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FORK: Simple Directmedia Layer
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testsem.c (3357B)

      1 /*
      2   Copyright (C) 1997-2020 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 }