Merge V1.4 to HEAD

- Ignored Enterprise-specific changes svn merge svn://svn.alfresco.com:3691/alfresco/BRANCHES/V1.4@3701 svn://svn.alfresco.com:3691/alfresco/BRANCHES/V1.4@3703 . svn merge svn://svn.alfresco.com:3691/alfresco/BRANCHES/V1.4@3704 svn://svn.alfresco.com:3691/alfresco/BRANCHES/V1.4@3705 . svn merge svn://svn.alfresco.com:3691/alfresco/BRANCHES/V1.4@3707 svn://svn.alfresco.com:3691/alfresco/BRANCHES/V1.4@3876 . svn revert root\projects\web-client\source\web\jsp\admin\admin-console.jsp git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@3879 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261
2025-07-24 17:32:48 +00:00 · 2006-09-21 23:35:51 +00:00
parent 89f39cd176
commit d2bce74f0b
103 changed files with 3569 additions and 1172 deletions
--- a/source/java/org/alfresco/repo/transaction/TransactionAwareSingleton.java
+++ b/source/java/org/alfresco/repo/transaction/TransactionAwareSingleton.java
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2006 Alfresco, Inc.
+ *
+ * Licensed under the Mozilla Public License version 1.1 
+ * with a permitted attribution clause. You may obtain a
+ * copy of the License at
+ *
+ *   http://www.alfresco.org/legal/license.txt
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+ * either express or implied. See the License for the specific
+ * language governing permissions and limitations under the
+ * License.
+ */
+package org.alfresco.repo.transaction;
+
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock.ReadLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock;
+
+/**
+ * A transactionally-safe storage class for singleton objects.  Changes to the singleton
+ * are only visibly promoted when the transaction is committed.
+ * <p>
+ * <code>
+ *    private static final TransactionAwareSingleton<Integer> MY_SINGLETON = new TransactionAwareSingleton<Integer>();
+ * </code>
+ * <p>
+ * All modifications to the singleton via {@link #get()} and {@link #put(T)} are made in a 
+ * transaction-local manner and promoted to the shared value in a thread-safe manner upon
+ * transacton completion.  Transaction-local changes take precedence over the shared value.
+ * 
+ * @see org.alfresco.repo.transaction.AlfrescoTransactionSupport
+ * 
+ * @author Derek Hulley
+ */
+public class TransactionAwareSingleton<T> extends TransactionListenerAdapter
+{
+    private static final String TRANSACTION_KEY = "TransactionAwareSingleton.storage";
+    
+    private final ReadLock singletonReadLock;
+    private final WriteLock singletonWriteLock;
+    private Object singletonValue;
+    
+    public TransactionAwareSingleton()
+    {
+        ReentrantReadWriteLock serverReadWriteLock = new ReentrantReadWriteLock();
+        singletonReadLock = serverReadWriteLock.readLock();
+        singletonWriteLock = serverReadWriteLock.writeLock();
+    }
+    
+    private void setValue(Object value)
+    {
+        // get a write lock
+        singletonWriteLock.lock();
+        try
+        {
+            singletonValue = value;
+        }
+        finally
+        {
+            singletonWriteLock.unlock();
+        }
+    }
+    
+    private Object getValue()
+    {
+        // get a read lock
+        singletonReadLock.lock();
+        try
+        {
+            return singletonValue;
+        }
+        finally
+        {
+            singletonReadLock.unlock();
+        }
+    }
+
+    /**
+     * @return Returns the transaction- and thread-safe wrapped instance
+     */
+    @SuppressWarnings("unchecked")
+    public T get()
+    {
+        // an in-transaction value overrides the singleton
+        TransactionStorage storage = (TransactionStorage) AlfrescoTransactionSupport.getResource(TRANSACTION_KEY);
+        if (storage != null)
+        {
+            return (T) storage.newValue;
+        }
+        else
+        {
+            return (T) getValue();
+        }
+    }
+    
+    /**
+     * Store the value in a transaction- and thread-safe manner.  It will only be persisted
+     * at the end of the transaction but will be visible to the current transaction from
+     * this call onwards.
+     * 
+     * @param value the value to store
+     */
+    public void put(T value)
+    {
+        // the value is changing
+        TransactionStorage storage = (TransactionStorage) AlfrescoTransactionSupport.getResource(TRANSACTION_KEY);
+        if (storage == null)
+        {
+            // it has not changed before
+            storage = new TransactionStorage();
+            AlfrescoTransactionSupport.bindResource(TRANSACTION_KEY, storage);
+            // listen to the transaction
+            AlfrescoTransactionSupport.bindListener(this);
+        }
+        storage.newValue = value;
+    }
+    
+    /**
+     * Promotes the storage value to the single value, if required
+     */
+    public void afterCommit()
+    {
+        TransactionStorage storage = (TransactionStorage) AlfrescoTransactionSupport.getResource(TRANSACTION_KEY);
+        if (storage != null)
+        {
+            // the value was overridden
+            setValue(storage.newValue);
+        }
+    }
+    
+    /**
+     * In-transaction storage of the altered value
+     * @author Derek Hulley
+     */
+    private static class TransactionStorage
+    {
+        public Object newValue;
+    }
+}