/* 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 "portable.h"
#include "context_private.h"
-#include "xbt/error.h"
+#include "xbt/log.h"
#include "xbt/dynar.h"
-#include "gras_config.h"
-XBT_LOG_NEW_DEFAULT_SUBCATEGORY(context, xbt, "Context");
+#include "xbt/xbt_os_thread.h"
+#include "xbt/ex_interface.h"
-#ifndef HAVE_UCONTEXT_H
-/* 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"
-#endif
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_ctx, xbt, "Context");
-static context_t current_context = NULL;
-static xbt_dynar_t context_to_destroy = NULL;
+#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;
-void context_init(void)
-{
- if(!current_context) {
- current_context = xbt_new0(s_context_t,1);
- context_to_destroy = xbt_dynar_new(sizeof(context_t),xbt_free);
- }
-}
-void context_empty_trash(void)
+
+/********************/
+/* Module init/exit */
+/********************/
+#ifndef CONTEXT_THREADS
+/* callback: context fetching (used only with ucontext, os_thread deal with it
+ for us otherwise) */
+static ex_ctx_t *_context_ex_ctx(void)
{
- xbt_dynar_reset(context_to_destroy);
+ return current_context->exception;
}
-static void *__context_wrapper(void *c)
+/* callback: termination */
+static void _context_ex_terminate(xbt_ex_t * e)
{
- context_t context = c;
- int i;
+ xbt_ex_display(e);
-/* msg_global->current_process = process; */
+ abort();
+ /* FIXME: there should be a configuration variable to
+ choose to kill everyone or only this one */
+}
+#endif
- /* WARNING("Calling the main function"); */
- (context->code) (context->argc,context->argv);
+#ifdef CONTEXT_THREADS
- for(i=0;i<context->argc; i++)
- if(context->argv[i]) xbt_free(context->argv[i]);
- if(context->argv) xbt_free(context->argv);
+static void
+schedule(xbt_context_t c);
- xbt_dynar_push(context_to_destroy, &context);
+static void
+yield(xbt_context_t c);
- context_yield(context);
+static void
+schedule(xbt_context_t c)
+{
+ xbt_os_sem_release(c->begin);
+ xbt_os_sem_acquire(c->end);
+}
- return NULL;
+static void yield(xbt_context_t c)
+{
+ xbt_os_sem_release(c->end);
+ xbt_os_sem_acquire(c->begin);
}
+#endif
-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);
+ DEBUG1("Init Context (%p)", init_context);
+ init_context->iwannadie = 0; /* useless but makes valgrind happy */
+ 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);
+
+ #ifndef CONTEXT_THREADS
+ init_context->exception = xbt_new(ex_ctx_t, 1);
+ XBT_CTX_INITIALIZE(init_context->exception);
+ __xbt_ex_ctx = _context_ex_ctx;
+ __xbt_ex_terminate = _context_ex_terminate;
+#endif
+ }
+}
-/* TBX_FIFO_insert(msg_global->process, process); */
-/* TBX_FIFO_insert(msg_global->process_to_run, process); */
+/**
+ * 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;
- /* WARNING("Assigning __MSG_process_launcher to context (%p)",context); */
- makecontext (&(context->uc), (void (*) (void)) __context_wrapper,
- 1, context);
+ xbt_context_empty_trash();
- return;
-}
+ while ((context = xbt_swag_extract(context_living))) {
+ if (context != init_context) {
+ xbt_context_kill(context);
+ }
+ }
-context_t context_create(context_function_t code,
- int argc, char *argv[])
-{
- context_t res = NULL;
+#ifndef CONTEXT_THREADS
+ free(init_context->exception);
+#endif
+
+ free(init_context);
+ init_context = current_context = NULL;
+
+ xbt_context_empty_trash();
+ xbt_swag_free(context_to_destroy);
+ xbt_swag_free(context_living);
+
+}
- res = xbt_new0(s_context_t,1);
- /* WARNING("Initializing context (%p)",res); */
+/*******************************/
+/* Object creation/destruction */
+/*******************************/
+/**
+ * \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(const char *name,
+ xbt_main_func_t code,
+ void_f_pvoid_t startup_func,
+ void *startup_arg,
+ void_f_pvoid_t cleanup_func,
+ void *cleanup_arg, int argc, char *argv[]
+ )
+{
+ 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 */
+ res->name = xbt_strdup(name);
+
+#ifdef CONTEXT_THREADS
+ /*
+ * initialize the semaphores used to schedule/yield
+ * the process associated to the newly created context
+ */
+ res->begin = xbt_os_sem_init(0);
+ res->end = xbt_os_sem_init(0);
+#else
+
+ 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.*/
- res->uc.uc_stack.ss_sp = res->stack;
- res->uc.uc_stack.ss_size = STACK_SIZE;
+ father), is awaken... Theorically, the wrapper should prevent using
+ this feature. */
+ res->uc.uc_stack.ss_sp = pth_skaddr_makecontext(res->stack, STACK_SIZE);
+ res->uc.uc_stack.ss_size = pth_sksize_makecontext(res->stack, STACK_SIZE);
+
+ res->exception = xbt_new(ex_ctx_t, 1);
+ XBT_CTX_INITIALIZE(res->exception);
+#endif /* CONTEXT_THREADS or not */
+
+ res->iwannadie = 0; /* useless but makes valgrind happy */
+
+ 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;
+
+ xbt_swag_insert(res, context_living);
+
return res;
}
-static void context_destroy(context_t context)
+/* Scenario for the end of a context:
+ *
+ * CASE 1: death after end of function
+ * __context_wrapper, called by os thread, calls xbt_context_stop after user code stops
+ * xbt_context_stop calls user cleanup_func if any (in context settings),
+ * add current to trashbin
+ * yields back to maestro (destroy os thread on need)
+ * From time to time, maestro calls xbt_context_empty_trash,
+ * which maps xbt_context_free on the content
+ * xbt_context_free frees some more memory,
+ * joins os thread
+ *
+ * CASE 2: brutal death
+ * xbt_context_kill (from any context)
+ * set context->wannadie to 1
+ * yields to the context
+ * the context is awaken in the middle of __yield.
