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diff --git a/src/server/Broadcaster.hpp b/src/server/Broadcaster.hpp
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+/*
+  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_BROADCASTER_HPP
+#define INGEN_ENGINE_BROADCASTER_HPP
+
+#include <atomic>
+#include <list>
+#include <mutex>
+#include <set>
+#include <string>
+
+#include "ingen/Interface.hpp"
+#include "ingen/types.hpp"
+
+#include "BlockFactory.hpp"
+
+namespace Ingen {
+namespace Server {
+
+/** Broadcaster for all clients.
+ *
+ * This is an Interface that forwards all messages to all registered
+ * clients (for updating all clients on state changes in the engine).
+ *
+ * \ingroup engine
+ */
+class Broadcaster : public Interface
+{
+public:
+	Broadcaster();
+	~Broadcaster();
+
+	void register_client(SPtr<Interface> client);
+	bool unregister_client(SPtr<Interface> client);
+
+	void set_broadcast(SPtr<Interface> client, bool broadcast);
+
+	/** Ignore a client when broadcasting.
+	 *
+	 * This is used to prevent feeding back updates to the client that
+	 * initiated a property set in the first place.
+	 */
+	void set_ignore_client(SPtr<Interface> client) { _ignore_client = client; }
+	void clear_ignore_client()                     { _ignore_client.reset(); }
+
+	/** Return true iff there are any clients with broadcasting enabled.
+	 *
+	 * This is used in the audio thread to decide whether or not notifications
+	 * should be calculated and emitted.
+	 */
+	bool must_broadcast() const { return _must_broadcast; }
+
+	/** A handle that represents a transfer of possibly several changes.
+	 *
+	 * This object going out of scope signifies the transfer is completed.
+	 * This makes doing the right thing in recursive functions that send
+	 * updates simple (e.g. Event::post_process()).
+	 */
+	class Transfer : public Raul::Noncopyable {
+	public:
+		explicit Transfer(Broadcaster& b) : broadcaster(b) {
+			if (++broadcaster._bundle_depth == 1) {
+				broadcaster.bundle_begin();
+			}
+		}
+		~Transfer() {
+			if (--broadcaster._bundle_depth == 0) {
+				broadcaster.bundle_end();
+			}
+		}
+		Broadcaster& broadcaster;
+	};
+
+	void send_plugins(const BlockFactory::Plugins& plugins);
+	void send_plugins_to(Interface*, const BlockFactory::Plugins& plugins);
+
+	void message(const Message& msg) override {
+		std::lock_guard<std::mutex> lock(_clients_mutex);
+		for (const auto& c : _clients) {
+			if (c != _ignore_client) {
+				c->message(msg);
+			}
+		}
+	}
+
+	URI uri() const override { return URI("ingen:/broadcaster"); }
+
+private:
+	friend class Transfer;
+
+	typedef std::set<SPtr<Interface>> Clients;
+
+	std::mutex                  _clients_mutex;
+	Clients                     _clients;
+	std::set< SPtr<Interface> > _broadcastees;
+	std::atomic<bool>           _must_broadcast;
+	unsigned                    _bundle_depth;
+	SPtr<Interface>             _ignore_client;
+};
+
+} // namespace Server
+} // namespace Ingen
+
+#endif // INGEN_ENGINE_BROADCASTER_HPP