com.atlassian.utt.concurrency

Class Barrier

java.lang.Object

com.atlassian.utt.concurrency.Barrier

public class Barrier
extends Object

Simple self-timing-out barrier for building multi-threaded tests.

Since:

v0.0.1

Field Summary

Fields

Modifier and Type	Field and Description
static long	DEFAULT_TIMEOUT The default timeout that will be used by await().
static String	DEFAULT_TIMEOUT_PROPERTY A system property that may be used to override the value of DEFAULT_TIMEOUT: "com.atlassian.utt.concurrency.Barrier.DEFAULT_TIMEOUT".

Constructor Summary

Constructors

Constructor and Description
Barrier()

Method Summary

Modifier and Type	Method and Description
void	await() Waits DEFAULT_TIMEOUT for the barrier to be signalled.
void	await(long timeout) Waits the specified time in milliseconds for the barrier to be signalled.
static long	getDefaultTimeout() Returns the DEFAULT_TIMEOUT, or whatever value DEFAULT_TIMEOUT_PROPERTY specified to override it with.
void	signal() Signals (drops) this barrier.
boolean	trySignal() Attempts to signal this barrier.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_TIMEOUT_PROPERTY

public static final String DEFAULT_TIMEOUT_PROPERTY

A system property that may be used to override the value of DEFAULT_TIMEOUT: "com.atlassian.utt.concurrency.Barrier.DEFAULT_TIMEOUT".

See Also:

Constant Field Values

DEFAULT_TIMEOUT

public static final long DEFAULT_TIMEOUT

The default timeout that will be used by await().

This is meant to make the test time out rather than deadlock indefinitely when the test does not follow the expected logical pathway. If you are trying to debug something, then you may need to set it to a much larger value to prevent barriers from timing out while you step through the tests.

See Also:

DEFAULT_TIMEOUT_PROPERTY, Constant Field Values

Constructor Detail

Barrier

public Barrier()

Method Detail

getDefaultTimeout

public static long getDefaultTimeout()

Returns the DEFAULT_TIMEOUT, or whatever value DEFAULT_TIMEOUT_PROPERTY specified to override it with.

Returns:

the default barrier timeout

signal

public void signal()

Signals (drops) this barrier.

Once the barrier has been signalled, it can't be signalled again or re-raised — it is done. Since this is meant for coordinating various threads within a test, getting signalled more than once probably means that someone has made a mistake. If it really does make sense for the barrier to get signalled multiple times, you probably want a normal CyclicBarrier, or maybe just to use trySignal() if it is only necessary to block the first time that something is called.

Throws:

AssertionError - if the barrier has already been signalled by somebody else

trySignal

public boolean trySignal()

Attempts to signal this barrier.

As documented for signal(), a Barrier may only be signalled once. If for some reason you want to be able to drop it from somewhere that gets called multiple times and don't mind that more than one attempt is made to drop the barrier, then you can use trySignal() instead.

Returns:

true if the barrier is successfully signalled; false if unable to signal the barrier because this has already happened.

await

public void await()

Waits DEFAULT_TIMEOUT for the barrier to be signalled.

Throws:

AssertionError - if this thread is interrupted while awaiting the signal or if the timeout expires without the barrier being signalled.

await

public void await(long timeout)

Waits the specified time in milliseconds for the barrier to be signalled.

Throws:

AssertionError - if this thread is interrupted while awaiting the signal or if the timeout expires without the barrier being signalled.