/*
- * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2008 Andre Noll <maan@systemlinux.org>
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
+ * 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 <dirent.h> /* readdir() */
+#include <assert.h>
#include <sys/time.h>
+
#include "para.h"
#include "ipc.h"
#include "fd.h"
#include "string.h"
#include "error.h"
-/**
- * The scheduler manages two lists of tasks. The pre_select list contains
- * pointers to functions that are called before calling select() from the main
- * loop. Similarly, \a post_select_list is a list of function pointers each of
- * which is called after the select call.
- */
-struct list_head pre_select_list, post_select_list;
+static struct list_head pre_select_list, post_select_list;
+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.
+ */
+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);
+ if (t->error >= 0)
+ t->error = -E_TASK_KILLED;
+};
+
+
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)
+ 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);
}
}
list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
t->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.
*
- * Short and sweet. It updates the global \a now pointer, calls all registered
+ * \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.
*
* \sa task, now.
*/
-int sched(struct sched *s)
+int schedule(struct sched *s)
{
+ int ret;
+ if (!initialized)
+ return -E_NOT_INITIALIZED;
gettimeofday(now, NULL);
again:
FD_ZERO(&s->rfds);
s->timeout = s->default_timeout;
s->max_fileno = -1;
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 = para_select(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
+ if (ret < 0)
+ return ret;
gettimeofday(now, NULL);
sched_post_select(s);
if (list_empty(&pre_select_list) && list_empty(&post_select_list))
}
/**
- * add a task to the scheduler
+ * Initialize the paraslash scheduler.
+ */
+static void init_sched(void)
+{
+ 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.
*
* \param t the task to add
*
*/
void register_task(struct task *t)
{
+ if (!initialized)
+ init_sched();
PARA_INFO_LOG("registering %s (%p)\n", t->status, t);
if (t->pre_select) {
PARA_DEBUG_LOG("pre_select: %p\n", &t->pre_select);
- 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);
- list_add(&t->post_select_node, &post_select_list);
+ list_add_tail(&t->post_select_node, &post_select_list);
}
}
/**
- * remove a task from the scheduler
- *
- * \param t the task to remove
+ * Unregister all tasks.
*
- * 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)
-{
- 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);
-};
-
-/**
- * initialize the paraslash scheduler
- */
-void init_sched(void)
-{
- INIT_LIST_HEAD(&pre_select_list);
- INIT_LIST_HEAD(&post_select_list);
-};
-
-/**
- * unregister all tasks
- *
- * This will cause \a sched() to return immediately because both the
+ * This will cause \a schedule() to return immediately because both the
* \a pre_select_list and the \a post_select_list are empty.
*/
void sched_shutdown(void)
{
struct task *t, *tmp;
+ if (!initialized)
+ 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.
{
struct task *t, *tmp;
char *msg = NULL;
+
+ if (!initialized)
+ return NULL;
list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
char *tmp_msg;
tmp_msg = make_message("%s%p\tpre\t%s\n", msg? msg : "", t, t->status);
}
/**
- * 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 sucess, negative if \a id does not correspond to a
- * registered task.
+ * \return Positive on success, negative on errors (e.g. if \a id does not
+ * correspond to a registered task).
*/
int kill_task(char *id)
{
struct task *t, *tmp;
char buf[20];
+
+ 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->ret = -E_TASK_KILLED;
- if (t->event_handler)
- t->event_handler(t);
+ t->error = -E_TASK_KILLED;
+ unregister_task(t);
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;
+ unregister_task(t);
return 1;
}
return -E_NO_SUCH_TASK;
projects / paraslash.git / blobdiff