From cff58e8d75a6eefebf05b3b843b4e120e02e3a13 Mon Sep 17 00:00:00 2001
From: Zhichao Cao <zhichao@fb.com>
Date: Fri, 29 Mar 2019 14:02:11 -0700
Subject: [PATCH 1/2] Fix the potential DB crash caused by accidentally call
 EndTrace before StartTrace

---
 db/db_impl.cc  | 9 +++++++--
 db/db_test2.cc | 2 ++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/db/db_impl.cc b/db/db_impl.cc
index becc8e8e224..bede0247191 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -3654,8 +3654,13 @@ Status DBImpl::StartTrace(const TraceOptions& trace_options,
 
 Status DBImpl::EndTrace() {
   InstrumentedMutexLock lock(&trace_mutex_);
-  Status s = tracer_->Close();
-  tracer_.reset();
+  Status s;
+  if (tracer_.get() != nullptr) {
+    s = tracer_->Close();
+    tracer_.reset();
+  } else {
+    return Status::IOError("No trace file to close");
+  }
   return s;
 }
 
diff --git a/db/db_test2.cc b/db/db_test2.cc
index b62a1d5773b..99bf9bb7642 100644
--- a/db/db_test2.cc
+++ b/db/db_test2.cc
@@ -2874,6 +2874,8 @@ TEST_F(DBTest2, TraceAndReplay) {
   Random rnd(301);
   Iterator* single_iter = nullptr;
 
+  ASSERT_TRUE(db_->EndTrace().IsIOError());
+
   std::string trace_filename = dbname_ + "/rocksdb.trace";
   std::unique_ptr<TraceWriter> trace_writer;
   ASSERT_OK(NewFileTraceWriter(env_, env_opts, trace_filename, &trace_writer));

From 3261f104f78b2c855de68652228f551c824060a5 Mon Sep 17 00:00:00 2001
From: Zhichao Cao <zhichao@fb.com>
Date: Tue, 2 Apr 2019 15:02:35 -0700
Subject: [PATCH 2/2] Updated the unique pointer

---
 db/db_impl.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/db/db_impl.cc b/db/db_impl.cc
index bede0247191..4ae2ed4d530 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -3655,7 +3655,7 @@ Status DBImpl::StartTrace(const TraceOptions& trace_options,
 Status DBImpl::EndTrace() {
   InstrumentedMutexLock lock(&trace_mutex_);
   Status s;
-  if (tracer_.get() != nullptr) {
+  if (tracer_ != nullptr) {
     s = tracer_->Close();
     tracer_.reset();
   } else {