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authornobody <nobody@ae88bc3d-4319-0410-8dbf-d08b4c9d3795>2000-08-01 16:43:24 +0000
committernobody <nobody@ae88bc3d-4319-0410-8dbf-d08b4c9d3795>2000-08-01 16:43:24 +0000
commitb462a7a9d307c5f5eff30a24008045c0e3d0185a (patch)
treea9efcb39b9e041e5cf70e17090c76df8b5354b47 /java/src/MessageQueue.java
parent7e1358bc65c1d08e3ba99af5b7e5869e1cd2c47f (diff)
downloadATCD-b462a7a9d307c5f5eff30a24008045c0e3d0185a.tar.gz
This commit was manufactured by cvs2svn to create tag 'TAO-1_1_7'.TAO-1_1_7
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diff --git a/java/src/MessageQueue.java b/java/src/MessageQueue.java
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-/*************************************************
- *
- * = PACKAGE
- * JACE.ASX
- *
- * = FILENAME
- * MessageQueue.java
- *
- *@author Prashant Jain
- *
- *************************************************/
-package JACE.ASX;
-
-import java.util.Date;
-import JACE.OS.*;
-import JACE.Reactor.*;
-
-class NotFullCondition extends TimedWait
-{
- public NotFullCondition (MessageQueue mq)
- {
- super (mq);
- this.mq_ = mq;
- }
-
- public boolean condition () {
- // Delegate to the appropriate conditional
- // check on the MessageQueue.
- return !this.mq_.isFull ();
- }
- private MessageQueue mq_;
-}
-
-class NotEmptyCondition extends TimedWait
-{
- public NotEmptyCondition (MessageQueue mq)
- {
- super (mq);
- this.mq_ = mq;
- }
-
- public boolean condition () {
- // Delegate to the appropriate conditional
- // check on the MessageQueue.
- return !this.mq_.isEmpty ();
- }
- private MessageQueue mq_;
-}
-
-
-/**
- * <hr>
- * <h2>SYNOPSIS</h2>
- *<blockquote>
- * A thread-safe message queueing facility, modeled after the
- * queueing facilities in System V StreamS.
- *</blockquote>
- *
- * <h2>DESCRIPTION</h2>
- *</blockquote>
- * <tt>MessageQueue</tt> is the central queueing facility for messages
- * in the ASX framework. All operations are thread-safe, as it is intended
- * to be used for inter-thread communication (<em>e.g.</em>, a producer and
- * consumer thread joined by a <tt>MessageQueue</tt>). The queue
- * consiste of <tt>MessageBlock</tt>s.
- *</blockquote>
- *
- *@see MessageBlock
- *@see TimeValue
- */
-public class MessageQueue
-{
- /**
- * Default constructor
- */
- public MessageQueue ()
- {
- this (DEFAULT_HWM, DEFAULT_LWM);
- }
-
- /**
- * Create a Message Queue with high and low water marks.
- *@param hwm High water mark (max number of bytes allowed in the
- * queue)
- *@param lwm Low water mark (min number of bytes in the queue)
- */
- public MessageQueue (int hwm, int lwm)
- {
- if (this.open (hwm, lwm) == -1)
- ACE.ERROR ("open");
- }
-
- /**
- * Initialize a Message Queue with high and low water marks.
- *@param hwm High water mark (max number of bytes allowed in the
- * queue)
- *@param lwm Low water mark (min number of bytes in the queue)
- */
- public synchronized int open (int hwm, int lwm)
- {
- this.highWaterMark_ = hwm;
- this.lowWaterMark_ = lwm;
- this.deactivated_ = false;
- this.currentBytes_ = 0;
- this.currentCount_ = 0;
- this.tail_ = null;
- this.head_ = null;
- return 0;
- }
-
- // ************ Note! ***********
- // = For enqueue, enqueueHead, enqueueTail, and dequeueHead if
- // timeout is specified, the caller will wait until the *absolute time*
- // tv. Calls will return, however, when queue is closed,
- // deactivated, or if it is past the time tv
-
- /**
- * Enqueue a <MessageBlock> into the <MessageQueue> in accordance
- * with its <msgPriority> (0 is lowest priority). Note that the
- * call will block (unless the queue has been deactivated).
- *
- *@exception java.lang.InterruptedException Interrupted while accessing queue
- *@param newItem item to enqueue onto the Message Queue
- *@return -1 on failure, else the number of items still on the queue.
- */
- public synchronized int enqueue (MessageBlock newItem) throws InterruptedException
- {
- return this.enqueue (newItem, null);
- }
-
- /**
- * Enqueue a <MessageBlock> into the <MessageQueue> in accordance
- * with its <msgPriority> (0 is lowest priority). Note that the
- * call will return if the queue has been deactivated or it is
- * later than the specified absolute time value.
