
+  // Wait for first flush scheduled.
+  TEST_SYNC_POINT(
+      "DBFlushTest::FireOnFlushCompletedAfterCommittedResult:WaitFirst");
+  // The second flush will exit early without commit its result. The work
+  // is delegated to the first flush.
+  ASSERT_OK(Put("bar", "v"));
+  listener->seq2 = db_->GetLatestSequenceNumber();
+  FlushOptions flush_opts;
+  flush_opts.wait = false;
+  ASSERT_OK(db_->Flush(flush_opts));
+  t1.join();
+  ASSERT_TRUE(listener->completed1);
+  ASSERT_TRUE(listener->completed2);
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->ClearAllCallBacks();
+}
+#endif  // !ROCKSDB_LITE
+
 TEST_P(DBAtomicFlushTest, ManualAtomicFlush) {
   Options options = CurrentOptions();
   options.create_if_missing = true;

db/db_impl/db_impl.h

@@ -1005,11 +1005,11 @@ class DBImpl : public DB {
 
   void NotifyOnFlushBegin(ColumnFamilyData* cfd, FileMetaData* file_meta,
                           const MutableCFOptions& mutable_cf_options,
-                          int job_id, TableProperties prop);
+                          int job_id);
 
-  void NotifyOnFlushCompleted(ColumnFamilyData* cfd, FileMetaData* file_meta,
+  void NotifyOnFlushCompleted(
-                              const MutableCFOptions& mutable_cf_options,
+      ColumnFamilyData* cfd, const MutableCFOptions& mutable_cf_options,
-                              int job_id, TableProperties prop);
+      std::list<std::unique_ptr<FlushJobInfo>>* flush_jobs_info);
 
   void NotifyOnCompactionBegin(ColumnFamilyData* cfd, Compaction* c,
                                const Status& st,

db/db_impl/db_impl_compaction_flush.cc

@@ -164,8 +164,7 @@ Status DBImpl::FlushMemTableToOutputFile(
 
 #ifndef ROCKSDB_LITE
   // may temporarily unlock and lock the mutex.
-  NotifyOnFlushBegin(cfd, &file_meta, mutable_cf_options, job_context->job_id,
+  NotifyOnFlushBegin(cfd, &file_meta, mutable_cf_options, job_context->job_id);
-                     flush_job.GetTableProperties());
 #endif  // ROCKSDB_LITE
 
   Status s;
@@ -213,8 +212,8 @@ Status DBImpl::FlushMemTableToOutputFile(
   if (s.ok()) {
 #ifndef ROCKSDB_LITE
     // may temporarily unlock and lock the mutex.
-    NotifyOnFlushCompleted(cfd, &file_meta, mutable_cf_options,
+    NotifyOnFlushCompleted(cfd, mutable_cf_options,
-                           job_context->job_id, flush_job.GetTableProperties());
+                           flush_job.GetCommittedFlushJobsInfo());
     auto sfm = static_cast<SstFileManagerImpl*>(
         immutable_db_options_.sst_file_manager.get());
     if (sfm) {
@@ -233,6 +232,7 @@ Status DBImpl::FlushMemTableToOutputFile(
     }
 #endif  // ROCKSDB_LITE
   }
+  TEST_SYNC_POINT("DBImpl::FlushMemTableToOutputFile:Finish");
   return s;
 }
 
@@ -303,7 +303,7 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
 
   autovector<Directory*> distinct_output_dirs;
   autovector<std::string> distinct_output_dir_paths;
-  std::vector<FlushJob> jobs;
+  std::vector<std::unique_ptr<FlushJob>> jobs;
   std::vector<MutableCFOptions> all_mutable_cf_options;
   int num_cfs = static_cast<int>(cfds.size());
   all_mutable_cf_options.reserve(num_cfs);
@@ -330,7 +330,7 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
     all_mutable_cf_options.emplace_back(*cfd->GetLatestMutableCFOptions());
     const MutableCFOptions& mutable_cf_options = all_mutable_cf_options.back();
     const uint64_t* max_memtable_id = &(bg_flush_args[i].max_memtable_id_);
-    jobs.emplace_back(
+    jobs.emplace_back(new FlushJob(
         dbname_, cfd, immutable_db_options_, mutable_cf_options,
         max_memtable_id, env_options_for_compaction_, versions_.get(), &mutex_,
         &shutting_down_, snapshot_seqs, earliest_write_conflict_snapshot,
@@ -338,8 +338,8 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
         data_dir, GetCompressionFlush(*cfd->ioptions(), mutable_cf_options),
         stats_, &event_logger_, mutable_cf_options.report_bg_io_stats,
         false /* sync_output_directory */, false /* write_manifest */,
-        thread_pri);
+        thread_pri));
-    jobs.back().PickMemTable();
+    jobs.back()->PickMemTable();
   }
 
