X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=sched.c;h=ba43b10cff143960d3741fb6c0f7238b351de865;hp=c5b2c5ea1b4badf8b5f2e02fe94a03c9cdb6421f;hb=3e3b0dce3c7b301392f0a4fcbf8ac72bbc76b141;hpb=7d1805d1559e08e0af701155574aef220925d411

diff --git a/sched.c b/sched.c
index c5b2c5ea..ba43b10c 100644
--- a/sched.c
+++ b/sched.c
@@ -1,4 +1,15 @@
+/*
+ * Copyright (C) 2006-2007 Andre Noll <maan@systemlinux.org>
+ *
+ * Licensed under the GPL v2. For licencing details see COPYING.
+ */
+
+/** \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"
@@ -7,8 +18,8 @@
 #include "string.h"
 #include "error.h"
 
-struct list_head pre_select_list;
-struct list_head 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;
@@ -42,9 +53,25 @@ static void sched_post_select(struct sched *s)
 	}
 }
 
-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)
 {
-
+	if (!initialized)
+		return -E_NOT_INITIALIZED;
 	gettimeofday(now, NULL);
 again:
 	FD_ZERO(&s->rfds);
@@ -63,22 +90,54 @@ again:
 	goto again;
 }
 
-void *register_task(struct task *t)
+/**
+ * initialize the paraslash scheduler
+ */
+static void init_sched(void)
+{
+	PARA_INFO_LOG("%s", "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
+ *
+ * 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)
 {
+	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);
+		para_list_add(&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);
+		para_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)
 {
+	if (!initialized)
+		return;
 	PARA_INFO_LOG("unregistering %s (%p)\n", t->status, t);
 	if (t->pre_select)
 		list_del(&t->pre_select_node);
@@ -86,27 +145,42 @@ void unregister_task(struct task *t)
 		list_del(&t->post_select_node);
 };
 
-void init_sched(void)
-{
-	INIT_LIST_HEAD(&pre_select_list);
-	INIT_LIST_HEAD(&post_select_list);
-};
-
+/**
+ * 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.
+ */
 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.
+ *
+ * \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;
 	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);
@@ -125,10 +199,24 @@ 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 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))