*/
  @GuardedBy("lock")
  private int runningTasks = 0;

  @GuardedBy("lock")
  private boolean shutdown = false;

  @Override
  public void execute(Runnable command) {
    startTask();
    try {
      command.run();
    } finally {
      endTask();
    }
  }

  @Override
  public boolean isShutdown() {
    synchronized (lock) {
      return shutdown;
    }
  }

            }
        } finally {
            lock.writeLock().unlock();
        }
    }

    /**
     * Remove a child entry
     *
     * @param childName child file name
     */
    public void removeChild(String childName) {
        lock.writeLock().lock();
        try {
            if (children.remove(childName) != null) {

```sh
aws s3api put-object --bucket testbucket --key lockme --object-lock-mode GOVERNANCE --object-lock-retain-until-date "2019-11-20"  --body /etc/issue
```

    for (int i = 0; i < reps; i++) {
      lock.lock();
      lock.unlock();
    }
  }

  @Benchmark
  void orderedPlainLocks(int reps) {
    lockAndUnlockNested(plainLocks, reps);
  }

  @Benchmark
  void orderedCycleDetectingLocks(int reps) {
    lockAndUnlockNested(detectingLocks, reps);
  }

  private static void lockAndUnlockNested(Lock[] locks, int reps) {

     * always under a lock.
     */
    private static final class SupplantableFuture implements Cancellable {
      private final ReentrantLock lock;

      @GuardedBy("lock")
      private Future<@Nullable Void> currentFuture;

      SupplantableFuture(ReentrantLock lock, Future<@Nullable Void> currentFuture) {
        this.lock = lock;
        this.currentFuture = currentFuture;
      }

     * always under a lock.
     */
    private static final class SupplantableFuture implements Cancellable {
      private final ReentrantLock lock;

      @GuardedBy("lock")
      private Future<@Nullable Void> currentFuture;

      SupplantableFuture(ReentrantLock lock, Future<@Nullable Void> currentFuture) {
        this.lock = lock;
        this.currentFuture = currentFuture;
      }

			buf.Reset()
			bytebufferpool.Put(buf)
		}()

		block := newMetacacheWriter(buf, 1<<20)
		defer block.Close()
		finishBlock := func() {
			if err := block.Close(); err != nil {
				w.streamErr = err
				return
			}
			current.data = buf.Bytes()
			w.streamErr = nextBlock(&current)
			// Prepare for next
			current.n++
			buf.Reset()
			block.Reset(buf)
			current.First = ""
		}

     * error-prone code like:
     *
     * Striped<Lock> stripedLock = Striped.lazyWeakXXX(...)'
     * Iterable<Lock> locks = stripedLock.bulkGet(keys);
     * for (Lock lock : locks) {
     *   lock.lock();
     * }
     * operation();
     * for (Lock lock : locks) {
     *   lock.unlock();
     * }
     *

     * returned.
     *
     * If upstream would be selected but another thread is already reading upstream this will
     * block until that read completes. It is possible to time out while waiting for that.
     */
    @Throws(IOException::class)
    override fun read(
      sink: Buffer,
      byteCount: Long,
    ): Long {
      check(fileOperator != null)

func (t *transitionState) addLastDayStats(tier string, ts tierStats) {
	t.lastDayMu.Lock()
	defer t.lastDayMu.Unlock()

	if _, ok := t.lastDayStats[tier]; !ok {
		t.lastDayStats[tier] = &lastDayTierStats{}
	}
	t.lastDayStats[tier].addStats(ts)
}

func (t *transitionState) getDailyAllTierStats() DailyAllTierStats {
	t.lastDayMu.RLock()
	defer t.lastDayMu.RUnlock()