From d471d41232cab47ef6f17bc6ab07b9263c056b21 Mon Sep 17 00:00:00 2001
From: Sergey Evdokimov <sergey.evdokimov@jetbrains.com>
Date: Thu, 26 Apr 2012 14:07:03 +0400
Subject: [PATCH] Bug fix: MavenMergingUpdateQueue suspend forever if
 beforeRootsChange comes twice in a row without rootsChanged.

---
 .../maven/utils/MavenMergingUpdateQueue.java     | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/plugins/maven/src/main/java/org/jetbrains/idea/maven/utils/MavenMergingUpdateQueue.java b/plugins/maven/src/main/java/org/jetbrains/idea/maven/utils/MavenMergingUpdateQueue.java
index 1a09f4530dc8..da50a2cb2a24 100644
--- a/plugins/maven/src/main/java/org/jetbrains/idea/maven/utils/MavenMergingUpdateQueue.java
+++ b/plugins/maven/src/main/java/org/jetbrains/idea/maven/utils/MavenMergingUpdateQueue.java
@@ -88,19 +88,21 @@ public class MavenMergingUpdateQueue extends MergingUpdateQueue {
           }, MavenMergingUpdateQueue.this);
 
         ProjectRootManager.getInstance(project).addModuleRootListener(new ModuleRootListener() {
-            boolean beforeCalled = false;
+            int beforeCalled;
 
             public void beforeRootsChange(ModuleRootEvent event) {
-              suspend();
-              beforeCalled = true;
+              if (beforeCalled++ == 0) {
+                suspend();
+              }
             }
 
             public void rootsChanged(ModuleRootEvent event) {
-              if (!beforeCalled) return;
-              beforeCalled = false;
+              if (beforeCalled == 0) return; // This may occur if listener has been added between beforeRootsChange() and rootsChanged() calls.
 
-              resume();
-              MavenMergingUpdateQueue.this.restartTimer();
+              if (--beforeCalled == 0) {
+                resume();
+                MavenMergingUpdateQueue.this.restartTimer();
+              }
             }
           }, MavenMergingUpdateQueue.this);
       }