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"
14 #include "xbt/error.h"
15 #include "xbt/dynar.h"
16 #include "gras_config.h"
18 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(context, xbt, "Context");
20 /* #define WARNING(format, ...) (fprintf(stderr, "[%s , %s : %d] ", __FILE__, __FUNCTION__, __LINE__),\ */
21 /* fprintf(stderr, format, ## __VA_ARGS__), \ */
22 /* fprintf(stderr, "\n")) */
23 /* #define VOIRP(expr) WARNING(" {" #expr " = %p }", expr) */
25 #ifndef HAVE_UCONTEXT_H
26 /* don't want to play with conditional compilation in automake tonight, sorry.
27 include directly the c file from here when needed. */
28 # include "context_win32.c"
31 static xbt_context_t current_context = NULL;
32 static xbt_context_t init_context = NULL;
33 static xbt_swag_t context_to_destroy = NULL;
34 static xbt_swag_t context_living = NULL;
36 static void __xbt_context_yield(xbt_context_t context)
40 xbt_assert0(current_context,"You have to call context_init() first.");
42 DEBUG2("--------- current_context (%p) is yielding to context(%p) ---------",
43 current_context,context);
46 DEBUG1("current_context->save = %p",current_context->save);
48 /* if(context) VOIRP(context->save); */
51 if(context->save==NULL) {
52 /* WARNING("**** Yielding to somebody else ****"); */
53 /* WARNING("Saving current_context value (%p) to context(%p)->save",current_context,context); */
54 context->save = current_context ;
55 /* WARNING("current_context becomes context(%p) ",context); */
56 current_context = context ;
57 /* WARNING("Current position memorized (context->save). Jumping to context (%p)",context); */
58 return_value = swapcontext (&(context->save->uc), &(context->uc));
59 xbt_assert0((return_value==0),"Context swapping failure");
60 /* WARNING("I am (%p). Coming back\n",context); */
62 xbt_context_t old_context = context->save ;
63 /* WARNING("**** Back ! ****"); */
64 /* WARNING("Setting current_context (%p) to context(%p)->save",current_context,context); */
65 current_context = context->save ;
66 /* WARNING("Setting context(%p)->save to NULL",context); */
67 context->save = NULL ;
68 /* WARNING("Current position memorized (%p). Jumping to context (%p)",context,old_context); */
69 return_value = swapcontext (&(context->uc), &(old_context->uc));
70 xbt_assert0((return_value==0),"Context swapping failure");
71 /* WARNING("I am (%p). Coming back\n",context); */
78 static void xbt_context_destroy(xbt_context_t context)
86 * \ingroup XBT_context
89 /** Context module initialization
91 * \warning It has to be called before using any other function of this module.
93 void xbt_context_init(void)
95 if(!current_context) {
96 current_context = init_context = xbt_new0(s_xbt_context_t,1);
97 context_to_destroy = xbt_swag_new(xbt_swag_offset(*current_context,hookup));
98 context_living = xbt_swag_new(xbt_swag_offset(*current_context,hookup));
99 xbt_swag_insert(init_context, context_living);
103 /** Garbage collection
105 * Should be called some time to time to free the memory allocated for contexts
106 * that have finished executing their main functions.
108 void xbt_context_empty_trash(void)
110 xbt_context_t context=NULL;
112 while((context=xbt_swag_extract(context_to_destroy)))
113 xbt_context_destroy(context);
116 static void *__context_wrapper(void *c)
118 xbt_context_t context = c;
121 /* msg_global->current_process = process; */
123 if(context->startup_func)
124 context->startup_func(context->startup_arg);
126 /* WARNING("Calling the main function"); */
127 /* xbt_context_yield(context); */
128 (context->code) (context->argc,context->argv);
130 for(i=0;i<context->argc; i++)
131 if(context->argv[i]) free(context->argv[i]);
132 if(context->argv) free(context->argv);
134 if(context->cleanup_func)
135 context->cleanup_func(context->cleanup_arg);
137 xbt_swag_remove(context, context_living);
138 xbt_swag_insert(context, context_to_destroy);
140 __xbt_context_yield(context);
141 xbt_assert0(0,"You're cannot be here!");
146 * \param context the context to start
148 * Calling this function prepares \a context to be run. It will
149 however run effectively only when calling #xbt_context_schedule
151 void xbt_context_start(xbt_context_t context)
153 /* xbt_fifo_insert(msg_global->process, process); */
154 /* xbt_fifo_insert(msg_global->process_to_run, process); */
156 makecontext (&(context->uc), (void (*) (void)) __context_wrapper,
162 * \param code a main function
163 * \param startup_func a function to call when running the context for
164 * the first time and just before the main function \a code
165 * \param startup_arg the argument passed to the previous function (\a startup_func)
166 * \param cleanup_func a function to call when running the context, just after
167 the termination of the main function \a code
168 * \param cleanup_arg the argument passed to the previous function (\a cleanup_func)
169 * \param argc first argument of function \a code
170 * \param argv seconde argument of function \a code
172 xbt_context_t xbt_context_new(xbt_context_function_t code,
173 void_f_pvoid_t startup_func, void *startup_arg,
174 void_f_pvoid_t cleanup_func, void *cleanup_arg,
175 int argc, char *argv[])
177 xbt_context_t res = NULL;
179 res = xbt_new0(s_xbt_context_t,1);
181 /* FIXME: strerror is not thread safe */
182 xbt_assert2(getcontext(&(res->uc))==0,"Error in context saving: %d (%s)", errno, strerror(errno));
185 res->uc.uc_link = NULL;
188 /* res->uc.uc_link = &(current_context->uc); */
189 /* WARNING : when this context is over, the current_context (i.e. the
190 father), is awaken... Theorically, the wrapper should prevent using
192 res->uc.uc_stack.ss_sp = res->stack;
193 res->uc.uc_stack.ss_size = STACK_SIZE;
194 res->startup_func = startup_func;
195 res->startup_arg = startup_arg;
196 res->cleanup_func = cleanup_func;
197 res->cleanup_arg = cleanup_arg;
199 xbt_swag_insert(res, context_living);
206 * Calling this function makes the current context yield. The context
207 * that scheduled it returns from xbt_context_schedule as if nothing
210 void xbt_context_yield(void)
212 __xbt_context_yield(current_context);
217 * \param context the winner
219 * Calling this function blocks the current context and schedule \a context.
220 * When \a context will call xbt_context_yield, it will return
221 * to this function as if nothing had happened.
223 void xbt_context_schedule(xbt_context_t context)
225 xbt_assert0((current_context==init_context),
226 "You are not supposed to run this function here!");
227 __xbt_context_yield(context);
231 * This function kill all existing context and free all the memory
232 * that has been allocated in this module.
234 void xbt_context_exit(void) {
235 xbt_context_t context=NULL;
237 xbt_context_empty_trash();
238 xbt_swag_free(context_to_destroy);
240 while((context=xbt_swag_extract(context_living)))
241 xbt_context_free(context);
243 xbt_swag_free(context_living);
245 init_context = current_context = NULL ;
249 * \param context poor victim
251 * This function simply kills \a context... scarry isn't it ?
253 void xbt_context_free(xbt_context_t context)
257 xbt_swag_remove(context, context_living);
258 for(i=0;i<context->argc; i++)
259 if(context->argv[i]) free(context->argv[i]);
260 if(context->argv) free(context->argv);
262 if(context->cleanup_func)
263 context->cleanup_func(context->cleanup_arg);
264 xbt_context_destroy(context);