/* a fast and simple context switching library */
/* Copyright (c) 2004 Arnaud Legrand. */
-/* Copyright (c) 2004 Martin Quinson. */
+/* Copyright (c) 2004, 2005 Martin Quinson. */
/* All rights reserved. */
/* This program is free software; you can redistribute it and/or modify it
#include "xbt/error.h"
#include "xbt/dynar.h"
#include "gras_config.h"
+
XBT_LOG_NEW_DEFAULT_SUBCATEGORY(context, xbt, "Context");
-#ifndef HAVE_UCONTEXT_H
+#define VOIRP(expr) DEBUG1(" {" #expr " = %p }", expr)
+
+static xbt_context_t current_context = NULL;
+static xbt_context_t init_context = NULL;
+static xbt_swag_t context_to_destroy = NULL;
+static xbt_swag_t context_living = NULL;
+
+#ifndef USE_PTHREADS /* USE_PTHREADS and USE_CONTEXT are exclusive */
+# ifndef USE_UCONTEXT
/* don't want to play with conditional compilation in automake tonight, sorry.
include directly the c file from here when needed. */
-# include "context_win32.c"
+# include "context_win32.c"
+# endif
#endif
-static context_t current_context = NULL;
-static xbt_dynar_t context_to_destroy = NULL;
-
-void context_init(void)
+static void __xbt_context_yield(xbt_context_t context)
{
- if(!current_context) {
- current_context = xbt_new0(s_context_t,1);
- context_to_destroy = xbt_dynar_new(sizeof(context_t),xbt_free);
+ int return_value = 0;
+
+ xbt_assert0(current_context,"You have to call context_init() first.");
+
+ DEBUG2("--------- current_context (%p) is yielding to context(%p) ---------",
+ current_context,context);
+
+#ifdef USE_PTHREADS
+ if (context) {
+ xbt_context_t self = current_context;
+ DEBUG0("**** Locking ****");
+ pthread_mutex_lock(&(context->mutex));
+ DEBUG0("**** Updating current_context ****");
+ current_context = context;
+ DEBUG0("**** Releasing the prisonner ****");
+ pthread_cond_signal(&(context->cond));
+ DEBUG0("**** Going to jail ****");
+ pthread_cond_wait(&(context->cond), &(context->mutex));
+ DEBUG0("**** Unlocking ****");
+ pthread_mutex_unlock(&(context->mutex));
+ DEBUG0("**** Updating current_context ****");
+ current_context = self;
+ }
+#else
+ if(current_context)
+ VOIRP(current_context->save);
+
+ VOIRP(context);
+ if(context) VOIRP(context->save);
+ if (context) {
+ if(context->save==NULL) {
+ DEBUG0("**** Yielding to somebody else ****");
+ DEBUG2("Saving current_context value (%p) to context(%p)->save",current_context,context);
+ context->save = current_context ;
+ DEBUG1("current_context becomes context(%p) ",context);
+ current_context = context ;
+ DEBUG1("Current position memorized (context->save). Jumping to context (%p)",context);
+ return_value = swapcontext (&(context->save->uc), &(context->uc));
+ xbt_assert0((return_value==0),"Context swapping failure");
+ DEBUG1("I am (%p). Coming back\n",context);
+ } else {
+ xbt_context_t old_context = context->save ;
+ DEBUG0("**** Back ! ****");
+ DEBUG2("Setting current_context (%p) to context(%p)->save",current_context,context);
+ current_context = context->save ;
+ DEBUG1("Setting context(%p)->save to NULL",context);
+ context->save = NULL ;
+ DEBUG2("Current position memorized (%p). Jumping to context (%p)",context,old_context);
+ return_value = swapcontext (&(context->uc), &(old_context->uc));
+ xbt_assert0((return_value==0),"Context swapping failure");
+ DEBUG1("I am (%p). Coming back\n",context);
+ }
}
+#endif
+ return;
}
-void context_empty_trash(void)
+static void xbt_context_destroy(xbt_context_t context)
{
- xbt_dynar_reset(context_to_destroy);
+#ifdef USE_PTHREADS
+ xbt_free(context->thread);
+ pthread_mutex_destroy(&(context->mutex));
+ pthread_cond_destroy(&(context->cond));
+#endif
+ free(context);
+ return;
}
static void *__context_wrapper(void *c)
{
- context_t context = c;
+ xbt_context_t context = c;
int i;
-/* msg_global->current_process = process; */
+#ifdef USE_PTHREADS
+ DEBUG0("**** Lock ****");
+ pthread_mutex_lock(&(context->mutex));
