From fb4ce33375bd4693e418089e2f379554ee52df67 Mon Sep 17 00:00:00 2001
From: Chow Loong Jin <hyperair@ubuntu.com>
Date: Mon, 7 Nov 2011 08:15:27 +0800
Subject: [PATCH] Add TrapSignals and UntrapSignals to Connection.cs

This allows for locking signals from the bus while connecting to signals on a
BusObject, and releasing them after.

This is needed for Mono.Zeroconf's implementation of Avahi's DBus protocol.
---
 src/Connection.cs | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/src/Connection.cs b/src/Connection.cs
index e593db9..1e577e3 100644
--- a/src/Connection.cs
+++ b/src/Connection.cs
@@ -176,6 +176,25 @@ internal virtual uint Send (Message msg)
 		//temporary hack
 		internal void DispatchSignals ()
 		{
+			lock (delayed_signals)
+			lock (delayed_signals_recycle) {
+				if (trap_signals_flush) {
+					delayed_signals.Clear ();
+					delayed_signals_recycle.Clear ();
+					trap_signals_flush = false;
+				} else {
+					while (delayed_signals.Count != 0) {
+						Message msg = delayed_signals.Dequeue ();
+						HandleSignal (msg);
+					}
+
+					while (delayed_signals_recycle.Count != 0) {
+						delayed_signals.Enqueue (delayed_signals_recycle.Dequeue ());
+					}
+				}
+			}
+
+
 			lock (Inbound) {
 				while (Inbound.Count != 0) {
 					Message msg = Inbound.Dequeue ();
@@ -268,6 +287,23 @@ internal virtual void HandleMessage (Message msg)
 
 		Dictionary<uint,PendingCall> pendingCalls = new Dictionary<uint,PendingCall> ();
 
+		private Queue<Message> delayed_signals = new Queue<Message> ();
+		private Queue<Message> delayed_signals_recycle = new Queue<Message> ();
+		private int trap_signals_ref;
+		private bool trap_signals_flush;
+
+		public void TrapSignals ()
+		{
+			Interlocked.Increment (ref trap_signals_ref);
+		}
+
+		public void UntrapSignals ()
+		{
+			if (Interlocked.Decrement (ref trap_signals_ref) == 0) {
+				trap_signals_flush = true;
+			}
+		}
+
 		//this might need reworking with MulticastDelegate
 		internal void HandleSignal (Message msg)
 		{
@@ -304,6 +340,12 @@ internal void HandleSignal (Message msg)
 				//TODO: how should we handle this condition? sending an Error may not be appropriate in this case
 				if (Protocol.Verbose)
 					Console.Error.WriteLine ("Warning: No signal handler for " + signal.Member);
+
+				if (trap_signals_ref > 0) {
+					lock (delayed_signals_recycle) {
+						delayed_signals_recycle.Enqueue (msg);
+					}
+				}
 			}
 		}