Examples of java.nio.channels.FileChannel.tryLock()

java.nio.channels.FileChannel.tryLock()
Attempts to acquire an exclusive lock on this file without blocking.
This is a convenience method for attempting to acquire a maximum length lock on the file. It is equivalent to:
```
 fileChannel.tryLock(0L, Long.MAX_VALUE, false) 
```
The method returns null if the acquisition would result in an overlapped lock with another OS process.
@return the file lock object, or null if the lock wouldoverlap an existing exclusive lock in another OS process. @throws ClosedChannelException the file channel is closed. @throws OverlappingFileLockException Either a lock is already held that overlaps this lock request, or another thread is waiting to acquire a lock that will overlap with this request. @throws IOException if any I/O error occurs

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      sf.deleteOnExit();
      sf.createNewFile();
      raf = new RandomAccessFile(sf,"rw");
      channel = raf.getChannel();
      lock = channel.tryLock();
      
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        System.exit(0);
      }

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                    }
                }


                // get the lock using either try lock or not depending on if we are using timeout or not
                try {
                    lock = timeout > 0 ? channel.tryLock() : channel.lock();
                } catch (IllegalStateException ex) {
                    // Also catch the OverlappingFileLockException here. Do nothing here                    
                }
                if (lock != null) {
                    LOG.trace("Acquired exclusive read lock: {} to file: {}", lock, target);

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        final long dropDeadTime = System.currentTimeMillis() + waitMS;
        final File file = new File(lockTempDir, c.getName() + ".lock");
        randomAccessFile = new RandomAccessFile(file, "rw");
        final FileChannel fileChannel = randomAccessFile.getChannel();
        while (System.currentTimeMillis() < dropDeadTime) {
          fileLock = fileChannel.tryLock();
          if (fileLock != null) {
            break;
          }
          Thread.sleep(250); // 4 attempts/sec
        }

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                /*
                 * if lock is unsupported and IOException thrown, just let the
                 * IOException throws out and exit otherwise it will go into an
                 * undead cycle
                 */
                lock = channel.tryLock();
                if (null == lock) {
                    try {
                        fileStream.close();
                    } catch (Exception e) {
                        // ignore

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                /*
                 * if lock is unsupported and IOException thrown, just let the
                 * IOException throws out and exit otherwise it will go into an
                 * undead cycle
                 */
                lock = channel.tryLock();
                if (null == lock) {
                    try {
                        fileStream.close();
                    } catch (Exception e) {
                        // ignore

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                /*
                 * if lock is unsupported and IOException thrown, just let the
                 * IOException throws out and exit otherwise it will go into an
                 * undead cycle
                 */
                lock = channel.tryLock();
                if (null == lock) {
                    try {
                        fileStream.close();
                    } catch (Exception e) {
                        // ignore

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                /*
                 * if lock is unsupported and IOException thrown, just let the
                 * IOException throws out and exit otherwise it will go into an
                 * undead cycle
                 */
                lock = channel.tryLock();
                if (null == lock) {
                    try {
                        fileStream.close();
                    } catch (Exception e) {
                        // ignore

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                    // We got an IOException while trying to open the file.
                    // Try the next file.
                    continue;
                }
                try {
                    FileLock fl = fc.tryLock();
                    if (fl == null) {
                        // We failed to get the lock.  Try next file.
                        continue;
                    }
                    // We got the lock OK.

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                    FileLock markerLock = null;
                    try {
                        try {
                            markerFile = new RandomAccessFile(marker, "rw");
                            markerChannel = markerFile.getChannel();
                            markerLock = markerChannel.tryLock();
                            inUse = markerLock == null;
                            if (inUse) {
                                LOGGER.config("EP cleanup: the marker " + marker + " is locked in another JVM");
                            } else {
                                LOGGER.config("EP cleanup: " + workDir + " was probably not deleted due to "

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                if (file.getParentFile().exists() || file.getParentFile().mkdirs()) {
                    RandomAccessFile raf =
                        new RandomAccessFile(file, "rw");            
                    FileChannel channel = raf.getChannel();
                    try {
                        FileLock l = channel.tryLock();
                        if (l != null) {
                            synchronized (this) {
                                locks.put(file, l);
                            }
                            return true;

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