+ DEBUG0("**** Releasing the prisonner ****");
+ pthread_cond_signal(&(context->cond));
+ DEBUG0("**** Going to Jail ****");
+ pthread_cond_wait(&(context->cond), &(context->mutex));
+ DEBUG0("**** Unlocking ****");
+ pthread_mutex_unlock(&(context->mutex));
+#endif
+
+ if(context->startup_func)
+ context->startup_func(context->startup_arg);
- /* WARNING("Calling the main function"); */
+ DEBUG0("Calling the main function");
(context->code) (context->argc,context->argv);
for(i=0;i<context->argc; i++)
- if(context->argv[i]) xbt_free(context->argv[i]);
- if(context->argv) xbt_free(context->argv);
+ if(context->argv[i]) free(context->argv[i]);
+ if(context->argv) free(context->argv);
- xbt_dynar_push(context_to_destroy, &context);
+ if(context->cleanup_func)
+ context->cleanup_func(context->cleanup_arg);
- context_yield(context);
+ xbt_swag_remove(context, context_living);
+ xbt_swag_insert(context, context_to_destroy);
+ __xbt_context_yield(context);
+ xbt_assert0(0,"You're cannot be here!");
return NULL;
}
-void context_start(context_t context)
+/** \name Functions
+ * \ingroup XBT_context
+ */
+/* @{ */
+/** Context module initialization
+ *
+ * \warning It has to be called before using any other function of this module.
+ */
+void xbt_context_init(void)
+{
+ if(!current_context) {
+ current_context = init_context = xbt_new0(s_xbt_context_t,1);
+ context_to_destroy = xbt_swag_new(xbt_swag_offset(*current_context,hookup));
+ context_living = xbt_swag_new(xbt_swag_offset(*current_context,hookup));
+ xbt_swag_insert(init_context, context_living);
+ }
+}
+
+/** Garbage collection
+ *
+ * Should be called some time to time to free the memory allocated for contexts
+ * that have finished executing their main functions.
+ */
+void xbt_context_empty_trash(void)
{
+ xbt_context_t context=NULL;
-/* TBX_FIFO_insert(msg_global->process, process); */
-/* TBX_FIFO_insert(msg_global->process_to_run, process); */
+ while((context=xbt_swag_extract(context_to_destroy)))
+ xbt_context_destroy(context);
+}
- /* WARNING("Assigning __MSG_process_launcher to context (%p)",context); */
+/**
+ * \param context the context to start
+ *
+ * Calling this function prepares \a context to be run. It will
+ however run effectively only when calling #xbt_context_schedule
+ */
+void xbt_context_start(xbt_context_t context)
+{
+#ifdef USE_PTHREADS
+ /* Launch the thread */
+ DEBUG0("**** Locking ****");
+ pthread_mutex_lock(&(context->mutex));
+ DEBUG0("**** Pthread create ****");
+ xbt_assert0(!pthread_create(context->thread, NULL, __context_wrapper, context),
+ "Unable to create a thread.");
+ DEBUG0("**** Going to jail ****");
+ pthread_cond_wait(&(context->cond), &(context->mutex));
+ DEBUG0("**** Unlocking ****");
+ pthread_mutex_unlock(&(context->mutex));
+#else
makecontext (&(context->uc), (void (*) (void)) __context_wrapper,
1, context);
-
+#endif
return;
}
-context_t context_create(context_function_t code,
- int argc, char *argv[])
+/**
+ * \param code a main function
+ * \param startup_func a function to call when running the context for
+ * the first time and just before the main function \a code
+ * \param startup_arg the argument passed to the previous function (\a startup_func)
+ * \param cleanup_func a function to call when running the context, just after
+ the termination of the main function \a code
+ * \param cleanup_arg the argument passed to the previous function (\a cleanup_func)
+ * \param argc first argument of function \a code
+ * \param argv seconde argument of function \a code
+ */
+xbt_context_t xbt_context_new(xbt_context_function_t code,
+ void_f_pvoid_t startup_func, void *startup_arg,
+ void_f_pvoid_t cleanup_func, void *cleanup_arg,
+ int argc, char *argv[])
{
- context_t res = NULL;
-
- res = xbt_new0(s_context_t,1);
-
- /* WARNING("Initializing context (%p)",res); */
+ xbt_context_t res = NULL;
