1// Copyright 2017 The Gemmlowp Authors. All Rights Reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15// pthread_everywhere.h: Either includes <pthread.h> or implements a
16// subset of pthread functionality on top of C++11 <thread> for portability.
17
18#ifndef GEMMLOWP_PROFILING_PTHREAD_EVERYWHERE_H_
19#define GEMMLOWP_PROFILING_PTHREAD_EVERYWHERE_H_
20
21#ifndef _WIN32
22#define GEMMLOWP_USE_PTHREAD
23#endif
24
25#if defined GEMMLOWP_USE_PTHREAD
26#include <pthread.h>
27#else
28// Implement a small subset of pthread on top of C++11 threads.
29// The function signatures differ from true pthread functions in two ways:
30// - True pthread functions return int error codes, ours return void.
31// Rationale: the c++11 <thread> equivalent functions return void
32// and use exceptions to report errors; we don't want to deal with
33// exceptions in this code, so we couldn't meaningfully return errors
34// in the polyfill. Also, the gemmlowp code using these pthread functions
35// never checks their return values anyway.
36// - True pthread *_create/*_init functions take pointers to 'attribute'
37// structs; ours take nullptr_t. That is because gemmlowp always passes
38// nullptr at the moment, so any support we would code for non-null
39// attribs would be unused.
40#include <condition_variable>
41#include <cstddef>
42#include <mutex>
43#include <thread>
44namespace gemmlowp {
45using pthread_t = std::thread *;
46using pthread_mutex_t = std::mutex *;
47using pthread_cond_t = std::condition_variable *;
48inline void pthread_create(pthread_t *thread, std::nullptr_t,
49 void *(*start_routine)(void *), void *arg) {
50 *thread = new std::thread(start_routine, arg);
51}
52inline void pthread_join(pthread_t thread, std::nullptr_t) { thread->join(); }
53inline void pthread_mutex_init(pthread_mutex_t *mutex, std::nullptr_t) {
54 *mutex = new std::mutex;
55}
56inline void pthread_mutex_lock(pthread_mutex_t *mutex) { (*mutex)->lock(); }
57inline void pthread_mutex_unlock(pthread_mutex_t *mutex) { (*mutex)->unlock(); }
58inline void pthread_mutex_destroy(pthread_mutex_t *mutex) { delete *mutex; }
59inline void pthread_cond_init(pthread_cond_t *cond, std::nullptr_t) {
60 *cond = new std::condition_variable;
61}
62inline void pthread_cond_signal(pthread_cond_t *cond) { (*cond)->notify_one(); }
63inline void pthread_cond_broadcast(pthread_cond_t *cond) {
64 (*cond)->notify_all();
65}
66inline void pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) {
67 std::unique_lock<std::mutex> lock(**mutex, std::adopt_lock);
68 (*cond)->wait(lock);
69 // detach lock from mutex so when we leave this conext
70 // the lock is not released
71 lock.release();
72}
73inline void pthread_cond_destroy(pthread_cond_t *cond) { delete *cond; }
74} // end namespace gemmlowp
75#endif
76
77#endif // GEMMLOWP_PROFILING_PTHREAD_EVERYWHERE_H_
78