src/thread/SDL_thread.c - third_party/sdl - Git at Google

 /*
     SDL - Simple DirectMedia Layer
     Copyright (C) 1997-2009 Sam Lantinga

     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.

     This library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.

     You should have received a copy of the GNU Lesser General Public
     License along with this library; if not, write to the Free Software
     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

     Sam Lantinga
     slouken@libsdl.org
 */
 #include "SDL_config.h"

 /* System independent thread management routines for SDL */

 #include "SDL_mutex.h"
 #include "SDL_thread.h"
 #include "SDL_thread_c.h"
 #include "SDL_systhread.h"

 #define ARRAY_CHUNKSIZE	32
 /* The array of threads currently active in the application
    (except the main thread)
    The manipulation of an array here is safer than using a linked list.
 */
 static int SDL_maxthreads = 0;
 static int SDL_numthreads = 0;
 static SDL_Thread **SDL_Threads = NULL;
 static SDL_mutex *thread_lock = NULL;

 int SDL_ThreadsInit(void)
 {
 	int retval;

 	retval = 0;
 	thread_lock = SDL_CreateMutex();
 	if ( thread_lock == NULL ) {
 		retval = -1;
 	}
 	return(retval);
 }

 /* This should never be called...
    If this is called by SDL_Quit(), we don't know whether or not we should
    clean up threads here.  If any threads are still running after this call,
    they will no longer have access to any per-thread data.
  */
 void SDL_ThreadsQuit(void)
 {
 	SDL_mutex *mutex;

 	mutex = thread_lock;
 	thread_lock = NULL;
 	if ( mutex != NULL ) {
 		SDL_DestroyMutex(mutex);
 	}
 }

 /* Routines for manipulating the thread list */
 static void SDL_AddThread(SDL_Thread *thread)
 {
 	/* WARNING:
 	   If the very first threads are created simultaneously, then
 	   there could be a race condition causing memory corruption.
 	   In practice, this isn't a problem because by definition there
 	   is only one thread running the first time this is called.
 	*/
 	if ( !thread_lock ) {
 		if ( SDL_ThreadsInit() < 0 ) {
 			return;
 		}
 	}
 	SDL_mutexP(thread_lock);

 	/* Expand the list of threads, if necessary */
 #ifdef DEBUG_THREADS
 	printf("Adding thread (%d already - %d max)\n",
 			SDL_numthreads, SDL_maxthreads);
 #endif
 	if ( SDL_numthreads == SDL_maxthreads ) {
 		SDL_Thread **threads;
 		threads = (SDL_Thread **)SDL_realloc(SDL_Threads,
 			(SDL_maxthreads+ARRAY_CHUNKSIZE)*(sizeof *threads));
 		if ( threads == NULL ) {
 			SDL_OutOfMemory();
 			goto done;
 		}
 		SDL_maxthreads += ARRAY_CHUNKSIZE;
 		SDL_Threads = threads;
 	}
 	SDL_Threads[SDL_numthreads++] = thread;
 done:
 	SDL_mutexV(thread_lock);
 }

 static void SDL_DelThread(SDL_Thread *thread)
 {
 	int i;

 	if ( !thread_lock ) {
 		return;
 	}
 	SDL_mutexP(thread_lock);
 	for ( i=0; i<SDL_numthreads; ++i ) {
 		if ( thread == SDL_Threads[i] ) {
 			break;
 		}
 	}
 	if ( i < SDL_numthreads ) {
 		if ( --SDL_numthreads > 0 ) {
 			while ( i < SDL_numthreads ) {
 				SDL_Threads[i] = SDL_Threads[i+1];
 				++i;
 			}
 		} else {
 			SDL_maxthreads = 0;
 			SDL_free(SDL_Threads);
 			SDL_Threads = NULL;
 		}
 #ifdef DEBUG_THREADS
 		printf("Deleting thread (%d left - %d max)\n",
 				SDL_numthreads, SDL_maxthreads);
 #endif
 	}
 	SDL_mutexV(thread_lock);

 #if 0	/* There could be memory corruption if another thread is starting */
 	if ( SDL_Threads == NULL ) {
 		SDL_ThreadsQuit();
 	}
 #endif
 }

