SDL  2.0
testsem.c
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1 /*
2  Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.org>
3 
4  This software is provided 'as-is', without any express or implied
5  warranty. In no event will the authors be held liable for any damages
6  arising from the use of this software.
7 
8  Permission is granted to anyone to use this software for any purpose,
9  including commercial applications, and to alter it and redistribute it
10  freely.
11 */
12 
13 /* Simple test of the SDL semaphore code */
14 
15 #include <stdio.h>
16 #include <stdlib.h>
17 #include <signal.h>
18 
19 #include "SDL.h"
20 
21 #define NUM_THREADS 10
22 
23 static SDL_sem *sem;
24 int alive = 1;
25 
26 int SDLCALL
27 ThreadFunc(void *data)
28 {
29  int threadnum = (int) (uintptr_t) data;
30  while (alive) {
31  SDL_SemWait(sem);
32  SDL_Log("Thread number %d has got the semaphore (value = %d)!\n",
33  threadnum, SDL_SemValue(sem));
34  SDL_Delay(200);
35  SDL_SemPost(sem);
36  SDL_Log("Thread number %d has released the semaphore (value = %d)!\n",
37  threadnum, SDL_SemValue(sem));
38  SDL_Delay(1); /* For the scheduler */
39  }
40  SDL_Log("Thread number %d exiting.\n", threadnum);
41  return 0;
42 }
43 
44 static void
45 killed(int sig)
46 {
47  alive = 0;
48 }
49 
50 static void
51 TestWaitTimeout(void)
52 {
53  Uint32 start_ticks;
54  Uint32 end_ticks;
55  Uint32 duration;
56  int retval;
57 
58  sem = SDL_CreateSemaphore(0);
59  SDL_Log("Waiting 2 seconds on semaphore\n");
60 
61  start_ticks = SDL_GetTicks();
62  retval = SDL_SemWaitTimeout(sem, 2000);
63  end_ticks = SDL_GetTicks();
64 
65  duration = end_ticks - start_ticks;
66 
67  /* Accept a little offset in the effective wait */
68  if (duration > 1900 && duration < 2050)
69  SDL_Log("Wait done.\n");
70  else
71  SDL_Log("Wait took %d milliseconds\n", duration);
72 
73  /* Check to make sure the return value indicates timed out */
74  if (retval != SDL_MUTEX_TIMEDOUT)
75  SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SDL_SemWaitTimeout returned: %d; expected: %d\n", retval, SDL_MUTEX_TIMEDOUT);
76 }
77 
78 int
79 main(int argc, char **argv)
80 {
81  SDL_Thread *threads[NUM_THREADS];
82  uintptr_t i;
83  int init_sem;
84 
85  /* Enable standard application logging */
86  SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
87 
88  if (argc < 2) {
89  SDL_Log("Usage: %s init_value\n", argv[0]);
90  return (1);
91  }
92 
93  /* Load the SDL library */
94  if (SDL_Init(0) < 0) {
95  SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't initialize SDL: %s\n", SDL_GetError());
96  return (1);
97  }
98  signal(SIGTERM, killed);
99  signal(SIGINT, killed);
100 
101  init_sem = atoi(argv[1]);
102  sem = SDL_CreateSemaphore(init_sem);
103 
104  SDL_Log("Running %d threads, semaphore value = %d\n", NUM_THREADS,
105  init_sem);
106  /* Create all the threads */
107  for (i = 0; i < NUM_THREADS; ++i) {
108  char name[64];
109  SDL_snprintf(name, sizeof (name), "Thread%u", (unsigned int) i);
110  threads[i] = SDL_CreateThread(ThreadFunc, name, (void *) i);
111  }
112 
113  /* Wait 10 seconds */
114  SDL_Delay(10 * 1000);
115 
116  /* Wait for all threads to finish */
117  SDL_Log("Waiting for threads to finish\n");
118  alive = 0;
119  for (i = 0; i < NUM_THREADS; ++i) {
120  SDL_WaitThread(threads[i], NULL);
121  }
122  SDL_Log("Finished waiting for threads\n");
123 
124  SDL_DestroySemaphore(sem);
125 
126  TestWaitTimeout();
127 
128  SDL_Quit();
129  return (0);
130 }