org.jcsp.util
Class InfiniteBuffer

java.lang.Object
  org.jcsp.util.InfiniteBuffer

All Implemented Interfaces:

Serializable, Cloneable, ChannelDataStore

public class InfiniteBuffer
extends Object
implements ChannelDataStore, 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.

Author:

P.D. Austin

See Also:

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

Field Summary

Fields inherited from interface org.jcsp.util.ChannelDataStore

EMPTY, FULL, NONEMPTYFULL

Constructor Summary

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

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.
Object	get() Returns the oldest Object from the InfiniteBuffer and removes it.
int	getState() Returns the current state of the InfiniteBuffer.
void	put(Object value) Puts a new Object into the InfiniteBuffer.
void	removeAll() Deletes all items in the buffer, leaving it empty.
Object	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

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 Object 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

Returns:

the oldest Object from the InfiniteBuffer

startGet

public Object 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

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

See Also:

ChannelDataStore.startGet()

put

public void put(Object 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

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

Returns:

the current state of the InfiniteBuffer (EMPTY or NONEMPTYFULL)

clone

public 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

Overrides:

clone in class 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