EDU.oswego.cs.dl.util.concurrent
Class Slot

java.lang.Object
  EDU.oswego.cs.dl.util.concurrent.SemaphoreControlledChannel
      EDU.oswego.cs.dl.util.concurrent.Slot

All Implemented Interfaces:

BoundedChannel, Channel, Puttable, Takable

public class Slot
extends SemaphoreControlledChannel

A one-slot buffer, using semaphores to control access. Slots are usually more efficient and controllable than using other bounded buffers implementations with capacity of 1.

Among other applications, Slots can be convenient in token-passing designs: Here. the Slot holds a some object serving as a token, that can be obtained and returned by various threads.

[ Introduction to this package. ]

Field Summary

protected java.lang.Object

item_ The slot

Fields inherited from class EDU.oswego.cs.dl.util.concurrent.SemaphoreControlledChannel

capacity_, putGuard_, takeGuard_

Constructor Summary

Slot()
Create a new Slot using default Semaphore implementations

Slot(java.lang.Class semaphoreClass)
Create a buffer with the given capacity, using the supplied Semaphore class for semaphores.

Method Summary

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
java.lang.Object	peek() Return, but do not remove object at head of Channel, or null if it is empty.

Methods inherited from class EDU.oswego.cs.dl.util.concurrent.SemaphoreControlledChannel

capacity, offer, poll, put, size, take

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 slot

Constructor Detail

Slot

public Slot(java.lang.Class semaphoreClass)
     throws java.lang.NoSuchMethodException,
            java.lang.SecurityException,
            java.lang.InstantiationException,
            java.lang.IllegalAccessException,
            java.lang.reflect.InvocationTargetException

Create a buffer with the given capacity, using the supplied Semaphore class for semaphores.

Throws:

java.lang.NoSuchMethodException - If class does not have constructor that intializes permits

java.lang.SecurityException - if constructor information not accessible

java.lang.InstantiationException - if semaphore class is abstract

java.lang.IllegalAccessException - if constructor cannot be called

java.lang.reflect.InvocationTargetException - if semaphore constructor throws an exception

Slot

public Slot()

Create a new Slot using default Semaphore implementations

Method Detail

insert

protected void insert(java.lang.Object x)

Set the item in preparation for a take

Specified by:

insert in class SemaphoreControlledChannel

extract

protected java.lang.Object extract()

Take item known to exist

Specified by:

extract in class SemaphoreControlledChannel

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.