org.jcsp.util

Class InfiniteBuffer<T>

java.lang.Object

org.jcsp.util.InfiniteBuffer<T>

All Implemented Interfaces:

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

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

This is used to create a buffered object channel that always accepts and never loses any input.

Description

InfiniteBuffer is an implementation of ChannelDataStore that yields a FIFO buffered semantics for a channel. When empty, the channel blocks readers. However, its capacity is infinite (expanding to whatever is needed so far as the underlying memory system will permit). So, it never gets full and blocks a writer. See the static construction methods of Channel (Channel.one2one(org.jcsp.util.ChannelDataStore) etc.).

The getState method returns EMPTY or NONEMPTYFULL, but never FULL.

An initial size for the buffer can be specified during construction.

See Also:

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

Field Summary

Fields

Modifier and Type	Field and Description
private T[]	buffer The storage for the buffered Objects
private int	counter The number of Objects stored in the InfiniteBuffer
private static int	DEFAULT_SIZE The default size of the buffer
private int	firstIndex The index of the oldest element (when counter > 0)
private int	initialSize The initial size of the buffer
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 and Description
InfiniteBuffer() Construct a new InfiniteBuffer with the default size (of 8).
InfiniteBuffer(int initialSize) Construct a new InfiniteBuffer with the specified initial size.

Method Summary

Modifier and Type	Method and Description
java.lang.Object	clone() Returns a new (and EMPTY) InfiniteBuffer 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 InfiniteBuffer and removes it.
int	getState() Returns the current state of the InfiniteBuffer.
void	put(T value) Puts a new Object into the InfiniteBuffer.
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

DEFAULT_SIZE

private static final int DEFAULT_SIZE

The default size of the buffer

See Also:

Constant Field Values

initialSize

private int initialSize

The initial size of the buffer

buffer

private T[] buffer

The storage for the buffered Objects

counter

private int counter

The number of Objects stored in the InfiniteBuffer

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

InfiniteBuffer

public InfiniteBuffer()

Construct a new InfiniteBuffer with the default size (of 8).

InfiniteBuffer

public InfiniteBuffer(int initialSize)

Construct a new InfiniteBuffer with the specified initial size.

Parameters:

initialSize - the number of Objects the InfiniteBuffer can initially store.

Throws:

BufferSizeError - if size is zero or 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 InfiniteBuffer and removes it.

Pre-condition: getState must not currently return EMPTY.

Specified by:

get in interface ChannelDataStore<T>

Returns:

the oldest Object from the InfiniteBuffer

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 InfiniteBuffer.

Implementation note: if InfiniteBuffer is full, a new internal buffer with double the capacity is constructed and the old data copied across.

Specified by:

put in interface ChannelDataStore<T>

Parameters:

value - the Object to put into the InfiniteBuffer

getState

public int getState()

Returns the current state of the InfiniteBuffer.

Specified by:

getState in interface ChannelDataStore<T>

Returns:

the current state of the InfiniteBuffer (EMPTY or NONEMPTYFULL)

clone

public java.lang.Object clone()

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

Note: Only the initial size and structure of the InfiniteBuffer 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 InfiniteBuffer.

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>