   std::vector<FileMetaData> file_meta(num_cfs);
@@ -351,7 +351,7 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
     const MutableCFOptions& mutable_cf_options = all_mutable_cf_options.at(i);
     // may temporarily unlock and lock the mutex.
     NotifyOnFlushBegin(cfds[i], &file_meta[i], mutable_cf_options,
-                       job_context->job_id, jobs[i].GetTableProperties());
+                       job_context->job_id);
   }
 #endif /* !ROCKSDB_LITE */
 
@@ -373,7 +373,7 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
     // TODO (yanqin): parallelize jobs with threads.
     for (int i = 1; i != num_cfs; ++i) {
       exec_status[i].second =
-          jobs[i].Run(&logs_with_prep_tracker_, &file_meta[i]);
+          jobs[i]->Run(&logs_with_prep_tracker_, &file_meta[i]);
       exec_status[i].first = true;
     }
     if (num_cfs > 1) {
@@ -382,8 +382,10 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
       TEST_SYNC_POINT(
           "DBImpl::AtomicFlushMemTablesToOutputFiles:SomeFlushJobsComplete:2");
     }
+    assert(exec_status.size() > 0);
+    assert(!file_meta.empty());
     exec_status[0].second =
-        jobs[0].Run(&logs_with_prep_tracker_, &file_meta[0]);
+        jobs[0]->Run(&logs_with_prep_tracker_, &file_meta[0]);
     exec_status[0].first = true;
 
     Status error_status;
@@ -424,7 +426,7 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
     auto wait_to_install_func = [&]() {
       bool ready = true;
       for (size_t i = 0; i != cfds.size(); ++i) {
-        const auto& mems = jobs[i].GetMemTables();
+        const auto& mems = jobs[i]->GetMemTables();
         if (cfds[i]->IsDropped()) {
           // If the column family is dropped, then do not wait.
           continue;
@@ -465,7 +467,7 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
     autovector<const MutableCFOptions*> mutable_cf_options_list;
     autovector<FileMetaData*> tmp_file_meta;
     for (int i = 0; i != num_cfs; ++i) {
-      const auto& mems = jobs[i].GetMemTables();
+      const auto& mems = jobs[i]->GetMemTables();
       if (!cfds[i]->IsDropped() && !mems.empty()) {
         tmp_cfds.emplace_back(cfds[i]);
         mems_list.emplace_back(&mems);
@@ -501,12 +503,13 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
 #ifndef ROCKSDB_LITE
     auto sfm = static_cast<SstFileManagerImpl*>(
         immutable_db_options_.sst_file_manager.get());
+    assert(all_mutable_cf_options.size() == static_cast<size_t>(num_cfs));
     for (int i = 0; i != num_cfs; ++i) {
       if (cfds[i]->IsDropped()) {
         continue;
       }
-      NotifyOnFlushCompleted(cfds[i], &file_meta[i], all_mutable_cf_options[i],
+      NotifyOnFlushCompleted(cfds[i], all_mutable_cf_options[i],
-                             job_context->job_id, jobs[i].GetTableProperties());
+                             jobs[i]->GetCommittedFlushJobsInfo());
       if (sfm) {
         std::string file_path = MakeTableFileName(
             cfds[i]->ioptions()->cf_paths[0].path, file_meta[i].fd.GetNumber());
@@ -530,12 +533,12 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
     // unref the versions.
     for (int i = 0; i != num_cfs; ++i) {
       if (!exec_status[i].first) {
-        jobs[i].Cancel();
+        jobs[i]->Cancel();
       }
     }
     for (int i = 0; i != num_cfs; ++i) {
       if (exec_status[i].first && exec_status[i].second.ok()) {
-        auto& mems = jobs[i].GetMemTables();
+        auto& mems = jobs[i]->GetMemTables();
         cfds[i]->imm()->RollbackMemtableFlush(mems,
                                               file_meta[i].fd.GetNumber());
       }
@@ -549,7 +552,7 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
 
