3 /* a fast and simple context switching library */
5 /* Copyright (c) 2004 Arnaud Legrand. */
6 /* Copyright (c) 2004 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 /** \defgroup XBT_context User-level context library
19 * \brief This section describes how to use high-level functions
20 * (as opposed to <tt>setjump/longjmp</tt>) to schedule non-preemptible
24 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(context, xbt, "Context");
26 /* #define WARNING(format, ...) (fprintf(stderr, "[%s , %s : %d] ", __FILE__, __FUNCTION__, __LINE__),\ */
27 /* fprintf(stderr, format, ## __VA_ARGS__), \ */
28 /* fprintf(stderr, "\n")) */
29 /* #define VOIRP(expr) WARNING(" {" #expr " = %p }", expr) */
31 #ifndef HAVE_UCONTEXT_H
32 /* don't want to play with conditional compilation in automake tonight, sorry.
33 include directly the c file from here when needed. */
34 # include "context_win32.c"
37 static xbt_context_t current_context = NULL;
38 static xbt_context_t init_context = NULL;
39 static xbt_swag_t context_to_destroy = NULL;
40 static xbt_swag_t context_living = NULL;
42 static void __xbt_context_yield(xbt_context_t context)
46 xbt_assert0(current_context,"You have to call context_init() first.");
48 /* WARNING("--------- current_context (%p) is yielding to context(%p) ---------",current_context,context); */
49 /* VOIRP(current_context); */
50 /* if(current_context) VOIRP(current_context->save); */
52 /* if(context) VOIRP(context->save); */
55 if(context->save==NULL) {
56 /* WARNING("**** Yielding to somebody else ****"); */
57 /* WARNING("Saving current_context value (%p) to context(%p)->save",current_context,context); */
58 context->save = current_context ;
59 /* WARNING("current_context becomes context(%p) ",context); */
60 current_context = context ;
61 /* WARNING("Current position memorized (context->save). Jumping to context (%p)",context); */
62 return_value = swapcontext (&(context->save->uc), &(context->uc));
63 xbt_assert0((return_value==0),"Context swapping failure");
64 /* WARNING("I am (%p). Coming back\n",context); */
66 xbt_context_t old_context = context->save ;
67 /* WARNING("**** Back ! ****"); */
68 /* WARNING("Setting current_context (%p) to context(%p)->save",current_context,context); */
69 current_context = context->save ;
70 /* WARNING("Setting context(%p)->save to NULL",context); */
71 context->save = NULL ;
72 /* WARNING("Current position memorized (%p). Jumping to context (%p)",context,old_context); */
73 return_value = swapcontext (&(context->uc), &(old_context->uc));
74 xbt_assert0((return_value==0),"Context swapping failure");
75 /* WARNING("I am (%p). Coming back\n",context); */
82 static void xbt_context_destroy(xbt_context_t context)
90 * \ingroup XBT_context
93 /** Context module initialization
95 * \warning It has to be called before using any other function of this module.
97 void xbt_context_init(void)
99 if(!current_context) {
100 current_context = init_context = xbt_new0(s_xbt_context_t,1);
101 context_to_destroy = xbt_swag_new(xbt_swag_offset(*current_context,hookup));
102 context_living = xbt_swag_new(xbt_swag_offset(*current_context,hookup));
103 xbt_swag_insert(init_context, context_living);
107 /** Garbage collection
109 * Should be called some time to time to free the memory allocated for contexts
110 * that have finished executing their main functions.
