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org.ematgine.utils.concurrent
Class SynchronousChannel  

java.lang.Object
  org.ematgine.utils.concurrent.SynchronousChannel

All Implemented Interfaces:

BoundedChannel, Channel, Puttable, Takable

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public class SynchronousChannel

extends java.lang.Object

implements BoundedChannel

[ Introduction to this package. ]

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. This implementation uses WaiterPreferenceSemaphores to help avoid infinite overtaking among multiple threads trying to perform puts or takes.

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

For a usage example, see the implementation of PooledExecutor

[ Introduction to this package. ]

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Field Summary
protected  java.lang.Object	item_           The item currently being transferred.
protected  Semaphore	itemAvailable_           (binary) Semaphore that is released when an item has been put, so a take may proceed.
protected  Semaphore	itemTaken_           (binary) Semaphore that is released when an item has been taken, so a put may proceed.
protected  java.lang.Object	onePut_           Lock to ensure that only one put at a time proceeds
protected  Semaphore	unclaimedTakers_           Semaphore maintaining count of number of takes that are waiting for puts.

 

Constructor Summary

SynchronousChannel()           Create a new channel.

 

Method Summary
int	capacity()           Return the maximum number of elements that can be held.
protected  void	doPut(java.lang.Object x)
protected  java.lang.Object	doTake(boolean timed, long msecs)
protected  java.lang.Object	extract()           Take item known to exist
protected  void	insert(java.lang.Object x)           Set the item in preparation for a take
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

item_

protected java.lang.Object item_

The item currently being transferred.

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unclaimedTakers_

protected Semaphore unclaimedTakers_

Semaphore maintaining count of number of takes that are waiting for puts.

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itemAvailable_

protected Semaphore itemAvailable_

(binary) Semaphore that is released when an item has been put, so a take may proceed.

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itemTaken_

protected Semaphore itemTaken_

(binary) Semaphore that is released when an item has been taken, so a put may proceed. Since only one thread at a time can ever be waiting on this, fairness is not important, so we use cheapest implementation.

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onePut_

protected java.lang.Object onePut_

Lock to ensure that only one put at a time proceeds

Constructor Detail

SynchronousChannel

public SynchronousChannel()

Create a new channel.

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

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insert

protected void insert(java.lang.Object x)

Set the item in preparation for a take

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extract

protected java.lang.Object extract()

Take item known to exist

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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

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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

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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

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doTake

protected java.lang.Object doTake(boolean timed,
                                  long msecs)
                           throws java.lang.InterruptedException

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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

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doPut

protected void doPut(java.lang.Object x)

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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

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> org >> ematgine >> utils >> [ concurrent overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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