1 files changed, 138 insertions, 0 deletions
diff --git a/src/rocksdb/third-party/folly/folly/synchronization/AtomicNotification-inl.h b/src/rocksdb/third-party/folly/folly/synchronization/AtomicNotification-inl.h
new file mode 100644
index 000000000..c0b143d0a
--- /dev/null
+++ b/src/rocksdb/third-party/folly/folly/synchronization/AtomicNotification-inl.h
@@ -0,0 +1,138 @@
+//  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 <folly/detail/Futex.h>
+#include <folly/synchronization/ParkingLot.h>
+
+#include <condition_variable>
+#include <cstdint>
+
+namespace folly {
+namespace detail {
+namespace atomic_notification {
+/**
+ * We use Futex<std::atomic> as the alias that has the lowest performance
+ * overhead with respect to atomic notifications.  Assert that
+ * atomic_uint_fast_wait_t is the same as Futex<std::atomic>
+ */
+static_assert(std::is_same<atomic_uint_fast_wait_t, Futex<std::atomic>>{}, "");
+
+/**
+ * Implementation and specializations for the atomic_wait() family of
+ * functions
+ */
+inline std::cv_status toCvStatus(FutexResult result) {
+  return (result == FutexResult::TIMEDOUT) ? std::cv_status::timeout
+                                           : std::cv_status::no_timeout;
+}
+inline std::cv_status toCvStatus(ParkResult result) {
+  return (result == ParkResult::Timeout) ? std::cv_status::timeout
+                                         : std::cv_status::no_timeout;
+}
+
+// ParkingLot instantiation for futex management
+extern ParkingLot<std::uint32_t> parkingLot;
+
+template <template <typename...> class Atom, typename... Args>
+void atomic_wait_impl(
+    const Atom<std::uint32_t, Args...>* atomic,
+    std::uint32_t expected) {
+  futexWait(atomic, expected);
+  return;
+}
+
+template <template <typename...> class Atom, typename Integer, typename... Args>
+void atomic_wait_impl(const Atom<Integer, Args...>* atomic, Integer expected) {
+  static_assert(!std::is_same<Integer, std::uint32_t>{}, "");
+  parkingLot.park(
+      atomic, -1, [&] { return atomic->load() == expected; }, [] {});
+}
+
+template <
+    template <typename...> class Atom,
+    typename... Args,
+    typename Clock,
+    typename Duration>
+std::cv_status atomic_wait_until_impl(
+    const Atom<std::uint32_t, Args...>* atomic,
+    std::uint32_t expected,
+    const std::chrono::time_point<Clock, Duration>& deadline) {
+  return toCvStatus(futexWaitUntil(atomic, expected, deadline));
+}
+
+template <
+    template <typename...> class Atom,
+    typename Integer,
+    typename... Args,
+    typename Clock,
+    typename Duration>
+std::cv_status atomic_wait_until_impl(
+    const Atom<Integer, Args...>* atomic,
+    Integer expected,
+    const std::chrono::time_point<Clock, Duration>& deadline) {
+  static_assert(!std::is_same<Integer, std::uint32_t>{}, "");
+  return toCvStatus(parkingLot.park_until(
+      atomic, -1, [&] { return atomic->load() == expected; }, [] {}, deadline));
+}
+
+template <template <typename...> class Atom, typename... Args>
+void atomic_notify_one_impl(const Atom<std::uint32_t, Args...>* atomic) {
+  futexWake(atomic, 1);
+  return;
+}
+
+template <template <typename...> class Atom, typename Integer, typename... Args>
+void atomic_notify_one_impl(const Atom<Integer, Args...>* atomic) {
+  static_assert(!std::is_same<Integer, std::uint32_t>{}, "");
+  parkingLot.unpark(atomic, [&](std::uint32_t data) {
+    assert(data == std::numeric_limits<std::uint32_t>::max());
+    return UnparkControl::RemoveBreak;
+  });
+}
+
+template <template <typename...> class Atom, typename... Args>
+void atomic_notify_all_impl(const Atom<std::uint32_t, Args...>* atomic) {
+  futexWake(atomic);
+  return;
+}
+
+template <template <typename...> class Atom, typename Integer, typename... Args>
+void atomic_notify_all_impl(const Atom<Integer, Args...>* atomic) {
+  static_assert(!std::is_same<Integer, std::uint32_t>{}, "");
+  parkingLot.unpark(atomic, [&](std::uint32_t data) {
+    assert(data == std::numeric_limits<std::uint32_t>::max());
+    return UnparkControl::RemoveContinue;
+  });
+}
+} // namespace atomic_notification
+} // namespace detail
+
+template <typename Integer>
+void atomic_wait(const std::atomic<Integer>* atomic, Integer expected) {
+  detail::atomic_notification::atomic_wait_impl(atomic, 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) {
+  return detail::atomic_notification::atomic_wait_until_impl(
+      atomic, expected, deadline);
+}
+
+template <typename Integer>
+void atomic_notify_one(const std::atomic<Integer>* atomic) {
+  detail::atomic_notification::atomic_notify_one_impl(atomic);
+}
+
+template <typename Integer>
+void atomic_notify_all(const std::atomic<Integer>* atomic) {
+  detail::atomic_notification::atomic_notify_all_impl(atomic);
+}
+
+} // namespace folly