X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=sched.c;h=b0e9ce12f221e901d761108899d98190ccf984d6;hp=42c5f14215df5e3f28ff91c11469b5dacf9f2e4a;hb=02b4964346686a2e50f75d57a22b4cb209c259b9;hpb=c8862b9e246b4ef6ff1fe103946e18cf2537ecde diff --git a/sched.c b/sched.c index 42c5f142..b0e9ce12 100644 --- a/sched.c +++ b/sched.c @@ -1,11 +1,12 @@ /* - * Copyright (C) 2006-2008 Andre Noll + * Copyright (C) 2006-2011 Andre Noll * * Licensed under the GPL v2. For licencing details see COPYING. */ -/** \file sched.c paraslash's scheduling functions */ +/** \file sched.c Paraslash's scheduling functions. */ +#include #include /* readdir() */ #include #include @@ -16,6 +17,7 @@ #include "list.h" #include "sched.h" #include "string.h" +#include "time.h" #include "error.h" static struct list_head pre_select_list, post_select_list; @@ -24,39 +26,90 @@ static int initialized; static struct timeval now_struct; struct timeval *now = &now_struct; +/* + * Remove a task from the scheduler. + * + * \param t The task to remove. + * + * If the pre_select pointer of \a t is not \p NULL, it is removed from + * the pre_select list of the scheduler. Same goes for \a post_select. + */ +static void unregister_task(struct task *t) +{ + if (!initialized) + return; + PARA_INFO_LOG("unregistering %s (%s)\n", t->status, + t->error <0? para_strerror(-t->error) : "shutdown"); + if (t->pre_select) + list_del(&t->pre_select_node); + if (t->post_select) + list_del(&t->post_select_node); + t->error = -E_TASK_UNREGISTERED; +} + + static void sched_preselect(struct sched *s) { struct task *t, *tmp; -again: list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) { - t->pre_select(s, t); + if (t->error >= 0 && t->pre_select) + t->pre_select(s, t); // PARA_INFO_LOG("%s \n", t->status); - if (t->ret > 0) - continue; - if (!t->event_handler) + if (t->error >= 0) continue; - t->event_handler(t); - goto again; + /* + * We have to check whether the list is empty because the call + * to ->pre_select() might have called sched_shutdown(). In + * this case t has been unregistered already, so we must not + * unregister it again. + */ + if (list_empty(&pre_select_list)) + return; + unregister_task(t); } } +//#define SCHED_DEBUG 1 +static inline void call_post_select(struct sched *s, struct task *t) +{ +#ifndef SCHED_DEBUG + t->post_select(s, t); +#else + struct timeval t1, t2, diff; + unsigned long pst; + + gettimeofday(&t1, NULL); + t->post_select(s, t); + gettimeofday(&t2, NULL); + tv_diff(&t1, &t2, &diff); + pst = tv2ms(&diff); + if (pst > 50) + PARA_WARNING_LOG("%s: post_select time: %lums\n", + t->status, pst); +#endif +} + static void sched_post_select(struct sched *s) { struct task *t, *tmp; list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) { - t->post_select(s, t); + if (t->error >= 0) + call_post_select(s, t); // PARA_INFO_LOG("%s: %d\n", t->status, t->ret); - if (t->ret > 0 || !t->event_handler) + if (t->error >= 0) continue; - t->event_handler(t); + /* nec., see sched_preselect() */ + if (list_empty(&post_select_list)) + return; + unregister_task(t); } } /** - * the core function for all paraslash programs + * The core function for all paraslash programs. * - * \param s pointer to the scheduler struct + * \param s Pointer to the scheduler struct. * * This function updates the global \a now pointer, calls all registered * pre_select hooks which may set the timeout and add any file descriptors to @@ -70,19 +123,35 @@ static void sched_post_select(struct sched *s) */ int schedule(struct sched *s) { + int ret; + if (!initialized) return -E_NOT_INITIALIZED; - gettimeofday(now, NULL); + if (!s->select_function) + s->select_function = para_select; again: FD_ZERO(&s->rfds); FD_ZERO(&s->wfds); - s->timeout = s->default_timeout; + s->select_timeout = s->default_timeout; s->max_fileno = -1; + gettimeofday(now, NULL); sched_preselect(s); - s->select_ret = para_select(s->max_fileno + 1, &s->rfds, - &s->wfds, &s->timeout); - if (s->select_ret < 0) - return s->select_ret; + if (list_empty(&pre_select_list) && list_empty(&post_select_list)) + return 0; + ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds, + &s->select_timeout); + if (ret < 0) + return ret; + if (ret == 0) { + /* + * APUE: Be careful not to check the descriptor sets on return + * unless the return value is greater than zero. The return + * state of the descriptor sets is implementation dependent if + * either a signal is caught or the timer expires. + */ + FD_ZERO(&s->rfds); + FD_ZERO(&s->wfds); + } gettimeofday(now, NULL); sched_post_select(s); if (list_empty(&pre_select_list) && list_empty(&post_select_list)) @@ -90,19 +159,19 @@ again: goto again; } -/** - * initialize the paraslash scheduler +/* + * Initialize the paraslash scheduler. */ static void init_sched(void) { - PARA_INFO_LOG("%s", "initializing scheduler\n"); + PARA_INFO_LOG("initializing scheduler\n"); INIT_LIST_HEAD(&pre_select_list); INIT_LIST_HEAD(&post_select_list); initialized = 1; -}; +} /** - * add a task to the scheduler + * Add a task to the scheduler. * * \param t the task to add * @@ -118,35 +187,16 @@ void register_task(struct task *t) PARA_INFO_LOG("registering %s (%p)\n", t->status, t); if (t->pre_select) { PARA_DEBUG_LOG("pre_select: %p\n", &t->pre_select); - para_list_add(&t->pre_select_node, &pre_select_list); + list_add_tail(&t->pre_select_node, &pre_select_list); } if (t->post_select) { - PARA_DEBUG_LOG("post_select: %p\n", &t->pre_select); - para_list_add(&t->post_select_node, &post_select_list); + PARA_DEBUG_LOG("post_select: %p\n", &t->post_select); + list_add_tail(&t->post_select_node, &post_select_list); } } /** - * remove a task from the scheduler - * - * \param t the task to remove - * - * If the pre_select pointer of \a t is not \p NULL, it is removed from - * the pre_select list of the scheduler. Same goes for \a post_select. - */ -void unregister_task(struct task *t) -{ - if (!initialized) - return; - PARA_INFO_LOG("unregistering %s (%p)\n", t->status, t); - if (t->pre_select) - list_del(&t->pre_select_node); - if (t->post_select) - list_del(&t->post_select_node); -}; - -/** - * unregister all tasks + * Unregister all tasks. * * This will cause \a schedule() to return immediately because both the * \a pre_select_list and the \a post_select_list are empty. @@ -159,20 +209,19 @@ void sched_shutdown(void) return; list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) unregister_task(t); - /* remove tasks which do not have a pre_select hook */ list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) unregister_task(t); initialized = 0; -}; +} /** - * get the list of all registered tasks. + * Get the list of all registered tasks. * - * \return the task list + * \return The task list. * * Each entry of the list contains an identifier which is simply a hex number * that may be used in \a kill_task() to terminate the task. - * The result ist dynamically allocated and must be freed by the caller. + * The result is dynamically allocated and must be freed by the caller. */ char *get_task_list(void) { @@ -200,12 +249,12 @@ char *get_task_list(void) } /** - * simulate an error for the given task + * Simulate an error for the given task. * - * \param id the task identifier + * \param id The task identifier. * - * Find the task identified by \a id, set the tasks' return value to - * \p -E_TASK_KILLED and call the event handler of the task. + * Find the task identified by \a id, set the tasks' error value to + * \p -E_TASK_KILLED and unregister the task. * * \return Positive on success, negative on errors (e.g. if \a id does not * correspond to a registered task). @@ -221,19 +270,100 @@ int kill_task(char *id) sprintf(buf, "%p", t); if (strcmp(id, buf)) continue; - t->ret = -E_TASK_KILLED; - if (t->event_handler) - t->event_handler(t); + t->error = -E_TASK_KILLED; return 1; } list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) { sprintf(buf, "%p", t); if (strcmp(id, buf)) continue; - t->ret = -E_TASK_KILLED; - if (t->event_handler) - t->event_handler(t); + t->error = -E_TASK_KILLED; return 1; } return -E_NO_SUCH_TASK; } + +/** + * Set the select timeout to the minimal possible value. + * + * \param s Pointer to the scheduler struct. + * + * This causes the next select() call to return immediately. + */ +void sched_min_delay(struct sched *s) +{ + s->select_timeout.tv_sec = 0; + s->select_timeout.tv_usec = 1; +} + +/** + * Impose an upper bound for the timeout of the next select() call. + * + * \param to Maximal allowed timeout. + * \param s Pointer to the scheduler struct. + * + * If the current scheduler timeout is already smaller than \a to, this + * function does nothing. Otherwise the timeout for the next select() call is + * set to the given value. + * + * \sa sched_request_timeout_ms(). + */ +void sched_request_timeout(struct timeval *to, struct sched *s) +{ + if (tv_diff(&s->select_timeout, to, NULL) > 0) + s->select_timeout = *to; +} + +/** + * Force the next select() call to return before the given amount of milliseconds. + * + * \param ms The maximal allowed timeout in milliseconds. + * \param s Pointer to the scheduler struct. + * + * Like sched_request_timeout() this imposes an upper bound on the timeout + * value for the next select() call. + */ +void sched_request_timeout_ms(long unsigned ms, struct sched *s) +{ + struct timeval tv; + ms2tv(ms, &tv); + sched_request_timeout(&tv, s); +} + +/** + * Force the next select() call to return before the given future time. + * + * \param barrier Absolute time before select() should return. + * \param s Pointer to the scheduler struct. + * + * If \a barrier is in the past, this function does nothing. + * + * \sa sched_request_barrier_or_min_delay(). + */ +void sched_request_barrier(struct timeval *barrier, struct sched *s) +{ + struct timeval diff; + + if (tv_diff(now, barrier, &diff) > 0) + return; + sched_request_timeout(&diff, s); +} + +/** + * Force the next select() call to return before the given time. + * + * \param barrier Absolute time before select() should return. + * \param s Pointer to the scheduler struct. + * + * If \a barrier is in the past, this function requests a minimal timeout. + * + * \sa sched_min_delay(), sched_request_barrier(). + */ +void sched_request_barrier_or_min_delay(struct timeval *barrier, struct sched *s) +{ + struct timeval diff; + + if (tv_diff(now, barrier, &diff) > 0) + return sched_min_delay(s); + sched_request_timeout(&diff, s); +}