Fix data race #5

Summary: TSAN complained that these are non-atomic reads and writes from different threads.

Test Plan: TSAN no longer complains

Reviewers: yhchiang, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D32409

util/thread_status_util_debug.cc

@@ -3,6 +3,8 @@
 // LICENSE file in the root directory of this source tree. An additional grant
 // of patent rights can be found in the PATENTS file in the same directory.
 
+#include <atomic>
+
 #include "rocksdb/env.h"
 #include "util/thread_status_updater.h"
 #include "util/thread_status_util.h"
@@ -11,30 +13,29 @@ namespace rocksdb {
 
 #ifndef NDEBUG
 // the delay for debugging purpose.
-static int operations_delay[ThreadStatus::NUM_OP_TYPES] ={0};
-static int states_delay[ThreadStatus::NUM_STATE_TYPES] = {0};
+static std::atomic<int> operations_delay[ThreadStatus::NUM_OP_TYPES];
+static std::atomic<int> states_delay[ThreadStatus::NUM_STATE_TYPES];
 
 void ThreadStatusUtil::TEST_SetStateDelay(
     const ThreadStatus::StateType state, int micro) {
-  states_delay[state] = micro;
+  states_delay[state].store(micro, std::memory_order_relaxed);
 }
 
 void ThreadStatusUtil::TEST_StateDelay(
     const ThreadStatus::StateType state) {
   Env::Default()->SleepForMicroseconds(
-      states_delay[state]);
+      states_delay[state].load(std::memory_order_relaxed));
 }
 
 void ThreadStatusUtil::TEST_SetOperationDelay(
     const ThreadStatus::OperationType operation, int micro) {
-  operations_delay[operation] = micro;
+  operations_delay[operation].store(micro, std::memory_order_relaxed);
 }
 
-
 void ThreadStatusUtil::TEST_OperationDelay(
     const ThreadStatus::OperationType operation) {
   Env::Default()->SleepForMicroseconds(
-      operations_delay[operation]);
+      operations_delay[operation].load(std::memory_order_relaxed));
 }
 #endif  // !NDEBUG