X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=sched.c;h=66a17418027a5e9fa2d92bee412cf682561115b9;hp=44e66c9b62664eb3add50d9924db6b311ea7e273;hb=3150a0caa27a34d44556fb77f4a5aebc3d978580;hpb=684ea7f70948c9ce5077a8a6460946ff86fefe46;ds=sidebyside diff --git a/sched.c b/sched.c index 44e66c9b..66a17418 100644 --- a/sched.c +++ b/sched.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2006-2009 Andre Noll + * Copyright (C) 2006-2011 Andre Noll * * Licensed under the GPL v2. For licencing details see COPYING. */ @@ -7,9 +7,9 @@ /** \file sched.c Paraslash's scheduling functions. */ #include -#include /* readdir() */ #include #include +#include #include "para.h" #include "ipc.h" @@ -17,6 +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; @@ -25,7 +26,7 @@ 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. @@ -37,48 +38,73 @@ static void unregister_task(struct task *t) { if (!initialized) return; + assert(t->error < 0); PARA_INFO_LOG("unregistering %s (%s)\n", t->status, - t->error <0? para_strerror(-t->error) : "shutdown"); + para_strerror(-t->error)); 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 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; list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) { - if (t->error >= 0 && t->pre_select) - t->pre_select(s, t); -// PARA_INFO_LOG("%s \n", t->status); - if (t->error >= 0) + if (t->error < 0) { + unregister_task(t); continue; - /* - * 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); + } + 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) { if (t->error >= 0) - t->post_select(s, t); + call_post_select(s, t); // PARA_INFO_LOG("%s: %d\n", t->status, t->ret); if (t->error >= 0) continue; - /* nec., see sched_preselect() */ + /* + * 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(&post_select_list)) return; unregister_task(t); @@ -108,26 +134,42 @@ int schedule(struct sched *s) return -E_NOT_INITIALIZED; if (!s->select_function) s->select_function = para_select; - gettimeofday(now, NULL); 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); 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->timeout); - if (ret < 0) - return ret; - gettimeofday(now, NULL); + 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)) return 0; goto again; } -/** +/* * Initialize the paraslash scheduler. */ static void init_sched(void) @@ -167,7 +209,8 @@ void register_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. + * \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(void) { @@ -175,10 +218,14 @@ void sched_shutdown(void) if (!initialized) return; - list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) + list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) { + t->error = -E_SCHED_SHUTDOWN; unregister_task(t); - list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) + } + list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) { + t->error = -E_SCHED_SHUTDOWN; unregister_task(t); + } initialized = 0; } @@ -187,9 +234,8 @@ void sched_shutdown(void) * * \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. + * 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(void) { @@ -217,36 +263,91 @@ char *get_task_list(void) } /** - * Simulate an error for the given 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 = s->select_timeout.tv_usec = 0; +} + +/** + * Impose an upper bound for the timeout of the next select() call. * - * \param id The task identifier. + * \param to Maximal allowed timeout. + * \param s Pointer to the scheduler struct. * - * Find the task identified by \a id, set the tasks' error value to - * \p -E_TASK_KILLED and unregister the task. + * 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. * - * \return Positive on success, negative on errors (e.g. if \a id does not - * correspond to a registered task). + * \sa sched_request_timeout_ms(). */ -int kill_task(char *id) +void sched_request_timeout(struct timeval *to, struct sched *s) { - struct task *t, *tmp; - char buf[20]; + if (tv_diff(&s->select_timeout, to, NULL) > 0) + s->select_timeout = *to; +} - if (!initialized) - return -E_NOT_INITIALIZED; - list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) { - sprintf(buf, "%p", t); - if (strcmp(id, buf)) - continue; - 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->error = -E_TASK_KILLED; - return 1; +/** + * 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; } - return -E_NO_SUCH_TASK; + sched_request_timeout(&diff, s); + return 1; }