Squashed commit of the following:v20130128-050843

304132 - [shared] upgrading shared base causes loss of user installer
plug-ins

commit 8461eae803454c36f6a18013c44e37c20810d141
Merge: 23bc40c c847dee
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Sun Jan 27 22:11:45 2013 -0500

    Merge branch 'master' into prapicau/sharedInstall-part1

commit 23bc40c4f85b01f37fb0ac23992524a7c8ccd892
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Sun Jan 27 21:38:07 2013 -0500

    Use constant and fix copyright header

commit bc11d565b32b5b5c8bb5c93e5ea666b1d06b43ff
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Sun Jan 27 21:33:32 2013 -0500

    Annotate new profile with a base profile timestamp

commit ba4e7abda6e44ad47aead2fade320f9be08b27d5
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Sun Jan 27 21:32:20 2013 -0500

    Add constants

commit 54c8d356527d1321e25bd837e674b758aa61e248
Author: Krzysztof Daniel <kdaniel@redhat.com>
Date:   Thu Jan 24 13:23:15 2013 +0100

    SimpleConfiguratorImpl refactoring and tests.

commit 6177c466083fb7676ebfe5790bc0951043b3b727
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Thu Jan 24 11:59:45 2013 -0500

    detection of change in the reconciler

commit f04f46d6d283a6235367872b5eaa7e3e483509ed
Merge: 5243d49 c32f111
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Thu Jan 24 11:43:01 2013 -0500

    Merge branch 'master' into prapicau/sharedInstall-part1

commit 5243d497142b0f2631bcda8b5fed67d7ce0ddbd5
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Wed Jan 23 15:26:41 2013 -0500

    always use shared install when the ignoreUserConfig property is set

commit 12eccdad23420e7ba91f99221c852f7e32eb11de
Merge: c68f394 1e9fc23
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Wed Jan 23 10:29:56 2013 -0500

    Merge branch 'master' into prapicau/sharedInstall-part1

commit c68f394a39c4215ed7ac960495a3c59eb3cf3eee
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Tue Jan 22 22:24:04 2013 -0500

    Bug 398853 - [UI] installed IU shows as update

commit aa6d632dea7ff54e9ba7c3c7f9f2ecd30afe5906
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Tue Jan 22 13:50:05 2013 -0500

    Differentiate initial profile creation from reset.

commit 4fb3429ed3fd673d5daf7ca1ce9bf1184a0afcb3
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Tue Jan 22 13:49:23 2013 -0500

    Only show migration dialog once

commit a34eac29e330a41991d003e2dcd2d8b264d77145
Author: Krzysztof Daniel <kdaniel@redhat.com>
Date:   Mon Jan 21 12:40:36 2013 +0100

    397216: [Shared] Better shared configuration change discovery

    Perform dropins reindexing after master configuration had been changed.

    https://bugs.eclipse.org/bugs/show_bug.cgi?id=397216

commit 6981ca8bd3c1db9ab2dd9484a1f7c8950fcd1abe
Merge: dfec14b 33ca260
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Mon Jan 21 15:04:28 2013 -0500

    Merge branch 'master' into prapicau/sharedInstall-part1

commit dfec14b67a69b6fa14efb860ef8a986053a58917
Merge: 6067d05 ba5f048
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Mon Jan 21 11:34:38 2013 -0500

    Merge branch 'master' into prapicau/sharedInstall-part1

commit ba5f048a3ac5563430104adeb173dc4f7dda6eca
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Mon Jan 21 11:28:20 2013 -0500

    Bug 398539 - Got a NPE trying to add a new update site

commit 6067d05e402fe796debd9d25604cae7026df5b48
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Fri Jan 18 16:16:18 2013 -0500

    only write timestamp file for shared install

commit 8ab9410d8c797e6a8d2a97e4ba46da3d548440fa
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Fri Jan 18 13:56:46 2013 -0500

    Cache the fact that the state.properties is missing

commit fefbc5bdec2ce6cdb7fd71b1790bf8abdee8737a
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Fri Jan 18 13:51:54 2013 -0500

    Fix bug in change detection logic

commit 3de6f8593d5c1b21be3bd21000e34acb945056b1
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Wed Jan 16 19:50:32 2013 -0500