 void DBImpl::NotifyOnFlushBegin(ColumnFamilyData* cfd, FileMetaData* file_meta,
                                 const MutableCFOptions& mutable_cf_options,
-                                int job_id, TableProperties prop) {
+                                int job_id) {
 #ifndef ROCKSDB_LITE
   if (immutable_db_options_.listeners.size() == 0U) {
     return;
@@ -580,7 +583,6 @@ void DBImpl::NotifyOnFlushBegin(ColumnFamilyData* cfd, FileMetaData* file_meta,
     info.triggered_writes_stop = triggered_writes_stop;
     info.smallest_seqno = file_meta->fd.smallest_seqno;
     info.largest_seqno = file_meta->fd.largest_seqno;
-    info.table_properties = prop;
     info.flush_reason = cfd->GetFlushReason();
     for (auto listener : immutable_db_options_.listeners) {
       listener->OnFlushBegin(this, info);
@@ -594,15 +596,14 @@ void DBImpl::NotifyOnFlushBegin(ColumnFamilyData* cfd, FileMetaData* file_meta,
   (void)file_meta;
   (void)mutable_cf_options;
   (void)job_id;
-  (void)prop;
 #endif  // ROCKSDB_LITE
 }
 
-void DBImpl::NotifyOnFlushCompleted(ColumnFamilyData* cfd,
+void DBImpl::NotifyOnFlushCompleted(
-                                    FileMetaData* file_meta,
+    ColumnFamilyData* cfd, const MutableCFOptions& mutable_cf_options,
-                                    const MutableCFOptions& mutable_cf_options,
+    std::list<std::unique_ptr<FlushJobInfo>>* flush_jobs_info) {
-                                    int job_id, TableProperties prop) {
 #ifndef ROCKSDB_LITE
+  assert(flush_jobs_info != nullptr);
   if (immutable_db_options_.listeners.size() == 0U) {
     return;
   }
@@ -619,34 +620,22 @@ void DBImpl::NotifyOnFlushCompleted(ColumnFamilyData* cfd,
   // release lock while notifying events
   mutex_.Unlock();
   {
-    FlushJobInfo info;
+    for (auto& info : *flush_jobs_info) {
-    info.cf_id = cfd->GetID();
+      info->triggered_writes_slowdown = triggered_writes_slowdown;
-    info.cf_name = cfd->GetName();
+      info->triggered_writes_stop = triggered_writes_stop;
-    // TODO(yhchiang): make db_paths dynamic in case flush does not
-    //                 go to L0 in the future.
-    info.file_path = MakeTableFileName(cfd->ioptions()->cf_paths[0].path,
-                                       file_meta->fd.GetNumber());
-    info.thread_id = env_->GetThreadID();
-    info.job_id = job_id;
-    info.triggered_writes_slowdown = triggered_writes_slowdown;
-    info.triggered_writes_stop = triggered_writes_stop;
-    info.smallest_seqno = file_meta->fd.smallest_seqno;
-    info.largest_seqno = file_meta->fd.largest_seqno;
-    info.table_properties = prop;
-    info.flush_reason = cfd->GetFlushReason();
       for (auto listener : immutable_db_options_.listeners) {
-      listener->OnFlushCompleted(this, info);
+        listener->OnFlushCompleted(this, *info);
       }
     }
+    flush_jobs_info->clear();
+  }
   mutex_.Lock();
   // no need to signal bg_cv_ as it will be signaled at the end of the
   // flush process.
 #else
   (void)cfd;
-  (void)file_meta;
   (void)mutable_cf_options;
-  (void)job_id;
+  (void)flush_jobs_info;
-  (void)prop;
 #endif  // ROCKSDB_LITE
 }
 

