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*/
36static int SDL_maxthreads = 0;
37static int SDL_numthreads = 0;
38static SDL_Thread **SDL_Threads = NULL;
39static SDL_mutex *thread_lock = NULL;
40
41int 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 */
58void 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 */
70static 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;
102done:
103	SDL_mutexV(thread_lock);
104}
105
106static 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 */
143static SDL_error SDL_global_error;
144
145/* Routine to get the thread-specific error variable */
146SDL_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 */
170typedef struct {
171	int (SDLCALL *func)(void *);
172	void *data;
173	SDL_Thread *info;
174	SDL_sem *wait;
175} thread_args;
176
177void 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
207DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data, pfnSDL_CurrentBeginThread pfnBeginThread, pfnSDL_CurrentEndThread pfnEndThread)
208#else
209DECLSPEC 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
267void 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
279Uint32 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
291void SDL_KillThread(SDL_Thread *thread)
292{
293	if ( thread ) {
294		SDL_SYS_KillThread(thread);
295		SDL_WaitThread(thread, NULL);
296	}
297}
298
299