1/*
2 * Copyright 2015-present Facebook, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <folly/SharedMutex.h>
18
19namespace folly {
20// Explicitly instantiate SharedMutex here:
21template class SharedMutexImpl<true>;
22template class SharedMutexImpl<false>;
23
24namespace detail {
25std::unique_lock<std::mutex> sharedMutexAnnotationGuard(void* ptr) {
26 if (folly::kIsSanitizeThread) {
27 // On TSAN builds, we have an array of mutexes and index into them based on
28 // the address. If the array is of prime size things will work out okay
29 // without a complicated hash function.
30 static constexpr std::size_t kNumAnnotationMutexes = 251;
31 static std::array<std::mutex, kNumAnnotationMutexes> kAnnotationMutexes{};
32 auto index = reinterpret_cast<uintptr_t>(ptr) % kNumAnnotationMutexes;
33 return std::unique_lock<std::mutex>(kAnnotationMutexes[index]);
34 } else {
35 return std::unique_lock<std::mutex>();
36 }
37}
38} // namespace detail
39
40} // namespace folly
41