db/flush_job.cc

@@ -241,7 +241,7 @@ Status FlushJob::Run(LogsWithPrepTracker* prep_tracker,
     s = cfd_->imm()->TryInstallMemtableFlushResults(
         cfd_, mutable_cf_options_, mems_, prep_tracker, versions_, db_mutex_,
         meta_.fd.GetNumber(), &job_context_->memtables_to_free, db_directory_,
-        log_buffer_);
+        log_buffer_, &committed_flush_jobs_info_);
   }
 
   if (s.ok() && file_meta != nullptr) {
@@ -392,7 +392,7 @@ Status FlushJob::WriteLevel0Table() {
     if (s.ok() && output_file_directory_ != nullptr && sync_output_directory_) {
       s = output_file_directory_->Fsync();
     }
-    TEST_SYNC_POINT("FlushJob::WriteLevel0Table");
+    TEST_SYNC_POINT_CALLBACK("FlushJob::WriteLevel0Table", &mems_);
     db_mutex_->Lock();
   }
   base_->Unref();
@@ -410,6 +410,10 @@ Status FlushJob::WriteLevel0Table() {
                    meta_.fd.smallest_seqno, meta_.fd.largest_seqno,
                    meta_.marked_for_compaction, meta_.oldest_blob_file_number);
   }
+#ifndef ROCKSDB_LITE
+  // Piggyback FlushJobInfo on the first first flushed memtable.
+  mems_[0]->SetFlushJobInfo(GetFlushJobInfo());
+#endif  // !ROCKSDB_LITE
 
   // Note that here we treat flush as level 0 compaction in internal stats
   InternalStats::CompactionStats stats(CompactionReason::kFlush, 1);
@@ -424,4 +428,22 @@ Status FlushJob::WriteLevel0Table() {
   return s;
 }
 
+#ifndef ROCKSDB_LITE
+std::unique_ptr<FlushJobInfo> FlushJob::GetFlushJobInfo() const {
+  db_mutex_->AssertHeld();
+  std::unique_ptr<FlushJobInfo> info(new FlushJobInfo);
+  info->cf_id = cfd_->GetID();
+  info->cf_name = cfd_->GetName();
+  info->file_path = MakeTableFileName(cfd_->ioptions()->cf_paths[0].path,
+                                      meta_.fd.GetNumber());
+  info->thread_id = db_options_.env->GetThreadID();
+  info->job_id = job_context_->job_id;
+  info->smallest_seqno = meta_.fd.smallest_seqno;
+  info->largest_seqno = meta_.fd.largest_seqno;
+  info->table_properties = table_properties_;
+  info->flush_reason = cfd_->GetFlushReason();
+  return info;
+}
+#endif  // !ROCKSDB_LITE
+
 }  // namespace rocksdb

db/flush_job.h

@@ -11,10 +11,11 @@
 #include <atomic>
 #include <deque>
 #include <limits>
+#include <list>
 #include <set>
+#include <string>
 #include <utility>
 #include <vector>
-#include <string>
 
 #include "db/column_family.h"
 #include "db/dbformat.h"
@@ -34,6 +35,7 @@
 #include "port/port.h"
 #include "rocksdb/db.h"
 #include "rocksdb/env.h"
+#include "rocksdb/listener.h"
 #include "rocksdb/memtablerep.h"
 #include "rocksdb/transaction_log.h"
 #include "table/scoped_arena_iterator.h"
@@ -79,14 +81,22 @@ class FlushJob {
   Status Run(LogsWithPrepTracker* prep_tracker = nullptr,
              FileMetaData* file_meta = nullptr);
   void Cancel();
-  TableProperties GetTableProperties() const { return table_properties_; }
   const autovector<MemTable*>& GetMemTables() const { return mems_; }
 
