[Exist-commits] SF.net SVN: exist:[18626] trunk/eXist/src/org/exist/storage /journal/FileSyncThread.java

[<wol...@us...>]

Revision: 18626
          http://sourceforge.net/p/exist/code/18626
Author:   wolfgang_m
Date:     2013-06-29 16:56:53 +0000 (Sat, 29 Jun 2013)
Log Message:
-----------
[bugfix] Applied patch: #820 FileSyncThread may access null endOfLog

Modified Paths:
--------------
    trunk/eXist/src/org/exist/storage/journal/FileSyncThread.java

Modified: trunk/eXist/src/org/exist/storage/journal/FileSyncThread.java
===================================================================
--- trunk/eXist/src/org/exist/storage/journal/FileSyncThread.java	2013-06-29 16:52:39 UTC (rev 18625)
+++ trunk/eXist/src/org/exist/storage/journal/FileSyncThread.java	2013-06-29 16:56:53 UTC (rev 18626)
@@ -39,14 +39,16 @@
  */
 public class FileSyncThread extends Thread {
 
+	// guarded by latch
     private FileChannel endOfLog;
-
+    private Object latch;
+    
+    // guarded by this
     private boolean syncTriggered = false;
 
-    private boolean shutdown = false;
+    // used as termination flag, volatile semantics are sufficient
+    private volatile boolean shutdown = false;
 
-    private Object latch;
-
     /**
      * Create a new FileSyncThread, using the specified latch
      * to synchronize on.
@@ -66,7 +68,9 @@
      * @param channel
      */
     public void setChannel(FileChannel channel) {
-        endOfLog = channel;
+    	synchronized (latch) {
+            endOfLog = channel;			
+		}
     }
 
     /**
@@ -82,7 +86,7 @@
     /**
      * Shutdown the sync thread.
      */
-    public synchronized void shutdown() {
+    public void shutdown() {
         shutdown = true;
         interrupt();
     }
@@ -92,11 +96,13 @@
      */
     public void closeChannel() {
         synchronized (latch) {
-            try {
-                endOfLog.close();
-            } catch (final IOException e) {
-                //Nothing to do
-            }
+        	if (endOfLog != null) {
+        		try {
+        			endOfLog.close();
+        		} catch (final IOException e) {
+        			// may occur during shutdown
+        		}
+        	}
         }
     }
 
@@ -124,11 +130,14 @@
 
     private void sync() {
         synchronized (latch) {
-            try {
-                endOfLog.force(false);
-            } catch (final IOException e) {
-                // may occur during shutdown
-            }
+        	//endOfLog may be null if setChannel wasn't called for some reason.
+        	if (endOfLog != null) {
+        		try {
+        			endOfLog.force(false);
+        		} catch (final IOException e) {
+        			// may occur during shutdown
+        		}
+        	}
             syncTriggered = false;
         }
     }