Code cleanup for trace replayer (#8652)

Summary:
- Remove extra `;` in trace_record.h
- Remove some unnecessary `assert` in trace_record_handler.cc
- Initialize `env_` after` exec_handler_` in `ReplayerImpl` to let db be asserted in creating the handler before getting `db->GetEnv()`.
- Update history to include the new `TraceReader::Reset()`

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8652

Reviewed By: ajkr

Differential Revision: D30276872

Pulled By: autopear

fbshipit-source-id: 476ee162e0f241490c6209307448343a5b326b37

HISTORY.md

@@ -18,7 +18,7 @@
 * Fast forward option in Trace replay changed to double type to allow replaying at a lower speed, by settings the value between 0 and 1. This option can be set via `ReplayOptions` in `Replayer::Replay()`, or via `--trace_replay_fast_forward` in db_bench.
 
 ## Public API change
-* Added APIs to decode and replay trace file via Replayer class. Added `DB::NewDefaultReplayer()` to create a default Replayer instance. Created trace_record.h and utilities/replayer.h files to access decoded Trace records and replay them.
+* Added APIs to decode and replay trace file via Replayer class. Added `DB::NewDefaultReplayer()` to create a default Replayer instance. Added `TraceReader::Reset()` to restart reading a trace file. Created trace_record.h and utilities/replayer.h files to access decoded Trace records and replay them.
 
 ### Performance Improvements
 * Try to avoid updating DBOptions if `SetDBOptions()` does not change any option value.

include/rocksdb/trace_record.h

@@ -95,7 +95,7 @@ class WriteQueryTraceRecord : public QueryTraceRecord {
 
   virtual ~WriteQueryTraceRecord() override;
 
-  TraceType GetTraceType() const override { return kTraceWrite; };
+  TraceType GetTraceType() const override { return kTraceWrite; }
 
   virtual Slice GetWriteBatchRep() const;
 
@@ -116,7 +116,7 @@ class GetQueryTraceRecord : public QueryTraceRecord {
 
   virtual ~GetQueryTraceRecord() override;
 
-  TraceType GetTraceType() const override { return kTraceGet; };
+  TraceType GetTraceType() const override { return kTraceGet; }
 
   virtual uint32_t GetColumnFamilyID() const;
 
@@ -187,7 +187,7 @@ class MultiGetQueryTraceRecord : public QueryTraceRecord {
 
   virtual ~MultiGetQueryTraceRecord() override;
 
-  TraceType GetTraceType() const override { return kTraceMultiGet; };
+  TraceType GetTraceType() const override { return kTraceMultiGet; }
 
   virtual std::vector<uint32_t> GetColumnFamilyIDs() const;
 

trace_replay/trace_record_handler.cc

@@ -38,7 +38,6 @@ Status TraceExecutionHandler::Handle(const GetQueryTraceRecord& record) {
   if (it == cf_map_.end()) {
     return Status::Corruption("Invalid Column Family ID.");
   }
-  assert(it->second != nullptr);
 
   std::string value;
   Status s = db_->Get(read_opts_, it->second, record.GetKey(), &value);
@@ -53,7 +52,6 @@ Status TraceExecutionHandler::Handle(
   if (it == cf_map_.end()) {
     return Status::Corruption("Invalid Column Family ID.");
   }
-  assert(it->second != nullptr);
 
   Iterator* single_iter = db_->NewIterator(read_opts_, it->second);
 
@@ -80,7 +78,6 @@ Status TraceExecutionHandler::Handle(const MultiGetQueryTraceRecord& record) {
     if (it == cf_map_.end()) {
       return Status::Corruption("Invalid Column Family ID.");
     }
-    assert(it->second != nullptr);
     handles.push_back(it->second);
   }
 

utilities/trace/replayer_impl.cc

@@ -25,12 +25,13 @@ ReplayerImpl::ReplayerImpl(DB* db,
                            const std::vector<ColumnFamilyHandle*>& handles,
                            std::unique_ptr<TraceReader>&& reader)
     : Replayer(),
-      env_(db->GetEnv()),
       trace_reader_(std::move(reader)),
       prepared_(false),
       trace_end_(false),
       header_ts_(0),
-      exec_handler_(TraceRecord::NewExecutionHandler(db, handles)) {}
+      exec_handler_(TraceRecord::NewExecutionHandler(db, handles)),
+      env_(db->GetEnv()),
+      trace_file_version_(-1) {}
 
 ReplayerImpl::~ReplayerImpl() {
   exec_handler_.reset();

utilities/trace/replayer_impl.h

@@ -62,17 +62,17 @@ class ReplayerImpl : public Replayer {
   // Generic function to execute a Trace in a thread pool.
   static void BackgroundWork(void* arg);
 
-  Env* env_;
   std::unique_ptr<TraceReader> trace_reader_;
-  // When reading the trace header, the trace file version can be parsed.
-  // Replayer will use different decode method to get the trace content based
-  // on different trace file version.
-  int trace_file_version_;
   std::mutex mutex_;
   std::atomic<bool> prepared_;
   std::atomic<bool> trace_end_;
   uint64_t header_ts_;
   std::unique_ptr<TraceRecord::Handler> exec_handler_;
+  Env* env_;
+  // When reading the trace header, the trace file version can be parsed.
+  // Replayer will use different decode method to get the trace content based
+  // on different trace file version.
+  int trace_file_version_;
 };
 
 // The passin arg of MultiThreadRepkay for each trace record.