1 /*

     2     SDL - Simple DirectMedia Layer

     3     Copyright (C) 1997-2006 Sam Lantinga

     4 

     5     This library is free software; you can redistribute it and/or

     6     modify it under the terms of the GNU Lesser General Public

     7     License as published by the Free Software Foundation; either

     8     version 2.1 of the License, or (at your option) any later version.

     9 

    10     This library is distributed in the hope that it will be useful,

    11     but WITHOUT ANY WARRANTY; without even the implied warranty of

    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    13     Lesser General Public License for more details.

    14 

    15     You should have received a copy of the GNU Lesser General Public

    16     License along with this library; if not, write to the Free Software

    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    18 

    19     Sam Lantinga

    20     slouken@libsdl.org

    21 */

    22 #include "SDL_config.h"

    23 

    24 /* System independent thread management routines for SDL */

    25 

    26 #include "SDL_mutex.h"

    27 #include "SDL_thread.h"

    28 #include "SDL_thread_c.h"

    29 #include "SDL_systhread.h"

    30 

    31 #define ARRAY_CHUNKSIZE	32

    32 /* The array of threads currently active in the application

    33    (except the main thread)

    34    The manipulation of an array here is safer than using a linked list.

    35 */

    36 static int SDL_maxthreads = 0;

    37 static int SDL_numthreads = 0;

    38 static SDL_Thread **SDL_Threads = NULL;

    39 static SDL_mutex *thread_lock = NULL;

    40 

    41 int SDL_ThreadsInit(void)

    42 {

    43 	int retval;

    44 

    45 	retval = 0;

    46 	thread_lock = SDL_CreateMutex();

    47 	if ( thread_lock == NULL ) {

    48 		retval = -1;

    49 	}

    50 	return(retval);

    51 }

    52 

    53 /* This should never be called...

    54    If this is called by SDL_Quit(), we don't know whether or not we should

    55    clean up threads here.  If any threads are still running after this call,

    56    they will no longer have access to any per-thread data.

    57  */

    58 void SDL_ThreadsQuit(void)

    59 {

    60 	SDL_mutex *mutex;

    61 

    62 	mutex = thread_lock;

    63 	thread_lock = NULL;

    64 	if ( mutex != NULL ) {

    65 		SDL_DestroyMutex(mutex);

    66 	}

    67 }

    68 

    69 /* Routines for manipulating the thread list */

    70 static void SDL_AddThread(SDL_Thread *thread)

    71 {

    72 	/* WARNING:

    73 	   If the very first threads are created simultaneously, then

    74 	   there could be a race condition causing memory corruption.

    75 	   In practice, this isn't a problem because by definition there

    76 	   is only one thread running the first time this is called.

    77 	*/

    78 	if ( !thread_lock ) {

    79 		if ( SDL_ThreadsInit() < 0 ) {

    80 			return;

    81 		}

    82 	}

    83 	SDL_mutexP(thread_lock);

    84 

    85 	/* Expand the list of threads, if necessary */

    86 #ifdef DEBUG_THREADS

    87 	printf("Adding thread (%d already - %d max)\n",

    88 			SDL_numthreads, SDL_maxthreads);

    89 #endif

    90 	if ( SDL_numthreads == SDL_maxthreads ) {

    91 		SDL_Thread **threads;

    92 		threads = (SDL_Thread **)SDL_realloc(SDL_Threads,

    93 			(SDL_maxthreads+ARRAY_CHUNKSIZE)*(sizeof *threads));

    94 		if ( threads == NULL ) {

    95 			SDL_OutOfMemory();

    96 			goto done;

    97 		}

    98 		SDL_maxthreads += ARRAY_CHUNKSIZE;

    99 		SDL_Threads = threads;

   100 	}

   101 	SDL_Threads[SDL_numthreads++] = thread;

   102 done:

   103 	SDL_mutexV(thread_lock);

   104 }

   105 

   106 static void SDL_DelThread(SDL_Thread *thread)

   107 {

   108 	int i;

   109 

   110 	if ( !thread_lock ) {

   111 		return;

   112 	}

   113 	SDL_mutexP(thread_lock);

   114 	for ( i=0; i<SDL_numthreads; ++i ) {

   115 		if ( thread == SDL_Threads[i] ) {

   116 			break;

   117 		}

   118 	}

   119 	if ( i < SDL_numthreads ) {

   120 		if ( --SDL_numthreads > 0 ) {

   121 			while ( i < SDL_numthreads ) {

   122 				SDL_Threads[i] = SDL_Threads[i+1];

   123 				++i;

   124 			}

   125 		} else {

   126 			SDL_maxthreads = 0;

   127 			SDL_free(SDL_Threads);

   128 			SDL_Threads = NULL;

   129 		}

   130 #ifdef DEBUG_THREADS

   131 		printf("Deleting thread (%d left - %d max)\n",

   132 				SDL_numthreads, SDL_maxthreads);

   133 #endif

   134 	}

   135 	SDL_mutexV(thread_lock);

   136 

   137 	if ( SDL_Threads == NULL ) {

   138 		SDL_ThreadsQuit();

   139 	}

   140 }

   141 

   142 /* The default (non-thread-safe) global error variable */

   143 static SDL_error SDL_global_error;

