Defer graph compilation in atomic bundles

This avoids situations like compiling a graph hundreds of times when it
is loaded because it has hundreds of nodes and each event triggers a
re-compile.

This speeds things up dramatically, but exacerbates the theoretical
problem of there not being enough time in a cycle to execute a bundle.
As far as I can tell, the execute phase of events is very fast, so
hundreds or thousands can easily run in a tiny fraction of the process
cycle, but this still needs resolution to be truly hard real-time.  What
probably needs to happen is that all context and state used to process
is moved to CompiledGraph and nodes do not access their own fields at
all, but have some references into the CompiledGraph.  This way, a
compiled graph is separate from its "source code", and an old one could
continue to be run while a new one is beng applied across several
cycles.

1 files changed, 70 insertions, 0 deletions

diff --git a/src/server/PreProcessContext.hpp b/src/server/PreProcessContext.hpp
new file mode 100644
index 00000000..bf1115e8
--- /dev/null
+++ b/src/server/PreProcessContext.hpp
@@ -0,0 +1,70 @@
+/*
+  This file is part of Ingen.
+  Copyright 2007-2016 David Robillard <http://drobilla.net/>
+
+  Ingen is free software: you can redistribute it and/or modify it under the
+  terms of the GNU Affero General Public License as published by the Free
+  Software Foundation, either version 3 of the License, or any later version.
+
+  Ingen is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU Affero General Public License for details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with Ingen.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef INGEN_ENGINE_PREPROCESSCONTEXT_HPP
+#define INGEN_ENGINE_PREPROCESSCONTEXT_HPP
+
+#include <unordered_set>
+
+#include "GraphImpl.hpp"
+
+namespace Ingen {
+namespace Server {
+
+/** Event pre-processing context.
+ *
+ * \ingroup engine
+ */
+class PreProcessContext
+{
+public:
+	typedef std::unordered_set<GraphImpl*> DirtyGraphs;
+
+	/** Return true iff an atomic bundle is currently being pre-processed. */
+	bool in_bundle() const { return _in_bundle; }
+
+	/** Set/unset atomic bundle flag. */
+	void set_in_bundle(bool b) { _in_bundle = b; }
+
+	/** Return true iff graph should be compiled now (after a change).
+	 *
+	 * This may return false when an atomic bundle is deferring compilation, in
+	 * which case the graph is flagged as dirty for later compilation.
+	 */
+	bool must_compile(GraphImpl* graph) {
+		if (!graph->enabled()) {
+			return false;
+		} else if (_in_bundle) {
+			_dirty_graphs.insert(graph);
+			return false;
+		} else {
+			return true;
+		}
+	}
+
+	/** Return all graphs that require compilation after an atomic bundle. */
+	const DirtyGraphs& dirty_graphs() const { return _dirty_graphs; }
+	DirtyGraphs&       dirty_graphs()       { return _dirty_graphs; }
+
+private:
+	DirtyGraphs _dirty_graphs;
+	bool        _in_bundle = false;
+};
+
+} // namespace Server
+} // namespace Ingen
+
+#endif // INGEN_ENGINE_PREPROCESSCONTEXT_HPP