1/*
2    SDL - Simple DirectMedia Layer
3    Copyright (C) 1997-2012 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 0	/* There could be memory corruption if another thread is starting */
138	if ( SDL_Threads == NULL ) {
139		SDL_ThreadsQuit();
140	}
141#endif
142}
143
144/* The default (non-thread-safe) global error variable */
145static SDL_error SDL_global_error;
146
147/* Routine to get the thread-specific error variable */
148SDL_error *SDL_GetErrBuf(void)
149{
150	SDL_error *errbuf;
151
152	errbuf = &SDL_global_error;
153	if ( SDL_Threads ) {
154		int i;
155		Uint32 this_thread;
156
157		this_thread = SDL_ThreadID();
158		SDL_mutexP(thread_lock);
159		for ( i=0; i<SDL_numthreads; ++i ) {
160			if ( this_thread == SDL_Threads[i]->threadid ) {
161				errbuf = &SDL_Threads[i]->errbuf;
162				break;
163			}
164		}
165		SDL_mutexV(thread_lock);
166	}
167	return(errbuf);
168}
169
170
171/* Arguments and callback to setup and run the user thread function */
172typedef struct {
173	int (SDLCALL *func)(void *);
174	void *data;
175	SDL_Thread *info;
176	SDL_sem *wait;
177} thread_args;
178
179void SDL_RunThread(void *data)
180{
181	thread_args *args;
182	int (SDLCALL *userfunc)(void *);
183	void *userdata;
184	int *statusloc;
185
186	/* Perform any system-dependent setup
187	   - this function cannot fail, and cannot use SDL_SetError()
188	 */
189	SDL_SYS_SetupThread();
190
191	/* Get the thread id */
192	args = (thread_args *)data;
193	args->info->threadid = SDL_ThreadID();
194
195	/* Figure out what function to run */
196	userfunc = args->func;
197	userdata = args->data;
198	statusloc = &args->info->status;
199
200	/* Wake up the parent thread */
201	SDL_SemPost(args->wait);
202
203	/* Run the function */
204	*statusloc = userfunc(userdata);
205}
206
207#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
208#undef SDL_CreateThread
209DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data, pfnSDL_CurrentBeginThread pfnBeginThread, pfnSDL_CurrentEndThread pfnEndThread)
210#else
211DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data)
212#endif
213{
214	SDL_Thread *thread;
215	thread_args *args;
216	int ret;
217
218	/* Allocate memory for the thread info structure */
219	thread = (SDL_Thread *)SDL_malloc(sizeof(*thread));
220	if ( thread == NULL ) {
221		SDL_OutOfMemory();
222		return(NULL);
223	}
224	SDL_memset(thread, 0, (sizeof *thread));
225	thread->status = -1;
226
227	/* Set up the arguments for the thread */
228	args = (thread_args *)SDL_malloc(sizeof(*args));
229	if ( args == NULL ) {
230		SDL_OutOfMemory();
231		SDL_free(thread);
232		return(NULL);
233	}
234	args->func = fn;
235	args->data = data;
236	args->info = thread;
237	args->wait = SDL_CreateSemaphore(0);
238	if ( args->wait == NULL ) {
239		SDL_free(thread);
240		SDL_free(args);
241		return(NULL);
242	}
243
244	/* Add the thread to the list of available threads */
245	SDL_AddThread(thread);
246
247	/* Create the thread and go! */
248#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
249	ret = SDL_SYS_CreateThread(thread, args, pfnBeginThread, pfnEndThread);
250#else
251	ret = SDL_SYS_CreateThread(thread, args);
252#endif
253	if ( ret >= 0 ) {
254		/* Wait for the thread function to use arguments */
255		SDL_SemWait(args->wait);
256	} else {
257		/* Oops, failed.  Gotta free everything */
258		SDL_DelThread(thread);
259		SDL_free(thread);
260		thread = NULL;
261	}
262	SDL_DestroySemaphore(args->wait);
263	SDL_free(args);
264
265	/* Everything is running now */
266	return(thread);
267}
268
269void SDL_WaitThread(SDL_Thread *thread, int *status)
270{
271	if ( thread ) {
272		SDL_SYS_WaitThread(thread);
273		if ( status ) {
274			*status = thread->status;
275		}
276		SDL_DelThread(thread);
277		SDL_free(thread);
278	}
279}
280
281Uint32 SDL_GetThreadID(SDL_Thread *thread)
282{
283	Uint32 id;
284
285	if ( thread ) {
286		id = thread->threadid;
287	} else {
288		id = SDL_ThreadID();
289	}
290	return(id);
291}
292
293void SDL_KillThread(SDL_Thread *thread)
294{
295	if ( thread ) {
296		SDL_SYS_KillThread(thread);
297		SDL_WaitThread(thread, NULL);
298	}
299}
300
301