1 files changed, 48 insertions, 0 deletions
diff --git a/src/rocksdb/util/distributed_mutex.h b/src/rocksdb/util/distributed_mutex.h
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+++ b/src/rocksdb/util/distributed_mutex.h
@@ -0,0 +1,48 @@
+//  Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include "rocksdb/rocksdb_namespace.h"
+
+// This file declares a wrapper around the efficient folly DistributedMutex
+// that falls back on a standard mutex when not available. See
+// https://github.com/facebook/folly/blob/main/folly/synchronization/DistributedMutex.h
+// for benefits and limitations.
+
+// At the moment, only scoped locking is supported using DMutexLock
+// RAII wrapper, because lock/unlock APIs will vary.
+
+#ifdef USE_FOLLY
+
+#include <folly/synchronization/DistributedMutex.h>
+
+namespace ROCKSDB_NAMESPACE {
+
+class DMutex : public folly::DistributedMutex {
+ public:
+  static const char* kName() { return "folly::DistributedMutex"; }
+
+  explicit DMutex(bool IGNORED_adaptive = false) { (void)IGNORED_adaptive; }
+
+  // currently no-op
+  void AssertHeld() {}
+};
+using DMutexLock = std::lock_guard<folly::DistributedMutex>;
+
+}  // namespace ROCKSDB_NAMESPACE
+
+#else
+
+#include "port/port.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+using DMutex = port::Mutex;
+using DMutexLock = std::lock_guard<DMutex>;
+
+}  // namespace ROCKSDB_NAMESPACE
+
+#endif