import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
+import java.io.RandomAccessFile;
import java.nio.channels.FileLock;
/**
* transient object representing a file lock
- *
+ * This lock should hold for all processes interacting in a session.
*
* @author jimp
*
public class Lock {
FileLock lock = null;
+ RandomAccessFile rafile=null;
/**
* creates a valid Lock (test with <method>isLocked</method>)
* if a lock could be obtained for <param>lockfile</param>
public Lock(java.io.File lockfile) {
// try and get a lock.
lock = null;
-
+
try {
if (!lockfile.exists())
if (!lockfile.createNewFile()) {
return;
}
-
- lock = new FileOutputStream(lockfile).getChannel().tryLock();
+
+ lock = (rafile=new RandomAccessFile(lockfile,"rw")).getChannel().tryLock();
+ if (lock==null || !lock.isValid())
+ // failed to get lock. Close the file channel
+ rafile.getChannel().close();
} catch (FileNotFoundException e) {
System.err.println("Error! Couldn't create a lockfile at "
+ lockfile.getAbsolutePath());
e.printStackTrace();
}
}
-
+
boolean isLocked() {
if (lock != null && lock.isValid()) {
return true;
}
return false;
}
-
+ public void release() {
+ try {
+ if (lock!=null && lock.isValid())
+ lock.release();
+ if (rafile!=null && rafile.getChannel().isOpen())
+ rafile.getChannel().close();
+ } catch (IOException e) {
+ // TODO Auto-generated catch block
+ e.printStackTrace(System.err);
+ }
+ lock=null;
+ rafile=null;
+ }
+
/* Explicitly release lock (probably don't need to do this!)
* @see java.lang.Object#finalize()
*/
protected void finalize() throws Throwable {
- if (lock!=null)
- lock.release();
+ release();
super.finalize();
}