 /* The default (non-thread-safe) global error variable */
 static SDL_error SDL_global_error;

 /* Routine to get the thread-specific error variable */
 SDL_error *SDL_GetErrBuf(void)
 {
 	SDL_error *errbuf;

 	errbuf = &SDL_global_error;
 	if ( SDL_Threads ) {
 		int i;
 		Uint32 this_thread;

 		this_thread = SDL_ThreadID();
 		SDL_mutexP(thread_lock);
 		for ( i=0; i<SDL_numthreads; ++i ) {
 			if ( this_thread == SDL_Threads[i]->threadid ) {
 				errbuf = &SDL_Threads[i]->errbuf;
 				break;
 			}
 		}
 		SDL_mutexV(thread_lock);
 	}
 	return(errbuf);
 }


 /* Arguments and callback to setup and run the user thread function */
 typedef struct {
 	int (SDLCALL *func)(void *);
 	void *data;
 	SDL_Thread *info;
 	SDL_sem *wait;
 } thread_args;

 void SDL_RunThread(void *data)
 {
 	thread_args *args;
 	int (SDLCALL *userfunc)(void *);
 	void *userdata;
 	int *statusloc;

 	/* Perform any system-dependent setup
 	   - this function cannot fail, and cannot use SDL_SetError()
 	 */
 	SDL_SYS_SetupThread();

 	/* Get the thread id */
 	args = (thread_args *)data;
 	args->info->threadid = SDL_ThreadID();

 	/* Figure out what function to run */
 	userfunc = args->func;
 	userdata = args->data;
 	statusloc = &args->info->status;

 	/* Wake up the parent thread */
 	SDL_SemPost(args->wait);

 	/* Run the function */
 	*statusloc = userfunc(userdata);
 }

 #ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
 #undef SDL_CreateThread
 DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data, pfnSDL_CurrentBeginThread pfnBeginThread, pfnSDL_CurrentEndThread pfnEndThread)
 #else
 DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data)
 #endif
 {
 	SDL_Thread *thread;
 	thread_args *args;
 	int ret;

 	/* Allocate memory for the thread info structure */
 	thread = (SDL_Thread *)SDL_malloc(sizeof(*thread));
 	if ( thread == NULL ) {
 		SDL_OutOfMemory();
 		return(NULL);
 	}
 	SDL_memset(thread, 0, (sizeof *thread));
 	thread->status = -1;

 	/* Set up the arguments for the thread */
 	args = (thread_args *)SDL_malloc(sizeof(*args));
 	if ( args == NULL ) {
 		SDL_OutOfMemory();
 		SDL_free(thread);
 		return(NULL);
 	}
 	args->func = fn;
 	args->data = data;
 	args->info = thread;
 	args->wait = SDL_CreateSemaphore(0);
 	if ( args->wait == NULL ) {
 		SDL_free(thread);
 		SDL_free(args);
 		return(NULL);
 	}

 	/* Add the thread to the list of available threads */
 	SDL_AddThread(thread);

 	/* Create the thread and go! */
 #ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
 	ret = SDL_SYS_CreateThread(thread, args, pfnBeginThread, pfnEndThread);
 #else
 	ret = SDL_SYS_CreateThread(thread, args);
 #endif
 	if ( ret >= 0 ) {
 		/* Wait for the thread function to use arguments */
 		SDL_SemWait(args->wait);
 	} else {
 		/* Oops, failed.  Gotta free everything */
 		SDL_DelThread(thread);
 		SDL_free(thread);
 		thread = NULL;
 	}
 	SDL_DestroySemaphore(args->wait);
 	SDL_free(args);

 	/* Everything is running now */
 	return(thread);
 }

 void SDL_WaitThread(SDL_Thread *thread, int *status)
 {
 	if ( thread ) {
 		SDL_SYS_WaitThread(thread);
 		if ( status ) {
 			*status = thread->status;
 		}
 		SDL_DelThread(thread);
 		SDL_free(thread);
 	}
 }

 Uint32 SDL_GetThreadID(SDL_Thread *thread)
 {
 	Uint32 id;

 	if ( thread ) {
 		id = thread->threadid;
 	} else {
 		id = SDL_ThreadID();
 	}
 	return(id);
 }

 void SDL_KillThread(SDL_Thread *thread)
 {
 	if ( thread ) {
 		SDL_SYS_KillThread(thread);
 		SDL_WaitThread(thread, NULL);
 	}
 }
	/*
	SDL - Simple DirectMedia Layer
	Copyright (C) 1997-2009 Sam Lantinga

	This library is free software; you can redistribute it and/or
	modify it under the terms of the GNU Lesser General Public
	License as published by the Free Software Foundation; either
	version 2.1 of the License, or (at your option) any later version.

