javax.realtime
Class WaitFreeWriteQueue

java.lang.Object
  javax.realtime.WaitFreeWriteQueue

public class WaitFreeWriteQueue

extends Object

A queue that provides unsynchronized nonblocking write() and synchronized blocking read().

Since:

0.3.8

Author:

Morgan Deters

Constructor Summary

WaitFreeWriteQueue(Thread writer, Thread reader, int maximum, MemoryArea memory)
Constructs a new WaitFreeWriteQueue.

Method Summary

void	clear() Empties the queue.
boolean	force(Object object) Replace the last object with this object.
boolean	isEmpty() Checks if the queue is empty.
boolean	isFull() Checks if the queue is full.
Object	read() A synchronized and blocking read operation.
int	size() Returns the number of elements in the queue.
boolean	write(Object object) An unsynchronized and nonblocking write operation.

Methods inherited from class java.lang.Object

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

Constructor Detail

WaitFreeWriteQueue

public WaitFreeWriteQueue(Thread writer,
                          Thread reader,
                          int maximum,
                          MemoryArea memory)
                   throws IllegalArgumentException,
                          InstantiationException,
                          ClassNotFoundException,
                          IllegalAccessException

Constructs a new WaitFreeWriteQueue.

Parameters:

writer - the writing thread

reader - the reading thread

maximum - the capacity of the queue

memory - the MemoryArea in which to allocate the queue's buffer; if null, then the current memory area is used

Method Detail

clear

public void clear()

Empties the queue. This method is unsynchronized; if it could be called at the same time as a read() operation, the callers need to synchronize.

isEmpty

public boolean isEmpty()

Checks if the queue is empty.

Returns:

true if the queue is empty, false otherwise

isFull

public boolean isFull()

Checks if the queue is full.

Returns:

true if the queue is full, false otherwise

read

public Object read()

A synchronized and blocking read operation.

Returns:

the object removed from the queue

size

public int size()

Returns the number of elements in the queue.

Returns:

the number of elements in the queue

force

public boolean force(Object object)
              throws MemoryScopeException

Replace the last object with this object. Returns false if the reader removed the other object as this operation was updating it.

Parameters:

object - the object to write to the queue

Returns:

true upon success, false otherwise

Throws:

MemoryScopeException - if the object is in an incompatible memory area

write

public boolean write(Object object)
              throws MemoryScopeException

An unsynchronized and nonblocking write operation.

Parameters:

object - the object to write to the queue

Returns:

true upon success, false otherwise

Throws:

MemoryScopeException - if the object is in an incompatible memory area