- xbt_assert0(getcontext(&(res->uc))==0,"Error in context saving.");
+ res = xbt_new0(s_xbt_context_t,1);
- /* VOIRP(res->uc); */
res->code = code;
- res->uc.uc_link = &(current_context->uc); /* FIXME LATER */
+#ifdef USE_PTHREADS
+ res->thread = xbt_new0(pthread_t,1);
+ xbt_assert0(!pthread_mutex_init(&(res->mutex), NULL), "Mutex initialization error");
+ xbt_assert0(!pthread_cond_init(&(res->cond), NULL), "Condition initialization error");
+#else
+ /* FIXME: strerror is not thread safe */
+ xbt_assert2(getcontext(&(res->uc))==0,"Error in context saving: %d (%s)", errno, strerror(errno));
+ res->uc.uc_link = NULL;
+ /* res->uc.uc_link = &(current_context->uc); */
/* WARNING : when this context is over, the current_context (i.e. the
- father), is awaken... May result in bugs later.*/
+ father), is awaken... Theorically, the wrapper should prevent using
+ this feature. */
res->uc.uc_stack.ss_sp = res->stack;
res->uc.uc_stack.ss_size = STACK_SIZE;
- return res;
-}
+#endif
+ res->argc = argc;
+ res->argv = argv;
+ res->startup_func = startup_func;
+ res->startup_arg = startup_arg;
+ res->cleanup_func = cleanup_func;
+ res->cleanup_arg = cleanup_arg;
-static void context_destroy(context_t context)
-{
- xbt_free(context);
+ xbt_swag_insert(res, context_living);
- return;
+ return res;
}
-void context_yield(context_t context)
+/**
+ * Calling this function makes the current context yield. The context
+ * that scheduled it returns from xbt_context_schedule as if nothing
+ * had happened.
+ */
+void xbt_context_yield(void)
{
-
- xbt_assert0(current_context,"You have to call context_init() first.");
-
- /* __MSG_context_init(); */
- /* fprintf(stderr,"\n"); */
- /* WARNING("--------- current_context (%p) is yielding to context(%p) ---------",current_context,context); */
- /* VOIRP(current_context); */
- /* if(current_context) VOIRP(current_context->save); */
- /* VOIRP(context); */
- /* if(context) VOIRP(context->save); */
-
- if (context) {
-/* m_process_t self = msg_global->current_process; */
- if(context->save==NULL) {
- /* WARNING("**** Yielding to somebody else ****"); */
- /* WARNING("Saving current_context value (%p) to context(%p)->save",current_context,context); */
- context->save = current_context ;
- context->uc.uc_link = &(current_context->uc);
- /* WARNING("current_context becomes context(%p) ",context); */
- current_context = context ;
- /* WARNING("Current position memorized (context->save). Jumping to context (%p)",context); */
- if(!swapcontext (&(context->save->uc), &(context->uc)))
- xbt_assert0(0,"Context swapping failure");
- /* WARNING("I am (%p). Coming back\n",context); */
- } else {
- context_t old_context = context->save ;
- /* WARNING("**** Back ! ****"); */
- /* WARNING("Setting current_context (%p) to context(%p)->save",current_context,context); */
- current_context = context->save ;
- /* WARNING("Setting context(%p)->save to NULL",current_context,context); */
- context->save = NULL ;
- /* WARNING("Current position memorized (%p). Jumping to context (%p)",context,old_context); */
- if(!swapcontext (&(context->uc), &(old_context->uc)) )
- xbt_assert0(0,"Context swapping failure");
- /* WARNING("I am (%p). Coming back\n",context); */
- }
-/* msg_global->current_process = self; */
- }
-
- return;
+ __xbt_context_yield(current_context);
}
-
-/****************************** PTHREADS ***************************/
-
-/* FIXME: this is dead code as we don't really need it.
- If you have pthreads, you have contexts (which are better) */
-
-#if 0
-#ifdef HAVE_LIBPTHREAD /* Nevermind, let's use pthreads... */
-
-static void *__MSG_process_launcher(void *p)
+/**
+ * \param context the winner
+ *
+ * Calling this function blocks the current context and schedule \a context.
+ * When \a context will call xbt_context_yield, it will return
+ * to this function as if nothing had happened.
