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

Fields
Modifier and Type Field Description

protected Object item_
The slot
- Fields inherited from class EDU.oswego.cs.dl.util.concurrent.SemaphoreControlledChannel
  capacity_, putGuard_, takeGuard_

Constructor Summary

Constructors
Constructor	Description
`Slot()`	Create a new Slot using default Semaphore implementations
`Slot(Class semaphoreClass)`	Create a buffer with the given capacity, using the supplied Semaphore class for semaphores.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected Object`	`extract()`	Take item known to exist
`protected void`	`insert(Object x)`	Set the item in preparation for a take
`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 Object item_
```
    The slot
- Constructor Detail
  - Slot
```
public Slot(Class semaphoreClass)
     throws NoSuchMethodException,
            SecurityException,
            InstantiationException,
            IllegalAccessException,
            InvocationTargetException
```
    Create a buffer with the given capacity, using the supplied Semaphore class for semaphores.
    
    Throws:
    
    NoSuchMethodException - If class does not have constructor that intializes permits
    
    SecurityException - if constructor information not accessible
    
    InstantiationException - if semaphore class is abstract
    
    IllegalAccessException - if constructor cannot be called
    
    InvocationTargetException - if semaphore constructor throws an exception
  - Slot
```
public Slot()
```
    Create a new Slot using default Semaphore implementations
- Method Detail
  - insert
```
protected void insert(Object x)
```
    Set the item in preparation for a take
    
    Specified by:
    
    insert in class SemaphoreControlledChannel
  - extract
```
protected Object extract()
```
    Take item known to exist
    
    Specified by:
    
    extract in class SemaphoreControlledChannel
  - peek
```
public Object peek()
```
    Description copied from interface: Channel
    
    Return, but do not remove object at head of Channel, or null if it is empty.