src/thread/SDL_thread.c
author Sam Lantinga <slouken@libsdl.org>
Wed, 17 May 2006 08:18:28 +0000
branchSDL-1.3
changeset 1659 14717b52abc0
parent 1612 97d0966f4bf7
child 1662 782fd950bd46
child 1895 c121d94672cb
child 4159 a1b03ba2fcd0
permissions -rw-r--r--
Merge trunk-1.3-3
     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