+#ifndef ROCKSDB_LITE
+  std::list<std::unique_ptr<FlushJobInfo>>* GetCommittedFlushJobsInfo() {
+    return &committed_flush_jobs_info_;
+  }
+#endif  // !ROCKSDB_LITE
+
  private:
   void ReportStartedFlush();
   void ReportFlushInputSize(const autovector<MemTable*>& mems);
   void RecordFlushIOStats();
   Status WriteLevel0Table();
+#ifndef ROCKSDB_LITE
+  std::unique_ptr<FlushJobInfo> GetFlushJobInfo() const;
+#endif  // !ROCKSDB_LITE
 
   const std::string& dbname_;
   ColumnFamilyData* cfd_;
@@ -131,6 +141,10 @@ class FlushJob {
   // In this case, only after all flush jobs succeed in flush can RocksDB
   // commit to the MANIFEST.
   const bool write_manifest_;
+  // The current flush job can commit flush result of a concurrent flush job.
+  // We collect FlushJobInfo of all jobs committed by current job and fire
+  // OnFlushCompleted for them.
+  std::list<std::unique_ptr<FlushJobInfo>> committed_flush_jobs_info_;
 
   // Variables below are set by PickMemTable():
   FileMetaData meta_;

db/flush_job_test.cc

@@ -347,18 +347,18 @@ TEST_F(FlushJobTest, FlushMemtablesMultipleColumnFamilies) {
 
   EventLogger event_logger(db_options_.info_log.get());
   SnapshotChecker* snapshot_checker = nullptr;  // not relevant
-  std::vector<FlushJob> flush_jobs;
+  std::vector<std::unique_ptr<FlushJob>> flush_jobs;
   k = 0;
   for (auto cfd : all_cfds) {
     std::vector<SequenceNumber> snapshot_seqs;
-    flush_jobs.emplace_back(
+    flush_jobs.emplace_back(new FlushJob(
         dbname_, cfd, db_options_, *cfd->GetLatestMutableCFOptions(),
         &memtable_ids[k], env_options_, versions_.get(), &mutex_,
         &shutting_down_, snapshot_seqs, kMaxSequenceNumber, snapshot_checker,
         &job_context, nullptr, nullptr, nullptr, kNoCompression,
         db_options_.statistics.get(), &event_logger, true,
         false /* sync_output_directory */, false /* write_manifest */,
-        Env::Priority::USER);
+        Env::Priority::USER));
     k++;
   }
   HistogramData hist;
@@ -367,12 +367,12 @@ TEST_F(FlushJobTest, FlushMemtablesMultipleColumnFamilies) {
   file_metas.reserve(flush_jobs.size());
   mutex_.Lock();
   for (auto& job : flush_jobs) {
-    job.PickMemTable();
+    job->PickMemTable();
   }
   for (auto& job : flush_jobs) {
     FileMetaData meta;
     // Run will release and re-acquire  mutex
-    ASSERT_OK(job.Run(nullptr /**/, &meta));
+    ASSERT_OK(job->Run(nullptr /**/, &meta));
     file_metas.emplace_back(meta);
   }
   autovector<FileMetaData*> file_meta_ptrs;
@@ -381,7 +381,7 @@ TEST_F(FlushJobTest, FlushMemtablesMultipleColumnFamilies) {
   }
   autovector<const autovector<MemTable*>*> mems_list;
   for (size_t i = 0; i != all_cfds.size(); ++i) {
-    const auto& mems = flush_jobs[i].GetMemTables();
+    const auto& mems = flush_jobs[i]->GetMemTables();
     mems_list.push_back(&mems);
   }
   autovector<const MutableCFOptions*> mutable_cf_options_list;

db/memtable.h

@@ -32,6 +32,7 @@
 
 namespace rocksdb {
 
+struct FlushJobInfo;
 class Mutex;
 class MemTableIterator;
 class MergeContext;
@@ -423,6 +424,16 @@ class MemTable {
     flush_in_progress_ = in_progress;
   }
 
+#ifndef ROCKSDB_LITE
+  void SetFlushJobInfo(std::unique_ptr<FlushJobInfo>&& info) {
+    flush_job_info_ = std::move(info);
+  }
+
+  std::unique_ptr<FlushJobInfo> ReleaseFlushJobInfo() {
+    return std::move(flush_job_info_);
+  }
+#endif  // !ROCKSDB_LITE
+
  private:
   enum FlushStateEnum { FLUSH_NOT_REQUESTED, FLUSH_REQUESTED, FLUSH_SCHEDULED };
 
