Add Lua binding for unit-tests to sync with process-cb

libs/ardour/ardour/lua_api.h

@@ -228,6 +228,15 @@ namespace ARDOUR { namespace LuaAPI {
 	 */
 	int timecode_to_sample_lua (lua_State *L);
 
+	/**
+	 * Delay execution until next prcess cycle starts.
+	 * @param n_cycles process-cycles to wait for.
+	 *        0: means wait until next cycle-start, otherwise skip given number of cycles.
+	 * @param timeout_ms wait at most this many milliseconds
+	 * @return true on success,  false if timeout was reached or engine was not running
+	 */
+	bool wait_for_process_callback (size_t n_cycles, int64_t timeout_ms);
+
 	class Vamp {
 	/** Vamp Plugin Interface
 	 *

libs/ardour/lua_api.cc

@@ -25,8 +25,10 @@
 #include "pbd/failed_constructor.h"
 
 #include "ardour/analyser.h"
+#include "ardour/audioengine.h"
 #include "ardour/audiofilesource.h"
 #include "ardour/audiosource.h"
+#include "ardour/internal_send.h"
 #include "ardour/lua_api.h"
 #include "ardour/luaproc.h"
 #include "ardour/luascripting.h"
@@ -424,6 +426,46 @@ ARDOUR::LuaAPI::timecode_to_sample_lua (lua_State *L)
 	return 1;
 }
 
+
+static
+void proc_cycle_start (size_t* cnt)
+{
+	++*cnt;
+}
+
+bool
+ARDOUR::LuaAPI::wait_for_process_callback (size_t n_cycles, int64_t timeout_ms)
+{
+	if (!AudioEngine::instance()->running()) {
+		return false;
+	}
+#if 0
+	if (AudioEngine::instance()->freewheeling()) {
+		return false;
+	}
+#endif
+	if (AudioEngine::instance()->measuring_latency() != AudioEngine::MeasureNone) {
+		return false;
+	}
+	if (!AudioEngine::instance()->session() ) {
+		return false;
+	}
+
+	size_t cnt = 0;
+	ScopedConnection c;
+
+	InternalSend::CycleStart.connect_same_thread (c, boost::bind (&proc_cycle_start, &cnt));
+	while (cnt <= n_cycles) {
+		Glib::usleep (1000);
+		if (timeout_ms > 0) {
+			if (--timeout_ms == 0) {
+				return cnt > n_cycles;
+			}
+		}
+	}
+	return true;
+}
+
 int
 ARDOUR::LuaOSC::Address::send (lua_State *L)
 {

libs/ardour/luabindings.cc

@@ -2554,6 +2554,7 @@ LuaBindings::common (lua_State* L)
 		.addFunction ("note_list", ARDOUR::LuaAPI::note_list)
 		.addCFunction ("sample_to_timecode", ARDOUR::LuaAPI::sample_to_timecode)
 		.addCFunction ("timecode_to_sample", ARDOUR::LuaAPI::timecode_to_sample)
+		.addFunction ("wait_for_process_callback", ARDOUR::LuaAPI::wait_for_process_callback)
 
 		.beginNamespace ("FileTest")
 		.addConst ("IsRegular", Glib::FILE_TEST_IS_REGULAR)