Package org.jcsp.util

Class Buffer<T>

java.lang.Object

org.jcsp.util.Buffer<T>

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, ChannelDataStore<T>

public class Buffer<T>
extends java.lang.Object
implements ChannelDataStore<T>, java.io.Serializable

This is used to create a buffered object channel that never loses data.

Description

Buffer is an implementation of ChannelDataStore that yields a blocking FIFO buffered semantics for a channel. See the static construction methods of Channel (Channel.one2one(org.jcsp.util.ChannelDataStore) etc.).

The getState method returns EMPTY, NONEMPTYFULL or FULL according to the state of the buffer.

See Also:

ZeroBuffer, OverWriteOldestBuffer, OverWritingBuffer, OverFlowingBuffer, InfiniteBuffer, Channel, Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private T[]	buffer	The storage for the buffered Objects
private int	counter	The number of Objects stored in the Buffer
private int	firstIndex	The index of the oldest element (when counter > 0)
private int	lastIndex	The index of the next free element (when counter < buffer.length)

Fields inherited from interface org.jcsp.util.ChannelDataStore

EMPTY, FULL, NONEMPTYFULL

Constructor Summary

Constructors

Constructor	Description
Buffer(int size)	Construct a new Buffer with the specified size.

Method Summary

Modifier and Type	Method	Description
java.lang.Object	clone()	Returns a new (and EMPTY) Buffer with the same creation parameters as this one.
void	endGet()	Removes the oldest object from the buffer.
T	get()	Returns the oldest Object from the Buffer and removes it.
int	getState()	Returns the current state of the Buffer.
void	put(T value)	Puts a new Object into the Buffer.
void	removeAll()	Deletes all items in the buffer, leaving it empty.
T	startGet()	Returns the oldest object from the buffer but does not remove it.

Methods inherited from class java.lang.Object

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

Field Detail

buffer

private final T[] buffer

The storage for the buffered Objects

counter

private int counter

The number of Objects stored in the Buffer

firstIndex

private int firstIndex

The index of the oldest element (when counter > 0)

lastIndex

private int lastIndex

The index of the next free element (when counter < buffer.length)

Constructor Detail

Buffer

public Buffer(int size)

Construct a new Buffer with the specified size.

Parameters:

size - the number of Objects the Buffer can store.

Throws:

BufferSizeError - if size is negative. Note: no action should be taken to try/catch this exception - application code generating it is in error and needs correcting.

Method Detail

get

public T get()

Returns the oldest Object from the Buffer and removes it.

Pre-condition: getState must not currently return EMPTY.

Specified by:

get in interface ChannelDataStore<T>

Returns:

the oldest Object from the Buffer

startGet

public T startGet()

Returns the oldest object from the buffer but does not remove it. Pre-condition: getState must not currently return EMPTY.

Specified by:

startGet in interface ChannelDataStore<T>

Returns:

the oldest Object from the Buffer

See Also:

ChannelDataStore.endGet()

endGet

public void endGet()

Removes the oldest object from the buffer.

Specified by:

endGet in interface ChannelDataStore<T>

See Also:

ChannelDataStore.startGet()

put

public void put(T value)

Puts a new Object into the Buffer.

Pre-condition: getState must not currently return FULL.

Specified by:

put in interface ChannelDataStore<T>

Parameters:

value - the Object to put into the Buffer

getState

public int getState()

Returns the current state of the Buffer.

Specified by:

getState in interface ChannelDataStore<T>

Returns:

the current state of the Buffer (EMPTY, NONEMPTYFULL or FULL)

clone

public java.lang.Object clone()

Returns a new (and EMPTY) Buffer with the same creation parameters as this one.

Note: Only the size and structure of the Buffer is cloned, not any stored data.

Specified by:

clone in interface ChannelDataStore<T>

Overrides:

clone in class java.lang.Object

Returns:

the cloned instance of this Buffer

removeAll

public void removeAll()

Description copied from interface: ChannelDataStore

Deletes all items in the buffer, leaving it empty.

Specified by:

removeAll in interface ChannelDataStore<T>