/*
- * Copyright (C) 2006-2008 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2009 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 <dirent.h> /* readdir() */
#include <assert.h>
#include <sys/time.h>
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.
*/
-void unregister_task(struct task *t)
+static void unregister_task(struct task *t)
{
if (!initialized)
return;
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;
list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
- if (t->error >= 0)
+ if (t->error >= 0 && t->pre_select)
t->pre_select(s, t);
// PARA_INFO_LOG("%s \n", t->status);
if (t->error >= 0)
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->max_fileno = -1;
+ gettimeofday(now, NULL);
sched_preselect(s);
if (list_empty(&pre_select_list) && list_empty(&post_select_list))
return 0;
- ret = para_select(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
+ ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds, &s->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))
goto again;
}
-/**
+/*
* Initialize the paraslash scheduler.
*/
static void init_sched(void)
INIT_LIST_HEAD(&pre_select_list);
INIT_LIST_HEAD(&post_select_list);
initialized = 1;
-};
+}
/**
* Add a task to the scheduler.
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_DEBUG_LOG("post_select: %p\n", &t->post_select);
list_add_tail(&t->post_select_node, &post_select_list);
}
}
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.
*
* 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)
{
}
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->timeout.tv_sec = 0;
+ s->timeout.tv_usec = 1;
+}
+
+/**
+ * Impose an upper bound for the timeout of the next select() call.
+ *
+ * \param timeout Maximal allowed timeout.
+ * \param s Pointer to the scheduler struct.
+ *
+ * If the current scheduler timeout is already smaller than \a timeout, 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 *timeout, struct sched *s)
+{
+ if (tv_diff(&s->timeout, timeout, NULL) > 0)
+ s->timeout = *timeout;
+}
+
+/**
+ * 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);
+}