3 /* a fast and simple context switching library */
5 /* Copyright (c) 2004 Arnaud Legrand. */
6 /* Copyright (c) 2004, 2005 Martin Quinson. */
7 /* All rights reserved. */
9 /* This program is free software; you can redistribute it and/or modify it
10 * under the terms of the license (GNU LGPL) which comes with this package. */
13 #include "context_private.h"
15 #include "xbt/dynar.h"
16 #include "gras_config.h"
18 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(context, xbt, "Context");
20 #define VOIRP(expr) DEBUG1(" {" #expr " = %p }", expr)
22 static xbt_context_t current_context = NULL;
23 static xbt_context_t init_context = NULL;
24 static xbt_swag_t context_to_destroy = NULL;
25 static xbt_swag_t context_living = NULL;
27 #ifndef USE_PTHREADS /* USE_PTHREADS and USE_CONTEXT are exclusive */
29 /* don't want to play with conditional compilation in automake tonight, sorry.
30 include directly the c file from here when needed. */
31 # include "context_win32.c"
32 # define USE_WIN_CONTEXT
36 static void __xbt_context_yield(xbt_context_t context)
38 xbt_assert0(current_context,"You have to call context_init() first.");
40 DEBUG2("--------- current_context (%p) is yielding to context(%p) ---------",
41 current_context,context);
45 xbt_context_t self = current_context;
46 DEBUG0("**** Locking ****");
47 pthread_mutex_lock(&(context->mutex));
48 DEBUG0("**** Updating current_context ****");
49 current_context = context;
50 DEBUG0("**** Releasing the prisonner ****");
51 pthread_cond_signal(&(context->cond));
52 DEBUG0("**** Going to jail ****");
53 pthread_cond_wait(&(context->cond), &(context->mutex));
54 DEBUG0("**** Unlocking ****");
55 pthread_mutex_unlock(&(context->mutex));
56 DEBUG0("**** Updating current_context ****");
57 current_context = self;
61 VOIRP(current_context->save);
64 if(context) VOIRP(context->save);
69 if(context->save==NULL) {
70 DEBUG0("**** Yielding to somebody else ****");
71 DEBUG2("Saving current_context value (%p) to context(%p)->save",current_context,context);
72 context->save = current_context ;
73 DEBUG1("current_context becomes context(%p) ",context);
74 current_context = context ;
75 DEBUG1("Current position memorized (context->save). Jumping to context (%p)",context);
76 return_value = swapcontext (&(context->save->uc), &(context->uc));
77 xbt_assert0((return_value==0),"Context swapping failure");
78 DEBUG1("I am (%p). Coming back\n",context);
80 xbt_context_t old_context = context->save ;
81 DEBUG0("**** Back ! ****");
82 DEBUG2("Setting current_context (%p) to context(%p)->save",current_context,context);
83 current_context = context->save ;
84 DEBUG1("Setting context(%p)->save to NULL",context);
85 context->save = NULL ;
86 DEBUG2("Current position memorized (%p). Jumping to context (%p)",context,old_context);
87 return_value = swapcontext (&(context->uc), &(old_context->uc));
88 xbt_assert0((return_value==0),"Context swapping failure");
89 DEBUG1("I am (%p). Coming back\n",context);
96 static void xbt_context_destroy(xbt_context_t context)
99 xbt_free(context->thread);
100 pthread_mutex_destroy(&(context->mutex));
101 pthread_cond_destroy(&(context->cond));
103 if(context->exception) free(context->exception);
108 static void *__context_wrapper(void *c)
110 xbt_context_t context = c;
114 DEBUG2("**[%p:%p]** Lock ****",context,(void*)pthread_self());
115 pthread_mutex_lock(&(context->mutex));
116 DEBUG2("**[%p:%p]** Releasing the prisonner ****",context,(void*)pthread_self());
117 pthread_cond_signal(&(context->cond));
118 DEBUG2("**[%p:%p]** Going to Jail ****",context,(void*)pthread_self());
119 pthread_cond_wait(&(context->cond), &(context->mutex));
120 DEBUG2("**[%p:%p]** Unlocking ****",context,(void*)pthread_self());
121 pthread_mutex_unlock(&(context->mutex));
124 if(context->startup_func)
125 context->startup_func(context->startup_arg);
127 DEBUG0("Calling the main function");
128 (context->code) (context->argc,context->argv);
130 DEBUG0("Freeing arguments");
131 for(i=0;i<context->argc; i++)
132 if(context->argv[i]) free(context->argv[i]);
133 if(context->argv) free(context->argv);
135 if(context->cleanup_func) {
136 DEBUG0("Calling cleanup function");
137 context->cleanup_func(context->cleanup_arg);
140 DEBUG0("Putting context in the to_destroy set");
141 xbt_swag_remove(context, context_living);
142 xbt_swag_insert(context, context_to_destroy);
143 DEBUG0("Context put in the to_destroy set");
147 DEBUG0("**** Locking ****");
148 pthread_mutex_lock(&(context->mutex));
149 DEBUG0("**** Updating current_context ****");
150 current_context = context;
151 DEBUG0("**** Releasing the prisonner ****");
152 pthread_cond_signal(&(context->cond));
153 DEBUG0("**** Unlocking ****");
154 pthread_mutex_unlock(&(context->mutex));
155 DEBUG0("**** Exiting ****");
158 __xbt_context_yield(context);
160 xbt_assert0(0,"You can't be here!");
164 /* callback: context fetching */
165 static ex_ctx_t *__context_ex_ctx(void)
167 return current_context->exception;
170 /* callback: termination */
171 static void __context_ex_terminate(xbt_ex_t *e)
177 * \ingroup XBT_context
180 /** Context module initialization
182 * \warning It has to be called before using any other function of this module.
