Class SemaphoreControlledChannel

java.lang.Object
EDU.oswego.cs.dl.util.concurrent.SemaphoreControlledChannel
All Implemented Interfaces:
BoundedChannel, Channel, Puttable, Takable
Direct Known Subclasses:
BoundedPriorityQueue, PipedChannel, Slot

public abstract class SemaphoreControlledChannel extends Object implements BoundedChannel
Abstract class for channels that use Semaphores to control puts and takes.

[ Introduction to this package. ]

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected int
     
    protected final Semaphore
     
    protected final Semaphore
     
  • Constructor Summary

    Constructors
    Constructor
    Description
    Create a channel with the given capacity and default semaphore implementation
    SemaphoreControlledChannel(int capacity, Class semaphoreClass)
    Create a channel with the given capacity and semaphore implementations instantiated from the supplied class
  • Method Summary

    Modifier and Type
    Method
    Description
    int
    Return the maximum number of elements that can be held.
    protected abstract Object
    Internal mechanics of take.
    protected abstract void
    Internal mechanics of put.
    boolean
    offer(Object x, long msecs)
    Place item in channel only if it can be accepted within msecs milliseconds.
    poll(long msecs)
    Return and remove an item from channel only if one is available within msecs milliseconds.
    void
    Place item in the channel, possibly waiting indefinitely until it can be accepted.
    int
    Return the number of elements in the buffer.
    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

    Methods inherited from interface EDU.oswego.cs.dl.util.concurrent.Channel

    peek
  • Field Details

    • putGuard_

      protected final Semaphore putGuard_
    • takeGuard_

      protected final Semaphore takeGuard_
    • capacity_

      protected int capacity_
  • Constructor Details

  • Method Details

    • 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.
    • size

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

      protected abstract void insert(Object x)
      Internal mechanics of put.
    • extract

      protected abstract Object extract()
      Internal mechanics of take.
    • 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).