org.dbunit.util.concurrent
Class SynchronousChannel

java.lang.Object
  org.dbunit.util.concurrent.SynchronousChannel

All Implemented Interfaces:

BoundedChannel, Channel, Puttable, Takable

public class SynchronousChannel

extends java.lang.Object

implements BoundedChannel

A rendezvous channel, similar to those used in CSP and Ada. Each put must wait for a take, and vice versa. Synchronous channels are well suited for handoff designs, in which an object running in one thread must synch up with an object running in another thread in order to hand it some information, event, or task.

If you only need threads to synch up without exchanging information, consider using a Barrier. If you need bidirectional exchanges, consider using a Rendezvous.

[ Introduction to this package. ]

See Also:

CyclicBarrier, Rendezvous

Nested Class Summary

protected static class

SynchronousChannel.Queue Simple FIFO queue class to hold waiting puts/takes.

Field Summary

protected static java.lang.Object	CANCELLED Special marker used in queue nodes to indicate that the thread waiting for a change in the node has timed out or been interrupted.
protected SynchronousChannel.Queue	waitingPuts
protected SynchronousChannel.Queue	waitingTakes

Constructor Summary

SynchronousChannel()

Method Summary

int	capacity() Return the maximum number of elements that can be held.
boolean	offer(java.lang.Object x, long msecs) Place item in channel only if it can be accepted within msecs milliseconds.
java.lang.Object	peek() Return, but do not remove object at head of Channel, or null if it is empty.
java.lang.Object	poll(long msecs) Return and remove an item from channel only if one is available within msecs milliseconds.
void	put(java.lang.Object x) Place item in the channel, possibly waiting indefinitely until it can be accepted.
java.lang.Object	take() Return and remove an item from channel, possibly waiting indefinitely until such an item exists.

Methods inherited from class java.lang.Object

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

Field Detail

CANCELLED

protected static final java.lang.Object CANCELLED

Special marker used in queue nodes to indicate that the thread waiting for a change in the node has timed out or been interrupted.

waitingPuts

protected final SynchronousChannel.Queue waitingPuts

waitingTakes

protected final SynchronousChannel.Queue waitingTakes

Constructor Detail

SynchronousChannel

public SynchronousChannel()

Method Detail

capacity

public int capacity()

Description copied from interface: BoundedChannel

Return the maximum number of elements that can be held.

Specified by:

capacity in interface BoundedChannel

Returns:

zero -- Synchronous channels have no internal capacity.

peek

public java.lang.Object peek()

Description copied from interface: Channel

Return, but do not remove object at head of Channel, or null if it is empty.

Specified by:

peek in interface Channel

Returns:

null -- Synchronous channels do not hold contents unless actively taken

put

public void put(java.lang.Object x)
         throws java.lang.InterruptedException

Description copied from interface: Channel

Place item in the channel, possibly waiting indefinitely until it can be accepted. Channels implementing the BoundedChannel subinterface are generally guaranteed to block on puts upon reaching capacity, but other implementations may or may not block.

Specified by:

put in interface Channel

Parameters:

x - the element to be inserted. Should be non-null.

Throws:

java.lang.InterruptedException - if the current thread has been interrupted at a point at which interruption is detected, in which case the element is guaranteed not to be inserted. Otherwise, on normal return, the element is guaranteed to have been inserted.

take

public java.lang.Object take()
                      throws java.lang.InterruptedException

Description copied from interface: Channel

Return and remove an item from channel, possibly waiting indefinitely until such an item exists.

Specified by:

take in interface Channel

Returns:

some item from the channel. Different implementations may guarantee various properties (such as FIFO) about that item

Throws:

java.lang.InterruptedException - if the current thread has been interrupted at a point at which interruption is detected, in which case state of the channel is unchanged.

offer

public boolean offer(java.lang.Object x,
                     long msecs)
              throws java.lang.InterruptedException

Description copied from interface: Channel

Place item in channel only if it can be accepted within msecs milliseconds. The time bound is interpreted in a coarse-grained, best-effort fashion.

Specified by:

offer in interface Channel

Parameters:

x - the element to be inserted. Should be non-null.

msecs - the number of milliseconds to wait. If less than or equal to zero, the method does not perform any timed waits, but might still require access to a synchronization lock, which can impose unbounded delay if there is a lot of contention for the channel.

Returns:

true if accepted, else false

Throws:

java.lang.InterruptedException - if the current thread has been interrupted at a point at which interruption is detected, in which case the element is guaranteed not to be inserted (i.e., is equivalent to a false return).

poll

public java.lang.Object poll(long msecs)
                      throws java.lang.InterruptedException

Description copied from interface: Channel

Return and remove an item from channel only if one is available within msecs milliseconds. The time bound is interpreted in a coarse grained, best-effort fashion.

Specified by:

poll in interface Channel

Parameters:

msecs - the number of milliseconds to wait. If less than or equal to zero, the operation does not perform any timed waits, but might still require access to a synchronization lock, which can impose unbounded delay if there is a lot of contention for the channel.

Returns:

some item, or null if the channel is empty.

Throws:

java.lang.InterruptedException - if the current thread has been interrupted at a point at which interruption is detected, in which case state of the channel is unchanged (i.e., equivalent to a null return).