- *@param newItem item to enqueue onto the Message Queue
- *@param tv absolute TimeValue to timeout after
- *@return -1 on failure, else the number of items still on the
- * queue.
- *@exception java.lang.InterruptedException Interrupted while accessing queue
- */
- public synchronized int enqueue (MessageBlock newItem,
- TimeValue tv) throws InterruptedException
- {
- int result = -1;
- if (this.deactivated_)
- return -1;
- try
- {
- if (tv == null) // Need to do a blocking wait
- notFullCondition_.timedWait ();
- else // Need to do a timed wait
- notFullCondition_.timedWait (tv);
- }
- catch (TimeoutException e)
- {
- return -1;
- }
-
- // Check again if queue is still active
- if (this.deactivated_)
- return -1;
- else
- result = this.enqueueInternal (newItem);
-
- // Tell any blocked threads that the queue has a new item!
- this.notEmptyCondition_.broadcast ();
- return result;
- }
-
- /**
- * Enqueue a <MessageBlock> at the end of the <MessageQueue>. Note
- * that the call will block (unless the queue has been deactivated).
- *@param newItem item to enqueue onto the Message Queue
- *@return -1 on failure, else the number of items still on the queue.
- *@exception java.lang.InterruptedException Interrupted while accessing queue
- */
- public synchronized int enqueueTail (MessageBlock newItem) throws InterruptedException
- {
- return this.enqueueTail (newItem, null);
- }
-
- /**
- * Enqueue a <MessageBlock> at the end of the <MessageQueue>. Note
- * that the call will return when it's later than the given TimeValue or
- * if the queue has been deactivated.
- *@param newItem item to enqueue onto the Message Queue
- *@param tv absolute TimeValue to wait until before returning (unless
- * the operation compeltes before this time)
- *@return -1 on failure, else the number of items still on the queue.
- *@exception java.lang.InterruptedException Interrupted while accessing queue
- */
- public synchronized int enqueueTail (MessageBlock newItem,
- TimeValue tv) throws InterruptedException
- {
- int result = -1;
- if (this.deactivated_)
- return -1;
- try
- {
- if (tv == null) // Need to do a blocking wait
- notFullCondition_.timedWait ();
- else // Need to do a timed wait
- notFullCondition_.timedWait (tv);
- }
- catch (TimeoutException e)
- {
- return -1;
- }
-
- // Check again if queue is still active
- if (this.deactivated_)
- return -1;
- else
- result = this.enqueueTailInternal (newItem);
-
- // Tell any blocked threads that the queue has a new item!
- this.notEmptyCondition_.broadcast ();
- return result;
- }
-
- /**
- * Enqueue a <MessageBlock> at the head of the <MessageQueue>. Note
- * that the call will block (unless the queue has been deactivated).
- *@param newItem item to enqueue onto the Message Queue
- *@return -1 on failure, else the number of items still on the queue.
- *@exception java.lang.InterruptedException Interrupted while accessing queue
- */
- public synchronized int enqueueHead (MessageBlock newItem) throws InterruptedException
- {
- return this.enqueueHead (newItem, null);
- }
-
- /**
- * Enqueue a <MessageBlock> at the head of the <MessageQueue>. Note
- * that the call will return when it's later than the given TimeValue or
- * if the queue has been deactivated.
- *@param newItem item to enqueue onto the Message Queue
- *@param tv absolute TimeValue to wait until before returning (unless
- * the operation completes before that time)
- *@return -1 on failure, else the number of items still on the queue.
- *@exception java.lang.InterruptedException Interrupted while accessing queue
- */
- public synchronized int enqueueHead (MessageBlock newItem,
- TimeValue tv) throws InterruptedException
- {
- int result = -1;
- if (this.deactivated_)
- return -1;
- try
- {
- if (tv == null) // Need to do a blocking wait
- notFullCondition_.timedWait ();
- else // Need to do a timed wait
- notFullCondition_.timedWait (tv);
- }
- catch (TimeoutException e)
- {
- return -1;
- }
-
- // Check again if queue is still active
- if (this.deactivated_)
- return -1;
- else
- result = this.enqueueHeadInternal (newItem);
-
- // Tell any blocked threads that the queue has a new item!
- this.notEmptyCondition_.broadcast ();
- return result;
- }
-
- /**
- * Dequeue and return the <MessageBlock> at the head of the
- * <MessageQueue>. Note that the call will block (unless the queue
- * has been deactivated).
