-/* $Id$ */
-
-/* a fast and simple context switching library */
-
-/* Copyright (c) 2004 Arnaud Legrand. */
-/* Copyright (c) 2004, 2005 Martin Quinson. */
-/* All rights reserved. */
-
-/* This program is free software; you can redistribute it and/or modify it
- * under the terms of the license (GNU LGPL) which comes with this package. */
-
-#include "portable.h"
-#include "context_private.h"
-#include "xbt/log.h"
-#include "xbt/dynar.h"
-#include "xbt/xbt_os_thread.h"
-#include "xbt/ex_interface.h"
-
-XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_ctx, xbt, "Context");
-
-#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;
-
-
-
-/********************/
-/* 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)
-{
- return current_context->exception;
-}
-
-/* callback: termination */
-static void _context_ex_terminate(xbt_ex_t * e)
-{
- xbt_ex_display(e);
-
- abort();
- /* FIXME: there should be a configuration variable to
- choose to kill everyone or only this one */
-}
-#endif
-
-#ifdef CONTEXT_THREADS
-
-static void
-schedule(xbt_context_t c);
-
-static void
-yield(xbt_context_t c);
-
-static void
-schedule(xbt_context_t c)
-{
- xbt_os_sem_release(c->begin);
- xbt_os_sem_acquire(c->end);
-}
-
-static void yield(xbt_context_t c)
-{
- xbt_os_sem_release(c->end);
- xbt_os_sem_acquire(c->begin);
-}
-#endif
-
-/** \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
- }
-}
-
-/**
- * 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;
-
- xbt_context_empty_trash();
-
- while ((context = xbt_swag_extract(context_living))) {
- if (context != init_context) {
- xbt_context_kill(context);
- }
- }
-
-#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);
-
-}
-
-
-/*******************************/
-/* 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;
-
- res = xbt_new0(s_xbt_context_t, 1);
-
- res->code = code;
- 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... 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;
-}
-
-/* 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)
-{
- int i;
-
- if (!context)
- return;
-
- DEBUG1("Freeing %p", context);
- free(context->name);
-
- DEBUG0("Freeing arguments");
-
- for (i = 0; i < context->argc; i++)
- if (context->argv[i])
- free(context->argv[i]);
-
- if (context->argv)
- free(context->argv);
-
-#ifdef CONTEXT_THREADS
- DEBUG1("\t joining %p", (void *) context->thread);
-
- xbt_os_thread_join(context->thread, NULL);
-
- /* destroy the semaphore used to schedule/unshedule the process */
- xbt_os_sem_destroy(context->begin);
- xbt_os_sem_destroy(context->end);
-
- context->thread = NULL;
- context->begin = NULL;
- context->end = NULL;
-#else
- if (context->exception)
- free(context->exception);
-#endif
-
- free(context);
-}
-
-/************************/
-/* Start/stop a context */
-/************************/
-static void xbt_context_stop(int retvalue);
-static void __xbt_context_yield(xbt_context_t context);
-
-static void *__context_wrapper(void *c)
-{
- xbt_context_t context = current_context;
-
-#ifdef CONTEXT_THREADS
- context = (xbt_context_t) c;
- /*context->thread = xbt_os_thread_self();*/
-
- /* signal its starting to the maestro and wait to start its job*/
- yield(context);
-
-#endif
-
- 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
-}
-
-/* Stops current context: calls user's cleanup function, kills os thread, and yields back to maestro */
-static void xbt_context_stop(int retvalue)
-{
- DEBUG1("--------- %p is exiting ---------", current_context);
-
- if (current_context->cleanup_func) {
- DEBUG0("Calling cleanup function");
- current_context->cleanup_func(current_context->cleanup_arg);
- }
-
- DEBUG0("Putting context in the to_destroy set");
- xbt_swag_remove(current_context, context_living);
- xbt_swag_insert(current_context, context_to_destroy);
-
- DEBUG0("Yielding");
-
-#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;
-}
-
-
-
-/** 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;
-
- 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);
-}
-
-/*********************/
-/* context switching */
-/*********************/
-
-static void __xbt_context_yield(xbt_context_t context)
-{
- 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);
- }
-
-#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);
-}
-
-/**
- * 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);
-}
-
-/**
- * \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);
-}
-
-
-/**
- * \param context poor victim
- *
- * This function simply kills \a context... scarry isn't it ?
- */
-void xbt_context_kill(xbt_context_t context)
-{
- DEBUG1("Killing %p", context);
-
- context->iwannadie = 1;
-
- DEBUG1("Scheduling %p", context);
- __xbt_context_yield(context);
- DEBUG1("End of Scheduling %p", context);
-}
-
-/* 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;}
-
-/* @} */