   144 

   145 /* Routine to get the thread-specific error variable */

   146 SDL_error *SDL_GetErrBuf(void)

   147 {

   148 	SDL_error *errbuf;

   149 

   150 	errbuf = &SDL_global_error;

   151 	if ( SDL_Threads ) {

   152 		int i;

   153 		Uint32 this_thread;

   154 

   155 		this_thread = SDL_ThreadID();

   156 		SDL_mutexP(thread_lock);

   157 		for ( i=0; i<SDL_numthreads; ++i ) {

   158 			if ( this_thread == SDL_Threads[i]->threadid ) {

   159 				errbuf = &SDL_Threads[i]->errbuf;

   160 				break;

   161 			}

   162 		}

   163 		SDL_mutexV(thread_lock);

   164 	}

   165 	return(errbuf);

   166 }

   167 

   168 

   169 /* Arguments and callback to setup and run the user thread function */

   170 typedef struct {

   171 	int (SDLCALL *func)(void *);

   172 	void *data;

   173 	SDL_Thread *info;

   174 	SDL_sem *wait;

   175 } thread_args;

   176 

   177 void SDL_RunThread(void *data)

   178 {

   179 	thread_args *args;

   180 	int (SDLCALL *userfunc)(void *);

   181 	void *userdata;

   182 	int *statusloc;

   183 

   184 	/* Perform any system-dependent setup

   185 	   - this function cannot fail, and cannot use SDL_SetError()

   186 	 */

   187 	SDL_SYS_SetupThread();

   188 

   189 	/* Get the thread id */

   190 	args = (thread_args *)data;

   191 	args->info->threadid = SDL_ThreadID();

   192 

   193 	/* Figure out what function to run */

   194 	userfunc = args->func;

   195 	userdata = args->data;

   196 	statusloc = &args->info->status;

   197 

   198 	/* Wake up the parent thread */

   199 	SDL_SemPost(args->wait);

   200 

   201 	/* Run the function */

   202 	*statusloc = userfunc(userdata);

   203 }

   204 

   205 #ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD

   206 #undef SDL_CreateThread

   207 DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data, pfnSDL_CurrentBeginThread pfnBeginThread, pfnSDL_CurrentEndThread pfnEndThread)

   208 #else

   209 DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data)

   210 #endif

   211 {

   212 	SDL_Thread *thread;

   213 	thread_args *args;

   214 	int ret;

   215 

   216 	/* Allocate memory for the thread info structure */

   217 	thread = (SDL_Thread *)SDL_malloc(sizeof(*thread));

   218 	if ( thread == NULL ) {

   219 		SDL_OutOfMemory();

   220 		return(NULL);

   221 	}

   222 	SDL_memset(thread, 0, (sizeof *thread));

   223 	thread->status = -1;

   224 

   225 	/* Set up the arguments for the thread */

   226 	args = (thread_args *)SDL_malloc(sizeof(*args));

   227 	if ( args == NULL ) {

   228 		SDL_OutOfMemory();

   229 		SDL_free(thread);

   230 		return(NULL);

   231 	}

   232 	args->func = fn;

   233 	args->data = data;

   234 	args->info = thread;

   235 	args->wait = SDL_CreateSemaphore(0);

   236 	if ( args->wait == NULL ) {

   237 		SDL_free(thread);

   238 		SDL_free(args);

   239 		return(NULL);

   240 	}

   241 

   242 	/* Add the thread to the list of available threads */

   243 	SDL_AddThread(thread);

   244 

   245 	/* Create the thread and go! */

   246 #ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD

   247 	ret = SDL_SYS_CreateThread(thread, args, pfnBeginThread, pfnEndThread);

   248 #else

   249 	ret = SDL_SYS_CreateThread(thread, args);

   250 #endif

   251 	if ( ret >= 0 ) {

   252 		/* Wait for the thread function to use arguments */

   253 		SDL_SemWait(args->wait);

   254 	} else {

   255 		/* Oops, failed.  Gotta free everything */

   256 		SDL_DelThread(thread);

   257 		SDL_free(thread);

   258 		thread = NULL;

   259 	}

   260 	SDL_DestroySemaphore(args->wait);

   261 	SDL_free(args);

   262 

   263 	/* Everything is running now */

   264 	return(thread);

   265 }

   266 

   267 void SDL_WaitThread(SDL_Thread *thread, int *status)

   268 {

   269 	if ( thread ) {

   270 		SDL_SYS_WaitThread(thread);

   271 		if ( status ) {

   272 			*status = thread->status;

   273 		}

   274 		SDL_DelThread(thread);

   275 		SDL_free(thread);

   276 	}

   277 }

   278 

   279 Uint32 SDL_GetThreadID(SDL_Thread *thread)

   280 {

   281 	Uint32 id;

   282 

   283 	if ( thread ) {

   284 		id = thread->threadid;

   285 	} else {

   286 		id = SDL_ThreadID();

   287 	}

   288 	return(id);

   289 }

   290 

   291 void SDL_KillThread(SDL_Thread *thread)

   292 {

   293 	if ( thread ) {

   294 		SDL_SYS_KillThread(thread);

   295 		SDL_WaitThread(thread, NULL);

   296 	}

   297 }

   298