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root/i-scream/projects/cms/source/util/uk/org/iscream/cms/util/Queue.java

Comparing projects/cms/source/util/uk/org/iscream/cms/util/Queue.java (file contents):
Revision 1.14 by tdb, Thu Mar 1 01:05:49 2001 UTC vs.
Revision 1.27 by tdb, Sun Aug 1 10:41:08 2004 UTC

#	Line 1 | Line 1
1	+	/*
2	+	* i-scream central monitoring system
3	+	* http://www.i-scream.org
4	+	* Copyright (C) 2000-2002 i-scream
5	+	*
6	+	* This program is free software; you can redistribute it and/or
7	+	* modify it under the terms of the GNU General Public License
8	+	* as published by the Free Software Foundation; either version 2
9	+	* of the License, or (at your option) any later version.
10	+	*
11	+	* This program is distributed in the hope that it will be useful,
12	+	* but WITHOUT ANY WARRANTY; without even the implied warranty of
13	+	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14	+	* GNU General Public License for more details.
15	+	*
16	+	* You should have received a copy of the GNU General Public License
17	+	* along with this program; if not, write to the Free Software
18	+	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
19	+	*/
20	+
21		//---PACKAGE DECLARATION---
22	<	package uk.ac.ukc.iscream.util;
22	>	package uk.org.iscream.cms.util;
23
24		//---IMPORTS---
25		import java.util.LinkedList;
26		import java.util.NoSuchElementException;
27		import java.util.Random;
28	<	import uk.ac.ukc.iscream.util.*;
28	>	//import uk.org.iscream.cms.util.*;
29
30		/**
31		* A Queue class designed to operate in a multi-threaded environment, with
#	Line 49 | Line 69 | public class Queue {
69		*/
70		public static final int DROP = 3;
71
72	+	/**
73	+	* To allow opposite lookups.
74	+	*/
75	+	public static final String[] algorithms = {"RANDOM", "FIRST", "LAST", "DROP"};
76	+
77		//---STATIC METHODS---
78
79		//---CONSTRUCTORS---
#	Line 89 | Line 114 | public class Queue {
114		for(int i=0; i < _lists.size(); i++) {
115		// skip over any gaps left in the list
116		if(_lists.get(i) != null) {
117	<	// get size before adding to the Queue
118	<	int s = ((LinkedList) _lists.get(i)).size();
119	<	// check whether we need to remove an item from the current Queue
120	<	if(_maxSize!=-1 && s==_maxSize && _removeAlgorithm!=DROP) {
121	<	// we need to remove an item
122	<	removeQueueItem((LinkedList) _lists.get(i));
123	<	}
99	<	// check if we should add (not if Queue full, and using DROP algorithm)
100	<	if(!(s==_maxSize && _removeAlgorithm==DROP)) {
101	<	// add the next item, ensuring we lock
102	<	synchronized(this) {
103	<	// LinkedList.add() does the same thing, but this ensures behaviour
104	<	((LinkedList) _lists.get(i)).addLast(o);
117	>	synchronized(((LinkedList) _lists.get(i))) {
118	>	// get size before adding to the Queue
119	>	int s = ((LinkedList) _lists.get(i)).size();
120	>	// check whether we need to remove an item from the current Queue
121	>	if(_maxSize!=-1 && s>=_maxSize && _removeAlgorithm!=DROP) {
122	>	// we need to remove an item
123	>	removeQueueItem((LinkedList) _lists.get(i));
124		}
125	<	}
126	<	// if the queue was empty before the add it is possible
127	<	// that a consumer is waiting... so we notify them
128	<	if (s == 0) {
129	<	synchronized(((LinkedList) _lists.get(i))) {
130	<	((LinkedList) _lists.get(i)).notifyAll();
125	>	// check if we should add (not if Queue full, and using DROP algorithm)
126	>	if(!(s>=_maxSize && _removeAlgorithm==DROP)) {
127	>	// add the next item, ensuring we lock
128	>	synchronized(this) {
129	>	// LinkedList.add() does the same thing, but this ensures behaviour
130	>	((LinkedList) _lists.get(i)).addLast(o);
131	>	}
132	>	// if the queue was empty before the add it is possible
133	>	// that a consumer is waiting... so we notify them
134	>	//synchronized(((LinkedList) _lists.get(i))) {
135	>	((LinkedList) _lists.get(i)).notifyAll();
136	>	//}
137		}
138		}
139		}
#	Line 131 | Line 156 | public class Queue {
156		throw new InvalidQueueException("Requested queue "+queue+" does not exist");
157		}
158		// block if the queue is empty
159	<	if (((LinkedList) _lists.get(queue)).size() == 0) {
160	<	synchronized(((LinkedList) _lists.get(queue))) {
159	>	synchronized(((LinkedList) _lists.get(queue))) {
160	>	if (((LinkedList) _lists.get(queue)).size() == 0) {
161		try { ((LinkedList) _lists.get(queue)).wait(); } catch(Exception e) {}
162		}
163		}
#	Line 201 | Line 226 | public class Queue {
226		if(_maxSize != -1) {
227		status += " maxSize=\""+_maxSize+"\"";
228		}
229	<	status += "</queue>";
229	>	status += "></queue>";
230		return status;
231		}
232
#	Line 223 | Line 248 | public class Queue {
248
249		/**
250		* Returns the total numer of elements to have passed
251	<	* through this queue (ie. a counter on the add method).
251	>	* through this queue. This is essentially a counter
252	>	* on the add method.
253		*
254		* @return the element-ometer.
255		*/
#	Line 242 | Line 268 | public class Queue {
268		*
269		* @return An integer to be passed to the get() method.
270		*/
271	<	public int getQueue() {
271	>	public synchronized int getQueue() {
272		int pos = -1;
273		for(int i=0; i < _lists.size(); i++) {
274		if(_lists.get(i) == null) {
#	Line 266 | Line 292 | public class Queue {
292		*
293		* @param queue The integer identifier for the queue, given by getQueue().
294		*/
295	<	public void removeQueue(int queue) {
295	>	public synchronized void removeQueue(int queue) {
296		_lists.set(queue, null);
297		}
298
#	Line 327 | Line 353 | public class Queue {
353		* Overrides the {@link java.lang.Object#toString() Object.toString()}
354		* method to provide clean logging (every class should have this).
355		*
356	<	* This uses the uk.ac.ukc.iscream.util.FormatName class
356	>	* This uses the uk.org.iscream.cms.server.util.FormatName class
357		* to format the toString()
358		*
359		* @return the name of this class and its CVS revision.

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