AR-383: Optimized overwrite behaviour for ContentWriter. Content will only be duplicated for the writes if explicitly requesting a random-access file without the truncate option

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@2254 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/filesys/smb/server/repo/ContentDiskDriver.java

@@ -930,7 +930,7 @@ public class ContentDiskDriver implements DiskInterface, IOCtlInterface
             
             // Create the network file
             
-            NetworkFile netFile = ContentNetworkFile.createFile(nodeService, contentService, cifsHelper, nodeRef, params);
+            NetworkFile netFile = ContentNetworkFile.createFile(transactionService, nodeService, contentService, cifsHelper, nodeRef, params);
             
             // Create a file state for the open file
             
@@ -1039,7 +1039,7 @@ public class ContentDiskDriver implements DiskInterface, IOCtlInterface
             NodeRef nodeRef = cifsHelper.createNode(deviceRootNodeRef, path, true);
             
             // create the network file
-            NetworkFile netFile = ContentNetworkFile.createFile(nodeService, contentService, cifsHelper, nodeRef, params);
+            NetworkFile netFile = ContentNetworkFile.createFile(transactionService, nodeService, contentService, cifsHelper, nodeRef, params);
             
             // Add a file state for the new file/folder
             

source/java/org/alfresco/filesys/smb/server/repo/ContentNetworkFile.java

@@ -29,14 +29,17 @@ import org.alfresco.filesys.server.filesys.FileOpenParams;
 import org.alfresco.filesys.server.filesys.NetworkFile;
 import org.alfresco.i18n.I18NUtil;
 import org.alfresco.model.ContentModel;
-import org.alfresco.repo.content.RandomAccessContent;
 import org.alfresco.repo.content.filestore.FileContentReader;
+import org.alfresco.repo.transaction.TransactionUtil;
+import org.alfresco.repo.transaction.TransactionUtil.TransactionWork;
 import org.alfresco.service.cmr.repository.ContentAccessor;
 import org.alfresco.service.cmr.repository.ContentData;
 import org.alfresco.service.cmr.repository.ContentReader;
 import org.alfresco.service.cmr.repository.ContentService;
+import org.alfresco.service.cmr.repository.ContentWriter;
 import org.alfresco.service.cmr.repository.NodeRef;
 import org.alfresco.service.cmr.repository.NodeService;
+import org.alfresco.service.transaction.TransactionService;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
@@ -52,6 +55,7 @@ public class ContentNetworkFile extends NetworkFile
 {
     private static final Log logger = LogFactory.getLog(ContentNetworkFile.class);
     
+    private TransactionService transactionService;
     private NodeService nodeService;
     private ContentService contentService;
     private NodeRef nodeRef;
@@ -65,17 +69,12 @@ public class ContentNetworkFile extends NetworkFile
     // Flag to indicate if the file channel is writable
     
     private boolean writableChannel;
-    
+
     /**
      * Helper method to create a {@link NetworkFile network file} given a node reference.
-     * 
-     * @param serviceRegistry
-     * @param filePathCache used to speed up repeated searches
-     * @param nodeRef the node representing the file or directory
-     * @param params the parameters dictating the path and other attributes with which the file is being accessed
-     * @return Returns a new instance of the network file
      */
     public static ContentNetworkFile createFile(
+            TransactionService transactionService,
             NodeService nodeService,
             ContentService contentService,
             CifsHelper cifsHelper,
@@ -88,7 +87,7 @@ public class ContentNetworkFile extends NetworkFile
         // TODO: Check access writes and compare to write requirements
         
         // create the file
-        ContentNetworkFile netFile = new ContentNetworkFile(nodeService, contentService, nodeRef, path);
+        ContentNetworkFile netFile = new ContentNetworkFile(transactionService, nodeService, contentService, nodeRef, path);
         // set relevant parameters
         if (params.isReadOnlyAccess())
         {
@@ -151,10 +150,16 @@ public class ContentNetworkFile extends NetworkFile
         return netFile;
     }
 
-    private ContentNetworkFile(NodeService nodeService, ContentService contentService, NodeRef nodeRef, String name)
+    private ContentNetworkFile(
+            TransactionService transactionService,
+            NodeService nodeService,
+            ContentService contentService,
+            NodeRef nodeRef,
+            String name)
     {
         super(name);
         setFullName(name);
+        this.transactionService = transactionService;
         this.nodeService = nodeService;
         this.contentService = contentService;
         this.nodeRef = nodeRef;
@@ -259,6 +264,10 @@ public class ContentNetworkFile extends NetworkFile
             // Indicate that we have a writable channel to the file
             
             writableChannel = true;
+            
+            // get the writable channel
+            // TODO: Decide on truncation strategy
+            channel = ((ContentWriter) content).getFileChannel(false);
         }
         else
         {
@@ -272,17 +281,10 @@ public class ContentNetworkFile extends NetworkFile
             // Indicate that we only have a read-only channel to the data
             
             writableChannel = false;
+            
+            // get the read-only channel
+            channel = ((ContentReader) content).getFileChannel();
         }
-        // wrap the channel accessor, if required
-        if (!(content instanceof RandomAccessContent))
-        {
-            // TODO: create a temp, random access file and put a FileContentWriter on it
-            //       barf for now
-            throw new AlfrescoRuntimeException("Can only use a store that supplies randomly accessible channel");
-        }
-        RandomAccessContent randAccessContent = (RandomAccessContent) content;
-        // get the channel - we can only make this call once
-        channel = randAccessContent.getChannel();
     }
 