- *@return null on failure, else the <MessageBlock> at the head of queue.
- *@exception java.lang.InterruptedException Interrupted while accessing queue
- */
- public synchronized MessageBlock dequeueHead () throws InterruptedException
- {
- return this.dequeueHead (null);
- }
-
- /**
- * Dequeue and return the <MessageBlock> at the head of the
- * <MessageQueue>. Note that the call when return if the queue has
- * been deactivated or when the current time is later than the given
- * time value.
- *@param tv absolute time timeout (blocks indefinitely if null)
- *@return null on failure, else the <MessageBlock> at the head of queue.
- *@exception InterruptedException Interrupted while accessing queue
- */
- public synchronized MessageBlock dequeueHead (TimeValue tv)
- throws InterruptedException
- {
- MessageBlock result = null;
- if (this.deactivated_)
- return null;
- try
- {
- if (tv == null) // Need to do a blocking wait
- notEmptyCondition_.timedWait ();
- else // Need to do a timed wait
- notEmptyCondition_.timedWait (tv);
- }
- catch (TimeoutException e)
- {
- return null;
- }
-
- // Check again if queue is still active
- if (this.deactivated_)
- return null;
- else
- result = this.dequeueHeadInternal ();
-
- // Tell any blocked threads that the queue has room for an item!
- this.notFullCondition_.broadcast ();
- return result;
- }
-
- /**
- * Check if queue is full.
- *@return true if queue is full, else false.
- */
- public synchronized boolean isFull ()
- {
- return this.isFullInternal ();
- }
-
- /**
- * Check if queue is empty.
- *@return true if queue is empty, else false.
- */
- public synchronized boolean isEmpty ()
- {
- return this.isEmptyInternal ();
- }
-
- /**
- * Get total number of bytes on the queue.
- *@return total number number of bytes on the queue
- */
- public int messageBytes ()
- {
- return this.currentBytes_;
- }
-
- /**
- * Get total number of messages on the queue.
- *@return total number number of messages on the queue
- */
- public int messageCount ()
- {
- return this.currentCount_;
- }
-
- // = Flow control routines
-
- /**
- * Get high watermark.
- *@return high watermark
- */
- public int highWaterMark ()
- {
- return this.highWaterMark_;
- }
-
- /**
- * Set high watermark.
- *@param hwm high watermark
- */
- public void highWaterMark (int hwm)
- {
- this.highWaterMark_ = hwm;
- }
-
- /**
- * Get low watermark.
- *@return low watermark
- */
- public int lowWaterMark ()
- {
- return this.lowWaterMark_;
- }
-
- /**
- * Set low watermark.
- *@param lwm low watermark
- */
- public void lowWaterMark (int lwm)
- {
- this.lowWaterMark_ = lwm;
- }
-
- // = Activation control methods.
-
- /**
- * Deactivate the queue and wakeup all threads waiting on the queue
- * so they can continue. No messages are removed from the queue,
- * however. Any other operations called until the queue is
- * activated again will immediately return -1.
- *@return WAS_INACTIVE if queue was inactive before the call and
- * WAS_ACTIVE if queue was active before the call.
- */
- public synchronized int deactivate ()
- {
- return this.deactivateInternal ();
- }
-
-
- /**
- * Reactivate the queue so that threads can enqueue and dequeue
- * messages again.
- *@return WAS_INACTIVE if queue was inactive before the call and
- * WAS_ACTIVE if queue was active before the call.
- */
- public synchronized int activate ()
- {
- return this.activateInternal ();
- }
-
- protected boolean isEmptyInternal ()
- {
- // Not sure about this one!!!!
- return this.currentBytes_ <= this.lowWaterMark_ && this.currentCount_ <= 0;
- }
-
- protected boolean isFullInternal ()
- {
- return this.currentBytes_ > this.highWaterMark_;
- }
-
- protected int deactivateInternal ()
- {
- int currentStatus =
- this.deactivated_ ? WAS_INACTIVE : WAS_ACTIVE;
-
- this.notFullCondition_.broadcast ();
- this.notEmptyCondition_.broadcast ();
-
- this.deactivated_ = true;
- return currentStatus;
- }
-
- protected int activateInternal ()
- {
- int currentStatus =
- this.deactivated_ ? WAS_INACTIVE : WAS_ACTIVE;
- this.deactivated_ = false;
-
- return currentStatus;
- }
-
- protected int enqueueTailInternal (MessageBlock newItem)
- {
- if (newItem == null)
- return -1;
-
- // List was empty, so build a new one.
- if (this.tail_ == null)
- {
- this.head_ = newItem;
- this.tail_ = newItem;
- newItem.next (null);
- newItem.prev (null);
- }
- // Link at the end.
