try {
        // requireNonNull is safe, as discussed above.
        Runnable localTask = requireNonNull(task);
        task = null;
        localTask.run();
        // Now check if our task attempted to reentrantly execute the next task.
        Runnable queuedTask;
        Executor queuedExecutor;
        // Intentionally using non-short-circuit operator
        while ((queuedTask = executingTaskQueue.nextTask) != null

## Version 4.5.0

_2020-04-06_

**This release fixes a severe bug where OkHttp incorrectly detected and recovered from unhealthy
connections.** Stale or canceled connections were incorrectly attempted when they shouldn't have
been, leading to rare cases of infinite retries. Please upgrade to this release!

 *  Fix: don't return stale DNS entries in `DnsOverHttps`. We were caching DNS results indefinitely

## Version 3.4.2

_2016-11-03_

 *  Fix: Recover gracefully when an HTTP/2 connection is shutdown. We had a
    bug where shutdown HTTP/2 connections were considered usable. This caused
    infinite loops when calls attempted to recover.


## Version 3.4.1

_2016-07-10_

 *  **Fix a major bug in encoding HTTP headers.** In 3.4.0 and 3.4.0-RC1 OkHttp
    had an off-by-one bug in our HPACK encoder. This bug could have caused the

		// to attempt a heal on the object.
		if countErrs(errs, errDiskNotFound) > 0 {
			return
		}

		var missingBlocks int
		for i := range errs {
			if IsErr(errs[i],
				errFileNotFound,
				errFileVersionNotFound,
				errFileCorrupt,
			) {
				missingBlocks++
			}
		}

		// if missing metadata can be reconstructed, attempt to reconstruct.

      acquiredLockList.add(node);
    }
  }

  /**
   * CycleDetectingLock implementations must call this method in a {@code finally} clause after any
   * attempt to change the lock state, including both lock and unlock attempts. Failure to do so can
   * result in corrupting the acquireLocks set.
   */
  private static void lockStateChanged(CycleDetectingLock lock) {
    if (!lock.isAcquiredByCurrentThread()) {

	})

	// initialize the object layer.
	defer setObjectLayer(z)

	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	attempt := 1
	for {
		var err error
		bootstrapTrace(fmt.Sprintf("poolMeta.Init: loading pool metadata, attempt: %d", attempt), func() {
			err = z.Init(ctx) // Initializes all pools.
		})
		if err != nil {
			if !configRetriableErrors(err) {

const (
	// StateUnconnected is the initial state of a connection.
	// When the first message is sent it will attempt to connect.
	StateUnconnected = iota

	// StateConnecting is the state from StateUnconnected while the connection is attempted to be established.
	// After this connection will be StateConnected or StateConnectionError.
	StateConnecting

	switch cache.Info.Name {
	case "", dataUsageRoot:
		return cache, errors.New("internal error: root scan attempted")
	}
	updatePath, closeDisk := globalScannerMetrics.currentPathUpdater(basePath, cache.Info.Name)
	defer closeDisk()

	s := folderScanner{
		root:                  basePath,
		getSize:               getSize,

    // We know that a fresh connection was created if the server recorded a request with sequence
    // number 0. Since the client may have attempted to reuse the broken connection just before
    // creating a fresh connection, the server may have recorded 2 requests at this point. The order
    // of recording is non-deterministic.
    val requestAfter = server.takeRequest()

    resolve_symlinks: (Bool) Translate symbolic links into the real filepath.
    n_ask_attempts: (Integer) Number of times to query for valid input before
      raising an error and quitting.

  Returns:
    [String] The value of var_name after querying for input.

  Raises:
    UserInputError: if a query has been attempted n_ask_attempts times without
      success, assume that the user has made a scripting error, and will