     @Override
@@ -296,20 +298,38 @@ public class ContentNetworkFile extends NetworkFile
         {
             return;
         }
-        else if (modified)              // file was modified
+        
+        
+        if (modified)              // file was modified
         {
-            // close it
+            // execute the close (with possible replication listeners, etc) and the
-            channel.close();
+            // node update in the same transaction.  A transaction will be started
-            channel = null;
+            // by the nodeService anyway, so it is merely widening the transaction
-            // write properties
+            // boundaries.
-            ContentData contentData = content.getContentData();
+            TransactionWork<Object> closeWork = new TransactionWork<Object>()
-            nodeService.setProperty(nodeRef, ContentModel.PROP_CONTENT, contentData);
+            {
+                public Object doWork() throws Exception
+                {
+                    // close the channel
+                    // close it
+                    channel.close();
+                    channel = null;
+                    // update node properties
+                    ContentData contentData = content.getContentData();
+                    nodeService.setProperty(nodeRef, ContentModel.PROP_CONTENT, contentData);
+                    // done
+                    return null;
+                }
+            };
+            TransactionUtil.executeInUserTransaction(transactionService, closeWork);
         }
         else
         {
             // close it - it was not modified
             channel.close();
             channel = null;
+            // no transaction used here.  Any listener operations against this (now unused) content
+            // are irrelevant.
         }
     }
 

source/java/org/alfresco/repo/content/AbstractContentAccessor.java

@@ -26,10 +26,10 @@ import java.nio.channels.ReadableByteChannel;
 import java.nio.channels.WritableByteChannel;
 import java.util.List;
 
-import org.alfresco.error.AlfrescoRuntimeException;
 import org.alfresco.repo.transaction.TransactionUtil;
 import org.alfresco.service.cmr.repository.ContentAccessor;
 import org.alfresco.service.cmr.repository.ContentData;
+import org.alfresco.service.cmr.repository.ContentIOException;
 import org.alfresco.service.cmr.repository.ContentStreamListener;
 import org.alfresco.service.transaction.TransactionService;
 import org.apache.commons.logging.Log;
@@ -139,17 +139,36 @@ public abstract class AbstractContentAccessor implements ContentAccessor
         this.encoding = encoding;
     }
     
+    /**
+     * Generate a callback instance of the {@link FileChannel FileChannel}.
+     *  
+     * @param directChannel the delegate that to perform the actual operations
+     * @param listeners the listeners to call
+     * @return Returns a new channel that functions just like the original, except
+     *      that it issues callbacks to the listeners
+     * @throws ContentIOException
+     */
+    protected FileChannel getCallbackFileChannel(
+            FileChannel directChannel,
+            List<ContentStreamListener> listeners)
+            throws ContentIOException
+    {
+        FileChannel ret = new CallbackFileChannel(directChannel, listeners);
+        // done
+        return ret;
+    }
+
     /**
      * Advise that listens for the completion of specific methods on the
      * {@link java.nio.channels.ByteChannel} interface.
      * 
      * @author Derek Hulley
      */
-    protected class ByteChannelCallbackAdvise implements AfterReturningAdvice
+    protected class ChannelCloseCallbackAdvise implements AfterReturningAdvice
     {
         private List<ContentStreamListener> listeners;
 
-        public ByteChannelCallbackAdvise(List<ContentStreamListener> listeners)
+        public ChannelCloseCallbackAdvise(List<ContentStreamListener> listeners)
         {
             this.listeners = listeners;
         }
@@ -173,11 +192,6 @@ public abstract class AbstractContentAccessor implements ContentAccessor
                 // nothing to do
                 return;
             }
-            // ensure that we are in a transaction
-            if (transactionService == null)
-            {
-                throw new AlfrescoRuntimeException("A transaction service is required when there are listeners present");
-            }
             TransactionUtil.TransactionWork<Object> work = new TransactionUtil.TransactionWork<Object>()
                     {
                         public Object doWork()
@@ -190,11 +204,26 @@ public abstract class AbstractContentAccessor implements ContentAccessor
                             return null;
                         }
                     };
-            TransactionUtil.executeInUserTransaction(transactionService, work);
+            if (transactionService != null)
+            {
+                // just create a transaction
+                TransactionUtil.executeInUserTransaction(transactionService, work);
+            }
+            else
+            {
+                try
+                {
+                    work.doWork();
+                }
+                catch (Exception e)
+                {
+                    throw new ContentIOException("Failed to executed channel close callbacks", e);
+                }
+            }
             // done
             if (logger.isDebugEnabled())
             {
-                logger.debug("Content listeners called: close");
+                logger.debug("" + listeners.size() + " content listeners called: close");
             }
         }
     }
@@ -202,6 +231,10 @@ public abstract class AbstractContentAccessor implements ContentAccessor
     /**
      * Wraps a <code>FileChannel</code> to provide callbacks to listeners when the
      * channel is {@link java.nio.channels.Channel#close() closed}.
+     * <p>
+     * This class is unfortunately necessary as the {@link FileChannel} doesn't have
+     * an single interface defining its methods, making it difficult to put an
+     * advice around the methods that require overriding.
      * 
      * @author Derek Hulley
      */
@@ -253,7 +286,6 @@ public abstract class AbstractContentAccessor implements ContentAccessor
                 // nothing to do
                 return;
             }
-            // create the work to update the listeners
             TransactionUtil.TransactionWork<Object> work = new TransactionUtil.TransactionWork<Object>()
                     {
                         public Object doWork()
@@ -266,14 +298,29 @@ public abstract class AbstractContentAccessor implements ContentAccessor
                             return null;
                         }
                     };
-            TransactionUtil.executeInUserTransaction(transactionService, work);
+            if (transactionService != null)
+            {
+                // just create a transaction
+                TransactionUtil.executeInUserTransaction(transactionService, work);
+            }
+            else
+            {
+                try
+                {
+                    work.doWork();
+                }
+                catch (Exception e)
+                {
+                    throw new ContentIOException("Failed to executed channel close callbacks", e);
+                }
+            }
             // done
             if (logger.isDebugEnabled())
             {
-                logger.debug("Content listeners called: close");
+                logger.debug("" + listeners.size() + " content listeners called: close");
             }
         }
-
+            
         @Override
         public void force(boolean metaData) throws IOException
         {

source/java/org/alfresco/repo/content/AbstractContentReadWriteTest.java

@@ -28,6 +28,8 @@ import java.nio.channels.FileChannel;
 import java.nio.channels.ReadableByteChannel;
 import java.util.Set;
 
