Merged HEAD-BUG-FIX (5.0/Cloud) to HEAD (5.0/Cloud)

84891: Merged PLATFORM1 (5.0/Cloud) to HEAD-BUG-FIX (5.0/Cloud)
      83367: ACE-2664 - AggregatingContentStore


git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@85211 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/content/replication/AggregatingContentStore.java

@@ -0,0 +1,215 @@
+/*
+ * Copyright (C) 2013-2013 Alfresco Software Limited.
+ *
+ * This file is part of Alfresco
+ *
+ * Alfresco is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Alfresco is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.alfresco.repo.content.replication;
+
+import java.util.Date;
+import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+import org.alfresco.error.AlfrescoRuntimeException;
+import org.alfresco.repo.content.AbstractContentStore;
+import org.alfresco.repo.content.ContentContext;
+import org.alfresco.repo.content.ContentStore;
+import org.alfresco.repo.content.caching.CachingContentStore;
+import org.alfresco.service.cmr.repository.ContentIOException;
+import org.alfresco.service.cmr.repository.ContentReader;
+import org.alfresco.service.cmr.repository.ContentWriter;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+/**
+ * </h1><u>Aggregating Content Store</u></h1>
+ * <p>
+ * A content store implementation that aggregates a set of stores.  Content is not 
+ * persisted by this store, but rather it relies on any number of
+ * child {@link org.alfresco.repo.content.ContentStore stores} to provide access 
+ * to content readers and writers.
+ * <p>
+ * The order in which the stores appear in the list of stores participating is
+ * important.  The first store in the list is known as the <i>primary store</i>.
+   <p>
+ * Content is written to the primary store only.  The other stores are
+ * only used to retrieve content and the primary store is not updated with
+ * the content.
+ * 
+ * @author Derek Hulley
+ * @author Mark Rogers
+ * @see CachingContentStore
+ */
+public class AggregatingContentStore extends AbstractContentStore
+{    
+    private static Log logger = LogFactory.getLog(AggregatingContentStore.class);
+    
+    private ContentStore primaryStore;
+    private List<ContentStore> secondaryStores;
+    
+    private Lock readLock;
+    private Lock writeLock;
+
+    /**
+     * Default constructor 
+     */
+    public AggregatingContentStore()
+    {       
+        ReadWriteLock storeLock = new ReentrantReadWriteLock();
+        readLock = storeLock.readLock();
+        writeLock = storeLock.writeLock();
+    }
+        
+    /**
+     * Set the primary store that content will be replicated to or from
+     * 
+     * @param primaryStore the primary content store
+     */
+    public void setPrimaryStore(ContentStore primaryStore)
+    {
+        this.primaryStore = primaryStore;
+    }
+
+    /**
+     * Set the secondary stores that this component will replicate to or from
+     * 
+     * @param stores a list of stores to replicate to or from
+     */
+    public void setSecondaryStores(List<ContentStore> secondaryStores)
+    {
+        this.secondaryStores = secondaryStores;
+    }
+    
+    /**
+     * @return      Returns <tt>true</tt> if the primary store supports writing
+     */
+    public boolean isWriteSupported()
+    {
+        return primaryStore.isWriteSupported();
+    }
+
+    /**
+     * @return      Returns <tt>true</tt> if the primary store supports the URL
+     */
+    @Override
+    public boolean isContentUrlSupported(String contentUrl)
+    {
+        return primaryStore.isContentUrlSupported(contentUrl);
+    }
+    
+    /**
+     * @return      Return the primary store root location
+     */
+    @Override
+    public String getRootLocation()
+    {
+        return primaryStore.getRootLocation();
+    }
+
+    /**
+     * Forwards the call directly to the first store in the list of stores.
+     */
+    public ContentReader getReader(String contentUrl) throws ContentIOException
+    {
+        if (primaryStore == null)
+        {
+            throw new AlfrescoRuntimeException("ReplicatingContentStore not initialised");
+        }
+        
+        // get a read lock so that we are sure that no replication is underway
+        readLock.lock();
+        try
+        {
+            // get a reader from the primary store
+            ContentReader primaryReader = primaryStore.getReader(contentUrl);
+            
+            // give it straight back if the content is there
+            if (primaryReader.exists())
+            {
+                return primaryReader;
+            }
+
+            // the content is not in the primary reader so we have to go looking for it
+            ContentReader secondaryContentReader = null;
+            for (ContentStore store : secondaryStores)
+            {
+                ContentReader reader = store.getReader(contentUrl);
+                if (reader.exists())
+                {
+                    // found the content in a secondary store
+                    return reader;
+                }
+            }
+
+            return primaryReader;
+        }
+        finally
+        {
+            readLock.unlock();
+        }     
+    }
+
+    public ContentWriter getWriter(ContentContext ctx)
+    {
+        // get the writer
+        ContentWriter writer = primaryStore.getWriter(ctx);
+                
+        return writer;
+    }
+
+    /**
+     * Performs a delete on the local store and if outbound replication is on, propogates
+     * the delete to the other stores too.
+     * 
+     * @return Returns the value returned by the delete on the primary store.
+     */
+    public boolean delete(String contentUrl) throws ContentIOException
+    {
+        // delete on the primary store
+        boolean deleted = primaryStore.delete(contentUrl);
+        
+        if (logger.isDebugEnabled())
+        {
+            logger.debug("Deleted content for URL: " + contentUrl);
+        }
+        return deleted;
+    }
+
+    /**
+     * Iterates over results as given by the primary store and all secondary stores.  It is up to the handler to eliminate
+     * duplicates that will occur between the primary and secondary stores.
+     */
+    @SuppressWarnings("deprecation")
+    public void getUrls(Date createdAfter, Date createdBefore, ContentUrlHandler handler) throws ContentIOException
+    {
+        // add in URLs from primary store
+        primaryStore.getUrls(createdAfter, createdBefore, handler);
+        
+        // add in URLs from secondary stores (they are visible for reads)
+        for (ContentStore secondaryStore : secondaryStores)
+        {
+            secondaryStore.getUrls(createdAfter, createdBefore, handler);
+        }
+        // done
+        if (logger.isDebugEnabled())
+        {
+            logger.debug("Iterated over content URLs: \n" +
+                    "   created after: " + createdAfter + "\n" +
+                    "   created before: " + createdBefore);
+        }
+    }
+}