view test/testsem.c @ 3877:81f66f258d77 SDL-1.2

Fixed bug #281 ------- Comment #2 From Christian Walther 2006-07-23 07:37 [reply] ------- Wow, that was an interesting bug to chase. It was a timing issue: it seems that for some reason, a certain time must pass between ShowMenuBar() being called in QZ_UnsetVideoMode() and the application quitting. Before rev. 1885, this delay was provided by the slow hand-coded fade. With the asynchronous Core Graphics fading introduced in rev. 1885, that delay was no longer present (most of the time) and the bug became apparent. Adding an SDL_Delay(100) somewhere between ShowMenuBar() and the end of QZ_VideoQuit() lowered the frequency of the bug appearing from "almost every time" to "very rarely" here. However, there is another solution: doing the ShowMenuBar() before releasing the captured display instead of afterwards. Apparently, no delay is necessary in that case, and it looks nicer to me anyway because it is the reverse order of the way things are set up in the beginning: capture display - set video mode - hide menu bar - ... - show menu bar - reset video mode - release captured display. So, this is what the attached patch does. In addition, I've taken the liberty of - removing some unused code that I forgot to remove in rev. 1885, - fixing two warnings about undeclared functions in SDL_QuartzVideo.m by including OpenGL.h (whose name is a bit misleading - it only declares CGL stuff, so there's no interference with SDL_opengl.h).
author Sam Lantinga <slouken@libsdl.org>
date Sun, 24 Sep 2006 01:27:40 +0000
parents 290b5baf2fca
children 782fd950bd46 c121d94672cb 99acf3d856cb
line wrap: on
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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);
}