+ * At the end of it, it checks that wannadie == 1, and call xbt_context_stop
+ * (same than first case afterward)
+ */
+
+
+/* Argument must be stopped first -- runs in maestro context */
+static void xbt_context_free(xbt_context_t context)
{
- xbt_free(context);
+ int i;
- return;
-}
+ if (!context)
+ return;
-void context_yield(context_t context)
-{
+ DEBUG1("Freeing %p", context);
+ free(context->name);
- 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; */
- }
+ DEBUG0("Freeing arguments");
- return;
-}
+ for (i = 0; i < context->argc; i++)
+ if (context->argv[i])
+ free(context->argv[i]);
+ if (context->argv)
+ free(context->argv);
-/****************************** PTHREADS ***************************/
+#ifdef CONTEXT_THREADS
+ DEBUG1("\t joining %p", (void *) context->thread);
-/* FIXME: this is dead code as we don't really need it.
- If you have pthreads, you have contexts (which are better) */
+ xbt_os_thread_join(context->thread, NULL);
-#if 0
-#ifdef HAVE_LIBPTHREAD /* Nevermind, let's use pthreads... */
+ /* destroy the semaphore used to schedule/unshedule the process */
+ xbt_os_sem_destroy(context->begin);
+ xbt_os_sem_destroy(context->end);
-static void *__MSG_process_launcher(void *p)
-{
- 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);
+ context->thread = NULL;
+ context->begin = NULL;
+ context->end = NULL;
+#else
+ if (context->exception)
+ free(context->exception);
+#endif
- TBX_FIFO_insert(msg_global->process_to_run, process);
-/* pthread_mutex_lock(&(sim_data->context->mutex)); */
- __MSG_context_yield(sim_data->context);
+ free(context);
+}
- (*sim_data->context->code) (sim_data->argc,sim_data->argv);
+/************************/
+/* Start/stop a context */
+/************************/
+static void xbt_context_stop(int retvalue);
+static void __xbt_context_yield(xbt_context_t context);
- TBX_FIFO_remove(msg_global->process, process);
- TBX_FIFO_remove(msg_global->process_to_run, process);
+static void *__context_wrapper(void *c)
+{
+ xbt_context_t context = current_context;
- /* 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)); */
+#ifdef CONTEXT_THREADS
+ context = (xbt_context_t) c;
+ /*context->thread = xbt_os_thread_self();*/
- context = sim_data->context;
+ /* signal its starting to the maestro and wait to start its job*/
+ yield(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);
+#endif
- TBX_FIFO_insert(msg_global->context_to_destroy,context);
- __MSG_context_yield(context);
-/* __MSG_context_destroy(&context); */
+ if (context->startup_func)
+ context->startup_func(context->startup_arg);
+ DEBUG0("Calling the main function");
+
+ xbt_context_stop((context->code) (context->argc, context->argv));
return NULL;
}
+/**
+ * \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 CONTEXT_THREADS
+ /* create the process and start it */
+ context->thread = xbt_os_thread_create(context->name,__context_wrapper, context);
+
+ /* wait the starting of the newly created process */
+ xbt_os_sem_acquire(context->end);
+#else
+ makecontext(&(context->uc), (void (*)(void)) __context_wrapper, 1, context);
+#endif
+}
-MSG_error_t __MSG_context_start(m_process_t process)
+/* Stops current context: calls user's cleanup function, kills os thread, and yields back to maestro */
+static void xbt_context_stop(int retvalue)
{
- sim_data_process_t sim_data = NULL;
+ DEBUG1("--------- %p is exiting ---------", current_context);
- sim_data = process->simdata;
+ if (current_context->cleanup_func) {
+ DEBUG0("Calling cleanup function");
+ current_context->cleanup_func(current_context->cleanup_arg);
+ }
- pthread_mutex_lock(&(sim_data->context->mutex));
+ DEBUG0("Putting context in the to_destroy set");
+ xbt_swag_remove(current_context, context_living);
+ xbt_swag_insert(current_context, context_to_destroy);
- /* 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); */
+ DEBUG0("Yielding");
- return MSG_OK;
+#ifdef CONTEXT_THREADS
+ /* signal to the maestro that it has finished */
+ xbt_os_sem_release(current_context->end);
+ /* exit*/
+ xbt_os_thread_exit(NULL); /* We should provide return value in case other wants it */
+#else
+ __xbt_context_yield(current_context);
+#endif