+import javax.transaction.UserTransaction;
+
 import junit.framework.TestCase;
 
 import org.alfresco.repo.transaction.DummyTransactionService;
@@ -35,6 +37,9 @@ import org.alfresco.service.cmr.repository.ContentIOException;
 import org.alfresco.service.cmr.repository.ContentReader;
 import org.alfresco.service.cmr.repository.ContentStreamListener;
 import org.alfresco.service.cmr.repository.ContentWriter;
+import org.alfresco.service.transaction.TransactionService;
+import org.alfresco.util.ApplicationContextHelper;
+import org.springframework.context.ApplicationContext;
 
 /**
  * Abstract base class that provides a set of tests for implementations
@@ -47,7 +52,11 @@ import org.alfresco.service.cmr.repository.ContentWriter;
  */
 public abstract class AbstractContentReadWriteTest extends TestCase
 {
+    private static final ApplicationContext ctx = ApplicationContextHelper.getApplicationContext();
+    
+    protected TransactionService transactionService;
     private String contentUrl;
+    private UserTransaction txn;
     
     public AbstractContentReadWriteTest()
     {
@@ -58,6 +67,14 @@ public abstract class AbstractContentReadWriteTest extends TestCase
     public void setUp() throws Exception
     {
         contentUrl = AbstractContentStore.createNewUrl();
+        transactionService = (TransactionService) ctx.getBean("TransactionService");
+        txn = transactionService.getUserTransaction();
+        txn.begin();
+    }
+    
+    public void tearDown() throws Exception
+    {
+        txn.rollback();
     }
     
     /**
@@ -539,16 +556,8 @@ public abstract class AbstractContentReadWriteTest extends TestCase
     public void testRandomAccessWrite() throws Exception
     {
         ContentWriter writer = getWriter();
-        if (!(writer instanceof RandomAccessContent))
-        {
-            // not much to do here
-            return;
-        }
-        RandomAccessContent randomWriter = (RandomAccessContent) writer;
-        // check that we are allowed to write
-        assertTrue("Expected random access writing", randomWriter.canWrite());
         
-        FileChannel fileChannel = randomWriter.getChannel();
+        FileChannel fileChannel = writer.getFileChannel(true);
         assertNotNull("No channel given", fileChannel);
         
         // check that no other content access is allowed
@@ -584,6 +593,22 @@ public abstract class AbstractContentReadWriteTest extends TestCase
         {
             assertEquals("Content doesn't match", content[i], buffer.get(i));
         }
+        
+        // get a new writer from the store, using the existing content and perform a truncation check
+        ContentWriter writerTruncate = getStore().getWriter(writer.getReader(), AbstractContentStore.createNewUrl());
+        assertEquals("Content size incorrect", 0, writerTruncate.getSize());
+        // get the channel with truncation
+        FileChannel fcTruncate = writerTruncate.getFileChannel(true);
+        fcTruncate.close();
+        assertEquals("Content not truncated", 0, writerTruncate.getSize());
+        
+        // get a new writer from the store, using the existing content and perform a non-truncation check
+        ContentWriter writerNoTruncate = getStore().getWriter(writer.getReader(), AbstractContentStore.createNewUrl());
+        assertEquals("Content size incorrect", 0, writerNoTruncate.getSize());
+        // get the channel without truncation
+        FileChannel fcNoTruncate = writerNoTruncate.getFileChannel(false);
+        fcNoTruncate.close();
+        assertEquals("Content was truncated", writer.getSize(), writerNoTruncate.getSize());
     }
     
     /**
@@ -599,16 +624,8 @@ public abstract class AbstractContentReadWriteTest extends TestCase
         byte[] bytes = content.getBytes();
         writer.putContent(content);
         ContentReader reader = writer.getReader();
-        if (!(reader instanceof RandomAccessContent))
-        {
-            // not much to do here
-            return;
-        }
-        RandomAccessContent randomReader = (RandomAccessContent) reader;
-        // check that we are NOT allowed to write
-        assertFalse("Expected read-only random access", randomReader.canWrite());
         
-        FileChannel fileChannel = randomReader.getChannel();
+        FileChannel fileChannel = reader.getFileChannel();
         assertNotNull("No channel given", fileChannel);
         
         // check that no other content access is allowed
@@ -631,5 +648,6 @@ public abstract class AbstractContentReadWriteTest extends TestCase
         buffer.get(bytes);
         String checkContent = new String(bytes);
         assertEquals("Content read failure", content, checkContent);
+        fileChannel.close();
     }
 }

source/java/org/alfresco/repo/content/AbstractContentReader.java

@@ -26,15 +26,18 @@ import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.io.Reader;
 import java.nio.channels.Channels;
+import java.nio.channels.FileChannel;
 import java.nio.channels.ReadableByteChannel;
 import java.util.ArrayList;
 import java.util.List;
 
 import org.alfresco.error.AlfrescoRuntimeException;
+import org.alfresco.repo.content.filestore.FileContentWriter;
 import org.alfresco.service.cmr.repository.ContentAccessor;
 import org.alfresco.service.cmr.repository.ContentIOException;
 import org.alfresco.service.cmr.repository.ContentReader;
 import org.alfresco.service.cmr.repository.ContentStreamListener;
+import org.alfresco.util.TempFileProvider;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.springframework.aop.framework.ProxyFactory;
@@ -152,24 +155,38 @@ public abstract class AbstractContentReader extends AbstractContentAccessor impl
     protected abstract ReadableByteChannel getDirectReadableChannel() throws ContentIOException;
 
