view test/testsem.c @ 3696:47d923feedb0

Fixed bug #935 Patrice Mandin Hello, I originally added pth support for threads in SDL 1.2 because on the Atari platform we did not have any thread library. I think pth support could be removed from SDL 1.3 for two reasons: - Atari platform removed - pth does not provides real (preemptive) threads, because it is user space, and expect the application to call one of its function to give CPU to another thread. So it is not exactly useful for applications, that expect threads to run simultaneously.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 24 Jan 2010 20:47:20 +0000
parents c121d94672cb
children d547877e355e
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/* Simple test of the SDL semaphore code */

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>

#include "SDL.h"
#include "SDL_thread.h"

#define NUM_THREADS 10

static SDL_sem *sem;
int alive = 1;

int SDLCALL
ThreadFunc(void *data)
{
    int threadnum = (int) (uintptr_t) data;
    while (alive) {
        SDL_SemWait(sem);
        fprintf(stderr,
                "Thread number %d has got the semaphore (value = %d)!\n",
                threadnum, SDL_SemValue(sem));
        SDL_Delay(200);
        SDL_SemPost(sem);
        fprintf(stderr,
                "Thread number %d has released the semaphore (value = %d)!\n",
                threadnum, SDL_SemValue(sem));
        SDL_Delay(1);           /* For the scheduler */
    }
    printf("Thread number %d exiting.\n", threadnum);
    return 0;
}

static void
killed(int sig)
{
    alive = 0;
}

int
main(int argc, char **argv)
{
    SDL_Thread *threads[NUM_THREADS];
    uintptr_t i;
    int init_sem;

    if (argc < 2) {
        fprintf(stderr, "Usage: %s init_value\n", argv[0]);
        return (1);
    }

    /* Load the SDL library */
    if (SDL_Init(0) < 0) {
        fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError());
        return (1);
    }
    signal(SIGTERM, killed);
    signal(SIGINT, killed);

    init_sem = atoi(argv[1]);
    sem = SDL_CreateSemaphore(init_sem);

    printf("Running %d threads, semaphore value = %d\n", NUM_THREADS,
           init_sem);
    /* Create all the threads */
    for (i = 0; i < NUM_THREADS; ++i) {
        threads[i] = SDL_CreateThread(ThreadFunc, (void *) i);
    }

    /* Wait 10 seconds */
    SDL_Delay(10 * 1000);

    /* Wait for all threads to finish */
    printf("Waiting for threads to finish\n");
    alive = 0;
    for (i = 0; i < NUM_THREADS; ++i) {
        SDL_WaitThread(threads[i], NULL);
    }
    printf("Finished waiting for threads\n");

    SDL_DestroySemaphore(sem);
    SDL_Quit();
    return (0);
}