X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=sched.c;h=f703890bdf52f9be843d3c3a545da36974254fde;hp=e58483e9385e5092c094ac0f2b30b06c905e6627;hb=e67116354084dcf587c03dccaeb18d8cee886c1b;hpb=fc100a582159c001bd5eb2244f314343309bb503

diff --git a/sched.c b/sched.c
index e58483e9..f703890b 100644
--- a/sched.c
+++ b/sched.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006-2009 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2010 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -17,6 +17,7 @@
 #include "list.h"
 #include "sched.h"
 #include "string.h"
+#include "time.h"
 #include "error.h"
 
 static struct list_head pre_select_list, post_select_list;
@@ -25,7 +26,7 @@ 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.
@@ -68,13 +69,33 @@ static void sched_preselect(struct sched *s)
 	}
 }
 
+#define SCHED_DEBUG 0
+static inline void call_post_select(struct sched *s, struct task *t)
+{
+#ifndef SCHED_DEBUG
+	t->post_select(s, t);
+#else
+	struct timeval t1, t2, diff;
+	unsigned long pst;
+
+	gettimeofday(&t1, NULL);
+	t->post_select(s, t);
+	gettimeofday(&t2, NULL);
+	tv_diff(&t1, &t2, &diff);
+	pst = tv2ms(&diff);
+	if (pst > 50)
+		PARA_WARNING_LOG("%s: post_select time: %lums\n",
+			t->status, pst);
+#endif
+}
+
 static void sched_post_select(struct sched *s)
 {
 	struct task *t, *tmp;
 
 	list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
 		if (t->error >= 0)
-			t->post_select(s, t);
+			call_post_select(s, t);
 //		PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
 		if (t->error >= 0)
 			continue;
@@ -120,6 +141,16 @@ again:
 	ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds, &s->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);
 	sched_post_select(s);
 	if (list_empty(&pre_select_list) && list_empty(&post_select_list))
@@ -127,7 +158,7 @@ again:
 	goto again;
 }
 
-/**
+/*
  * Initialize the paraslash scheduler.
  */
 static void init_sched(void)
@@ -189,7 +220,7 @@ void sched_shutdown(void)
  *
  * 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.
+ * The result is dynamically allocated and must be freed by the caller.
  */
 char *get_task_list(void)
 {
@@ -251,18 +282,46 @@ int kill_task(char *id)
 	return -E_NO_SUCH_TASK;
 }
 
+/**
+ * Set the select timeout to the minimal possible value.
+ *
+ * \param s Pointer to the scheduler struct.
+ *
+ * This causes the next select() call to return immediately.
+ */
 void sched_min_delay(struct sched *s)
 {
 	s->timeout.tv_sec = 0;
 	s->timeout.tv_usec = 1;
 }
 
+/**
+ * Impose an upper bound for the timeout of the next select() call.
+ *
+ * \param timeout Maximal allowed timeout.
+ * \param s Pointer to the scheduler struct.
+ *
+ * If the current scheduler timeout is already smaller than \a timeout, this
+ * function does nothing. Otherwise the timeout for the next select() call is
+ * set to the given value.
+ *
+ * \sa sched_request_timeout_ms().
+ */
 void sched_request_timeout(struct timeval *timeout, struct sched *s)
 {
 	if (tv_diff(&s->timeout, timeout, NULL) > 0)
 		s->timeout = *timeout;
 }
 
+/**
+ * Force the next select() call to return before the given amount of milliseconds.
+ *
+ * \param ms The maximal allowed timeout in milliseconds.
+ * \param s Pointer to the scheduler struct.
+ *
+ * Like sched_request_timeout() this imposes an upper bound on the timeout
+ * value for the next select() call.
+ */
 void sched_request_timeout_ms(long unsigned ms, struct sched *s)
 {
 	struct timeval tv;
@@ -270,6 +329,16 @@ void sched_request_timeout_ms(long unsigned ms, struct sched *s)
 	sched_request_timeout(&tv, s);
 }
 
+/**
+ * Force the next select() call to return before the given future time.
+ *
+ * \param barrier Absolute time before select() should return.
+ * \param s Pointer to the scheduler struct.
+ *
+ * If \a barrier is in the past, this function does nothing.
+ *
+ * \sa sched_request_barrier_or_min_delay().
+ */
 void sched_request_barrier(struct timeval *barrier, struct sched *s)
 {
 	struct timeval diff;
@@ -279,4 +348,21 @@ void sched_request_barrier(struct timeval *barrier, struct sched *s)
 	sched_request_timeout(&diff, s);
 }
 
+/**
+ * Force the next select() call to return before the given time.
+ *
+ * \param barrier Absolute time before select() should return.
+ * \param s Pointer to the scheduler struct.
+ *
+ * If \a barrier is in the past, this function requests a minimal timeout.
+ *
+ * \sa sched_min_delay(), sched_request_barrier().
+ */
+void sched_request_barrier_or_min_delay(struct timeval *barrier, struct sched *s)
+{
+	struct timeval diff;
 
+	if (tv_diff(now, barrier, &diff) > 0)
+		return sched_min_delay(s);
+	sched_request_timeout(&diff, s);
+}