     /**
-     * Optionally override to supply an alternate callback channel.
+     * Create a channel that performs callbacks to the given listeners.
      *  
      * @param directChannel the result of {@link #getDirectReadableChannel()}
      * @param listeners the listeners to call
      * @return Returns a channel
      * @throws ContentIOException
      */
-    protected ReadableByteChannel getCallbackReadableChannel(
+    private ReadableByteChannel getCallbackReadableChannel(
             ReadableByteChannel directChannel,
             List<ContentStreamListener> listeners)
             throws ContentIOException
     {
-        // introduce an advistor to handle the callbacks to the listeners
+        ReadableByteChannel callbackChannel = null;
-        ByteChannelCallbackAdvise advise = new ByteChannelCallbackAdvise(listeners);
+        if (directChannel instanceof FileChannel)
-        ProxyFactory proxyFactory = new ProxyFactory(directChannel);
+        {
-        proxyFactory.addAdvice(advise);
+            callbackChannel = getCallbackFileChannel((FileChannel) directChannel, listeners);
-        ReadableByteChannel callbackChannel = (ReadableByteChannel) proxyFactory.getProxy();
+        }
+        else
+        {
+            // introduce an advistor to handle the callbacks to the listeners
+            ChannelCloseCallbackAdvise advise = new ChannelCloseCallbackAdvise(listeners);
+            ProxyFactory proxyFactory = new ProxyFactory(directChannel);
+            proxyFactory.addAdvice(advise);
+            callbackChannel = (ReadableByteChannel) proxyFactory.getProxy();
+        }
         // done
+        if (logger.isDebugEnabled())
+        {
+            logger.debug("Created callback byte channel: \n" +
+                    "   original: " + directChannel + "\n" +
+                    "   new: " + callbackChannel);
+        }
         return callbackChannel;
     }
 
@@ -195,6 +212,90 @@ public abstract class AbstractContentReader extends AbstractContentAccessor impl
         return channel;
     }
     
+    
+    /**
+     * @inheritDoc
+     */
+    public FileChannel getFileChannel() throws ContentIOException
+    {
+        /*
+         * Where the underlying support is not present for this method, a temporary
+         * file will be used as a substitute.  When the write is complete, the
+         * results are copied directly to the underlying channel.
+         */
+        
+        // get the underlying implementation's best readable channel
+        channel = getReadableChannel();
+        // now use this channel if it can provide the random access, otherwise spoof it
+        FileChannel clientFileChannel = null;
+        if (channel instanceof FileChannel)
+        {
+            // all the support is provided by the underlying implementation
+            clientFileChannel = (FileChannel) channel;
+            // debug
+            if (logger.isDebugEnabled())
+            {
+                logger.debug("Content reader provided direct support for FileChannel: \n" +
+                        "   reader: " + this);
+            }
+        }
+        else
+        {
+            // No random access support is provided by the implementation.
+            // Spoof it by providing a 2-stage read from a temp file
+            File tempFile = TempFileProvider.createTempFile("random_read_spoof_", ".bin");
+            FileContentWriter spoofWriter = new FileContentWriter(tempFile);
+            // pull the content in from the underlying channel
+            FileChannel spoofWriterChannel = spoofWriter.getFileChannel(false);
+            try
+            {
+                long spoofFileSize = this.getSize();
+                spoofWriterChannel.transferFrom(channel, 0, spoofFileSize);
+            }
+            catch (IOException e)
+            {
+                throw new ContentIOException("Failed to copy from permanent channel to spoofed temporary channel: \n" +
+                        "   reader: " + this + "\n" +
+                        "   temp: " + spoofWriter,
+                        e);
+            }
+            finally
+            {
+                try { spoofWriterChannel.close(); } catch (IOException e) {}
+            }
+            // get a reader onto the spoofed content
+            final ContentReader spoofReader = spoofWriter.getReader();
+            // Attach a listener
+            // - ensure that the close call gets propogated to the underlying channel
+            ContentStreamListener spoofListener = new ContentStreamListener()
+                    {
+                        public void contentStreamClosed() throws ContentIOException
+                        {
+                            try
+                            {
+                                channel.close();
+                            }
+                            catch (IOException e)
+                            {
+                                throw new ContentIOException("Failed to close underlying channel", e);
+                            }
+                        }
+                    };
+            spoofReader.addListener(spoofListener);
+            // we now have the spoofed up channel that the client can work with
+            clientFileChannel = spoofReader.getFileChannel();
+            // debug
+            if (logger.isDebugEnabled())
+            {
+                logger.debug("Content writer provided indirect support for FileChannel: \n" +
+                        "   writer: " + this + "\n" +
+                        "   temp writer: " + spoofWriter);
+            }
+        }
+        // the file is now available for random access
+        return clientFileChannel;
+    }
+
     /**
      * @see Channels#newInputStream(java.nio.channels.ReadableByteChannel)
      */

source/java/org/alfresco/repo/content/AbstractContentWriter.java

@@ -24,16 +24,20 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.channels.Channels;
+import java.nio.channels.FileChannel;
+import java.nio.channels.ReadableByteChannel;
 import java.nio.channels.WritableByteChannel;
 import java.util.ArrayList;
 import java.util.List;
 
 import org.alfresco.error.AlfrescoRuntimeException;
+import org.alfresco.repo.content.filestore.FileContentWriter;
 import org.alfresco.service.cmr.repository.ContentAccessor;
 import org.alfresco.service.cmr.repository.ContentIOException;
 import org.alfresco.service.cmr.repository.ContentReader;
 import org.alfresco.service.cmr.repository.ContentStreamListener;
 import org.alfresco.service.cmr.repository.ContentWriter;
+import org.alfresco.util.TempFileProvider;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.springframework.aop.framework.ProxyFactory;
@@ -151,7 +155,7 @@ public abstract class AbstractContentWriter extends AbstractContentAccessor impl
             return false;
         }
     }
-
+    
     /**
      * Provides low-level access to write content to the repository.
      * <p>
@@ -165,24 +169,38 @@ public abstract class AbstractContentWriter extends AbstractContentAccessor impl
     protected abstract WritableByteChannel getDirectWritableChannel() throws ContentIOException;
     