+ THROW_IMPOSSIBLE;
}
-context_t __MSG_context_create(m_process_code_t code)
-{
- context_t res = NULL;
- res = CALLOC(1, sizeof(struct s_context));
- 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");
+/** 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;
- return res;
+ DEBUG1("Emptying trashbin (%d contexts to free)",
+ xbt_swag_size(context_to_destroy));
+
+ while ((context = xbt_swag_extract(context_to_destroy)))
+ xbt_context_free(context);
}
-MSG_error_t __MSG_context_destroy(context_t * context)
+/*********************/
+/* context switching */
+/*********************/
+
+static void __xbt_context_yield(xbt_context_t context)
{
- ASSERT(((context != NULL) && (*context != NULL)), "Invalid parameters");
+ xbt_assert0(current_context, "You have to call context_init() first.");
+ xbt_assert0(context, "Invalid argument");
+
+ if (current_context == context) {
+ DEBUG1
+ ("--------- current_context (%p) is yielding back to maestro ---------",
+ context);
+ } else {
+ DEBUG2
+ ("--------- current_context (%p) is yielding to context(%p) ---------",
+ current_context, context);
+ }
- FREE((*context)->thread);
- pthread_mutex_destroy(&((*context)->mutex));
- pthread_cond_destroy(&((*context)->cond));
+#ifdef CONTEXT_THREADS
+
+ if(current_context != init_context && !context->iwannadie)
+ {/* it's a process and it doesn't wants to die (xbt_context_yield()) */
+
+ /* save the current context */
+ xbt_context_t self = current_context;
+
+ /* update the current context to this context */
+ current_context = context;
+
+ /* yield itself */
+ yield(context);
+
+ /* restore the current context to the previously saved context */
+ current_context = self;
+ }
+ else
+ { /* maestro wants to schedule a process or a process wants to die (xbt_context_schedule() or xbt_context_kill())*/
+
+ /* save the current context */
+ xbt_context_t self = current_context;
+
+ /* update the current context */
+ current_context = context;
+
+ /* schedule the process associated with this context */
+ schedule(context);
+
+ /* restore the current context to the previously saved context */
+ current_context = self;
+ }
+
+#else /* use SUSv2 contexts */
+ VOIRP(current_context);
+ VOIRP(current_context->save);
+
+ VOIRP(context);
+ VOIRP(context->save);
+
+ int return_value = 0;
+
+ if (context->save == NULL) {
+ DEBUG1("[%p] **** Yielding to somebody else ****", current_context);
+ 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;
+
+ DEBUG1("[%p] **** Back ! ****", context);
+ 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
+
+ if (current_context->iwannadie)
+ xbt_context_stop(1);
+}
- FREE(*context);
- *context = NULL;
+/**
+ * Calling this function makes the current context yield. The context
+ * that scheduled it returns from xbt_context_schedule as if nothing
+ * had happened.
+ *
+ * Only the processes can call this function, giving back the control
+ * to the maestro
+ */
+void xbt_context_yield(void)
+{
+ __xbt_context_yield(current_context);
+}
- return MSG_OK;
+/**
+ * \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.
+ *
+ * Only the maestro can call this function to run a given process.
+ */
+void xbt_context_schedule(xbt_context_t context)
+{
+ DEBUG1("Scheduling %p", context);
+ xbt_assert0((current_context == init_context),
+ "You are not supposed to run this function here!");
+ __xbt_context_yield(context);
}
-MSG_error_t __MSG_context_yield(context_t context)
+
+/**
+ * \param context poor victim
+ *
+ * This function simply kills \a context... scarry isn't it ?
+ */
+void xbt_context_kill(xbt_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;
+ DEBUG1("Killing %p", context);
+
+ context->iwannadie = 1;
+
+ DEBUG1("Scheduling %p", context);
+ __xbt_context_yield(context);
+ DEBUG1("End of Scheduling %p", context);
}
-#endif /* HAVE_LIBPTHREAD */
-#endif /* 0 */
+
+/* Java cruft I'm gonna kill in the next cleanup round */
+void xbt_context_set_jprocess(xbt_context_t context, void *jp){}
+void* xbt_context_get_jprocess(xbt_context_t context){return NULL;}
+void xbt_context_set_jenv(xbt_context_t context,void* je){}
+void* xbt_context_get_jenv(xbt_context_t context){return NULL;}
+
+/* @} */