	This library is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public
	License along with this library; if not, write to the Free Software
	Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

	Sam Lantinga
	slouken@libsdl.org
	*/
	#include "SDL_config.h"

	/* System independent thread management routines for SDL */

	#include "SDL_mutex.h"
	#include "SDL_thread.h"
	#include "SDL_thread_c.h"
	#include "SDL_systhread.h"

	#define ARRAY_CHUNKSIZE 32
	/* The array of threads currently active in the application
	(except the main thread)
	The manipulation of an array here is safer than using a linked list.
	*/
	static int SDL_maxthreads = 0;
	static int SDL_numthreads = 0;
	static SDL_Thread **SDL_Threads = NULL;
	static SDL_mutex *thread_lock = NULL;

	int SDL_ThreadsInit(void)
	{
	int retval;

	retval = 0;
	thread_lock = SDL_CreateMutex();
	if ( thread_lock == NULL ) {
	retval = -1;
	}
	return(retval);
	}

	/* This should never be called...
	If this is called by SDL_Quit(), we don't know whether or not we should
	clean up threads here. If any threads are still running after this call,
	they will no longer have access to any per-thread data.
	*/
	void SDL_ThreadsQuit(void)
	{
	SDL_mutex *mutex;

	mutex = thread_lock;
	thread_lock = NULL;
	if ( mutex != NULL ) {
	SDL_DestroyMutex(mutex);
	}
	}

	/* Routines for manipulating the thread list */
	static void SDL_AddThread(SDL_Thread *thread)
	{
	/* WARNING:
	If the very first threads are created simultaneously, then
	there could be a race condition causing memory corruption.
	In practice, this isn't a problem because by definition there
	is only one thread running the first time this is called.
	*/
	if ( !thread_lock ) {
	if ( SDL_ThreadsInit() < 0 ) {
	return;
	}
	}
	SDL_mutexP(thread_lock);

	/* Expand the list of threads, if necessary */
	#ifdef DEBUG_THREADS
	printf("Adding thread (%d already - %d max)\n",
	SDL_numthreads, SDL_maxthreads);
	#endif
	if ( SDL_numthreads == SDL_maxthreads ) {
	SDL_Thread **threads;
	threads = (SDL_Thread **)SDL_realloc(SDL_Threads,
	(SDL_maxthreads+ARRAY_CHUNKSIZE)(sizeof threads));
	if ( threads == NULL ) {
	SDL_OutOfMemory();
	goto done;
	}
	SDL_maxthreads += ARRAY_CHUNKSIZE;
	SDL_Threads = threads;
	}
	SDL_Threads[SDL_numthreads++] = thread;
	done:
	SDL_mutexV(thread_lock);
	}

	static void SDL_DelThread(SDL_Thread *thread)
	{
	int i;

	if ( !thread_lock ) {
	return;
	}
	SDL_mutexP(thread_lock);
	for ( i=0; i<SDL_numthreads; ++i ) {
	if ( thread == SDL_Threads[i] ) {
	break;
	}
	}
	if ( i < SDL_numthreads ) {
	if ( --SDL_numthreads > 0 ) {
	while ( i < SDL_numthreads ) {
	SDL_Threads[i] = SDL_Threads[i+1];
	++i;
	}
	} else {
	SDL_maxthreads = 0;
	SDL_free(SDL_Threads);
	SDL_Threads = NULL;
	}
	#ifdef DEBUG_THREADS
	printf("Deleting thread (%d left - %d max)\n",
	SDL_numthreads, SDL_maxthreads);
	#endif
	}
	SDL_mutexV(thread_lock);

	#if 0 /* There could be memory corruption if another thread is starting */
	if ( SDL_Threads == NULL ) {
	SDL_ThreadsQuit();
	}
	#endif
	}

