1 files changed, 57 insertions, 0 deletions
diff --git a/src/rocksdb/third-party/folly/folly/synchronization/AtomicNotification.h b/src/rocksdb/third-party/folly/folly/synchronization/AtomicNotification.h
new file mode 100644
index 000000000..af87852cb
--- /dev/null
+++ b/src/rocksdb/third-party/folly/folly/synchronization/AtomicNotification.h
@@ -0,0 +1,57 @@
+//  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 <condition_variable>
+
+namespace folly {
+
+/**
+ * The behavior of the atomic_wait() family of functions is semantically
+ * identical to futex().  Correspondingly, calling atomic_notify_one(),
+ * atomic_notify_all() is identical to futexWake() with 1 and
+ * std::numeric_limits<int>::max() respectively
+ *
+ * The difference here compared to the futex API above is that it works with
+ * all types of atomic widths.  When a 32 bit atomic integer is used, the
+ * implementation falls back to using futex() if possible, and the
+ * compatibility implementation for non-linux systems otherwise.  For all
+ * other integer widths, the compatibility implementation is used
+ *
+ * The templating of this API is changed from the standard in the following
+ * ways
+ *
+ * - At the time of writing, libstdc++'s implementation of std::atomic<> does
+ *   not include the value_type alias.  So we rely on the atomic type being a
+ *   template class such that the first type is the underlying value type
+ * - The Atom parameter allows this API to be compatible with
+ *   DeterministicSchedule testing.
+ * - atomic_wait_until() does not exist in the linked paper, the version here
+ *   is identical to futexWaitUntil() and returns std::cv_status
+ */
+//  mimic: std::atomic_wait, p1135r0
+template <typename Integer>
+void atomic_wait(const std::atomic<Integer>* atomic, Integer expected);
+template <typename Integer, typename Clock, typename Duration>
+std::cv_status atomic_wait_until(
+    const std::atomic<Integer>* atomic,
+    Integer expected,
+    const std::chrono::time_point<Clock, Duration>& deadline);
+
+//  mimic: std::atomic_notify_one, p1135r0
+template <typename Integer>
+void atomic_notify_one(const std::atomic<Integer>* atomic);
+//  mimic: std::atomic_notify_all, p1135r0
+template <typename Integer>
+void atomic_notify_all(const std::atomic<Integer>* atomic);
+
+//  mimic: std::atomic_uint_fast_wait_t, p1135r0
+using atomic_uint_fast_wait_t = std::atomic<std::uint32_t>;
+
+} // namespace folly
+
+#include <folly/synchronization/AtomicNotification-inl.h>