-#include <sys/time.h>
+/*
+ * Copyright (C) 2006-2013 Andre Noll <maan@systemlinux.org>
+ *
+ * Licensed under the GPL v2. For licencing details see COPYING.
+ */
+
+/** \file sched.c Paraslash's scheduling functions. */
+
+#include <regex.h>
+#include <assert.h>
+
#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);
-// PARA_INFO_LOG("%s \n", t->status);
- if (t->ret > 0)
- continue;
- if (!t->event_handler)
- continue;
- t->event_handler(t);
- goto again;
+
+ list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) {
+ if (t->notification != 0)
+ sched_min_delay(s);
+ if (t->pre_select)
+ t->pre_select(s, t);
}
}
+//#define SCHED_DEBUG 1
+static inline void call_post_select(struct sched *s, struct task *t)
+{
+#ifndef SCHED_DEBUG
+ t->error = t->post_select(s, t);
+#else
+ struct timeval t1, t2, diff;
+ unsigned long pst;
+
+ clock_get_realtime(&t1);
+ t->error = t->post_select(s, t);
+ clock_get_realtime(&t2);
+ 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);
-// PARA_INFO_LOG("%s \n", t->status);
- 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);
+ t->notification = 0;
+ if (t->error >= 0)
continue;
- t->event_handler(t);
+ 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;
+ clock_get_realtime(now);
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);
+ 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);
+ }
+ clock_get_realtime(now);
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);
+ t->notification = 0;
+ 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)
+/**
+ * Get the list of all registered tasks.
+ *
+ * \param s The scheduler instance to get the task list from.
+ *
+ * \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)
{
- 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;
+ char *msg = NULL;
+
+ 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;
+}
-void init_sched(void)
+/**
+ * Set the notification value of a task.
+ *
+ * \param t The task to notify.
+ * \param err A positive error code.
+ *
+ * Tasks which honor notifications are supposed to call \ref
+ * task_get_notification() in their post_select function and act on the
+ * returned notification value.
+ *
+ * If the scheduler detects during its pre_select loop that at least one task
+ * has been notified, the loop terminates, and the post_select methods of all
+ * taks are immediately called again.
+ *
+ * The notification for a task is reset after the call to its post_select
+ * method.
+ *
+ * \sa \ref task_get_notification().
+ */
+void task_notify(struct task *t, int err)
{
- INIT_LIST_HEAD(&pre_select_list);
- INIT_LIST_HEAD(&post_select_list);
-};
+ assert(err > 0);
+ if (t->notification == -err) /* ignore subsequent notifications */
+ return;
+ PARA_INFO_LOG("notifying task %s: %s\n", t->status, para_strerror(err));
+ t->notification = -err;
+}
-void sched_shutdown(void)
+/**
+ * Return the notification value of a task.
+ *
+ * \param t The task to get the notification value from.
+ *
+ * \return The notification value. If this is negative, the task has been
+ * notified by another task. Tasks are supposed to check for notifications by
+ * calling this function from their post_select method.
+ *
+ * \sa \ref task_notify().
+ */
+int task_get_notification(struct task *t)
{
- struct task *t, *tmp;
+ return t->notification;
+}
- 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);
-};
+/**
+ * Set the notification value of all tasks of a scheduler instance.
+ *
+ * \param s The scheduler instance whose tasks should be notified.
+ * \param err A positive error code.
+ *
+ * This simply iterates over all existing tasks of \a s and sets each
+ * task's notification value to \p -err.
+ */
+void task_notify_all(struct sched *s, int err)
+{
+ struct task *t;
+ list_for_each_entry(t, &s->pre_select_list, pre_select_node)
+ task_notify(t, err);
+ list_for_each_entry(t, &s->post_select_list, post_select_node)
+ task_notify(t, err);
+}
-//char *get_tast_list();
+/**
+ * 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 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;
+}
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