/**
* Performs locking. If returns {@code true}, locking was successful and caller holds the lock.
* Multiple invocations, after lock is acquired, does not have any effect, locking happens only
* once.
*/
public synchronized boolean lock() {
if (fileLock != null) {
return true;
}
try {
randomAccessFile = new RandomAccessFile(lockFile, "rws");
fileLock = randomAccessFile.getChannel().tryLock(0L, 1L, false);
if (fileLock != null) {
randomAccessFile.setLength(0);
randomAccessFile.seek(0);
randomAccessFile.write(payload);
}
} catch (IOException | OverlappingFileLockException e) {
// handle it as null result
fileLock = null;
} finally {
if (fileLock == null) {
release();
return false;
}
}
return true;
}
