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/* |
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* i-scream central monitoring system |
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* http://www.i-scream.org.uk |
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* Copyright (C) 2000-2002 i-scream |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public License |
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* as published by the Free Software Foundation; either version 2 |
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* of the License, or (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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*/ |
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|
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//---PACKAGE DECLARATION--- |
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package uk.org.iscream.util; |
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package uk.org.iscream.cms.server.util; |
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//---IMPORTS--- |
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import java.util.LinkedList; |
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import java.util.NoSuchElementException; |
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import java.util.Random; |
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import uk.org.iscream.util.*; |
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import uk.org.iscream.cms.server.util.*; |
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/** |
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* A Queue class designed to operate in a multi-threaded environment, with |
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for(int i=0; i < _lists.size(); i++) { |
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// skip over any gaps left in the list |
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if(_lists.get(i) != null) { |
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// get size before adding to the Queue |
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int s = ((LinkedList) _lists.get(i)).size(); |
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// check whether we need to remove an item from the current Queue |
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if(_maxSize!=-1 && s==_maxSize && _removeAlgorithm!=DROP) { |
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// we need to remove an item |
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removeQueueItem((LinkedList) _lists.get(i)); |
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} |
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// check if we should add (not if Queue full, and using DROP algorithm) |
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if(!(s==_maxSize && _removeAlgorithm==DROP)) { |
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// add the next item, ensuring we lock |
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synchronized(this) { |
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// LinkedList.add() does the same thing, but this ensures behaviour |
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((LinkedList) _lists.get(i)).addLast(o); |
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synchronized(((LinkedList) _lists.get(i))) { |
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// get size before adding to the Queue |
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int s = ((LinkedList) _lists.get(i)).size(); |
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// check whether we need to remove an item from the current Queue |
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if(_maxSize!=-1 && s>=_maxSize && _removeAlgorithm!=DROP) { |
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// we need to remove an item |
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removeQueueItem((LinkedList) _lists.get(i)); |
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} |
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} |
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// if the queue was empty before the add it is possible |
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// that a consumer is waiting... so we notify them |
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if (s == 0) { |
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synchronized(((LinkedList) _lists.get(i))) { |
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((LinkedList) _lists.get(i)).notifyAll(); |
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// check if we should add (not if Queue full, and using DROP algorithm) |
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if(!(s>=_maxSize && _removeAlgorithm==DROP)) { |
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// add the next item, ensuring we lock |
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synchronized(this) { |
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// LinkedList.add() does the same thing, but this ensures behaviour |
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((LinkedList) _lists.get(i)).addLast(o); |
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} |
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// if the queue was empty before the add it is possible |
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// that a consumer is waiting... so we notify them |
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//synchronized(((LinkedList) _lists.get(i))) { |
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((LinkedList) _lists.get(i)).notifyAll(); |
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//} |
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} |
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} |
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} |
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/** |
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* Returns the total numer of elements to have passed |
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* through this queue (ie. a counter on the add method). |
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* through this queue. This is essentially a counter |
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* on the add method. |
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* |
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* @return the element-ometer. |
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*/ |
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* Overrides the {@link java.lang.Object#toString() Object.toString()} |
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* method to provide clean logging (every class should have this). |
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* |
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* This uses the uk.org.iscream.util.FormatName class |
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* This uses the uk.org.iscream.cms.server.util.FormatName class |
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* to format the toString() |
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* |
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* @return the name of this class and its CVS revision. |