     /**
-     * Optionally override to supply an alternate callback channel.
+     * Create a channel that performs callbacks to the given listeners.
-     *
+     *  
      * @param directChannel the result of {@link #getDirectWritableChannel()}
      * @param listeners the listeners to call
-     * @return Returns a callback channel
+     * @return Returns a channel that executes callbacks
      * @throws ContentIOException
      */
-    protected WritableByteChannel getCallbackWritableChannel(
+    private WritableByteChannel getCallbackWritableChannel(
             WritableByteChannel directChannel,
             List<ContentStreamListener> listeners)
             throws ContentIOException
     {
-        // proxy to add an advise
+        WritableByteChannel callbackChannel = null;
-        ByteChannelCallbackAdvise advise = new ByteChannelCallbackAdvise(listeners);
+        if (directChannel instanceof FileChannel)
-        ProxyFactory proxyFactory = new ProxyFactory(directChannel);
+        {
-        proxyFactory.addAdvice(advise);
+            callbackChannel = getCallbackFileChannel((FileChannel) directChannel, listeners);
-        WritableByteChannel callbackChannel = (WritableByteChannel) proxyFactory.getProxy();
+        }
+        else
+        {
+            // introduce an advistor to handle the callbacks to the listeners
+            ChannelCloseCallbackAdvise advise = new ChannelCloseCallbackAdvise(listeners);
+            ProxyFactory proxyFactory = new ProxyFactory(directChannel);
+            proxyFactory.addAdvice(advise);
+            callbackChannel = (WritableByteChannel) proxyFactory.getProxy();
+        }
         // done
+        if (logger.isDebugEnabled())
+        {
+            logger.debug("Created callback byte channel: \n" +
+                    "   original: " + directChannel + "\n" +
+                    "   new: " + callbackChannel);
+        }
         return callbackChannel;
     }
 
@@ -210,6 +228,126 @@ public abstract class AbstractContentWriter extends AbstractContentAccessor impl
         return channel;
     }
     
+    /**
+     * @inheritDoc
+     */
+    public FileChannel getFileChannel(boolean truncate) throws ContentIOException
+    {
+        /*
+         * By calling this method, clients indicate that they wish to make random
+         * changes to the file.  It is possible that the client might only want
+         * to update a tiny proportion of the file (truncate == false) or
+         * start afresh (truncate == true).
+         * 
+         * Where the underlying support is not present for this method, a temporary
+         * file will be used as a substitute.  When the write is complete, the
+         * results are copied directly to the underlying channel.
+         */
+        
+        // get the underlying implementation's best writable channel
+        channel = getWritableChannel();
+        // now use this channel if it can provide the random access, otherwise spoof it
+        FileChannel clientFileChannel = null;
+        if (channel instanceof FileChannel)
+        {
+            // all the support is provided by the underlying implementation
+            clientFileChannel = (FileChannel) channel;
+            // copy over the existing content, if required
+            if (!truncate && existingContentReader != null)
+            {
+                ReadableByteChannel existingContentChannel = existingContentReader.getReadableChannel();
+                long existingContentLength = existingContentReader.getSize();
+                // copy the existing content
+                try
+                {
+                    clientFileChannel.transferFrom(existingContentChannel, 0, existingContentLength);
+                    // copy complete
+                    if (logger.isDebugEnabled())
+                    {
+                        logger.debug("Copied content for random access: \n" +
+                                "   writer: " + this + "\n" +
+                                "   existing: " + existingContentReader);
+                    }
+                }
+                catch (IOException e)
+                {
+                    throw new ContentIOException("Failed to copy from existing content to enable random access: \n" +
+                            "   writer: " + this + "\n" +
+                            "   existing: " + existingContentReader,
+                            e);
+                }
+                finally
+                {
+                    try { existingContentChannel.close(); } catch (IOException e) {}
+                }
+            }
+            // debug
+            if (logger.isDebugEnabled())
+            {
+                logger.debug("Content writer provided direct support for FileChannel: \n" +
+                        "   writer: " + this);
+            }
+        }
+        else
+        {
+            // No random access support is provided by the implementation.
+            // Spoof it by providing a 2-stage write via a temp file
+            File tempFile = TempFileProvider.createTempFile("random_write_spoof_", ".bin");
+            final FileContentWriter spoofWriter = new FileContentWriter(
+                    tempFile,                           // the file to write to
+                    getExistingContentReader());        // this ensures that the existing content is pulled in
+            // Attach a listener
+            // - to ensure that the content gets loaded from the temp file once writing has finished
+            // - to ensure that the close call gets passed on to the underlying channel
+            ContentStreamListener spoofListener = new ContentStreamListener()
+            {
+                public void contentStreamClosed() throws ContentIOException
+                {
+                    // the spoofed temp channel has been closed, so get a new reader for it
+                    ContentReader spoofReader = spoofWriter.getReader();
+                    FileChannel spoofChannel = spoofReader.getFileChannel();
+                    // upload all the temp content to the real underlying channel
+                    try
+                    {
+                        long spoofFileSize = spoofChannel.size();
+                        spoofChannel.transferTo(0, spoofFileSize, channel);
+                    }
+                    catch (IOException e)
+                    {
+                        throw new ContentIOException("Failed to copy from spoofed temporary channel to permanent channel: \n" +
+                                "   writer: " + this + "\n" +
+                                "   temp: " + spoofReader,
+                                e);
+                    }
+                    finally
+                    {
+                        try { spoofChannel.close(); } catch (Throwable e) {}
+                        try
+                        {
+                            channel.close();
+                        }
+                        catch (IOException e)
+                        {
+                            throw new ContentIOException("Failed to close underlying channel", e);
+                        }
+                    }
+                }
+            };
+            spoofWriter.addListener(spoofListener);
+            // we now have the spoofed up channel that the client can work with
+            clientFileChannel = spoofWriter.getFileChannel(truncate);
+            // debug
+            if (logger.isDebugEnabled())
+            {
+                logger.debug("Content writer provided indirect support for FileChannel: \n" +
+                        "   writer: " + this + "\n" +
+                        "   temp writer: " + spoofWriter);
+            }
+        }
+        // the file is now available for random access
+        return clientFileChannel;
+    }
+
     /**
      * @see Channels#newOutputStream(java.nio.channels.WritableByteChannel)
      */

