From 2fbdcbaeb28e62fffb4c63c5118fdc5243b426bc Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Tue, 19 Aug 2008 21:42:33 +0000
Subject: Gracefully handle full event queue on the engine side (fix loading
 massive patches).

git-svn-id: http://svn.drobilla.net/lad/ingen@1450 a436a847-0d15-0410-975c-d299462d15a1
---
 src/libs/engine/QueuedEventSource.cpp | 47 +++++++++++++++++++++--------------
 1 file changed, 29 insertions(+), 18 deletions(-)

(limited to 'src/libs/engine/QueuedEventSource.cpp')

diff --git a/src/libs/engine/QueuedEventSource.cpp b/src/libs/engine/QueuedEventSource.cpp
index 4b63b6c4..69ab805a 100644
--- a/src/libs/engine/QueuedEventSource.cpp
+++ b/src/libs/engine/QueuedEventSource.cpp
@@ -29,12 +29,13 @@ namespace Ingen {
 
 
 QueuedEventSource::QueuedEventSource(size_t queued_size, size_t stamped_size)
-: _front(0),
-  _back(0),
-  _prepared_back(0),
-  _size(queued_size+1),
-  _blocking_semaphore(0),
-  _stamped_queue(stamped_size)
+	: _front(0)
+	, _back(0)
+	, _prepared_back(0)
+	, _size(queued_size+1)
+	, _blocking_semaphore(0)
+	, _full_semaphore(0)
+	, _stamped_queue(stamped_size)
 {
 	_events = (QueuedEvent**)calloc(_size, sizeof(QueuedEvent*));
 
@@ -62,14 +63,20 @@ QueuedEventSource::push_queued(QueuedEvent* const ev)
 {
 	assert(!ev->is_prepared());
 
-	if (_events[_back] != NULL) {
-		cerr << "[QueuedEventSource] Error: Queue is full!  Event is lost, please report!" << endl;
-		delete ev;
-	} else {
-		_events[_back] = ev;
-		_back = (_back + 1) % _size;
+	unsigned back = _back.get();
+	bool full = (((_front.get() - back + _size) % _size) == 1);
+	while (full) {
 		whip();
+		cerr << "WARNING: Event queue full.  Waiting..." << endl;
+		_full_semaphore.wait();
+		back = _back.get();
+		full = (((_front.get() - back + _size) % _size) == 1);
 	}
+		
+	assert(_events[back] == NULL);
+	_events[back] = ev;
+	_back = (back + 1) % _size;
+	whip();
 }
 
 
@@ -107,6 +114,9 @@ QueuedEventSource::process(PostProcessor& dest, ProcessContext& context)
 		++num_events_processed;
 	}
 
+	if (_full_semaphore.has_waiter() && num_events_processed > 0)
+		_full_semaphore.post();
+
 	/*if (num_events_processed > 0)
 	    dest.whip();*/
 	//else
@@ -130,12 +140,13 @@ QueuedEventSource::pop_earliest_queued_before(const SampleCount time)
 {
 	assert(ThreadManager::current_thread_id() == THREAD_PROCESS);
 
-	QueuedEvent* const front_event = _events[_front];
+	const unsigned front = _front.get();
+	QueuedEvent* const front_event = _events[front];
 	
 	// Pop
 	if (front_event && front_event->is_prepared() && front_event->time() < time) {
-		_events[_front] = NULL;
-		_front = (_front + 1) % _size;
+		_events[front] = NULL;
+		_front = (front + 1) % _size;
 		return front_event;
 	} else {
 		return NULL;
@@ -150,8 +161,8 @@ QueuedEventSource::pop_earliest_queued_before(const SampleCount time)
 void
 QueuedEventSource::_whipped()
 {
-	QueuedEvent* const ev = _events[_prepared_back];
-	//assert(ev);
+	const unsigned prepared_back = _prepared_back.get();
+	QueuedEvent* const ev = _events[prepared_back];
 	if (!ev)
 		return;
 	
@@ -159,7 +170,7 @@ QueuedEventSource::_whipped()
 	ev->pre_process();
 	assert(ev->is_prepared());
 
-	_prepared_back = (_prepared_back+1) % _size;
+	_prepared_back = (prepared_back + 1) % _size;
 
 	// If event was blocking, wait for event to being run through the
 	// process thread before preparing the next event
-- 
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