    Detect changes in the bundles.info

commit 446649c95063dca689f4d2c886b26975a11f3499
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Tue Jan 15 14:04:57 2013 -0500

    Simple notification to let the user know that the base has changed.

commit e004dc5270abd33a60da9a8d0340409bc8e4a38d
Author: Pascal Rapicault <pascal@rapicault.net>
Date:   Fri Jan 11 14:15:20 2013 +0100

    ignore user config.ini if out of sync with base

commit a0235c0c95b9047e64d6e24c9d8f6b8588087113
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Wed Dec 12 09:57:36 2012 -0500

    Obtain specific profile state properties without locking

commit 1d0f129ca70716e7a181631e1ba0e71f16e35e08
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Mon Dec 10 16:06:38 2012 -0500

    Remember the timestamp of the base config.ini

commit 3134caecfd244fd88386f3ce4bd1a6fc71fe8007
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Wed Dec 5 16:21:50 2012 -0500

    Support to ignore the existing profile if the base has changed

commit 7f0ba4e643f40bc0143617b93b2238388d38216d
Author: Pascal Rapicault (Ericsson) <pascal.rapicault@ericsson.com>
Date:   Tue Dec 4 11:23:37 2012 -0500

    Remove externalization warning

1 files changed, 78 insertions, 25 deletions

diff --git a/bundles/org.eclipse.equinox.simpleconfigurator/src/org/eclipse/equinox/internal/simpleconfigurator/SimpleConfiguratorImpl.java b/bundles/org.eclipse.equinox.simpleconfigurator/src/org/eclipse/equinox/internal/simpleconfigurator/SimpleConfiguratorImpl.java
index dbd2aec45..70d3b4c93 100644
--- a/bundles/org.eclipse.equinox.simpleconfigurator/src/org/eclipse/equinox/internal/simpleconfigurator/SimpleConfiguratorImpl.java
+++ b/bundles/org.eclipse.equinox.simpleconfigurator/src/org/eclipse/equinox/internal/simpleconfigurator/SimpleConfiguratorImpl.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- *  Copyright (c) 2007, 2010 IBM Corporation and others.
+ *  Copyright (c) 2007, 2013 IBM Corporation and others.
  *  All rights reserved. This program and the accompanying materials
  *  are made available under the terms of the Eclipse Public License v1.0
  *  which accompanies this distribution, and is available at
@@ -7,13 +7,14 @@
  * 
  *  Contributors:
  *      IBM Corporation - initial API and implementation
+ *      Ericsson AB (Pascal Rapicault) - Bug 397216 -[Shared] Better shared configuration change discovery 
  *******************************************************************************/
 package org.eclipse.equinox.internal.simpleconfigurator;
 
-import java.io.File;
-import java.io.IOException;
-import java.net.*;
-import java.util.List;
+import java.io.*;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.util.Properties;
 import org.eclipse.equinox.internal.provisional.configurator.Configurator;
 import org.eclipse.equinox.internal.simpleconfigurator.utils.*;
 import org.osgi.framework.Bundle;
@@ -42,6 +43,12 @@ public class SimpleConfiguratorImpl implements Configurator {
 	private ConfigApplier configApplier;
 	private Bundle bundle;
 
+	//for change detection in the base when running in shared install mode
+	private static final long NO_TIMESTAMP = -1;
+	public static final String BASE_TIMESTAMP_FILE_BUNDLESINFO = ".baseBundlesInfoTimestamp"; //$NON-NLS-1$
+	public static final String KEY_BUNDLESINFO_TIMESTAMP = "bundlesInfoTimestamp";
+	public static final String PROP_IGNORE_USER_CONFIGURATION = "eclipse.ignoreUserConfiguration"; //$NON-NLS-1$
+
 	public SimpleConfiguratorImpl(BundleContext context, Bundle bundle) {
 		this.context = context;
 		this.bundle = bundle;
@@ -80,27 +87,10 @@ public class SimpleConfiguratorImpl implements Configurator {
 			//if it is an relative file URL, then resolve it against the configuration area
 			// TODO Support relative file URLs when not on Equinox
 			URL[] configURL = EquinoxUtils.getConfigAreaURL(context);
-			if (configURL != null) {
-				File userConfig = new File(configURL[0].getFile(), url.getFile());
-				if (configURL.length == 1)
-					return userConfig.exists() ? userConfig.toURL() : null;
-
-				File sharedConfig = new File(configURL[1].getFile(), url.getFile());
-				if (!userConfig.exists())
-					return sharedConfig.exists() ? sharedConfig.toURL() : null;
-
-				if (!sharedConfig.exists())
-					return userConfig.toURL();
-
-				URI base = EquinoxUtils.getInstallLocationURI(context);
-
-				URL sharedConfigURL = sharedConfig.toURL();
-				List sharedBundles = SimpleConfiguratorUtils.readConfiguration(sharedConfigURL, base);
 
