com.rabbitmq.utility

Class BlockingCell<T>

java.lang.Object

com.rabbitmq.utility.BlockingCell<T>

Direct Known Subclasses:

BlockingValueOrException

public class BlockingCell<T>
extends Object

Simple one-shot IPC mechanism. Essentially a one-place buffer that cannot be emptied once filled.

Constructor Summary

Constructors

Constructor and Description
BlockingCell() Instantiate a new BlockingCell waiting for a value of the specified type.

Method Summary

Modifier and Type	Method and Description
T	get() Wait for a value, and when one arrives, return it (without clearing it).
T	get(long timeout) Wait for a value, and when one arrives, return it (without clearing it).
void	set(T newValue) Store a value in this BlockingCell, throwing IllegalStateException if the cell already has a value.
boolean	setIfUnset(T newValue) Store a value in this BlockingCell if it doesn't already have a value.
T	uninterruptibleGet() As get(), but catches and ignores InterruptedException, retrying until a value appears.
T	uninterruptibleGet(int timeout) As get(long timeout), but catches and ignores InterruptedException, retrying until a value appears or until specified timeout is reached.

Methods inherited from class java.lang.Object

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

Constructor Detail

BlockingCell

public BlockingCell()

Instantiate a new BlockingCell waiting for a value of the specified type.

Method Detail

get

public T get()
      throws InterruptedException

Wait for a value, and when one arrives, return it (without clearing it). If there's already a value present, there's no need to wait - the existing value is returned.

Returns:

the waited-for value

Throws:

InterruptedException - if this thread is interrupted

get

public T get(long timeout)
      throws InterruptedException,
             TimeoutException

Wait for a value, and when one arrives, return it (without clearing it). If there's already a value present, there's no need to wait - the existing value is returned. If timeout is reached and value hasn't arrived, TimeoutException is thrown.

Parameters:

timeout - timeout in milliseconds. -1 effectively means infinity

Returns:

the waited-for value

Throws:

InterruptedException - if this thread is interrupted

TimeoutException

uninterruptibleGet

public T uninterruptibleGet()

As get(), but catches and ignores InterruptedException, retrying until a value appears.

Returns:

the waited-for value

uninterruptibleGet

public T uninterruptibleGet(int timeout)
                     throws TimeoutException

As get(long timeout), but catches and ignores InterruptedException, retrying until a value appears or until specified timeout is reached. If timeout is reached, TimeoutException is thrown. We also use System.nanoTime() to behave correctly when system clock jumps around.

Parameters:

timeout - timeout in milliseconds. -1 means 'infinity': never time out

Returns:

the waited-for value

Throws:

TimeoutException

set

public void set(T newValue)

Store a value in this BlockingCell, throwing IllegalStateException if the cell already has a value.

Parameters:

newValue - the new value to store

setIfUnset

public boolean setIfUnset(T newValue)

Store a value in this BlockingCell if it doesn't already have a value.

Parameters:

newValue - the new value to store

Returns:

true if this call to setIfUnset actually updated the BlockingCell; false if the cell already had a value.