From f3a047ff44ceaeffe5cace07f3fee1d0a65d0697 Mon Sep 17 00:00:00 2001
From: angryziber <angryziber@375186e5-ef17-0410-b0b6-91563547dcda>
Date: Wed, 9 Apr 2008 22:52:44 +0000
Subject: [PATCH] slightly better synchronization in the state machine

git-svn-id: https://ipscan.svn.sourceforge.net/svnroot/ipscan/trunk@386 375186e5-ef17-0410-b0b6-91563547dcda
---
 TODO                                          |  1 +
 .../azib/ipscan/core/state/StateMachine.java  | 29 +++++++++++++++----
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/TODO b/TODO
index fb88122f..93b4fbc2 100644
--- a/TODO
+++ b/TODO
@@ -1,5 +1,6 @@
 Before 3.0:
 
+* windows 48 icon for Vista
 * command-line scanning start
 * fetcher-specific options
 * multiple port support web-detect
diff --git a/src/net/azib/ipscan/core/state/StateMachine.java b/src/net/azib/ipscan/core/state/StateMachine.java
index 0e083d3f..293a5a67 100644
--- a/src/net/azib/ipscan/core/state/StateMachine.java
+++ b/src/net/azib/ipscan/core/state/StateMachine.java
@@ -6,8 +6,8 @@
 package net.azib.ipscan.core.state;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 /**
  * StateMachine implementation.
@@ -17,9 +17,10 @@ import java.util.List;
  */
 public class StateMachine {
 	
-	private ScanningState state = ScanningState.IDLE;
+	private volatile ScanningState state = ScanningState.IDLE;
 	
-	private List<StateTransitionListener> transitionListeners = Collections.synchronizedList(new ArrayList<StateTransitionListener>());
+	private ReentrantReadWriteLock listenersLock = new ReentrantReadWriteLock();
+	private List<StateTransitionListener> transitionListeners = new ArrayList<StateTransitionListener>();
 	
 	/**
 	 * @param state
@@ -41,7 +42,13 @@ public class StateMachine {
 	 * @param listener instance
 	 */
 	public void addTransitionListener(StateTransitionListener listener) {
-		transitionListeners.add(listener);
+		try {
+			listenersLock.writeLock().lock();
+			transitionListeners.add(listener);
+		}
+		finally {
+			listenersLock.writeLock().unlock();
+		}
 	}
 	
 	/**
@@ -49,7 +56,13 @@ public class StateMachine {
 	 * @param killHandler
 	 */
 	public void removeTransitionListener(StateTransitionListener listener) {
-		transitionListeners.remove(listener);
+		try {
+			listenersLock.writeLock().lock();
+			transitionListeners.remove(listener);
+		}
+		finally {
+			listenersLock.writeLock().unlock();
+		}
 	}
 
 	/**
@@ -65,11 +78,15 @@ public class StateMachine {
 	}
 
 	private void notifyAboutTransition() {
-		synchronized (transitionListeners) {
+		try {
+			listenersLock.readLock().lock();
 			for (StateTransitionListener listener : transitionListeners) {
 				listener.transitionTo(state);
 			}			
 		}
+		finally {
+			listenersLock.readLock().unlock();
+		}
 	}
 
 	/**