From a13026fb2fa45a1cc0f03f5e426035088f394c0a Mon Sep 17 00:00:00 2001
From: Zhichao Cao <zhichao@fb.com>
Date: Thu, 16 May 2019 20:18:33 -0700
Subject: [PATCH] Added trace replay fast forward function (#5273)

Summary:
In the current db_bench trace replay, the replay process strictly follows the timestamp to issue the queries. In some cases, user does not care about the time. Therefore, fast forward is needed for users to speed up the replay process.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5273

Differential Revision: D15389232

Pulled By: zhichao-cao

fbshipit-source-id: 735d629b9d2a167b05af3e4fa0ddf9d5d0be1806
---
 tools/db_bench_tool.cc |  5 +++++
 util/trace_replay.cc   | 15 ++++++++++++++-
 util/trace_replay.h    |  2 ++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/tools/db_bench_tool.cc b/tools/db_bench_tool.cc
index b806fff89..18d873343 100644
--- a/tools/db_bench_tool.cc
+++ b/tools/db_bench_tool.cc
@@ -762,6 +762,9 @@ DEFINE_bool(use_stderr_info_logger, false,
 
 DEFINE_string(trace_file, "", "Trace workload to a file. ");
 
+DEFINE_int32(trace_replay_fast_forward, 1,
+             "Fast forward trace replay, must >= 1. ");
+
 static enum rocksdb::CompressionType StringToCompressionType(const char* ctype) {
   assert(ctype);
 
@@ -6163,6 +6166,8 @@ void VerifyDBFromDB(std::string& truth_db_name) {
     }
     Replayer replayer(db_with_cfh->db, db_with_cfh->cfh,
                       std::move(trace_reader));
+    replayer.SetFastForward(
+        static_cast<uint32_t>(FLAGS_trace_replay_fast_forward));
     s = replayer.Replay();
     if (s.ok()) {
       fprintf(stdout, "Replay started from trace_file: %s\n",
diff --git a/util/trace_replay.cc b/util/trace_replay.cc
index 28160b292..c90fef2ef 100644
--- a/util/trace_replay.cc
+++ b/util/trace_replay.cc
@@ -155,10 +155,22 @@ Replayer::Replayer(DB* db, const std::vector<ColumnFamilyHandle*>& handles,
   for (ColumnFamilyHandle* cfh : handles) {
     cf_map_[cfh->GetID()] = cfh;
   }
+  fast_forward_ = 1;
 }
 
 Replayer::~Replayer() { trace_reader_.reset(); }
 
+Status Replayer::SetFastForward(uint32_t fast_forward) {
+  Status s;
+  if (fast_forward < 1) {
+    s = Status::InvalidArgument("Wrong fast forward speed!");
+  } else {
+    fast_forward_ = fast_forward;
+    s = Status::OK();
+  }
+  return s;
+}
+
 Status Replayer::Replay() {
   Status s;
   Trace header;
@@ -182,7 +194,8 @@ Status Replayer::Replay() {
     }
 
     std::this_thread::sleep_until(
-        replay_epoch + std::chrono::microseconds(trace.ts - header.ts));
+        replay_epoch +
+        std::chrono::microseconds((trace.ts - header.ts) / fast_forward_));
     if (trace.type == kTraceWrite) {
       WriteBatch batch(trace.payload);
       db_->Write(woptions, &batch);
diff --git a/util/trace_replay.h b/util/trace_replay.h
index 749ea2f64..29c00c287 100644
--- a/util/trace_replay.h
+++ b/util/trace_replay.h
@@ -88,6 +88,7 @@ class Replayer {
   ~Replayer();
 
   Status Replay();
+  Status SetFastForward(uint32_t fast_forward);
 
  private:
   Status ReadHeader(Trace* header);
@@ -97,6 +98,7 @@ class Replayer {
   DBImpl* db_;
   std::unique_ptr<TraceReader> trace_reader_;
   std::unordered_map<uint32_t, ColumnFamilyHandle*> cf_map_;
+  uint32_t fast_forward_;
 };
 
 }  // namespace rocksdb