112 void xbt_context_empty_trash(void)
114 xbt_context_t context=NULL;
116 while((context=xbt_swag_extract(context_to_destroy)))
117 xbt_context_destroy(context);
120 static void *__context_wrapper(void *c)
122 xbt_context_t context = c;
125 /* msg_global->current_process = process; */
127 if(context->startup_func)
128 context->startup_func(context->startup_arg);
130 /* WARNING("Calling the main function"); */
131 /* xbt_context_yield(context); */
132 (context->code) (context->argc,context->argv);
134 for(i=0;i<context->argc; i++)
135 if(context->argv[i]) xbt_free(context->argv[i]);
136 if(context->argv) xbt_free(context->argv);
138 if(context->cleanup_func)
139 context->cleanup_func(context->cleanup_arg);
141 xbt_swag_remove(context, context_living);
142 xbt_swag_insert(context, context_to_destroy);
144 __xbt_context_yield(context);
145 xbt_assert0(0,"You're cannot be here!");
150 * \param context the context to start
152 * Calling this function prepares \a context to be run. It will
153 however run effectively only when calling #xbt_context_schedule
155 void xbt_context_start(xbt_context_t context)
157 /* xbt_fifo_insert(msg_global->process, process); */
158 /* xbt_fifo_insert(msg_global->process_to_run, process); */
160 makecontext (&(context->uc), (void (*) (void)) __context_wrapper,
166 * \param code a main function
167 * \param startup_func a function to call when running the context for
168 * the first time and just before the main function \a code
169 * \param startup_arg the argument passed to the previous function (\a startup_func)
170 * \param cleanup_func a function to call when running the context, just after
171 the termination of the main function \a code
172 * \param cleanup_arg the argument passed to the previous function (\a cleanup_func)
173 * \param argc first argument of function \a code
174 * \param argv seconde argument of function \a code
176 xbt_context_t xbt_context_new(xbt_context_function_t code,
177 void_f_pvoid_t startup_func, void *startup_arg,
178 void_f_pvoid_t cleanup_func, void *cleanup_arg,
179 int argc, char *argv[])
181 xbt_context_t res = NULL;
183 res = xbt_new0(s_xbt_context_t,1);
185 /* FIXME: strerror is not thread safe */
186 xbt_assert2(getcontext(&(res->uc))==0,"Error in context saving: %d (%s)", errno, strerror(errno));
189 res->uc.uc_link = NULL;
192 /* res->uc.uc_link = &(current_context->uc); */
193 /* WARNING : when this context is over, the current_context (i.e. the
194 father), is awaken... Theorically, the wrapper should prevent using
196 res->uc.uc_stack.ss_sp = res->stack;
197 res->uc.uc_stack.ss_size = STACK_SIZE;
198 res->startup_func = startup_func;
199 res->startup_arg = startup_arg;
200 res->cleanup_func = cleanup_func;
201 res->cleanup_arg = cleanup_arg;
203 xbt_swag_insert(res, context_living);
210 * Calling this function makes the current context yield. The context
211 * that scheduled it returns from xbt_context_schedule as if nothing
214 void xbt_context_yield(void)
216 __xbt_context_yield(current_context);
221 * \param context the winner
223 * Calling this function blocks the current context and schedule \a context.
224 * When \a context will call xbt_context_yield, it will return
225 * to this function as if nothing had happened.
227 void xbt_context_schedule(xbt_context_t context)
229 xbt_assert0((current_context==init_context),
230 "You are not supposed to run this function here!");
231 __xbt_context_yield(context);
235 * This function kill all existing context and free all the memory
236 * that has been allocated in this module.
238 void xbt_context_exit(void) {
239 xbt_context_t context=NULL;
241 xbt_context_empty_trash();
242 xbt_swag_free(context_to_destroy);
244 while((context=xbt_swag_extract(context_living)))
245 xbt_context_free(context);
247 xbt_swag_free(context_living);
249 init_context = current_context = NULL ;
253 * \param context poor victim
255 * This function simply kills \a context... scarry isn't it ?
257 void xbt_context_free(xbt_context_t context)
261 xbt_swag_remove(context, context_living);
262 for(i=0;i<context->argc; i++)
263 if(context->argv[i]) xbt_free(context->argv[i]);
264 if(context->argv) xbt_free(context->argv);
266 if(context->cleanup_func)
267 context->cleanup_func(context->cleanup_arg);
268 xbt_context_destroy(context);