1 /* a fast and simple context switching library */
3 /* Copyright (c) 2004-2008 the SimGrid team. */
4 /* All rights reserved. */
6 /* This program is free software; you can redistribute it and/or modify it
7 * under the terms of the license (GNU LGPL) which comes with this package. */
12 #include "xbt_context_private.h"
14 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_context, xbt,
15 "Context switching mecanism");
17 /* the context factory used to create the appropriate context
18 * each context implementation define its own context factory
19 * a context factory is responsable of the creation of the context
20 * associated with the maestro and of all the context based on
21 * the selected implementation.
23 * for example, the context switch based on java thread use the
24 * java implementation of the context and the java factory build
25 * the context depending of this implementation.
29 * This function is call by SIMIX_global_init() to initialize the context module.
31 void SIMIX_context_mod_init(void)
33 if (!simix_global->context_factory) {
34 /* select context factory to use to create the context(depends of the macro definitions) */
36 #ifdef CONTEXT_THREADS
37 /* context switch based os thread */
38 SIMIX_ctx_thread_factory_init(&simix_global->context_factory);
40 /* context switch based ucontext */
41 SIMIX_ctx_sysv_factory_init(&simix_global->context_factory);
43 /* context switch is not allowed on Windows */
44 #error ERROR [__FILE__, line __LINE__]: no context based implementation specified.
50 * This function is call by SIMIX_clean() to finalize the context module.
52 void SIMIX_context_mod_exit(void)
54 if (simix_global->context_factory) {
55 smx_process_t process = NULL;
56 smx_pfn_context_factory_finalize_t finalize_factory;
58 /* kill all the processes (except maestro)
59 * the killed processes are added in the list of the processes to destroy */
61 while ((process = xbt_swag_extract(simix_global->process_list)))
62 (*(simix_global->context_factory->kill)) (process);
64 /* destroy all processes in the list of process to destroy */
65 SIMIX_context_empty_trash();
67 /* finalize the context factory */
68 finalize_factory = simix_global->context_factory->finalize;
69 (*finalize_factory) (&simix_global->context_factory);
73 /*******************************/
74 /* Object creation/destruction */
75 /*******************************/
77 * \param smx_process the simix process that contains this context
78 * \param code a main function
80 int SIMIX_context_new(smx_process_t *process, xbt_main_func_t code)
82 /* use the appropriate context factory to create the appropriate context */
83 return (*(simix_global->context_factory->create_context)) (process, code);
87 int SIMIX_context_create_maestro(smx_process_t *process)
89 return (*(simix_global->context_factory->create_maestro_context)) (process);
92 /* Scenario for the end of a context:
94 * CASE 1: death after end of function
95 * __context_wrapper, called by os thread, calls xbt_context_stop after user code stops
96 * xbt_context_stop calls user cleanup_func if any (in context settings),
97 * add current to trashbin
98 * yields back to maestro (destroy os thread on need)
99 * From time to time, maestro calls xbt_context_empty_trash,
100 * which maps xbt_context_free on the content
101 * xbt_context_free frees some more memory,
104 * CASE 2: brutal death
105 * xbt_context_kill (from any context)
106 * set context->wannadie to 1
107 * yields to the context
108 * the context is awaken in the middle of __yield.
109 * At the end of it, it checks that wannadie == 1, and call xbt_context_stop
110 * (same than first case afterward)
114 /* Argument must be stopped first -- runs in maestro context */
115 void SIMIX_context_free(smx_process_t process)
117 (*(simix_global->context_factory->free)) (process);
120 void SIMIX_context_kill(smx_process_t process)
122 (*(simix_global->context_factory->kill)) (process);
126 * \param context the context to start
128 * Calling this function prepares \a process to be run. It will
129 however run effectively only when calling #SIMIX_context_schedule
131 void SIMIX_context_start(smx_process_t process)
133 (*(simix_global->context_factory->start)) (process);
137 * Calling this function makes the current process yield. The process
138 * that scheduled it returns from SIMIX_context_schedule as if nothing
141 * Only the processes can call this function, giving back the control
144 void SIMIX_context_yield(void)
146 (*(simix_global->context_factory->yield)) ();
150 * \param process to be scheduled
152 * Calling this function blocks the current process and schedule \a process.
153 * When \a process would call SIMIX_context_yield, it will return
154 * to this function as if nothing had happened.
156 * Only the maestro can call this function to run a given process.
158 void SIMIX_context_schedule(smx_process_t process)
160 (*(simix_global->context_factory->schedule)) (process);
163 void SIMIX_context_stop(int exit_code)
165 (*(simix_global->context_factory->stop)) (exit_code);
168 int SIMIX_context_select_factory(const char *name)
170 /* if a factory is already instantiated (SIMIX_context_mod_init() was called) */
171 if (simix_global->context_factory != NULL) {
172 /* if the desired factory is different of the current factory, call SIMIX_context_mod_exit() */
173 if (strcmp(simix_global->context_factory->name, name))
174 SIMIX_context_mod_exit();
176 /* the same context factory is requested return directly */
180 /* get the desired factory */
181 SIMIX_context_init_factory_by_name(&simix_global->context_factory, name);
183 /* maestro process specialisation */
184 (*(simix_global->context_factory->create_maestro_context)) (&simix_global->maestro_process);
186 /* the current process is the process of the maestro */
187 simix_global->current_process = simix_global->maestro_process;
189 /* the current context doesn't want to die */
190 simix_global->current_process->iwannadie = 0;
192 /* insert the current context in the list of the contexts in use */
193 xbt_swag_insert(simix_global->current_process, simix_global->process_list);
199 SIMIX_context_init_factory_by_name(smx_context_factory_t * factory,
202 if (!strcmp(name, "java"))
204 SIMIX_ctx_java_factory_init(factory);
206 THROW0(not_found_error, 0, "Factory 'Java' does not exist: Java support was not compiled in the SimGrid library");
207 #endif /* HAVE_JAVA */
209 else if (!strcmp(name, "thread"))
210 #ifdef CONTEXT_THREADS
211 SIMIX_ctx_thread_factory_init(factory);
213 THROW0(not_found_error, 0, "Factory 'thread' does not exist: thread support was not compiled in the SimGrid library");
214 #endif /* CONTEXT_THREADS */
216 else if (!strcmp(name, "sysv"))
217 #if !defined(WIN32) && !defined(CONTEXT_THREADS)
218 SIMIX_ctx_sysv_factory_init(factory);
220 THROW0(not_found_error, 0, "Factory 'sysv' does not exist: no System V thread support under Windows");
223 THROW1(not_found_error, 0, "Factory '%s' does not exist", name);
226 /** Garbage collection
228 * Should be called some time to time to free the memory allocated for processes
229 * that have finished (or killed).
231 void SIMIX_context_empty_trash(void)
233 smx_process_t process = NULL;
236 while ((process = xbt_swag_extract(simix_global->process_to_destroy))){
239 process->name = NULL;
242 for (i = 0; i < process->argc; i++)
243 if (process->argv[i])
244 free(process->argv[i]);