[FELIX-4566] Consistency in PersistenceManager and Cache is not guaranteed
git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1622684 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/configadmin/src/main/java/org/apache/felix/cm/impl/CachingPersistenceManagerProxy.java b/configadmin/src/main/java/org/apache/felix/cm/impl/CachingPersistenceManagerProxy.java
index 460b813..7f3225f 100644
--- a/configadmin/src/main/java/org/apache/felix/cm/impl/CachingPersistenceManagerProxy.java
+++ b/configadmin/src/main/java/org/apache/felix/cm/impl/CachingPersistenceManagerProxy.java
@@ -20,10 +20,16 @@
import java.io.IOException;
+import java.util.ArrayList;
import java.util.Dictionary;
import java.util.Enumeration;
import java.util.Hashtable;
+import java.util.Iterator;
import java.util.Map;
+import java.util.Vector;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.apache.felix.cm.PersistenceManager;
import org.osgi.framework.Constants;
@@ -37,13 +43,15 @@
*/
class CachingPersistenceManagerProxy implements PersistenceManager
{
-
/** the actual PersistenceManager */
private final PersistenceManager pm;
/** cached dictionaries */
private final Hashtable cache;
+ /** protecting lock */
+ private final ReadWriteLock globalLock = new ReentrantReadWriteLock();
+
/**
* Indicates whether the getDictionaries method has already been called
* and the cache is complete with respect to the contents of the underlying
@@ -70,8 +78,14 @@
*/
public void delete( String pid ) throws IOException
{
- cache.remove( pid );
- pm.delete( pid );
+ Lock lock = globalLock.writeLock();
+ try {
+ lock.lock();
+ cache.remove( pid );
+ pm.delete(pid);
+ } finally {
+ lock.unlock();
+ }
}
@@ -82,7 +96,13 @@
*/
public boolean exists( String pid )
{
- return cache.containsKey( pid ) || pm.exists( pid );
+ Lock lock = globalLock.readLock();
+ try {
+ lock.lock();
+ return cache.containsKey( pid ) || ( !fullyLoaded && pm.exists( pid ) );
+ } finally {
+ lock.unlock();
+ }
}
@@ -98,39 +118,42 @@
*/
public Enumeration getDictionaries() throws IOException
{
- // if not fully loaded, call back to the underlying persistence
- // manager and cach all dictionaries whose service.pid is set
- if ( !fullyLoaded )
- {
- Enumeration fromPm = pm.getDictionaries();
- while ( fromPm.hasMoreElements() )
+ Lock lock = globalLock.readLock();
+ try {
+ lock.lock();
+ // if not fully loaded, call back to the underlying persistence
+ // manager and cach all dictionaries whose service.pid is set
+ if ( !fullyLoaded )
{
- Dictionary next = ( Dictionary ) fromPm.nextElement();
- String pid = ( String ) next.get( Constants.SERVICE_PID );
- if ( pid != null )
+ lock.unlock();
+ lock = globalLock.writeLock();
+ lock.lock();
+ if ( !fullyLoaded )
{
- cache.put( pid, next );
+ Enumeration fromPm = pm.getDictionaries();
+ while (fromPm.hasMoreElements())
+ {
+ Dictionary next = (Dictionary) fromPm.nextElement();
+ String pid = (String) next.get(Constants.SERVICE_PID);
+ if (pid != null)
+ {
+ cache.put(pid, next);
+ }
+ }
+ fullyLoaded = true;
}
}
- fullyLoaded = true;
+
+ // Deep copy the configuration to avoid any threading issue
+ Vector configs = new Vector();
+ for (Object o : cache.values())
+ {
+ configs.add( copy( ( Dictionary ) o ) );
+ }
+ return configs.elements();
+ } finally {
+ lock.unlock();
}
-
- return new Enumeration()
- {
- final Enumeration base = cache.elements();
-
-
- public boolean hasMoreElements()
- {
- return base.hasMoreElements();
- }
-
-
- public Object nextElement()
- {
- return copy( ( Dictionary ) base.nextElement() );
- }
- };
}
@@ -146,16 +169,26 @@
*/
public Dictionary load( String pid ) throws IOException
{
- Dictionary loaded = ( Dictionary ) cache.get( pid );
- if ( loaded == null )
- {
- loaded = pm.load( pid );
- if ( loaded != null )
+ Lock lock = globalLock.readLock();
+ try {
+ lock.lock();
+ Dictionary loaded = ( Dictionary ) cache.get( pid );
+ if ( loaded == null && !fullyLoaded )
{
- cache.put( pid, loaded );
+ lock.unlock();
+ lock = globalLock.writeLock();
+ lock.lock();
+ loaded = ( Dictionary ) cache.get( pid );
+ if ( loaded == null )
+ {
+ loaded = pm.load(pid);
+ cache.put(pid, loaded);
+ }
}
+ return copy( loaded );
+ } finally {
+ lock.unlock();
}
- return copy( loaded );
}
@@ -170,8 +203,14 @@
*/
public void store( String pid, Dictionary properties ) throws IOException
{
- pm.store( pid, properties );
- cache.put( pid, copy( properties ) );
+ Lock lock = globalLock.writeLock();
+ try {
+ lock.lock();
+ pm.store( pid, properties );
+ cache.put( pid, copy( properties ) );
+ } finally {
+ lock.unlock();
+ }
}