Package org.dbunit.util.concurrent

Class BoundedBuffer

java.lang.Object
org.dbunit.util.concurrent.BoundedBuffer
All Implemented Interfaces:
BoundedChannel, Channel, Puttable, Takable
public class BoundedBuffer extends Object implements BoundedChannel
Efficient array-based bounded buffer class. Adapted from CPJ, chapter 8, which describes design.

[ Introduction to this package. ]

Since:
? (pre 2.1)
Version:
$Revision$ $Date$
Author:
Doug Lea, Last changed by: $Author$

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected final Object[]
    array_
    The elements.
    protected int
    emptySlots_
    Number of free slots (capacity - length).
    protected final Object
    putMonitor_
    Helper monitor to handle puts.
    protected int
    putPtr_
    Circular index of the next slot to put into.
    protected int
    takePtr_
    Circular index of the next element to take.
    protected int
    usedSlots_
    Number of occupied slots (the buffer's length).

  • Constructor Summary

    Constructors
    Constructor
    Description
    BoundedBuffer()
    Create a buffer with the current default capacity
    BoundedBuffer(int capacity)
    Create a BoundedBuffer with the given capacity.

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    capacity()
    Return the maximum number of elements that can be held.
    protected final Object
    extract()
    Removes and returns the element at takePtr_.
    protected void
    incEmptySlots()
    Increments the empty-slot count and wakes a thread waiting to put.
    protected void
    incUsedSlots()
    Increments the used-slot count and wakes a thread waiting to take.
    protected final void
    insert(Object x)
    Inserts the given element into the buffer at putPtr_.
    boolean
    offer(Object x, long msecs)
    Place item in channel only if it can be accepted within msecs milliseconds.
    Object
    peek()
    Return, but do not remove object at head of Channel, or null if it is empty.
    Object
    poll(long msecs)
    Return and remove an item from channel only if one is available within msecs milliseconds.
    void
    put(Object x)
    Place item in the channel, possibly waiting indefinitely until it can be accepted.
    int
    size()
    Return the number of elements in the buffer.
    Object
    take()
    Return and remove an item from channel, possibly waiting indefinitely until such an item exists.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • array_

      protected final Object[] array_
      The elements.

    • takePtr_

      protected int takePtr_
      Circular index of the next element to take.

    • putPtr_

      protected int putPtr_
      Circular index of the next slot to put into.

    • usedSlots_

      protected int usedSlots_
      Number of occupied slots (the buffer's length).

    • emptySlots_

      protected int emptySlots_
      Number of free slots (capacity - length).

    • putMonitor_

      protected final Object putMonitor_
      Helper monitor to handle puts.

  • Constructor Details

    • BoundedBuffer

      public BoundedBuffer(int capacity) throws IllegalArgumentException
      Create a BoundedBuffer with the given capacity.
      Parameters:
      capacity - the maximum number of elements the buffer can hold.
      Throws:
      IllegalArgumentException - if capacity less or equal to zero

    • BoundedBuffer

      public BoundedBuffer()
      Create a buffer with the current default capacity

  • Method Details

    • size

      public int size()
      Return the number of elements in the buffer. This is only a snapshot value, that may change immediately after returning.
      Returns:
      the number of elements in the buffer.

    • capacity

      public int capacity()
      Description copied from interface: BoundedChannel
      Return the maximum number of elements that can be held.
      Specified by:
      capacity in interface BoundedChannel
      Returns:
      the capacity of this channel.

    • incEmptySlots

      protected void incEmptySlots()
      Increments the empty-slot count and wakes a thread waiting to put.

    • incUsedSlots

      protected void incUsedSlots()
      Increments the used-slot count and wakes a thread waiting to take.

    • insert

      protected final void insert(Object x)
      Inserts the given element into the buffer at putPtr_.
      Parameters:
      x - the element to insert.

    • extract

      protected final Object extract()
      Removes and returns the element at takePtr_.
      Returns:
      the removed element.

    • 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.
      Specified by:
      peek in interface Channel
      Returns:
      the object at the head of the channel, or null if it is empty.

    • put

      public void put(Object x) throws InterruptedException
      Description copied from interface: Channel
      Place item in the channel, possibly waiting indefinitely until it can be accepted. Channels implementing the BoundedChannel subinterface are generally guaranteed to block on puts upon reaching capacity, but other implementations may or may not block.
      Specified by:
      put in interface Channel
      Specified by:
      put in interface Puttable
      Parameters:
      x - the element to be inserted. Should be non-null.
      Throws:
      InterruptedException - if the current thread has been interrupted at a point at which interruption is detected, in which case the element is guaranteed not to be inserted. Otherwise, on normal return, the element is guaranteed to have been inserted.

    • offer

      public boolean offer(Object x, long msecs) throws InterruptedException
      Description copied from interface: Channel
      Place item in channel only if it can be accepted within msecs milliseconds. The time bound is interpreted in a coarse-grained, best-effort fashion.
      Specified by:
      offer in interface Channel
      Specified by:
      offer in interface Puttable
      Parameters:
      x - the element to be inserted. Should be non-null.
      msecs - the number of milliseconds to wait. If less than or equal to zero, the method does not perform any timed waits, but might still require access to a synchronization lock, which can impose unbounded delay if there is a lot of contention for the channel.
      Returns:
      true if accepted, else false
      Throws:
      InterruptedException - if the current thread has been interrupted at a point at which interruption is detected, in which case the element is guaranteed not to be inserted (i.e., is equivalent to a false return).

    • take

      public Object take() throws InterruptedException
      Description copied from interface: Channel
      Return and remove an item from channel, possibly waiting indefinitely until such an item exists.
      Specified by:
      take in interface Channel
      Specified by:
      take in interface Takable
      Returns:
      some item from the channel. Different implementations may guarantee various properties (such as FIFO) about that item
      Throws:
      InterruptedException - if the current thread has been interrupted at a point at which interruption is detected, in which case state of the channel is unchanged.

    • poll

      public Object poll(long msecs) throws InterruptedException
      Description copied from interface: Channel
      Return and remove an item from channel only if one is available within msecs milliseconds. The time bound is interpreted in a coarse grained, best-effort fashion.
      Specified by:
      poll in interface Channel
      Specified by:
      poll in interface Takable
      Parameters:
      msecs - the number of milliseconds to wait. If less than or equal to zero, the operation does not perform any timed waits, but might still require access to a synchronization lock, which can impose unbounded delay if there is a lot of contention for the channel.
      Returns:
      some item, or null if the channel is empty.
      Throws:
      InterruptedException - if the current thread has been interrupted at a point at which interruption is detected, in which case state of the channel is unchanged (i.e., equivalent to a null return).