source/java/org/alfresco/repo/content/RandomAccessContent.java

@@ -1,50 +0,0 @@
-/*
- * Copyright (C) 2005 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.content;
-
-import java.nio.channels.FileChannel;
-
-import org.alfresco.service.cmr.repository.ContentIOException;
-
-/**
- * Supplementary interface for content readers and writers that allow random-access to
- * the underlying content.
- * <p>
- * The use of this interface by a client <b>may</b> preclude the use of any other
- * access to the underlying content - this depends on the underlying implementation.
- * 
- * @author Derek Hulley
- */
-public interface RandomAccessContent
-{
-    /**
-     * @return Returns true if the content can be written to 
-     */
-    public boolean canWrite();
-    
-    /**
-     * Get a channel to access the content.  The channel's behaviour is similar to that
-     * when a <tt>FileChannel</tt> is retrieved using {@link java.io.RandomAccessFile#getChannel()}.
-     * 
-     * @return Returns a channel to access the content
-     * @throws ContentIOException
-     *
-     * @see #canWrite()
-     * @see java.io.RandomAccessFile#getChannel()
-     */
-    public FileChannel getChannel() throws ContentIOException;
-}

source/java/org/alfresco/repo/content/filestore/FileContentReader.java

@@ -17,20 +17,18 @@
 package org.alfresco.repo.content.filestore;
 
 import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.RandomAccessFile;
-import java.nio.channels.FileChannel;
+import java.nio.channels.Channels;
 import java.nio.channels.ReadableByteChannel;
 import java.text.MessageFormat;
-import java.util.List;
 
-import org.alfresco.error.AlfrescoRuntimeException;
 import org.alfresco.repo.content.AbstractContentReader;
 import org.alfresco.repo.content.MimetypeMap;
-import org.alfresco.repo.content.RandomAccessContent;
 import org.alfresco.service.cmr.repository.ContentIOException;
 import org.alfresco.service.cmr.repository.ContentReader;
-import org.alfresco.service.cmr.repository.ContentStreamListener;
 import org.alfresco.service.cmr.repository.ContentWriter;
 import org.alfresco.util.TempFileProvider;
 import org.apache.commons.logging.Log;
@@ -43,11 +41,12 @@ import org.apache.commons.logging.LogFactory;
  * 
  * @author Derek Hulley
  */
-public class FileContentReader extends AbstractContentReader implements RandomAccessContent
+public class FileContentReader extends AbstractContentReader
 {
     private static final Log logger = LogFactory.getLog(FileContentReader.class);
     
     private File file;
+    private boolean allowRandomAccess;
     
     /**
      * Checks the existing reader provided and replaces it with a reader onto some
@@ -118,6 +117,12 @@ public class FileContentReader extends AbstractContentReader implements RandomAc
         super(url);
         
         this.file = file;
+        allowRandomAccess = true;
+    }
+    
+    /* package */ void setAllowRandomAccess(boolean allow)
+    {
+        this.allowRandomAccess = allow;
     }
     
     /**
@@ -170,7 +175,9 @@ public class FileContentReader extends AbstractContentReader implements RandomAc
     @Override
     protected ContentReader createReader() throws ContentIOException
     {
-        return new FileContentReader(this.file, getContentUrl());
+        FileContentReader reader = new FileContentReader(this.file, getContentUrl());
+        reader.setAllowRandomAccess(this.allowRandomAccess);
+        return reader;
     }
     
     @Override
@@ -184,12 +191,23 @@ public class FileContentReader extends AbstractContentReader implements RandomAc
                 throw new IOException("File does not exist");
             }
             // create the channel
-            RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r");  // won't create it
+            ReadableByteChannel channel = null;
-            FileChannel channel = randomAccessFile.getChannel();
+            if (allowRandomAccess)
+            {
+                RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r");  // won't create it
+                channel = randomAccessFile.getChannel();
+            }
+            else
+            {
+                InputStream is = new FileInputStream(file);
+                channel = Channels.newChannel(is);
+            }
             // done
             if (logger.isDebugEnabled())
             {
-                logger.debug("Opened channel to file: " + file);
+                logger.debug("Opened write channel to file: \n" +
+                        "   file: " + file + "\n" +
+                        "   random-access: " + allowRandomAccess);
             }
             return channel;
         }
@@ -199,25 +217,6 @@ public class FileContentReader extends AbstractContentReader implements RandomAc
         }
     }
 
-    /**
-     * @param directChannel a file channel
-     */
-    @Override
-    protected ReadableByteChannel getCallbackReadableChannel(
-            ReadableByteChannel directChannel,
-            List<ContentStreamListener> listeners) throws ContentIOException
-    {
-        if (!(directChannel instanceof FileChannel))
-        {
-            throw new AlfrescoRuntimeException("Expected read channel to be a file channel");
-        }
-        FileChannel fileChannel = (FileChannel) directChannel;
-        // wrap it
-        FileChannel callbackChannel = new CallbackFileChannel(fileChannel, listeners);
-        // done
-        return callbackChannel;
-    }
-
     /**
      * @return Returns false as this is a reader
      */
@@ -225,11 +224,4 @@ public class FileContentReader extends AbstractContentReader implements RandomAc
     {
         return false;   // we only allow reading
     }
-
-    public FileChannel getChannel() throws ContentIOException
-    {
-        // go through the super classes to ensure that all concurrency conditions
-        // and listeners are satisfied
-        return (FileChannel) super.getReadableChannel();
-    }
 }

source/java/org/alfresco/repo/content/filestore/FileContentStore.java

@@ -43,6 +43,7 @@ public class FileContentStore extends AbstractContentStore
     
     private File rootDirectory;
     private String rootAbsolutePath;
+    private boolean allowRandomAccess;
 
