X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=sched.c;h=6b893d33c9ccb2b07c65fcb8fd02ac168d7bc6f8;hb=c075e867311c77dfb7171241597e613290d1f62b;hp=c5b2c5ea1b4badf8b5f2e02fe94a03c9cdb6421f;hpb=95491e280363ddaed05599445138fd8191110dc1;p=paraslash.git

diff --git a/sched.c b/sched.c
index c5b2c5ea..6b893d33 100644
--- a/sched.c
+++ b/sched.c
@@ -1,3 +1,23 @@
+/*
+ * Copyright (C) 2006 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.
+ */
+
+/** \file sched.c paraslash's scheduling functions */
+
 #include <sys/time.h>
 #include "para.h"
 #include "ipc.h"
@@ -7,10 +27,16 @@
 #include "string.h"
 #include "error.h"
 
-struct list_head pre_select_list;
-struct list_head post_select_list;
+/**
+ * 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 timeval now_struct;
+
 struct timeval *now = &now_struct;
 
 static void sched_preselect(struct sched *s)
@@ -42,6 +68,19 @@ static void sched_post_select(struct sched *s)
 	}
 }
 
+/**
+ * the core function for all paraslash programs
+ *
+ * Short and sweet. It 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 sched(struct sched *s)
 {
 
@@ -63,7 +102,17 @@ again:
 	goto again;
 }
 
-void *register_task(struct task *t)
+/**
+ * add a task to the scheduler
+ *
+ * \param t the task to add
+ *
+ * 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 task *t)
 {
 	PARA_INFO_LOG("registering %s (%p)\n", t->status, t);
 	if (t->pre_select) {
@@ -74,9 +123,16 @@ void *register_task(struct task *t)
 		PARA_DEBUG_LOG("post_select: %p\n", &t->pre_select);
 		list_add(&t->post_select_node, &post_select_list);
 	}
-	return t;
 }
 
+/**
+ * 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)
 {
 	PARA_INFO_LOG("unregistering %s (%p)\n", t->status, t);
@@ -86,12 +142,21 @@ void unregister_task(struct task *t)
 		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
+ * \a pre_select_list and the \a post_select_list are empty.
+ */
 void sched_shutdown(void)
 {
 	struct task *t, *tmp;
@@ -103,6 +168,15 @@ void sched_shutdown(void)
 		unregister_task(t);
 };
 
+/**
+ * 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
+ * that may be used in \a kill_task() to terminate the task.
+ * The result ist dynamically allocated and must be freed by the caller.
+ */
 char *get_task_list(void)
 {
 	struct task *t, *tmp;
@@ -125,6 +199,17 @@ char *get_task_list(void)
 	return msg;
 }
 
+/**
+ * simulate an error for the given task
+ *
+ * \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.
+ *
+ * \return Positive on sucess, negative if \a id does not correspond to a
+ * registered task.
+ */
 int kill_task(char *id)
 {
 	struct task *t, *tmp;