// it is similar to LockedOpenFile with with syscall.LOCK_EX
// mode but along with syscall.LOCK_NB such that the function
// doesn't wait forever but instead returns if it cannot
// acquire a write lock.
func TryLockedOpenFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
	return lockedOpenFile(path, flag, perm, syscall.LOCK_NB)
}

// LockedOpenFile - initializes a new lock and protects

            throws CIFSException {
        this.parent = parent;
        this.wildcard = wildcard;
        this.nameFilter = filter;
        this.searchAttributes = searchAttributes;

        this.treeHandle = th.acquire();
        try {
            this.next = open();
            if ( this.next == null ) {
                doClose();
            }
        }
        catch ( Exception e ) {
            doClose();

        }
        else {
            throw new SmbException("The requested list operations is invalid: " + locator.getURL());
        }

        this.treeHandle = th.acquire();
        try {
            this.next = open();
        }
        catch ( Exception e ) {
            this.treeHandle.release();
            throw e;
        }

    }

        return this.transportContext;
    }


    /**
     * {@inheritDoc}
     *
     * @see jcifs.util.transport.Transport#acquire()
     */
    @Override
    public SmbTransportImpl acquire () {
        return (SmbTransportImpl) super.acquire();
    }


    /**
     * @return the server's encryption key
     */
    @Override
    public byte[] getServerEncryptionKey () {

// it is similar to LockedOpenFile with with syscall.LOCK_EX
// mode but along with syscall.LOCK_NB such that the function
// doesn't wait forever but instead returns if it cannot
// acquire a write lock.
func TryLockedOpenFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
	return lockedOpenFile(path, flag, perm, syscall.F_SETLK)
}

// LockedOpenFile - initializes a new lock and protects

		return
	}

	go func() {
		r := rand.New(rand.NewSource(time.Now().UnixNano()))
		// Leader node (that successfully acquires the lock inside runCallhome)
		// will keep performing the callhome. If the leader goes down for some reason,
		// the lock will be released and another node will acquire it and take over
		// because of this loop.
		for {
			if !globalCallhomeConfig.Enabled() {
				return
			}

			locked = true
		}
	} else {
		if !lm.isWriteLock {
			lm.ref++
			locked = true
		}
	}

	return locked
}

const (
	lockRetryInterval = 50 * time.Millisecond
)

// lockLoop will acquire either a read or a write lock
//
// The call will block until the lock is granted using a built-in
// timing randomized back-off algorithm to try again until successful

    /**
     * @return session increased usage count
     */
    public Transport acquire () {
        long usage = this.usageCount.incrementAndGet();
        if ( log.isTraceEnabled() ) {
            log.trace("Acquire transport " + usage + " " + this);
        }
        return this;
    }


    /**
     * {@inheritDoc}
     *

        Versioning versioning = null;
        try {
            if (metadata != null) {
                try (SyncContext syncContext = syncContextFactory.newInstance(session, true)) {
                    syncContext.acquire(null, Collections.singleton(metadata));

                    if (metadata.getPath() != null && Files.exists(metadata.getPath())) {
                        try (InputStream in = Files.newInputStream(metadata.getPath())) {

### Locks

We have 3 different things that we synchronize on.

#### Http2Connection

This lock guards internal state of each connection. This lock is never held for blocking operations. That means that we acquire the lock, read or write a few fields and release the lock. No I/O and no application-layer callbacks.

#### Http2Stream