-				URL userConfigURL = userConfig.toURL();
-				List userBundles = SimpleConfiguratorUtils.readConfiguration(userConfigURL, base);
-
-				return (userBundles.containsAll(sharedBundles)) ? userConfigURL : sharedConfigURL;
+			URL result = chooseConfigurationURL(url, configURL);
+			if (result != null) {
+				return result;
 			}
 		} catch (MalformedURLException e) {
 			return null;
@@ -116,6 +106,69 @@ public class SimpleConfiguratorImpl implements Configurator {
 		return null;
 	}
 
+	/**
+	 * This method is public for testing purposes only.
+	 * @param relativeURL - a relative URL of the configuration
+	 * @param configURL - an array of parent config URLs to which relativeURL can be appended. 
+	 */
+	public URL chooseConfigurationURL(URL relativeURL, URL[] configURL) throws MalformedURLException {
+		if (configURL != null) {
+			File userConfig = new File(configURL[0].getFile(), relativeURL.getFile());
+			if (configURL.length == 1)
+				return userConfig.exists() ? userConfig.toURL() : null;
+
+			File sharedConfig = new File(configURL[1].getFile(), relativeURL.getFile());
+			if (!userConfig.exists())
+				return sharedConfig.exists() ? sharedConfig.toURL() : null;
+
+			if (!sharedConfig.exists())
+				return userConfig.toURL();
+
+			if (Boolean.TRUE.toString().equals(System.getProperty(PROP_IGNORE_USER_CONFIGURATION)))
+				return sharedConfig.toURL();
+
+			long sharedBundlesInfoTimestamp = getCurrentBundlesInfoBaseTimestamp(sharedConfig);
+			long lastKnownBaseTimestamp = getLastKnownBundlesInfoBaseTimestamp(userConfig.getParentFile());
+
+			if (lastKnownBaseTimestamp == sharedBundlesInfoTimestamp || lastKnownBaseTimestamp == NO_TIMESTAMP) {
+				return userConfig.toURL();
+			} else {
+				System.setProperty(PROP_IGNORE_USER_CONFIGURATION, Boolean.TRUE.toString());
+				return sharedConfig.toURL();
+			}
+		}
+		return null;
+	}
+
+	private long getLastKnownBundlesInfoBaseTimestamp(File configFolder) {
+		File storedSharedTimestamp = new File(configFolder, BASE_TIMESTAMP_FILE_BUNDLESINFO);
+		if (!storedSharedTimestamp.exists())
+			return NO_TIMESTAMP;
+
+		Properties p = new Properties();
+		InputStream is = null;
+		try {
+			try {
+				is = new BufferedInputStream(new FileInputStream(storedSharedTimestamp));
+				p.load(is);
+				if (p.get(KEY_BUNDLESINFO_TIMESTAMP) != null) {
+					return Long.valueOf((String) p.get(KEY_BUNDLESINFO_TIMESTAMP)).longValue();
+				}
+			} finally {
+				is.close();
+			}
+		} catch (IOException e) {
+			return NO_TIMESTAMP;
+		}
+		return NO_TIMESTAMP;
+	}
+
+	private long getCurrentBundlesInfoBaseTimestamp(File sharedBundlesInfo) {
+		if (!sharedBundlesInfo.exists())
+			return NO_TIMESTAMP;
+		return sharedBundlesInfo.lastModified();
+	}
+
 	public void applyConfiguration(URL url) throws IOException {
 		synchronized (configurationLock) {
 			if (Activator.DEBUG)