@@ -505,6 +516,11 @@ class MemTable {
   // Gets refrshed inside `ApproximateMemoryUsage()` or `ShouldFlushNow`
   std::atomic<uint64_t> approximate_memory_usage_;
 
+#ifndef ROCKSDB_LITE
+  // Flush job info of the current memtable.
+  std::unique_ptr<FlushJobInfo> flush_job_info_;
+#endif  // !ROCKSDB_LITE
+
   // Returns a heuristic flush decision
   bool ShouldFlushNow();
 

db/memtable_list.cc

@@ -385,7 +385,8 @@ Status MemTableList::TryInstallMemtableFlushResults(
     const autovector<MemTable*>& mems, LogsWithPrepTracker* prep_tracker,
     VersionSet* vset, InstrumentedMutex* mu, uint64_t file_number,
     autovector<MemTable*>* to_delete, Directory* db_directory,
-    LogBuffer* log_buffer) {
+    LogBuffer* log_buffer,
+    std::list<std::unique_ptr<FlushJobInfo>>* committed_flush_jobs_info) {
   AutoThreadOperationStageUpdater stage_updater(
       ThreadStatus::STAGE_MEMTABLE_INSTALL_FLUSH_RESULTS);
   mu->AssertHeld();
@@ -443,6 +444,14 @@ Status MemTableList::TryInstallMemtableFlushResults(
                          cfd->GetName().c_str(), m->file_number_);
         edit_list.push_back(&m->edit_);
         memtables_to_flush.push_back(m);
+#ifndef ROCKSDB_LITE
+        std::unique_ptr<FlushJobInfo> info = m->ReleaseFlushJobInfo();
+        if (info != nullptr) {
+          committed_flush_jobs_info->push_back(std::move(info));
+        }
+#else
+        (void)committed_flush_jobs_info;
+#endif  // !ROCKSDB_LITE
       }
       batch_count++;
     }

db/memtable_list.h

@@ -33,6 +33,8 @@ class InstrumentedMutex;
 class MergeIteratorBuilder;
 class MemTableList;
 
+struct FlushJobInfo;
+
 // keeps a list of immutable memtables in a vector. the list is immutable
 // if refcount is bigger than one. It is used as a state for Get() and
 // Iterator code paths
@@ -254,7 +256,8 @@ class MemTableList {
       const autovector<MemTable*>& m, LogsWithPrepTracker* prep_tracker,
       VersionSet* vset, InstrumentedMutex* mu, uint64_t file_number,
       autovector<MemTable*>* to_delete, Directory* db_directory,
-      LogBuffer* log_buffer);
+      LogBuffer* log_buffer,
+      std::list<std::unique_ptr<FlushJobInfo>>* committed_flush_jobs_info);
 
   // New memtables are inserted at the front of the list.
   // Takes ownership of the referenced held on *m by the caller of Add().

db/memtable_list_test.cc

@@ -117,9 +117,11 @@ class MemTableListTest : public testing::Test {
     // Create dummy mutex.
     InstrumentedMutex mutex;
     InstrumentedMutexLock l(&mutex);
-    return list->TryInstallMemtableFlushResults(
+    std::list<std::unique_ptr<FlushJobInfo>> flush_jobs_info;
+    Status s = list->TryInstallMemtableFlushResults(
         cfd, mutable_cf_options, m, &dummy_prep_tracker, &versions, &mutex,
-        file_num, to_delete, nullptr, &log_buffer);
+        file_num, to_delete, nullptr, &log_buffer, &flush_jobs_info);
+    return s;
   }
 
   // Calls MemTableList::InstallMemtableFlushResults() and sets up all

include/rocksdb/listener.h

@@ -459,6 +459,7 @@ class EventListener {
 #else
 
 class EventListener {};
+struct FlushJobInfo {};
 
 #endif  // ROCKSDB_LITE