From: Robin Gareus <robin@gareus.org>
Date: Sat, 9 Sep 2017 01:07:01 +0000 (+0200)
Subject: LV2/midnam tweaks - fix race conditions
X-Git-Tag: 5.12~16
X-Git-Url: https://main.carlh.net/gitweb/?p=ardour.git;a=commitdiff_plain;h=7872e4033f236356f0b5a10d0a4eb889adca52d2

LV2/midnam tweaks - fix race conditions

* Emit signal once midnam was actually updated
* only re-read midnam if was it changed. This allows idempotent calls to
  read_midnam() - from the same thread.

At session-load a synth-plugin may load a soundfont in the background
and emit midnam_update() after the synth was initialized but before the
GUI thread connects to the signal. By making the call idempotent the
GUI can call read_midnam() after connecting to the signal to catch up.
---

diff --git a/libs/ardour/ardour/lv2_plugin.h b/libs/ardour/ardour/lv2_plugin.h
index d4b6ca819f..c3d437b6f7 100644
--- a/libs/ardour/ardour/lv2_plugin.h
+++ b/libs/ardour/ardour/lv2_plugin.h
@@ -344,6 +344,7 @@ class LIBARDOUR_API LV2Plugin : public ARDOUR::Plugin, public ARDOUR::Workee
 	bool has_midnam ();
 	bool read_midnam ();
 	std::string midnam_model ();
+	bool _midnam_dirty;
 #endif
 
 	void latency_compute_run ();
diff --git a/libs/ardour/ardour/plugin.h b/libs/ardour/ardour/plugin.h
index 52fbc71c68..f51f34b099 100644
--- a/libs/ardour/ardour/plugin.h
+++ b/libs/ardour/ardour/plugin.h
@@ -182,6 +182,7 @@ class LIBARDOUR_API Plugin : public PBD::StatefulDestructible, public Latent
 	virtual bool read_midnam () { return false; }
 	virtual std::string midnam_model () { return ""; }
 	PBD::Signal0<void> UpdateMidnam;
+	PBD::Signal0<void> UpdatedMidnam;
 
 	virtual bool knows_bank_patch () { return false; }
 	virtual uint32_t bank_patch (uint8_t chn) { return UINT32_MAX; }
diff --git a/libs/ardour/lv2_plugin.cc b/libs/ardour/lv2_plugin.cc
index 5311136afc..b51db65485 100644
--- a/libs/ardour/lv2_plugin.cc
+++ b/libs/ardour/lv2_plugin.cc
@@ -241,6 +241,7 @@ void
 LV2Plugin::midnam_update (LV2_Midnam_Handle handle)
 {
 	LV2Plugin* plugin = (LV2Plugin*)handle;
+	plugin->_midnam_dirty = true;
 	plugin->UpdateMidnam (); /* EMIT SIGNAL */
 }
 
@@ -590,6 +591,7 @@ LV2Plugin::init(const void* c_plugin, framecnt_t rate)
 	_midname_interface = (const LV2_Midnam_Interface*)
 		extension_data (LV2_MIDNAM__interface);
 	if (_midname_interface) {
+		_midnam_dirty = true;
 		read_midnam ();
 	}
 #endif
@@ -1029,7 +1031,7 @@ LV2Plugin::has_midnam () {
 bool
 LV2Plugin::read_midnam () {
 	bool rv = false;
-	if (!_midname_interface) {
+	if (!_midname_interface || !_midnam_dirty) {
 		return rv;
 	}
 	char* midnam = _midname_interface->midnam ((void*)_impl->instance->lv2_handle);
@@ -1047,6 +1049,10 @@ LV2Plugin::read_midnam () {
 	}
 #endif
 	_midname_interface->free (midnam);
+	if (rv) {
+		UpdatedMidnam ();
+		_midnam_dirty = false;
+	}
 	return rv;
 }