     /**
      * @param rootDirectory the root under which files will be stored.  The
@@ -60,6 +61,7 @@ public class FileContentStore extends AbstractContentStore
         }
         rootDirectory = rootDirectory.getAbsoluteFile();
         rootAbsolutePath = rootDirectory.getAbsolutePath();
+        allowRandomAccess = true;
     }
 
     public String toString()
@@ -70,7 +72,23 @@ public class FileContentStore extends AbstractContentStore
           .append("]");
         return sb.toString();
     }
-    
+
+    /**
+     * Stores may optionally produce readers and writers that support random access.
+     * Switch this off for this store by setting this to <tt>false</tt>.
+     * <p>
+     * This switch is primarily used during testing to ensure that the system has the
+     * ability to spoof random access in cases where the store is unable to produce
+     * readers and writers that allow random access.  Typically, stream-based access
+     * would be an example.
+     * 
+     * @param allowRandomAccess true to allow random access, false to have it faked
+     */
+    public void setAllowRandomAccess(boolean allowRandomAccess)
+    {
+        this.allowRandomAccess = allowRandomAccess;
+    }
+
     /**
      * Generates a new URL and file appropriate to it.
      * 
@@ -193,6 +211,7 @@ public class FileContentStore extends AbstractContentStore
         {
             File file = makeFile(contentUrl);
             FileContentReader reader = new FileContentReader(file, contentUrl);
+            reader.setAllowRandomAccess(allowRandomAccess);
             
             // done
             if (logger.isDebugEnabled())
@@ -233,6 +252,7 @@ public class FileContentStore extends AbstractContentStore
             }
             // create the writer
             FileContentWriter writer = new FileContentWriter(file, contentUrl, existingContentReader);
+            writer.setAllowRandomAccess(allowRandomAccess);
             
             // done
             if (logger.isDebugEnabled())

source/java/org/alfresco/repo/content/filestore/FileContentWriter.java

@@ -17,19 +17,16 @@
 package org.alfresco.repo.content.filestore;
 
 import java.io.File;
+import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.OutputStream;
 import java.io.RandomAccessFile;
-import java.nio.channels.FileChannel;
+import java.nio.channels.Channels;
-import java.nio.channels.ReadableByteChannel;
 import java.nio.channels.WritableByteChannel;
-import java.util.List;
 
-import org.alfresco.error.AlfrescoRuntimeException;
 import org.alfresco.repo.content.AbstractContentWriter;
-import org.alfresco.repo.content.RandomAccessContent;
 import org.alfresco.service.cmr.repository.ContentIOException;
 import org.alfresco.service.cmr.repository.ContentReader;
-import org.alfresco.service.cmr.repository.ContentStreamListener;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
@@ -40,11 +37,12 @@ import org.apache.commons.logging.LogFactory;
  * 
  * @author Derek Hulley
  */
-public class FileContentWriter extends AbstractContentWriter implements RandomAccessContent
+public class FileContentWriter extends AbstractContentWriter
 {
     private static final Log logger = LogFactory.getLog(FileContentWriter.class);
     
     private File file;
+    private boolean allowRandomAccess;
     
     /**
      * Constructor that builds a URL based on the absolute path of the file.
@@ -88,6 +86,12 @@ public class FileContentWriter extends AbstractContentWriter implements RandomAc
         super(url, existingContentReader);
         
         this.file = file;
+        allowRandomAccess = true;
+    }
+    
+    /* package */ void setAllowRandomAccess(boolean allow)
+    {
+        this.allowRandomAccess = allow;
     }
 
     /**
@@ -118,7 +122,9 @@ public class FileContentWriter extends AbstractContentWriter implements RandomAc
     @Override
     protected ContentReader createReader() throws ContentIOException
     {
-        return new FileContentReader(this.file, getContentUrl());
+        FileContentReader reader = new FileContentReader(this.file, getContentUrl());
+        reader.setAllowRandomAccess(this.allowRandomAccess);
+        return reader;
     }
     
     @Override
@@ -132,12 +138,23 @@ public class FileContentWriter extends AbstractContentWriter implements RandomAc
                 throw new IOException("File exists - overwriting not allowed");
             }
             // create the channel
-            RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");  // will create it
+            WritableByteChannel channel = null;
-            FileChannel channel = randomAccessFile.getChannel();
+            if (allowRandomAccess)
+            {
+                RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");  // will create it
+                channel = randomAccessFile.getChannel();
+            }
+            else
+            {
+                OutputStream os = new FileOutputStream(file);
+                channel = Channels.newChannel(os);
+            }
             // done
             if (logger.isDebugEnabled())
             {
-                logger.debug("Opened channel to file: " + file);
+                logger.debug("Opened write channel to file: \n" +
+                        "   file: " + file + "\n" +
+                        "   random-access: " + allowRandomAccess);
             }
             return channel;
         }
@@ -147,25 +164,6 @@ public class FileContentWriter extends AbstractContentWriter implements RandomAc
         }
     }
 
