X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=sched.c;h=4c94c423a548a8ddec894f1fcef4b28b14a6a003;hp=9db7c092e0209ac542283980773a9519a4f3b49a;hb=85094cd802bdb606d4e2bf7ed66dec51db2a0953;hpb=37db6c718cbd9e350d46703c36dc6860477de476 diff --git a/sched.c b/sched.c index 9db7c092..4c94c423 100644 --- a/sched.c +++ b/sched.c @@ -1,106 +1,332 @@ +/* + * Copyright (C) 2006-2011 Andre Noll + * + * Licensed under the GPL v2. For licencing details see COPYING. + */ + +/** \file sched.c Paraslash's scheduling functions. */ + +#include +#include #include + #include "para.h" #include "ipc.h" #include "fd.h" #include "list.h" #include "sched.h" #include "string.h" +#include "time.h" #include "error.h" -struct list_head pre_select_list; -struct list_head post_select_list; +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) +{ + assert(t->error < 0); + PARA_INFO_LOG("unregistering %s (%s)\n", t->status, + para_strerror(-t->error)); + if (t->pre_select) + list_del(&t->pre_select_node); + if (t->post_select) + list_del(&t->post_select_node); +} + +static inline bool timeout_is_zero(struct sched *s) +{ + struct timeval *tv = &s->select_timeout; + return tv->tv_sec == 0 && tv->tv_usec == 0; +} 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->ret > 0 || !t->event_handler) + list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) { + if (t->error < 0) { + unregister_task(t); continue; - t->event_handler(t); - goto again; + } + if (!t->pre_select) + continue; + t->pre_select(s, t); + if (timeout_is_zero(s)) + break; } } +//#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->ret > 0 || !t->event_handler) + list_for_each_entry_safe(t, tmp, &s->post_select_list, post_select_node) { + if (t->error >= 0) + call_post_select(s, t); +// PARA_INFO_LOG("%s: %d\n", t->status, t->ret); + if (t->error >= 0) continue; - t->event_handler(t); + /* + * We have to check whether the list is empty because the call + * to ->post_select() might have called sched_shutdown(). In + * this case t has been unregistered already, so we must not + * unregister it again. + */ + if (list_empty(&s->post_select_list)) + return; + unregister_task(t); } } -int sched(struct sched *s) +/** + * The core function for all paraslash programs. + * + * \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 + * the fd sets of \a s. Next, it calls para_select() and makes the result available + * to the registered tasks by calling their post_select hook. + * + * \return Zero if no more tasks are left in either of the two lists, negative + * if para_select returned an error. + * + * \sa task, now. + */ +int schedule(struct sched *s) { + int ret; - gettimeofday(&s->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; - gettimeofday(&s->now, NULL); + if (list_empty(&s->pre_select_list) && list_empty(&s->post_select_list)) + return 0; + if (!timeout_is_zero(s)) { + 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); + } else { + FD_ZERO(&s->rfds); + FD_ZERO(&s->wfds); + } sched_post_select(s); - if (list_empty(&pre_select_list) && list_empty(&post_select_list)) + if (list_empty(&s->pre_select_list) && list_empty(&s->post_select_list)) return 0; goto again; } -void *register_task(struct task *t) +/** + * Add a task to the scheduler. + * + * \param t The task to add. + * \param s The scheduler instance to add the task to. + * + * If the pre_select pointer of \a t is not \p NULL, it is added to + * the pre_select list of the scheduler. Same goes for post_select. + * + * \sa task::pre_select, task::post_select + */ +void register_task(struct sched *s, struct task *t) { PARA_INFO_LOG("registering %s (%p)\n", t->status, t); + if (!s->pre_select_list.next) + INIT_LIST_HEAD(&s->pre_select_list); + if (!s->post_select_list.next) + INIT_LIST_HEAD(&s->post_select_list); if (t->pre_select) { PARA_DEBUG_LOG("pre_select: %p\n", &t->pre_select); - if (t->flags & PRE_ADD_TAIL) - list_add_tail(&t->pre_select_node, &pre_select_list); - else - list_add(&t->pre_select_node, &pre_select_list); + list_add_tail(&t->pre_select_node, &s->pre_select_list); } if (t->post_select) { - PARA_DEBUG_LOG("post_select: %p\n", &t->pre_select); - if (t->flags & POST_ADD_TAIL) - list_add_tail(&t->post_select_node, &post_select_list); - else - 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, &s->post_select_list); } - return t; } -void unregister_task(struct task *t) +/** + * 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. This function + * must be called from the post_select (rather than the pre_select) method. + */ +void sched_shutdown(struct sched *s) { - 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); -}; + struct task *t, *tmp; -void init_sched(void) -{ - INIT_LIST_HEAD(&pre_select_list); - INIT_LIST_HEAD(&post_select_list); -}; + list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) { + t->error = -E_SCHED_SHUTDOWN; + unregister_task(t); + } + list_for_each_entry_safe(t, tmp, &s->post_select_list, post_select_node) { + t->error = -E_SCHED_SHUTDOWN; + unregister_task(t); + } +} -void sched_shutdown(void) +/** + * Get the list of all registered tasks. + * + * \return The task list. + * + * Each entry of the list contains an identifier which is simply a hex number. + * The result is dynamically allocated and must be freed by the caller. + */ +char *get_task_list(struct sched *s) { struct task *t, *tmp; + char *msg = NULL; - 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); -}; + list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) { + char *tmp_msg; + tmp_msg = make_message("%s%p\tpre\t%s\n", msg? msg : "", t, t->status); + free(msg); + msg = tmp_msg; + } + list_for_each_entry_safe(t, tmp, &s->post_select_list, post_select_node) { + char *tmp_msg; +// if (t->pre_select) +// continue; + tmp_msg = make_message("%s%p\tpost\t%s\n", msg? msg : "", t, t->status); + free(msg); + msg = tmp_msg; + } + //PARA_DEBUG_LOG("task list:\n%s", msg); + return msg; +} +/** + * 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 = s->select_timeout.tv_usec = 0; +} -//char *get_tast_list(); +/** + * 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. + * + * \return If \a barrier is in the past, this function does nothing and returns + * zero. Otherwise it returns one. + * + * \sa sched_request_barrier_or_min_delay(). + */ +int sched_request_barrier(struct timeval *barrier, struct sched *s) +{ + struct timeval diff; + + if (tv_diff(now, barrier, &diff) > 0) + return 0; + sched_request_timeout(&diff, s); + return 1; +} + +/** + * 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. + * + * \return If \a barrier is in the past, this function requests a minimal + * timeout and returns zero. Otherwise it returns one. + * + * \sa sched_min_delay(), sched_request_barrier(). + */ +int sched_request_barrier_or_min_delay(struct timeval *barrier, struct sched *s) +{ + struct timeval diff; + + if (tv_diff(now, barrier, &diff) > 0) { + sched_min_delay(s); + return 0; + } + sched_request_timeout(&diff, s); + return 1; +}