184 void xbt_context_init(void)
186 if(!current_context) {
187 current_context = init_context = xbt_new0(s_xbt_context_t,1);
188 init_context->exception = xbt_new(ex_ctx_t,1);
189 XBT_CTX_INITIALIZE(init_context->exception);
190 __xbt_ex_ctx = __context_ex_ctx;
191 __xbt_ex_terminate = __context_ex_terminate;
192 context_to_destroy = xbt_swag_new(xbt_swag_offset(*current_context,hookup));
193 context_living = xbt_swag_new(xbt_swag_offset(*current_context,hookup));
194 xbt_swag_insert(init_context, context_living);
198 /** Garbage collection
200 * Should be called some time to time to free the memory allocated for contexts
201 * that have finished executing their main functions.
203 void xbt_context_empty_trash(void)
205 xbt_context_t context=NULL;
207 while((context=xbt_swag_extract(context_to_destroy)))
208 xbt_context_destroy(context);
212 * \param context the context to start
214 * Calling this function prepares \a context to be run. It will
215 however run effectively only when calling #xbt_context_schedule
217 void xbt_context_start(xbt_context_t context)
220 /* Launch the thread */
221 DEBUG1("**[%p]** Locking ****",context);
222 pthread_mutex_lock(&(context->mutex));
223 DEBUG1("**[%p]** Pthread create ****",context);
224 xbt_assert0(!pthread_create(context->thread, NULL, __context_wrapper, context),
225 "Unable to create a thread.");
226 DEBUG2("**[%p]** Pthread created : %p ****",context,(void*)(*(context->thread)));
227 DEBUG1("**[%p]** Going to jail ****",context);
228 pthread_cond_wait(&(context->cond), &(context->mutex));
229 DEBUG1("**[%p]** Unlocking ****",context);
230 pthread_mutex_unlock(&(context->mutex));
232 makecontext (&(context->uc), (void (*) (void)) __context_wrapper,
239 * \param code a main function
240 * \param startup_func a function to call when running the context for
241 * the first time and just before the main function \a code
242 * \param startup_arg the argument passed to the previous function (\a startup_func)
243 * \param cleanup_func a function to call when running the context, just after
244 the termination of the main function \a code
245 * \param cleanup_arg the argument passed to the previous function (\a cleanup_func)
246 * \param argc first argument of function \a code
247 * \param argv seconde argument of function \a code
249 xbt_context_t xbt_context_new(xbt_context_function_t code,
250 void_f_pvoid_t startup_func, void *startup_arg,
251 void_f_pvoid_t cleanup_func, void *cleanup_arg,
252 int argc, char *argv[])
254 xbt_context_t res = NULL;
256 res = xbt_new0(s_xbt_context_t,1);
260 res->thread = xbt_new0(pthread_t,1);
261 xbt_assert0(!pthread_mutex_init(&(res->mutex), NULL), "Mutex initialization error");
262 xbt_assert0(!pthread_cond_init(&(res->cond), NULL), "Condition initialization error");
264 /* FIXME: strerror is not thread safe */
265 xbt_assert2(getcontext(&(res->uc))==0,"Error in context saving: %d (%s)", errno, strerror(errno));
266 res->uc.uc_link = NULL;
267 /* res->uc.uc_link = &(current_context->uc); */
268 /* WARNING : when this context is over, the current_context (i.e. the
269 father), is awaken... Theorically, the wrapper should prevent using
271 # ifndef USE_WIN_CONTEXT
272 res->uc.uc_stack.ss_sp = pth_skaddr_makecontext(res->stack,STACK_SIZE);
273 res->uc.uc_stack.ss_size = pth_sksize_makecontext(res->stack,STACK_SIZE);
274 # endif /* USE_WIN_CONTEXT */
275 #endif /* USE_PTHREADS or not */
278 res->startup_func = startup_func;
279 res->startup_arg = startup_arg;
280 res->cleanup_func = cleanup_func;
281 res->cleanup_arg = cleanup_arg;
282 res->exception = xbt_new(ex_ctx_t,1);
283 XBT_CTX_INITIALIZE(res->exception);
285 xbt_swag_insert(res, context_living);
291 * Calling this function makes the current context yield. The context
292 * that scheduled it returns from xbt_context_schedule as if nothing
295 void xbt_context_yield(void)
297 __xbt_context_yield(current_context);
301 * \param context the winner
303 * Calling this function blocks the current context and schedule \a context.
304 * When \a context will call xbt_context_yield, it will return
305 * to this function as if nothing had happened.
307 void xbt_context_schedule(xbt_context_t context)
309 DEBUG1("Scheduling %p",context);
310 xbt_assert0((current_context==init_context),
311 "You are not supposed to run this function here!");
312 __xbt_context_yield(context);
316 * This function kill all existing context and free all the memory
317 * that has been allocated in this module.
319 void xbt_context_exit(void) {
320 xbt_context_t context=NULL;
322 xbt_context_empty_trash();
323 xbt_swag_free(context_to_destroy);
325 while((context=xbt_swag_extract(context_living)))
326 xbt_context_free(context);
328 xbt_swag_free(context_living);
330 init_context = current_context = NULL ;
334 * \param context poor victim
336 * This function simply kills \a context... scarry isn't it ?
338 void xbt_context_free(xbt_context_t context)
342 xbt_swag_remove(context, context_living);
343 for(i=0;i<context->argc; i++)
344 if(context->argv[i]) free(context->argv[i]);
345 if(context->argv) free(context->argv);
347 if(context->cleanup_func)
348 context->cleanup_func(context->cleanup_arg);
349 xbt_context_destroy(context);