-    /**
-     * @param directChannel a file channel
-     */
-    @Override
-    protected WritableByteChannel getCallbackWritableChannel(
-            WritableByteChannel directChannel,
-            List<ContentStreamListener> listeners) throws ContentIOException
-    {
-        if (!(directChannel instanceof FileChannel))
-        {
-            throw new AlfrescoRuntimeException("Expected write channel to be a file channel");
-        }
-        FileChannel fileChannel = (FileChannel) directChannel;
-        // wrap it
-        FileChannel callbackChannel = new CallbackFileChannel(fileChannel, listeners);
-        // done
-        return callbackChannel;
-    }
-
     /**
      * @return Returns true always
      */
@@ -173,51 +171,4 @@ public class FileContentWriter extends AbstractContentWriter implements RandomAc
     {
         return true;    // this is a writer
     }
-
-    public FileChannel getChannel() throws ContentIOException
-    {
-        /*
-         * By calling this method, clients indicate that they wish to make random
-         * changes to the file.  It is possible that the client might only want
-         * to update a tiny proportion of the file - or even none of it.  Either
-         * way, the file must be as whole and complete as before it was accessed.
-         */
-        
-        // go through the super classes to ensure that all concurrency conditions
-        // and listeners are satisfied
-        FileChannel channel = (FileChannel) super.getWritableChannel();
-        // random access means that the the new content's starting point must be
-        // that of the existing content
-        ContentReader existingContentReader = getExistingContentReader();
-        if (existingContentReader != null)
-        {
-            ReadableByteChannel existingContentChannel = existingContentReader.getReadableChannel();
-            long existingContentLength = existingContentReader.getSize();
-            // copy the existing content
-            try
-            {
-                channel.transferFrom(existingContentChannel, 0, existingContentLength);
-                // copy complete
-                if (logger.isDebugEnabled())
-                {
-                    logger.debug("Copied content for random access: \n" +
-                            "   writer: " + this + "\n" +
-                            "   existing: " + existingContentReader);
-                }
-            }
-            catch (IOException e)
-            {
-                throw new ContentIOException("Failed to copy from existing content to enable random access: \n" +
-                        "   writer: " + this + "\n" +
-                        "   existing: " + existingContentReader,
-                        e);
-            }
-            finally
-            {
-                try { existingContentChannel.close(); } catch (IOException e) {}
-            }
-        }
-        // the file is now available for random access
-        return channel;
-    }
 }

source/java/org/alfresco/repo/content/filestore/NoRandomAccessFileContentStoreTest.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2005 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.content.filestore;
+
+import java.io.File;
+
+import org.alfresco.repo.content.AbstractContentReadWriteTest;
+import org.alfresco.repo.content.ContentStore;
+import org.alfresco.util.TempFileProvider;
+
+/**
+ * Tests the file-based store when random access is not allowed, i.e. has to be spoofed.
+ * 
+ * @see org.alfresco.repo.content.filestore.FileContentStore
+ * 
+ * @author Derek Hulley
+ */
+public class NoRandomAccessFileContentStoreTest extends AbstractContentReadWriteTest
+{
+    private FileContentStore store;
+    
+    @Override
+    public void setUp() throws Exception
+    {
+        super.setUp();
+        
+        // create a store that uses a subdirectory of the temp directory
+        File tempDir = TempFileProvider.getTempDir();
+        store = new FileContentStore(
+                tempDir.getAbsolutePath() +
+                File.separatorChar +
+                getName());
+        // disallow random access
+        store.setAllowRandomAccess(false);
+    }
+    
+    @Override
+    protected ContentStore getStore()
+    {
+        return store;
+    }
+}

source/java/org/alfresco/service/cmr/repository/ContentAccessor.java

@@ -45,6 +45,10 @@ public interface ContentAccessor
     
     /**
      * Set the transaction provider that will be used when stream listeners are called.
+     * No transactions are started unless there are listeners present to be executed.
+     * For consistency, the execution of listeners <b>will not</b> be allowed to proceed
+     * unless this property has been set OR the channel close operations are executed
+     * within the context of a live transaction.
      * 
      * @param transactionService a transaction provider
      */

source/java/org/alfresco/service/cmr/repository/ContentReader.java

@@ -19,6 +19,7 @@ package org.alfresco.service.cmr.repository;
 import java.io.File;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.nio.channels.FileChannel;
 import java.nio.channels.ReadableByteChannel;
 
 /**
@@ -86,6 +87,19 @@ public interface ContentReader extends ContentAccessor
      */
     public ReadableByteChannel getReadableChannel() throws ContentIOException;
     
+    /**
+     * Provides read-only, random-access to the underlying content.  In general, this method
+     * should be considered more expensive than the sequential-access method,
+     * {@link #getReadableChannel()}.
+     * 
+     * @return Returns a random-access channel onto the content
+     * @throws ContentIOException
+     *
+     * @see #getReadableChannel()
+     * @see java.io.RandomAccessFile#getChannel()
+     */
+    public FileChannel getFileChannel() throws ContentIOException;
+
     /**
      * Get a stream to read from the underlying channel
      * 

source/java/org/alfresco/service/cmr/repository/ContentWriter.java

@@ -19,6 +19,7 @@ package org.alfresco.service.cmr.repository;
 import java.io.File;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.nio.channels.FileChannel;
 import java.nio.channels.WritableByteChannel;
 
 
@@ -77,6 +78,23 @@ public interface ContentWriter extends ContentAccessor
      */
     public WritableByteChannel getWritableChannel() throws ContentIOException;
 
+    /**
+     * Provides read-write, random-access to the underlying content.  In general, this method
+     * should be considered more expensive than the sequential-access method,
+     * {@link #getWritableChannel()}.
+     * <p>
+     * Underlying implementations use the <code>truncate</code> parameter to determine the
+     * most effective means of providing access to the content.
+     * 
+     * @param truncate true to start with zero length content
+     * @return Returns a random-access channel onto the content
+     * @throws ContentIOException
+     *
+     * @see #getWritableChannel()
+     * @see java.io.RandomAccessFile#getChannel()
+     */
+    public FileChannel getFileChannel(boolean truncate) throws ContentIOException;
+
     /**
      * Get a stream to write to the underlying channel.
      *