Package org.jcsp.util

Class OverFlowingBuffer

java.lang.Object
org.jcsp.util.OverFlowingBuffer
All Implemented Interfaces:
Serializable, Cloneable, ChannelDataStore

public class OverFlowingBuffer extends Object implements ChannelDataStore, Serializable
This is used to create a buffered object channel that always accepts input, discarding its last entered data if full.

Description

It is an implementation of ChannelDataStore that yields a FIFO buffered semantics for a channel. When empty, the channel blocks readers. When full, a writer will be accepted but the written value overflows the buffer and is lost to the channel. See the static construction methods of Channel (Channel.one2one(org.jcsp.util.ChannelDataStore) etc.).

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

Author:
P.D. Austin
See Also:
  • Field Summary

    Fields inherited from interface org.jcsp.util.ChannelDataStore

    EMPTY, FULL, NONEMPTYFULL
  • Constructor Summary

    Constructors
    Constructor
    Description
    Construct a new OverFlowingBuffer with the specified size.
  • Method Summary

    Modifier and Type
    Method
    Description
    Returns a new (and EMPTY) OverFlowingBuffer with the same creation parameters as this one.
    void
    Removes the oldest object from the buffer.
    get()
    Returns the oldest Object from the OverFlowingBuffer and removes it.
    int
    Returns the current state of the OverFlowingBuffer.
    void
    put(Object value)
    Puts a new Object into the OverFlowingBuffer.
    void
    Deletes all items in the buffer, leaving it empty.
    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 Details

    • OverFlowingBuffer

      public OverFlowingBuffer(int size)
      Construct a new OverFlowingBuffer with the specified size.
      Parameters:
      size - the number of Objects the OverFlowingBuffer can 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 Details

    • get

      public Object get()
      Returns the oldest Object from the OverFlowingBuffer and removes it.

      Pre-condition: getState must not currently return EMPTY.

      Specified by:
      get in interface ChannelDataStore
      Returns:
      the oldest Object from the OverFlowingBuffer
    • 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:
    • endGet

      public void endGet()
      Removes the oldest object from the buffer.
      Specified by:
      endGet in interface ChannelDataStore
      See Also:
    • put

      public void put(Object value)
      Puts a new Object into the OverFlowingBuffer.

      If OverFlowingBuffer is full, the item is discarded.

      Specified by:
      put in interface ChannelDataStore
      Parameters:
      value - the Object to put into the OverFlowingBuffer
    • getState

      public int getState()
      Returns the current state of the OverFlowingBuffer.
      Specified by:
      getState in interface ChannelDataStore
      Returns:
      the current state of the OverFlowingBuffer (EMPTY or NONEMPTYFULL)
    • clone

      public Object clone()
      Returns a new (and EMPTY) OverFlowingBuffer with the same creation parameters as this one.

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

      Specified by:
      clone in interface ChannelDataStore
      Overrides:
      clone in class Object
      Returns:
      the cloned instance of this OverFlowingBuffer.
    • removeAll

      public void removeAll()
      Description copied from interface: ChannelDataStore
      Deletes all items in the buffer, leaving it empty.
      Specified by:
      removeAll in interface ChannelDataStore