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1 | #include <assert.h> | |
2 | #include <pthread.h> | |
3 | #include <stdio.h> | |
4 | #include <stdlib.h> | |
5 | #include <string.h> | |
6 | #include <unistd.h> | |
7 | #include <stdbool.h> | |
8 | #include <errno.h> | |
9 | #include <libkern/OSAtomic.h> | |
10 | ||
11 | struct context { | |
12 | pthread_cond_t cond; | |
13 | pthread_mutex_t mutex; | |
14 | long waiters; | |
15 | long count; | |
16 | }; | |
17 | ||
18 | void *wait_thread(void *ptr) { | |
19 | int res; | |
20 | struct context *context = ptr; | |
21 | ||
22 | int i = 0; | |
23 | char *str; | |
24 | ||
25 | bool loop = true; | |
26 | while (loop) { | |
27 | res = pthread_mutex_lock(&context->mutex); | |
28 | if (res) { | |
29 | fprintf(stderr, "[%ld] pthread_mutex_lock: %s\n", context->count, strerror(res)); | |
30 | abort(); | |
31 | } | |
32 | ||
33 | if (context->count > 0) { | |
34 | ++context->waiters; | |
35 | res = pthread_cond_wait(&context->cond, &context->mutex); | |
36 | if (res) { | |
37 | fprintf(stderr, "[%ld] pthread_rwlock_unlock: %s\n", context->count, strerror(res)); | |
38 | abort(); | |
39 | } | |
40 | --context->waiters; | |
41 | --context->count; | |
42 | } else { | |
43 | loop = false; | |
44 | } | |
45 | ||
46 | res = pthread_mutex_unlock(&context->mutex); | |
47 | if (res) { | |
48 | fprintf(stderr, "[%ld] pthread_mutex_unlock: %s\n", context->count, strerror(res)); | |
49 | abort(); | |
50 | } | |
51 | } | |
52 | ||
53 | return NULL; | |
54 | } | |
55 | ||
56 | int main(int argc, char *argv[]) | |
57 | { | |
58 | struct context context = { | |
59 | .cond = PTHREAD_COND_INITIALIZER, | |
60 | .mutex = PTHREAD_MUTEX_INITIALIZER, | |
61 | .waiters = 0, | |
62 | .count = 500000, | |
63 | }; | |
64 | int i; | |
65 | int res; | |
66 | int threads = 2; | |
67 | pthread_t p[threads]; | |
68 | for (i = 0; i < threads; ++i) { | |
69 | res = pthread_create(&p[i], NULL, wait_thread, &context); | |
70 | assert(res == 0); | |
71 | } | |
72 | ||
73 | long half = context.count / 2; | |
74 | ||
75 | bool loop = true; | |
76 | while (loop) { | |
77 | res = pthread_mutex_lock(&context.mutex); | |
78 | if (res) { | |
79 | fprintf(stderr, "[%ld] pthread_mutex_lock: %s\n", context.count, strerror(res)); | |
80 | abort(); | |
81 | } | |
82 | if (context.waiters) { | |
83 | char *str; | |
84 | if (context.count > half) { | |
85 | str = "pthread_cond_broadcast"; | |
86 | res = pthread_cond_broadcast(&context.cond); | |
87 | } else { | |
88 | str = "pthread_cond_signal"; | |
89 | res = pthread_cond_signal(&context.cond); | |
90 | } | |
91 | if (res != 0) { | |
92 | fprintf(stderr, "[%ld] %s: %s\n", context.count, str, strerror(res)); | |
93 | abort(); | |
94 | } | |
95 | } | |
96 | if (context.count <= 0) { | |
97 | loop = false; | |
98 | } | |
99 | ||
100 | res = pthread_mutex_unlock(&context.mutex); | |
101 | if (res) { | |
102 | fprintf(stderr, "[%ld] pthread_mutex_unlock: %s\n", context.count, strerror(res)); | |
103 | abort(); | |
104 | } | |
105 | } | |
106 | ||
107 | ||
108 | for (i = 0; i < threads; ++i) { | |
109 | res = pthread_join(p[i], NULL); | |
110 | assert(res == 0); | |
111 | } | |
112 | ||
113 | return 0; | |
114 | } |