X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=sched.c;h=7ee77027bc9c4cf6e26faed3533d37865c7cedbe;hp=041cf417723bd848ea56d2c7eb4935943abeeaef;hb=23b121a85984baa9252f4b4c0b8c4f186e394bb7;hpb=ef1f130a1f9ac61a51da10ee56c5bd9ef1b52366

diff --git a/sched.c b/sched.c
index 041cf417..7ee77027 100644
--- a/sched.c
+++ b/sched.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006-2011 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2013 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -9,7 +9,6 @@
 #include <regex.h>
 #include <assert.h>
 #include <sys/time.h>
-#include <stdbool.h>
 
 #include "para.h"
 #include "ipc.h"
@@ -56,6 +55,10 @@ static void sched_preselect(struct sched *s)
 			unregister_task(t);
 			continue;
 		}
+		if (t->notification != 0) {
+			sched_min_delay(s);
+			break;
+		}
 		if (!t->pre_select)
 			continue;
 		t->pre_select(s, t);
@@ -92,16 +95,9 @@ static void sched_post_select(struct sched *s)
 		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;
-		/*
-		 * We have to check whether the list is empty because the call
-		 * to ->post_select() might have called sched_shutdown(). In
-		 * this case t has been unregistered already, so we must not
-		 * unregister it again.
-		 */
-		if (list_empty(&s->post_select_list))
-			return;
 		unregister_task(t);
 	}
 }
@@ -176,6 +172,7 @@ again:
 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)
@@ -190,30 +187,11 @@ void register_task(struct sched *s, struct task *t)
 	}
 }
 
-/**
- * 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. This function
- * must be called from the post_select (rather than the pre_select) method.
- */
-void sched_shutdown(struct sched *s)
-{
-	struct task *t, *tmp;
-
-	list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) {
-		t->error = -E_SCHED_SHUTDOWN;
-		unregister_task(t);
-	}
-	list_for_each_entry_safe(t, tmp, &s->post_select_list, post_select_node) {
-		t->error = -E_SCHED_SHUTDOWN;
-		unregister_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.
@@ -242,6 +220,69 @@ char *get_task_list(struct sched *s)
 	return msg;
 }
 
+/**
+ * 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)
+{
+	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;
+}
+
+/**
+ * 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)
+{
+	return t->notification;
+}
+
+/**
+ * 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);
+}
+
 /**
  * Set the select timeout to the minimal possible value.
  *