	/* The default (non-thread-safe) global error variable */
	static SDL_error SDL_global_error;

	/* Routine to get the thread-specific error variable */
	SDL_error *SDL_GetErrBuf(void)
	{
	SDL_error *errbuf;

	errbuf = &SDL_global_error;
	if ( SDL_Threads ) {
	int i;
	Uint32 this_thread;

	this_thread = SDL_ThreadID();
	SDL_mutexP(thread_lock);
	for ( i=0; i<SDL_numthreads; ++i ) {
	if ( this_thread == SDL_Threads[i]->threadid ) {
	errbuf = &SDL_Threads[i]->errbuf;
	break;
	}
	}
	SDL_mutexV(thread_lock);
	}
	return(errbuf);
	}


	/* Arguments and callback to setup and run the user thread function */
	typedef struct {
	int (SDLCALL func)(void );
	void *data;
	SDL_Thread *info;
	SDL_sem *wait;
	} thread_args;

	void SDL_RunThread(void *data)
	{
	thread_args *args;
	int (SDLCALL userfunc)(void );
	void *userdata;
	int *statusloc;

	/* Perform any system-dependent setup
	- this function cannot fail, and cannot use SDL_SetError()
	*/
	SDL_SYS_SetupThread();

	/* Get the thread id */
	args = (thread_args *)data;
	args->info->threadid = SDL_ThreadID();

	/* Figure out what function to run */
	userfunc = args->func;
	userdata = args->data;
	statusloc = &args->info->status;

	/* Wake up the parent thread */
	SDL_SemPost(args->wait);

	/* Run the function */
	*statusloc = userfunc(userdata);
	}

	#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
	#undef SDL_CreateThread
	DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL fn)(void ), void *data, pfnSDL_CurrentBeginThread pfnBeginThread, pfnSDL_CurrentEndThread pfnEndThread)
	#else
	DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL fn)(void ), void *data)
	#endif
	{
	SDL_Thread *thread;
	thread_args *args;
	int ret;

	/* Allocate memory for the thread info structure */
	thread = (SDL_Thread )SDL_malloc(sizeof(thread));
	if ( thread == NULL ) {
	SDL_OutOfMemory();
	return(NULL);
	}
	SDL_memset(thread, 0, (sizeof *thread));
	thread->status = -1;

	/* Set up the arguments for the thread */
	args = (thread_args )SDL_malloc(sizeof(args));
	if ( args == NULL ) {
	SDL_OutOfMemory();
	SDL_free(thread);
	return(NULL);
	}
	args->func = fn;
	args->data = data;
	args->info = thread;
	args->wait = SDL_CreateSemaphore(0);
	if ( args->wait == NULL ) {
	SDL_free(thread);
	SDL_free(args);
	return(NULL);
	}

	/* Add the thread to the list of available threads */
	SDL_AddThread(thread);

	/* Create the thread and go! */
	#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
	ret = SDL_SYS_CreateThread(thread, args, pfnBeginThread, pfnEndThread);
	#else
	ret = SDL_SYS_CreateThread(thread, args);
	#endif
	if ( ret >= 0 ) {
	/* Wait for the thread function to use arguments */
	SDL_SemWait(args->wait);
	} else {
	/* Oops, failed. Gotta free everything */
	SDL_DelThread(thread);
	SDL_free(thread);
	thread = NULL;
	}
	SDL_DestroySemaphore(args->wait);
	SDL_free(args);

	/* Everything is running now */
	return(thread);
	}

	void SDL_WaitThread(SDL_Thread thread, int status)
	{
	if ( thread ) {
	SDL_SYS_WaitThread(thread);
	if ( status ) {
	*status = thread->status;
	}
	SDL_DelThread(thread);
	SDL_free(thread);
	}
	}

	Uint32 SDL_GetThreadID(SDL_Thread *thread)
	{
	Uint32 id;

	if ( thread ) {
	id = thread->threadid;
	} else {
	id = SDL_ThreadID();
	}
	return(id);
	}

	void SDL_KillThread(SDL_Thread *thread)
	{
	if ( thread ) {
	SDL_SYS_KillThread(thread);
	SDL_WaitThread(thread, NULL);
	}
	}