//                                                                    ================

    /**
     * Attempts to acquire a distributed lock for the specified operation.
     *
     * @param operationName the operation name used as the lock document ID.
     * @return {@code true} if the lock was acquired.
     */
    public boolean tryStartOperation(final String operationName) {
        return tryStartOperation(operationName, null);

			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

        release();
    }

    /**
     * @return tree handle with increased usage count
     */
    public SmbTreeHandleImpl acquire() {
        if (this.usageCount.incrementAndGet() == 1) {
            this.treeConnection.acquire();
        }
        return this;
    }

    @Override
    public void release() {
        final long us = this.usageCount.decrementAndGet();

        if (this.handle == null || !this.handle.isValid()) {
            // one extra acquire to keep this open till the stream is released
            this.handle =
                    this.file.openUnshared(this.openFlags, this.access, this.sharing, SmbConstants.ATTR_NORMAL, this.options).acquire();
            return this.handle;
        }
        return this.handle.acquire();
    }

    /**
     * Ensures that the file descriptor is openend

        @Test
        @DisplayName("open() acquires handle and closes it")
        void openDelegatesEnsureOpenAndCloses() throws Exception {
            SmbFileInputStream in = newStream();
            in.open();
            // ensureOpen returns acquired handle; try-with-resources must close it
            verify(mockHandle, times(1)).close();
            verify(mockHandle, atLeastOnce()).acquire();
        }

        @Test

		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
			}

* Nginx
* HAProxy

## Let's Encrypt { #lets-encrypt }

Before Let's Encrypt, these **HTTPS certificates** were sold by trusted third parties.

The process to acquire one of these certificates used to be cumbersome, require quite some paperwork and the certificates were quite expensive.

But then **[Let's Encrypt](https://letsencrypt.org/)** was created.

   * cancelled without a call to {@code cancel}, such as by calling {@code
   * setFuture(cancelledFuture)}.
   *
   * <p>Beware of completing a future while holding a lock. Its listeners may do slow work or
   * acquire other locks, risking deadlocks.
   */
  @CanIgnoreReturnValue
  @Override
  public boolean cancel(boolean mayInterruptIfRunning) {
    @RetainedLocalRef Object localValue = value();
    boolean rValue = false;

    } finally {
      if (!satisfied) {
        leave();
      }
    }
  }

  /**
   * Enters this monitor when the guard is satisfied. Blocks at most the given time, including both
   * the time to acquire the lock and the time to wait for the guard to be satisfied, and may be
   * interrupted.
   *
   * @return whether the monitor was entered, which guarantees that the guard is now satisfied

 * only meant as a utility for developers that want to employ the model builder outside of the Maven build system, Maven
 * plugins should always acquire model builder instances via dependency injection. Developers might want to subclass
 * this factory to provide custom implementations for some of the components used by the model builder.
 *