Fix data races caught by tsan

Summary:
This fixes the tsan build failures in:
- write_callback_test
- persistent_cache_test.*
Closes https://github.com/facebook/rocksdb/pull/2339

Differential Revision: D5101190

Pulled By: sagar0

fbshipit-source-id: 537e19ed05272b1f34cfbf793aa822b2264a1643

db/write_callback_test.cc

@@ -7,6 +7,7 @@
 
 #ifndef ROCKSDB_LITE
 
+#include <atomic>
 #include <functional>
 #include <string>
 #include <utility>
@@ -65,11 +66,19 @@ class WriteCallbackTestWriteCallback2 : public WriteCallback {
 class MockWriteCallback : public WriteCallback {
  public:
   bool should_fail_ = false;
-  bool was_called_ = false;
   bool allow_batching_ = false;
+  std::atomic<bool> was_called_{false};
+
+  MockWriteCallback() {}
+
+  MockWriteCallback(const MockWriteCallback& other) {
+    should_fail_ = other.should_fail_;
+    allow_batching_ = other.allow_batching_;
+    was_called_.store(other.was_called_.load());
+  }
 
   Status Callback(DB* db) override {
-    was_called_ = true;
+    was_called_.store(true);
     if (should_fail_) {
       return Status::Busy();
     } else {
@@ -92,7 +101,7 @@ TEST_F(WriteCallbackTest, WriteWithCallbackTest) {
     void Clear() {
       kvs_.clear();
       write_batch_.Clear();
-      callback_.was_called_ = false;
+      callback_.was_called_.store(false);
     }
 
     MockWriteCallback callback_;
@@ -265,7 +274,7 @@ TEST_F(WriteCallbackTest, WriteWithCallbackTest) {
             // check for keys
             string value;
             for (auto& w : write_group) {
-              ASSERT_TRUE(w.callback_.was_called_);
+              ASSERT_TRUE(w.callback_.was_called_.load());
               for (auto& kvp : w.kvs_) {
                 if (w.callback_.should_fail_) {
                   ASSERT_TRUE(

utilities/persistent_cache/block_cache_tier.h

@@ -12,6 +12,7 @@
 #include <unistd.h>
 #endif // ! OS_WIN
 
+#include <atomic>
 #include <list>
 #include <memory>
 #include <set>
@@ -123,10 +124,10 @@ class BlockCacheTier : public PersistentCacheTier {
     HistogramImpl read_hit_latency_;
     HistogramImpl read_miss_latency_;
     HistogramImpl write_latency_;
-    uint64_t cache_hits_ = 0;
-    uint64_t cache_misses_ = 0;
-    uint64_t cache_errors_ = 0;
-    uint64_t insert_dropped_ = 0;
+    std::atomic<uint64_t> cache_hits_{0};
+    std::atomic<uint64_t> cache_misses_{0};
+    std::atomic<uint64_t> cache_errors_{0};
+    std::atomic<uint64_t> insert_dropped_{0};
 
     double CacheHitPct() const {
       const auto lookups = cache_hits_ + cache_misses_;

utilities/persistent_cache/volatile_tier_impl.h

@@ -110,10 +110,10 @@ class VolatileCacheTier : public PersistentCacheTier {
   };
 
   struct Statistics {
-    uint64_t cache_misses_ = 0;
-    uint64_t cache_hits_ = 0;
-    uint64_t cache_inserts_ = 0;
-    uint64_t cache_evicts_ = 0;
+    std::atomic<uint64_t> cache_misses_{0};
+    std::atomic<uint64_t> cache_hits_{0};
+    std::atomic<uint64_t> cache_inserts_{0};
+    std::atomic<uint64_t> cache_evicts_{0};
 
     double CacheHitPct() const {
       auto lookups = cache_hits_ + cache_misses_;