X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=sched.c;h=385dde61f0fc210dd52bdb1192b392e39061977b;hp=65176bd91a875ab16ce07194299dbc9bde5a00a5;hb=5ff2b0b3a6f9242033c436fb8272245f5594dd8c;hpb=0bd00f72312a79900d211e735b135c220ddd0d68

diff --git a/sched.c b/sched.c
index 65176bd9..385dde61 100644
--- a/sched.c
+++ b/sched.c
@@ -9,6 +9,7 @@
 #include <regex.h>
 #include <assert.h>
 #include <sys/time.h>
+#include <stdbool.h>
 
 #include "para.h"
 #include "ipc.h"
@@ -46,24 +47,25 @@ static void unregister_task(struct task *t)
 		list_del(&t->post_select_node);
 }
 
+static inline bool timeout_is_zero(struct sched *s)
+{
+	struct timeval *tv = &s->select_timeout;
+	return tv->tv_sec == 0 && tv->tv_usec == 0;
+}
+
 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->pre_select)
-			t->pre_select(s, t);
-//		PARA_INFO_LOG("%s \n", t->status);
-		if (t->error >= 0)
+		if (t->error < 0) {
+			unregister_task(t);
 			continue;
-		/*
-		 * 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);
+		}
+		if (!t->pre_select)
+			continue;
+		t->pre_select(s, t);
+		if (timeout_is_zero(s))
+			break;
 	}
 }
 
@@ -97,7 +99,12 @@ static void sched_post_select(struct sched *s)
 //		PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
 		if (t->error >= 0)
 			continue;
-		/* nec., see sched_preselect() */
+		/*
+		 * 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(&post_select_list))
 			return;
 		unregister_task(t);
@@ -136,21 +143,23 @@ again:
 	sched_preselect(s);
 	if (list_empty(&pre_select_list) && list_empty(&post_select_list))
 		return 0;
-	ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds,
-		&s->select_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);
+	if (!timeout_is_zero(s)) {
+		ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds,
+			&s->select_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);
 	}
-	gettimeofday(now, NULL);
 	sched_post_select(s);
 	if (list_empty(&pre_select_list) && list_empty(&post_select_list))
 		return 0;
@@ -197,7 +206,8 @@ void register_task(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.
+ * \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(void)
 {
@@ -258,8 +268,7 @@ char *get_task_list(void)
  */
 void sched_min_delay(struct sched *s)
 {
-	s->select_timeout.tv_sec = 0;
-	s->select_timeout.tv_usec = 1;
+	s->select_timeout.tv_sec = s->select_timeout.tv_usec = 0;
 }
 
 /**