From 5bb44a414084464f133beb8810027a18b4254d1f Mon Sep 17 00:00:00 2001
From: Andre Noll <maan@systemlinux.org>
Date: Sun, 31 Mar 2013 14:58:18 +0000
Subject: [PATCH] audiod: Avoid delay when closing slot.

Currently we might wait up to a full scheduler interval until a slot
is closed.

This commit changes the pre_select method of the status task to check
whether some slot can be closed. In this case it requests a minimal
delay from the scheduler.

The current try_to_close_slot() is split into two functions,
must_close_slot() and close_unused_slots(). The former function is
called from ->pre_select(). It only checks whether a slot must be
closed but performs no action.

The latter function, close_unused_slots() probes all slots and closes
those for which must_close_slot() returns true.
---
 audiod.c | 44 +++++++++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 15 deletions(-)

diff --git a/audiod.c b/audiod.c
index 4f2d4151..6da2ccc7 100644
--- a/audiod.c
+++ b/audiod.c
@@ -1089,32 +1089,44 @@ static void set_stat_task_restart_barrier(unsigned seconds)
 	tv_add(now, &delay, &stat_task->restart_barrier);
 }
 
-static void try_to_close_slot(int slot_num)
+static bool must_close_slot(int slot_num)
 {
 	struct slot_info *s = &slot[slot_num];
 	struct audio_format_info *a = afi + s->format;
 	int i;
 
 	if (s->format < 0)
-		return;
+		return false;
 	if (s->receiver_node && s->receiver_node->task.error >= 0)
-		return;
+		return false;
 	for (i = 0; i < a->num_filters; i++)
 		if (s->fns && s->fns[i].task.error >= 0)
-			return;
+			return false;
 	if (a->num_writers > 0) {
 		for (i = 0; i < a->num_writers; i++)
 			if (s->wns && s->wns[i].task.error >= 0)
-				return;
+				return false;
 	} else {
 		if (s->wns && s->wns[0].task.error >= 0)
-			return;
+			return false;
+	}
+	return true;
+}
+
+static void close_unused_slots(void)
+{
+	int i;
+
+	FOR_EACH_SLOT(i) {
+		struct slot_info *s = slot + i;
+		if (!must_close_slot(i))
+			continue;
+		PARA_INFO_LOG("closing slot %d\n", i);
+		close_writers(s);
+		close_filters(s);
+		close_receiver(i);
+		clear_slot(i);
 	}
-	PARA_INFO_LOG("closing slot %d\n", slot_num);
-	close_writers(s);
-	close_filters(s);
-	close_receiver(slot_num);
-	clear_slot(slot_num);
 }
 
 /*
@@ -1123,12 +1135,11 @@ static void try_to_close_slot(int slot_num)
  */
 static void start_stop_decoders(void)
 {
-	int i, ret;
+	int ret;
 	struct slot_info *sl;
 	struct audio_format_info *a;
 
-	FOR_EACH_SLOT(i)
-		try_to_close_slot(i);
+	close_unused_slots();
 	if (audiod_status != AUDIOD_ON ||
 			!(stat_task->vss_status & VSS_STATUS_FLAG_PLAYING))
 		return notify_receivers(E_NOT_PLAYING);
@@ -1151,10 +1162,13 @@ static void start_stop_decoders(void)
 static void status_pre_select(struct sched *s, struct task *t)
 {
 	struct status_task *st = container_of(t, struct status_task, task);
-	int ret, cafn = stat_task->current_audio_format_num;
+	int i, ret, cafn = stat_task->current_audio_format_num;
 
 	if (must_start_decoder())
 		goto min_delay;
+	FOR_EACH_SLOT(i)
+		if (must_close_slot(i))
+			goto min_delay;
 	ret = btr_node_status(st->btrn, st->min_iqs, BTR_NT_LEAF);
 	if (ret > 0)
 		goto min_delay;
-- 
2.39.2