test/testlock.c

/* Test the thread and mutex locking functions 
   Also exercises the system's signal/thread interaction
*/

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

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

static SDL_mutex *mutex = NULL;
static SDL_threadID mainthread;
static SDL_Thread *threads[6];
static volatile int doterminate = 0;

/*
 * SDL_Quit() shouldn't be used with atexit() directly because
 *  calling conventions may differ...
 */
static void
SDL_Quit_Wrapper(void)
{
    SDL_Quit();
}

void
printid(void)
{
    printf("Process %lu:  exiting\n", SDL_ThreadID());
}

void
terminate(int sig)
{
    signal(SIGINT, terminate);
    doterminate = 1;
}

void
closemutex(int sig)
{
    SDL_threadID id = SDL_ThreadID();
    int i;
    printf("Process %lu:  Cleaning up...\n", id == mainthread ? 0 : id);
    doterminate = 1;
    for (i = 0; i < 6; ++i)
        SDL_WaitThread(threads[i], NULL);
    SDL_DestroyMutex(mutex);
    exit(sig);
}

int SDLCALL
Run(void *data)
{
    if (SDL_ThreadID() == mainthread)
        signal(SIGTERM, closemutex);
    while (!doterminate) {
        printf("Process %lu ready to work\n", SDL_ThreadID());
        if (SDL_mutexP(mutex) < 0) {
            fprintf(stderr, "Couldn't lock mutex: %s", SDL_GetError());
            exit(1);
        }
        printf("Process %lu, working!\n", SDL_ThreadID());
        SDL_Delay(1 * 1000);
        printf("Process %lu, done!\n", SDL_ThreadID());
        if (SDL_mutexV(mutex) < 0) {
            fprintf(stderr, "Couldn't unlock mutex: %s", SDL_GetError());
            exit(1);
        }
        /* If this sleep isn't done, then threads may starve */
        SDL_Delay(10);
    }
    if (SDL_ThreadID() == mainthread && doterminate) {
        printf("Process %lu:  raising SIGTERM\n", SDL_ThreadID());
        raise(SIGTERM);
    }
    return (0);
}

int
main(int argc, char *argv[])
{
    int i;
    int maxproc = 6;

    /* Load the SDL library */
    if (SDL_Init(0) < 0) {
        fprintf(stderr, "%s\n", SDL_GetError());
        exit(1);
    }
    atexit(SDL_Quit_Wrapper);

    if ((mutex = SDL_CreateMutex()) == NULL) {
        fprintf(stderr, "Couldn't create mutex: %s\n", SDL_GetError());
        exit(1);
    }

    mainthread = SDL_ThreadID();
    printf("Main thread: %lu\n", mainthread);
    atexit(printid);
    for (i = 0; i < maxproc; ++i) {
        if ((threads[i] = SDL_CreateThread(Run, NULL)) == NULL)
            fprintf(stderr, "Couldn't create thread!\n");
    }
    signal(SIGINT, terminate);
    Run(NULL);

    return (0);                 /* Never reached */
}