add subcompaction listener

db/compaction/compaction_job.cc

@@ -43,6 +43,7 @@
 #include "port/port.h"
 #include "rocksdb/db.h"
 #include "rocksdb/env.h"
+#include "rocksdb/listener.h"
 #include "rocksdb/sst_partitioner.h"
 #include "rocksdb/statistics.h"
 #include "rocksdb/status.h"
@@ -233,6 +234,8 @@ struct CompactionJob::SubcompactionState {
 
     return false;
   }
+
+  bool IsPartialCompaction() { return start || end; }
 };
 
 // Maintains state for the entire compaction
@@ -812,6 +815,19 @@ void CompactionJob::ProcessKeyValueCompaction(SubcompactionState* sub_compact) {
 
   ColumnFamilyData* cfd = sub_compact->compaction->column_family_data();
 
+#ifndef ROCKSDB_LITE
+  SubcompactionJobInfo info;
+  if (sub_compact->IsPartialCompaction()) {
+    info.cf_name = cfd->GetName();
+    info.thread_id = env_->GetThreadID();
+    info.base_input_level = sub_compact->compaction->start_level();
+    info.output_level = sub_compact->compaction->output_level();
+    for (auto listener : db_options_.listeners) {
+      listener->OnSubcompactionBegin(info);
+    }
+  }
+#endif  // !ROCKSDB_LITE
+
   // Create compaction filter and fail the compaction if
   // IgnoreSnapshots() = false because it is not supported anymore
   const CompactionFilter* compaction_filter =
@@ -1070,6 +1086,14 @@ void CompactionJob::ProcessKeyValueCompaction(SubcompactionState* sub_compact) {
   sub_compact->c_iter.reset();
   input.reset();
   sub_compact->status = status;
+#ifndef ROCKSDB_LITE
+  info.status = status;
+  if (sub_compact->IsPartialCompaction()) {
+    for (auto listener : db_options_.listeners) {
+      listener->OnSubcompactionCompleted(info);
+    }
+  }
+#endif  // !ROCKSDB_LITE
 }
 
 void CompactionJob::RecordDroppedKeys(

db/listener_test.cc

@@ -154,6 +154,59 @@ TEST_F(EventListenerTest, OnSingleDBCompactionTest) {
   }
 }
 
+class TestSubcompactionListener : public EventListener {
+ public:
+  TestSubcompactionListener() : compacted_(0) {}
+  void OnSubcompactionCompleted(const SubcompactionJobInfo& /*si*/) override {
+    compacted_.fetch_add(1);
+  }
+
+  std::atomic<int> compacted_;
+};
+
+TEST_F(EventListenerTest, OnSingleDBSubcompactionTest) {
+  const int kNumL0Files = 8;
+
+  Options options;
+  options.env = CurrentOptions().env;
+  options.create_if_missing = true;
+  options.max_subcompactions = 2;
+  options.compaction_style = kCompactionStyleLevel;
+  options.write_buffer_size = k110KB * 2;
+  options.target_file_size_base = options.write_buffer_size;
+  options.compression = kNoCompression;
+  options.level0_file_num_compaction_trigger = kNumL0Files;
+  options.table_properties_collector_factories.push_back(
+      std::make_shared<TestPropertiesCollectorFactory>());
+
+  TestSubcompactionListener* listener = new TestSubcompactionListener();
+  options.listeners.emplace_back(listener);
+  Reopen(options);
+  ASSERT_OK(Put("k1", std::string(90000, 'k')));
+  ASSERT_OK(Put("k4", std::string(90000, 'k')));
+  ASSERT_OK(dbfull()->CompactRange(
+      CompactRangeOptions(), db_->DefaultColumnFamily(), nullptr, nullptr));
+  // Three large files overlapped with L1 will trigger at least two
+  // subcompactions.
+  ASSERT_OK(Put("k1", std::string(90000, 'k')));
+  ASSERT_OK(Put("k2", std::string(90000, 'k')));
+  ASSERT_OK(Flush());
+  ASSERT_OK(Put("k2", std::string(90000, 'k')));
+  ASSERT_OK(Put("k3", std::string(90000, 'k')));
+  ASSERT_OK(Flush());
+  ASSERT_OK(Put("k3", std::string(90000, 'k')));
+  ASSERT_OK(Put("k4", std::string(90000, 'k')));
+  ASSERT_OK(Flush());
+  ASSERT_OK(dbfull()->RunManualCompaction(
+      reinterpret_cast<ColumnFamilyHandleImpl*>(db_->DefaultColumnFamily())
+          ->cfd(),
+      0 /* input_level */, 1 /* output_level */, CompactRangeOptions(),
+      nullptr /* begin */, nullptr /* end */, true /* exclusive */,
+      true /* disallow_trivial_move */,
+      port::kMaxUint64 /* max_file_num_to_ignore */));
+  ASSERT_EQ(listener->compacted_.load(), 2);
+}
+
 // This simple Listener can only handle one flush at a time.
 class TestFlushListener : public EventListener {
  public:

include/rocksdb/listener.h

@@ -233,6 +233,23 @@ struct CompactionJobInfo {
   CompactionJobStats stats;
 };
 
+struct SubcompactionJobInfo {
+  SubcompactionJobInfo() = default;
+
+  // the id of the column family where the compaction happened.
+  uint32_t cf_id;
+  // the name of the column family where the compaction happened.
+  std::string cf_name;
+  // the status indicating whether the compaction was successful or not.
+  Status status;
+  // the id of the thread that completed this compaction job.
+  uint64_t thread_id;
+  // the smallest input level of the compaction.
+  int base_input_level;
+  // the output level of the compaction.
+  int output_level;
+};
+
 struct MemTableInfo {
   // the name of the column family to which memtable belongs
   std::string cf_name;
@@ -345,6 +362,16 @@ class EventListener {
   virtual void OnCompactionCompleted(DB* /*db*/,
                                      const CompactionJobInfo& /*ci*/) {}
 
+  // A callback function for RocksDB which will be called each time when
+  // a registered RocksDB uses multiple subcompactions to compact a file. The
+  // callback is called by each subcompaction and in the same thread.
+  virtual void OnSubcompactionBegin(const SubcompactionJobInfo& /*si*/) {}
+
+  // A callback function for RocksDB which will be called each time when
+  // a registered RocksDB uses multiple subcompactions to compact a file. The
+  // callback is called by each subcompaction and in the same thread.
+  virtual void OnSubcompactionCompleted(const SubcompactionJobInfo& /*si*/) {}
+
   // A callback function for RocksDB which will be called whenever
   // a SST file is created.  Different from OnCompactionCompleted and
   // OnFlushCompleted, this callback is designed for external logging