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diff --git a/src/rocksdb/third-party/folly/folly/synchronization/AtomicUtil.h b/src/rocksdb/third-party/folly/folly/synchronization/AtomicUtil.h
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+++ b/src/rocksdb/third-party/folly/folly/synchronization/AtomicUtil.h
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+//  Copyright (c) 2011-present, Facebook, Inc.  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 <atomic>
+#include <cstdint>
+
+namespace folly {
+
+/**
+ * Sets a bit at the given index in the binary representation of the integer
+ * to 1.  Returns the previous value of the bit, so true if the bit was not
+ * changed, false otherwise
+ *
+ * On some architectures, using this is more efficient than the corresponding
+ * std::atomic::fetch_or() with a mask.  For example to set the first (least
+ * significant) bit of an integer, you could do atomic.fetch_or(0b1)
+ *
+ * The efficiency win is only visible in x86 (yet) and comes from the
+ * implementation using the x86 bts instruction when possible.
+ *
+ * When something other than std::atomic is passed, the implementation assumed
+ * incompatibility with this interface and calls Atomic::fetch_or()
+ */
+template <typename Atomic>
+bool atomic_fetch_set(
+    Atomic& atomic,
+    std::size_t bit,
+    std::memory_order order = std::memory_order_seq_cst);
+
+/**
+ * Resets a bit at the given index in the binary representation of the integer
+ * to 0.  Returns the previous value of the bit, so true if the bit was
+ * changed, false otherwise
+ *
+ * This follows the same underlying principle and implementation as
+ * fetch_set().  Using the optimized implementation when possible and falling
+ * back to std::atomic::fetch_and() when in debug mode or in an architecture
+ * where an optimization is not possible
+ */
+template <typename Atomic>
+bool atomic_fetch_reset(
+    Atomic& atomic,
+    std::size_t bit,
+    std::memory_order order = std::memory_order_seq_cst);
+
+} // namespace folly
+
+#include <folly/synchronization/AtomicUtil-inl.h>