ALF-10052 - Channel Exception when reading file

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@30470 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

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

@@ -68,26 +68,20 @@ public class ContentNetworkFile extends NodeRefNetworkFile
     private static final Log logger = LogFactory.getLog(ContentNetworkFile.class);
     
     // Services
-    
     private NodeService nodeService;
     private ContentService contentService;
     private MimetypeService mimetypeService;
     
-    // File channel to file content
     
-    private FileChannel channel;
+    private FileChannel channel;        // File channel to file content
+    private ContentAccessor content;    // content
 
-    // File content
-    
-    private ContentAccessor content;
     private String preUpdateContentURL;
     
     // Indicate if file has been written to or truncated/resized
-    
     private boolean modified;
     
     // Flag to indicate if the file channel is writable
-    
     private boolean writableChannel;
 
     /**
@@ -265,6 +259,8 @@ public class ContentNetworkFile extends NodeRefNetworkFile
     /**
      * Opens the channel for reading or writing depending on the access mode.
      * <p>
+     * Side effect: sets fileSize
+     * <p>
      * If the channel is already open, it is left.
      * 
      * @param write true if the channel must be writable
@@ -277,19 +273,31 @@ public class ContentNetworkFile extends NodeRefNetworkFile
      * @see NetworkFile#WRITEONLY
      * @see NetworkFile#READWRITE
      */
-    protected void openContent(boolean write, boolean trunc)
+    public void openContent(boolean write, boolean trunc)
     	throws AccessDeniedException, AlfrescoRuntimeException
     {
     	// Check if the file is a directory
     	
         if (isDirectory())
         {
-            throw new AlfrescoRuntimeException("Unable to open channel for a directory network file: " + this);
+            throw new AlfrescoRuntimeException("Unable to open content for a directory network file: " + this);
+        }
+        
+        if(channel != null && !write)
+        {
+            if(logger.isDebugEnabled())
+            {
+                logger.debug("channel is already open for read-only");
+            }
+            return;
         }
         
         // Check if write access is required and the current channel is read-only
         
-        else if ( write && writableChannel == false && channel != null)
+        // update of channel and content member variables need to be serialized 
+        synchronized(this)
+        {
+            if ( write && writableChannel == false && channel != null)
             {
                 // Close the existing read-only channel
             
@@ -297,6 +305,7 @@ public class ContentNetworkFile extends NodeRefNetworkFile
                 {
                     channel.close();
                     channel = null;
+                    content = null;
                 }
                 catch (IOException ex)
                 {
@@ -306,12 +315,13 @@ public class ContentNetworkFile extends NodeRefNetworkFile
                 // Debug
             
                 if ( logger.isDebugEnabled())
+                {
                     logger.debug("Switching to writable channel for " + getName());
                 }
+            }
             else if (channel != null)
             {
-            // Already have channel open
+                // Already have read/write channel open
-        	
                 return;
             }
   
@@ -322,14 +332,15 @@ public class ContentNetworkFile extends NodeRefNetworkFile
                 throw new AccessDeniedException("The network file was created for read-only: " + this);
             }
         
-        content = null;
             preUpdateContentURL = null;
+            
+            // Need to open content for write
             if (write)
             {
                 // Get a writeable channel to the content, along with the original content
                 if(logger.isDebugEnabled())
                 {
-                logger.debug("get writer for content property");
+                    logger.debug("open writer for content property");
                 }
         	
                 content = contentService.getWriter( getNodeRef(), ContentModel.PROP_CONTENT, false);
@@ -347,7 +358,6 @@ public class ContentNetworkFile extends NodeRefNetworkFile
                 writableChannel = true;
             
                 // Get the writable channel, do not copy existing content data if the file is to be truncated
-            
                 channel = ((ContentWriter) content).getFileChannel( trunc);
             }
             else
@@ -355,7 +365,7 @@ public class ContentNetworkFile extends NodeRefNetworkFile
                 // Get a read-only channel to the content
                 if(logger.isDebugEnabled())
                 {
-                logger.debug("get reader for content property");
+                    logger.debug("open reader for content property");
                 }
         	
                 content = contentService.getReader( getNodeRef(), ContentModel.PROP_CONTENT);
@@ -393,6 +403,7 @@ public class ContentNetworkFile extends NodeRefNetworkFile
             
                 setClosed( false);
             }
+        } // release lock
     }
 
     /**
@@ -420,9 +431,8 @@ public class ContentNetworkFile extends NodeRefNetworkFile
             setClosed( true);
             return;
         }
-        else if (!hasContent())
+        else if (!hasContent())        {
-        {
+        	// File was not read/written so content was not opened
-        	// File was not read/written so channel was not opened
             if(logger.isDebugEnabled())
             {
                 logger.debug("no content to write - nothing to do");
@@ -434,6 +444,10 @@ public class ContentNetworkFile extends NodeRefNetworkFile
         
         // Check if the file has been modified
         
+        // update of channel and content member variables need to be serialized 
+        synchronized(this)
+        {
+        
             if (modified)
             {
                 if(logger.isDebugEnabled())
@@ -446,6 +460,11 @@ public class ContentNetworkFile extends NodeRefNetworkFile
                 // We may be in a retry block, in which case this section will already have executed and channel will be null
                 if (channel != null)
                 {
+                    // Close the channel
+                    channel.close();
+                    channel = null;
+                }
+                
                 // Do we need the mimetype guessing for us when we're done?
                 if (content.getMimetype() == null || content.getMimetype().equals(MimetypeMap.MIMETYPE_BINARY) )
                 {
@@ -456,11 +475,6 @@ public class ContentNetworkFile extends NodeRefNetworkFile
                 // We always want the encoding guessing
                 writer.guessEncoding();
                 
-                // Close the channel
-                channel.close();
-                channel = null;
-            }
-            
                 // Retrieve the content data and stop the content URL from being 'eagerly deleted', in case we need to
                 // retry the transaction
 
@@ -496,6 +510,8 @@ public class ContentNetworkFile extends NodeRefNetworkFile
                     }
                     catch (ContentQuotaException qe)
                     {
+                        content = null;
+                        setClosed( true);
                         throw new DiskFullException(qe.getMessage());
                     }
                 }
@@ -505,12 +521,18 @@ public class ContentNetworkFile extends NodeRefNetworkFile
                 {
                     @Override
                     public void afterCommit()
+                    {
+                        synchronized(this)
+                        {
+                            if(channel == null)
                             {
                                 content = null;
                                 preUpdateContentURL = null;
-                    
                                 setClosed( true);
                             }
+                        }
+                       
+                    }
                 });
             }
             else if (channel != null)
@@ -523,6 +545,9 @@ public class ContentNetworkFile extends NodeRefNetworkFile
         	
                 channel.close();
                 channel = null;
+                content = null;
+                setClosed(true);
+            }
         }
     }
 
@@ -601,9 +626,9 @@ public class ContentNetworkFile extends NodeRefNetworkFile
     public void writeFile(byte[] buffer, int length, int position, long fileOffset)
     	throws IOException
     {
-    	try {
+    	try 
+    	{
 	        // Open the channel for writing    
-	        
 	        openContent(true, false);
     	}
     	catch ( ContentIOException ex) {
@@ -842,4 +867,5 @@ public class ContentNetworkFile extends NodeRefNetworkFile
         }
         return false;
     }
+    
 }