- else
- {
- newItem.next (null);
- this.tail_.next (newItem);
- newItem.prev (this.tail_);
- this.tail_ = newItem;
- }
-
- if (newItem.msgType() != MessageType.MB_OBJECT)
- {
- // Make sure to count *all* the bytes in a composite message!!!
- for (MessageBlock temp = newItem;
- temp != null;
- temp = temp.cont ())
- this.currentBytes_ += temp.size ();
- }
-
- this.currentCount_++;
- return this.currentCount_;
- }
-
- protected int enqueueHeadInternal (MessageBlock newItem)
- {
- if (newItem == null)
- return -1;
-
- newItem.prev (null);
- newItem.next (this.head_);
-
- if (this.head_ != null)
- this.head_.prev (newItem);
- else
- this.tail_ = newItem;
-
- this.head_ = newItem;
-
- if (newItem.msgType() != MessageType.MB_OBJECT)
- {
- // Make sure to count *all* the bytes in a composite message!!!
- for (MessageBlock temp = newItem;
- temp != null;
- temp = temp.cont ())
- this.currentBytes_ += temp.size ();
- }
-
- this.currentCount_++;
-
- return this.currentCount_;
- }
-
- protected int enqueueInternal (MessageBlock newItem)
- {
- if (newItem == null)
- return -1;
-
- if (this.head_ == null)
- // Check for simple case of an empty queue, where all we need to
- // do is insert <newItem> into the head.
- return this.enqueueHeadInternal (newItem);
- else
- {
- MessageBlock temp;
-
- // Figure out where the new item goes relative to its priority.
-
- for (temp = this.head_;
- temp != null;
- temp = temp.next ())
- {
- if (temp.msgPriority () <= newItem.msgPriority ())
- // Break out when we've located an item that has lower
- // priority that <newItem>.
- break;
- }
-
- if (temp == null)
- // Check for simple case of inserting at the end of the queue,
- // where all we need to do is insert <newItem> after the
- // current tail.
- return this.enqueueTailInternal (newItem);
- else if (temp.prev () == null)
- // Check for simple case of inserting at the beginning of the
- // queue, where all we need to do is insert <newItem> before
- // the current head.
- return this.enqueueHeadInternal (newItem);
- else
- {
- // Insert the message right before the item of equal or lower
- // priority.
- newItem.next (temp);
- newItem.prev (temp.prev ());
- temp.prev ().next (newItem);
- temp.prev (newItem);
- }
- }
-
- if (newItem.msgType() != MessageType.MB_OBJECT)
- {
- // Make sure to count *all* the bytes in a composite message!!!
- for (MessageBlock temp = newItem;
- temp != null;
- temp = temp.cont ())
- this.currentBytes_ += temp.size ();
- }
-
- this.currentCount_++;
- return this.currentCount_;
- }
-
- protected MessageBlock dequeueHeadInternal ()
- {
- MessageBlock firstItem = this.head_;
- this.head_ = this.head_.next ();
-
- if (this.head_ == null)
- this.tail_ = null;
-
- if (firstItem.msgType() != MessageType.MB_OBJECT)
- {
- // Make sure to subtract off all of the bytes associated with this
- // message.
- for (MessageBlock temp = firstItem;
- temp != null;
- temp = temp.cont ())
- this.currentBytes_ -= temp.size ();
- }
-
- this.currentCount_--;
- return firstItem;
- }
-
-
- /** Default high watermark (16 K). */
- public final static int DEFAULT_HWM = 16 * 1024;
-
- /** Default low watermark. */
- public final static int DEFAULT_LWM = 0;
-
- /** Message queue was active before activate() or deactivate(). */
- public final static int WAS_ACTIVE = 1;
-
- /** Message queue was inactive before activate() or deactivate(). */
- public final static int WAS_INACTIVE = 2;
-
- private int highWaterMark_;
- // Greatest number of bytes before blocking.
-
- private int lowWaterMark_;
- // Lowest number of bytes before unblocking occurs.
-
- private boolean deactivated_;
- // Indicates that the queue is inactive.
-
- private int currentBytes_;
- // Current number of bytes in the queue.
-
- private int currentCount_;
- // Current number of messages in the queue.
-
- private MessageBlock head_;
- // Head of Message_Block list.
-
- private MessageBlock tail_;
- // Tail of Message_Block list.
-
- // The Delegated Notification mechanisms.
- private NotFullCondition notFullCondition_ = new NotFullCondition (this);
- private NotEmptyCondition notEmptyCondition_ = new NotEmptyCondition (this);
-
-}