com.rabbitmq.jms.util

Class EntryExitManager

java.lang.Object

com.rabbitmq.jms.util.EntryExitManager

public class EntryExitManager
extends java.lang.Object

Manages threads entering and exiting a notional region. Entry is controlled by a gate, and exit is signalled by Completion. Can block threads entering, abort waiting threads and wait for threads which have entered to exit.

When the gate is open, threads are not prevented from entering. When the gate is closed, threads will block on enter(...), until the gate is opened (by some other thread).

Threads which enter the region must leave it by calling exit(). This will signal the exit of the thread. The manager offers a method waitToClear(...) which will block until all the currently entered threads have exited the region. Threads which enter during waitToClear(long, java.util.concurrent.TimeUnit) are not detected.

closeGate()

will close the gate to all threads,

openGate()

will open the gate, unblocking all waiting threads,

enter(...)

will allow the calling thread to enter the region, or block if the gate is closed,

exit()

will signal the calling thread to exit the region,

waitToClear(...)

will block until all the threads currently in the region have exited,

abortWaiters()

will reject all waiting threads with an AbortedException.

Constructor Summary

Constructors

Constructor and Description
EntryExitManager() Create an EntryExitManager, initially closed.

Method Summary

Modifier and Type	Method and Description
void	abortWaiters() Abort all threads waiting to enter with an AbortedException.
boolean	closeGate() Close the gate, if allowed, so subsequent enter()ing threads will block.
boolean	enter(long timeout, java.util.concurrent.TimeUnit unit) Returns true immediately if the gate is open.
boolean	enter(TimeTracker tt) Returns true immediately if the gate is open.
void	exit() This thread is exiting the region.
boolean	isClosed() Is the gate closed?
boolean	openGate() Opens the gate and wakes up all waiting threads.
boolean	waitToClear(long timeout, java.util.concurrent.TimeUnit unit) Wait for current threads to exit region.
boolean	waitToClear(TimeTracker tt) Wait for current threads to exit region.

Methods inherited from class java.lang.Object

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

Constructor Detail

EntryExitManager

public EntryExitManager()

Create an EntryExitManager, initially closed.

Method Detail

isClosed

public boolean isClosed()

Is the gate closed?

Returns:

true if the gate is closed, false otherwise.

closeGate

public boolean closeGate()

Close the gate, if allowed, so subsequent enter()ing threads will block.

Returns:

true in all cases.

openGate

public boolean openGate()

Opens the gate and wakes up all waiting threads. Does not block.

Returns:

true in all cases.

enter

public boolean enter(long timeout,
                     java.util.concurrent.TimeUnit unit)
              throws java.lang.InterruptedException,
                     AbortedException

Returns true immediately if the gate is open. Otherwise if the gate is closed the thread blocks until one of the following occurs:

gate is opened (by another thread);

timeout expires before gate is opened.

Parameters:

timeout - the time to wait for the gate to open.

unit - the time unit of the timeout argument.

Returns:

false if timeout was reached before gate opens; true if gate is open or opens while we are waiting.

Throws:

java.lang.InterruptedException - if the callers thread is interrupted while waiting.

AbortedException - if this thread is aborted by a stop() or close() while waiting.

enter

public boolean enter(TimeTracker tt)
              throws java.lang.InterruptedException,
                     AbortedException

Returns true immediately if the gate is open. Otherwise if the gate is closed the thread blocks until one of the following occurs:

gate is opened (by another thread);

timeout expires before gate is opened.

Parameters:

tt - the time tracker used to wait for the gate to open.

Returns:

false if timeout was reached before gate opens; true if gate is open or opens while we are waiting.

Throws:

java.lang.InterruptedException - if the callers thread is interrupted while waiting.

AbortedException - if this thread is aborted by a stop() or close() while waiting.

exit

public void exit()

This thread is exiting the region. Must be called eventually by the thread that entered the region.

waitToClear

public boolean waitToClear(long timeout,
                           java.util.concurrent.TimeUnit unit)
                    throws java.lang.InterruptedException

Wait for current threads to exit region.

Parameters:

timeout - max time to wait in units.

unit - of time measurement for timeout.

Returns:

true if they all exited in time, false otherwise.

Throws:

java.lang.InterruptedException - if thread is interrupted and is waiting.

waitToClear

public boolean waitToClear(TimeTracker tt)
                    throws java.lang.InterruptedException

Wait for current threads to exit region.

Parameters:

tt - timeout tracker.

Returns:

true if they all exited in time, false otherwise.

Throws:

java.lang.InterruptedException - if thread is interrupted and is waiting.

abortWaiters

public void abortWaiters()

Abort all threads waiting to enter with an AbortedException.