peak_amplitude_thread fix - #6807

On windows AudioRegionEditor d'tor never returns, stalling or
crashing in pthread_join() after pthread_cancel().
Crashes happen if two thread pools with the same name exist.
(but since the thread has no event loop, no pool is needed)

After showing Region Properties any operation that would close the dialog
will either cause the application to hang indefinitely or terminate.

This also consolidates code: CrossThreadChannel works on windows these days

1 files changed, 11 insertions, 23 deletions

diff --git a/gtk2_ardour/audio_region_editor.cc b/gtk2_ardour/audio_region_editor.cc
index 3446f58eee..a5890a656a 100644
--- a/gtk2_ardour/audio_region_editor.cc
+++ b/gtk2_ardour/audio_region_editor.cc
@@ -43,7 +43,6 @@ using namespace Gtkmm2ext;
 static void *
 _peak_amplitude_thread (void* arg)
 {
-	SessionEvent::create_per_thread_pool ("peak amplitude events", 64);
 	static_cast<AudioRegionEditor*>(arg)->peak_amplitude_thread ();
 	return 0;
 }
@@ -52,11 +51,7 @@ AudioRegionEditor::AudioRegionEditor (Session* s, boost::shared_ptr<AudioRegion>
 	: RegionEditor (s, r)
 	, _audio_region (r)
 	, gain_adjustment(accurate_coefficient_to_dB(_audio_region->scale_amplitude()), -40.0, +40.0, 0.1, 1.0, 0)
-#ifdef PLATFORM_WINDOWS
-	, m_peak_sem ("peak_semaphore", 0)
-#else
 	, _peak_channel (false)
-#endif
 {
 
 	Gtk::HBox* b = Gtk::manage (new Gtk::HBox);
@@ -92,14 +87,17 @@ AudioRegionEditor::AudioRegionEditor (Session* s, boost::shared_ptr<AudioRegion>
 	_peak_amplitude.set_text (_("Calculating..."));
 
 	PeakAmplitudeFound.connect (_peak_amplitude_connection, invalidator (*this), boost::bind (&AudioRegionEditor::peak_amplitude_found, this, _1), gui_context ());
-	pthread_create_and_store (X_("peak-amplitude"), &_peak_amplitude_thread_handle, _peak_amplitude_thread, this);
+
+	char name[64];
+	snprintf (name, 64, "peak amplitude-%p", this);
+	pthread_create_and_store (name, &_peak_amplitude_thread_handle, _peak_amplitude_thread, this);
 	signal_peak_thread ();
 }
 
 AudioRegionEditor::~AudioRegionEditor ()
 {
 	void* v;
-	pthread_cancel_one (_peak_amplitude_thread_handle);
+	_peak_channel.deliver ('t');
 	pthread_join (_peak_amplitude_thread_handle, &v);
 }
 
@@ -138,30 +136,20 @@ AudioRegionEditor::gain_adjustment_changed ()
 void
 AudioRegionEditor::signal_peak_thread ()
 {
-#ifdef PLATFORM_WINDOWS
-	m_peak_sem.signal ();
-#else
 	_peak_channel.deliver ('c');
-#endif
-}
-
-void
-AudioRegionEditor::wait_for_signal ()
-{
-#ifdef PLATFORM_WINDOWS
-	m_peak_sem.wait ();
-#else
-	char msg;
-	_peak_channel.receive (msg);
-#endif
 }
 
 void
 AudioRegionEditor::peak_amplitude_thread ()
 {
 	while (1) {
+		char msg;
 		/* await instructions to run */
-		wait_for_signal ();
+		_peak_channel.receive (msg);
+
+		if (msg == 't') {
+			break;
+		}
 
 		/* compute peak amplitude and signal the fact */
 		PeakAmplitudeFound (accurate_coefficient_to_dB (_audio_region->maximum_amplitude ())); /* EMIT SIGNAL */