1 | /* |
2 | * Copyright 2012-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/portability/Semaphore.h> |
18 | |
19 | #include <folly/portability/Windows.h> |
20 | |
21 | #include <errno.h> |
22 | #include <mutex> |
23 | |
24 | #if _WIN32 |
25 | namespace folly::portability::semaphore { |
26 | struct sem_t_ { |
27 | std::mutex mtx{}; |
28 | HANDLE sema{INVALID_HANDLE_VALUE}; |
29 | int32_t value{0}; |
30 | }; |
31 | |
32 | int sem_init(sem_t* s, int shared, unsigned int value) { |
33 | // Don't support cross-process shared semaphores. |
34 | if (shared != 0) { |
35 | return -1; |
36 | } |
37 | auto sem = CreateSemaphoreA(nullptr, 0, SEM_VALUE_MAX, nullptr); |
38 | if (sem == 0) { |
39 | return -1; |
40 | } |
41 | auto ret = new sem_t_(); |
42 | ret->sema = sem; |
43 | ret->value = value; |
44 | *s = ret; |
45 | return 0; |
46 | } |
47 | |
48 | int sem_destroy(sem_t* s) { |
49 | if (!CloseHandle((*s)->sema)) { |
50 | return -1; |
51 | } |
52 | delete *s; |
53 | *s = nullptr; |
54 | return 0; |
55 | } |
56 | |
57 | int sem_post(sem_t* s) { |
58 | std::lock_guard<std::mutex> lock{(*s)->mtx}; |
59 | if ((*s)->value < SEM_VALUE_MAX) { |
60 | if (++(*s)->value <= 0 && !ReleaseSemaphore((*s)->sema, 1, nullptr)) { |
61 | --(*s)->value; |
62 | errno = EINVAL; |
63 | return -1; |
64 | } |
65 | } else { |
66 | errno = ERANGE; |
67 | return -1; |
68 | } |
69 | return 0; |
70 | } |
71 | |
72 | int sem_trywait(sem_t* s) { |
73 | std::lock_guard<std::mutex> lock{(*s)->mtx}; |
74 | if ((*s)->value > 0) { |
75 | (*s)->value--; |
76 | return 0; |
77 | } else { |
78 | errno = EAGAIN; |
79 | return -1; |
80 | } |
81 | } |
82 | |
83 | int sem_wait(sem_t* s) { |
84 | int32_t value = 0; |
85 | { |
86 | std::lock_guard<std::mutex> lock{(*s)->mtx}; |
87 | value = --(*s)->value; |
88 | } |
89 | |
90 | if (value < 0) { |
91 | if (WaitForSingleObject((*s)->sema, INFINITE) != WAIT_OBJECT_0) { |
92 | errno = EINVAL; |
93 | return -1; |
94 | } |
95 | } |
96 | return 0; |
97 | } |
98 | } // namespace folly::portability::semaphore |
99 | #endif |
100 | |