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 | |
19 | namespace folly { |
20 | // Explicitly instantiate SharedMutex here: |
21 | template class SharedMutexImpl<true>; |
22 | template class SharedMutexImpl<false>; |
23 | |
24 | namespace detail { |
25 | std::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 | |