+ */
+void xbt_context_schedule(xbt_context_t context)
{
- m_process_t process = (m_process_t) p;
- sim_data_process_t sim_data = process->simdata;
- context_t context = NULL;
- int i;
- msg_global->current_process = process;
- TBX_FIFO_insert(msg_global->process, process);
-
- TBX_FIFO_insert(msg_global->process_to_run, process);
-/* pthread_mutex_lock(&(sim_data->context->mutex)); */
- __MSG_context_yield(sim_data->context);
-
- (*sim_data->context->code) (sim_data->argc,sim_data->argv);
-
- TBX_FIFO_remove(msg_global->process, process);
- TBX_FIFO_remove(msg_global->process_to_run, process);
-
- /* Free blocked process if any */
-/* pthread_mutex_lock(&(sim_data->context->mutex)); */
-/* pthread_cond_signal(&(sim_data->context->cond)); */
-/* pthread_mutex_unlock(&(sim_data->context->mutex)); */
-
- context = sim_data->context;
-
- for(i=0;i<sim_data->argc; i++)
- if(sim_data->argv[i]) FREE(sim_data->argv[i]);
- if(sim_data->argv) FREE(sim_data->argv);
- if(process->name) FREE(process->name);
- FREE(sim_data);
- FREE(process);
-
- TBX_FIFO_insert(msg_global->context_to_destroy,context);
- __MSG_context_yield(context);
-/* __MSG_context_destroy(&context); */
-
- return NULL;
+ xbt_assert0((current_context==init_context),
+ "You are not supposed to run this function here!");
+ __xbt_context_yield(context);
}
-MSG_error_t __MSG_context_start(m_process_t process)
-{
- sim_data_process_t sim_data = NULL;
+/**
+ * This function kill all existing context and free all the memory
+ * that has been allocated in this module.
+ */
+void xbt_context_exit(void) {
+ xbt_context_t context=NULL;
- sim_data = process->simdata;
+ xbt_context_empty_trash();
+ xbt_swag_free(context_to_destroy);
- pthread_mutex_lock(&(sim_data->context->mutex));
+ while((context=xbt_swag_extract(context_living)))
+ xbt_context_free(context);
- /* Launch the thread */
- if (pthread_create(sim_data->context->thread, NULL, __MSG_process_launcher,
- process) != 0) {
- WARNING("Unable to create a thread.");
- return MSG_FATAL;
- }
- pthread_cond_wait(&(sim_data->context->cond), &(sim_data->context->mutex));
- pthread_mutex_unlock(&(sim_data->context->mutex));
-/* __MSG_context_yield(sim_data->context); */
+ xbt_swag_free(context_living);
- return MSG_OK;
+ init_context = current_context = NULL ;
}
-context_t __MSG_context_create(m_process_code_t code)
+/**
+ * \param context poor victim
+ *
+ * This function simply kills \a context... scarry isn't it ?
+ */
+void xbt_context_free(xbt_context_t context)
{
- context_t res = NULL;
-
- res = CALLOC(1, sizeof(struct s_context));
+ int i ;
- res->code = code;
- res->thread = CALLOC(1, sizeof(pthread_t));
- if (pthread_mutex_init(&(res->mutex), NULL) != 0)
- FAILURE("Mutex initialization error");
- if (pthread_cond_init(&(res->cond), NULL) != 0)
- FAILURE("Condition initialization error");
-
- return res;
-}
-
-MSG_error_t __MSG_context_destroy(context_t * context)
-{
- ASSERT(((context != NULL) && (*context != NULL)), "Invalid parameters");
-
- FREE((*context)->thread);
- pthread_mutex_destroy(&((*context)->mutex));
- pthread_cond_destroy(&((*context)->cond));
-
- FREE(*context);
- *context = NULL;
-
- return MSG_OK;
-}
+ xbt_swag_remove(context, context_living);
+ for(i=0;i<context->argc; i++)
+ if(context->argv[i]) free(context->argv[i]);
+ if(context->argv) free(context->argv);
+
+ if(context->cleanup_func)
+ context->cleanup_func(context->cleanup_arg);
+ xbt_context_destroy(context);
-MSG_error_t __MSG_context_yield(context_t context)
-{
- if (context) {
- m_process_t self = msg_global->current_process;
- pthread_mutex_lock(&(context->mutex));
- pthread_cond_signal(&context->cond);
- pthread_cond_wait(&context->cond, &context->mutex);
- pthread_mutex_unlock(&(context->mutex));
- msg_global->current_process = self;
- }
- return MSG_OK;
+ return;
}
-#endif /* HAVE_LIBPTHREAD */
-#endif /* 0 */
+/* @} */
