org.metasyntactic.thread.concurrent
Class LinkedQueue

java.lang.Object
  |
  +--org.metasyntactic.thread.concurrent.LinkedQueue
All Implemented Interfaces:
Channel, Puttable, Takable

public class LinkedQueue
extends java.lang.Object
implements Channel

A linked list based channel implementation. The algorithm avoids contention between putsand takes when the queue is not empty. Normally a put and a take can proceed simultaneously. (Although it does not allow multiple concurrent puts or takes.) This class tends to perform more efficently than other Channel implementations in producer/consumer applications.


Nested Class Summary
 class LinkedQueue.LinkedNode
          A standard linked list node used in various queue classes
 
Constructor Summary
LinkedQueue()
           
 
Method Summary
 boolean isEmpty()
           
 boolean offer(java.lang.Object x, long msecs)
          Place item in channel only if it can be accepted within msecs milliseconds.
 java.lang.Object peek()
          Return, but do not remove object at head of Channel, or null if it is empty.
 java.lang.Object poll(long msecs)
          Return and remove an item from channel only if one is available within msecs milliseconds.
 void put(java.lang.Object x)
          Place item in the channel, possibly waiting indefinitely until it can be accepted.
 java.lang.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
 

Constructor Detail

LinkedQueue

public LinkedQueue()
Method Detail

put

public void put(java.lang.Object x)
         throws java.lang.InterruptedException
Description copied from interface: Puttable
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 Puttable
Parameters:
x - the element to be inserted. Should be non-null.
Throws:
java.lang.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(java.lang.Object x,
                     long msecs)
              throws java.lang.InterruptedException
Description copied from interface: Puttable
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 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:
java.lang.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 java.lang.Object take()
                      throws java.lang.InterruptedException
Description copied from interface: Takable
Return and remove an item from channel, possibly waiting indefinitely until such an item exists.

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:
java.lang.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.

peek

public java.lang.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 (possibly null) @ the head of the channel

isEmpty

public boolean isEmpty()

poll

public java.lang.Object poll(long msecs)
                      throws java.lang.InterruptedException
Description copied from interface: Takable
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 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:
java.lang.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 false return).