[Jrobin-commits] src/org/jrobin/core RrdNioBackend.java,1.12,1.13

[Sasa M. <sa...@us...>]

Update of /cvsroot/jrobin/src/org/jrobin/core
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv20380/org/jrobin/core

Modified Files:
	RrdNioBackend.java 
Log Message:
Completely redesigned and simplified RRDTool commander...

Index: RrdNioBackend.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/RrdNioBackend.java,v
retrieving revision 1.12
retrieving revision 1.13
diff -C2 -d -r1.12 -r1.13
*** RrdNioBackend.java	15 Jul 2004 14:22:12 -0000	1.12
--- RrdNioBackend.java	16 Jul 2004 07:40:49 -0000	1.13
***************
*** 37,40 ****
--- 37,62 ----
   */
  public class RrdNioBackend extends RrdFileBackend {
+ 	/**
+ 	 * Defines if the <code>System.gc()</code> method should be executed when necessary.
+ 	 * NIO backend uses large in-memory buffer to cache file data. The buffer remains 'active'
+ 	 * (by prohibiting file re-creation, for example) as long as it is not garbage collected.
+ 	 * By forcing <code>gc()</code> where appropriate, memory gets freed sooner and file
+ 	 * re-creation won't fail.<p>
+ 	 *
+ 	 * The constant is set to false initially and currently there is no API to change it
+ 	 * during runtime.<p>
+ 	 */
+ 	public static final boolean SHOULD_GC = true;
+ 
+ 	static {
+ 		if(SHOULD_GC) {
+ 			Runtime.getRuntime().addShutdownHook(new Thread() {
+ 				public void run() {
+ 					System.gc();
+ 				}
+ 			});
+ 		}
+ 	}
+ 
  	private static final Timer syncTimer = new Timer(true);
  
***************
*** 46,53 ****
  			throws IOException {
  		super(path, readOnly, lockMode);
  		this.syncMode = syncMode;
- 		FileChannel.MapMode mapMode =
- 				readOnly? FileChannel.MapMode.READ_ONLY: FileChannel.MapMode.READ_WRITE;
- 		this.byteBuffer = channel.map(mapMode, 0, getLength());
  		if(syncMode == RrdNioBackendFactory.SYNC_BACKGROUND && !readOnly) {
  			createSyncTask(syncPeriod);
--- 68,73 ----
  			throws IOException {
  		super(path, readOnly, lockMode);
+ 		map(false, readOnly);
  		this.syncMode = syncMode;
  		if(syncMode == RrdNioBackendFactory.SYNC_BACKGROUND && !readOnly) {
  			createSyncTask(syncPeriod);
***************
*** 55,58 ****
--- 75,93 ----
  	}
  
+ 	private void map(boolean isShorter, boolean readOnly) throws IOException {
+ 		if(isShorter) {
+ 			byteBuffer = null;
+ 			if(SHOULD_GC) {
+ 				System.gc();
+ 			}
+ 		}
+ 		long newLength = getLength();
+ 		if(newLength > 0) {
+ 			FileChannel.MapMode mapMode =
+ 				readOnly? FileChannel.MapMode.READ_ONLY: FileChannel.MapMode.READ_WRITE;
+ 			byteBuffer = channel.map(mapMode, 0, newLength);
+ 		}
+ 	}
+ 
  	private void createSyncTask(int syncPeriod) {
  		syncTask = new TimerTask() {
***************
*** 67,76 ****
  	 * Sets length of the underlying RRD file. This method is called only once, immediately
  	 * after a new RRD file gets created.
! 	 * @param length Length of the RRD file
  	 * @throws IOException Thrown in case of I/O error.
  	 */
! 	protected void setLength(long length) throws IOException {
! 		super.setLength(length);
! 		byteBuffer = channel.map(FileChannel.MapMode.READ_WRITE, 0, length);
  	}
  
--- 102,112 ----
  	 * Sets length of the underlying RRD file. This method is called only once, immediately
  	 * after a new RRD file gets created.
! 	 * @param newLength Length of the RRD file
  	 * @throws IOException Thrown in case of I/O error.
  	 */
! 	protected void setLength(long newLength) throws IOException {
! 		boolean isShorter = newLength < getLength();
! 		super.setLength(newLength);
! 		map(isShorter, false);
  	}
  
***************
*** 120,126 ****
  	 */
  	public void sync() {
! 		synchronized(byteBuffer) {
! 			// System.out.println("** SYNC **");
! 			byteBuffer.force();
  		}
  	}
--- 156,164 ----
  	 */
  	public void sync() {
! 		if(byteBuffer != null) {
! 			synchronized(byteBuffer) {
! 				// System.out.println("** SYNC **");
! 				byteBuffer.force();
! 			}
  		}
  	}