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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 1.24 by tdb, Sat May 18 18:16:03 2002 UTC

#	Line 1 | Line 1
1	+	/*
2	+	* i-scream central monitoring system
3	+	* Copyright (C) 2000-2002 i-scream
4	+	*
5	+	* This program is free software; you can redistribute it and/or
6	+	* modify it under the terms of the GNU General Public License
7	+	* as published by the Free Software Foundation; either version 2
8	+	* of the License, or (at your option) any later version.
9	+	*
10	+	* This program is distributed in the hope that it will be useful,
11	+	* but WITHOUT ANY WARRANTY; without even the implied warranty of
12	+	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13	+	* GNU General Public License for more details.
14	+	*
15	+	* You should have received a copy of the GNU General Public License
16	+	* along with this program; if not, write to the Free Software
17	+	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
18	+	*/
19	+
20		//---PACKAGE DECLARATION---
21	<	package uk.ac.ukc.iscream.util;
21	>	package uk.org.iscream.cms.server.util;
22
23		//---IMPORTS---
24		import java.util.LinkedList;
25		import java.util.NoSuchElementException;
26		import java.util.Random;
27	<	import uk.ac.ukc.iscream.util.*;
27	>	import uk.org.iscream.cms.server.util.*;
28
29		/**
30		* A Queue class designed to operate in a multi-threaded environment, with
#	Line 49 | Line 68 | public class Queue {
68		*/
69		public static final int DROP = 3;
70
71	+	/**
72	+	* To allow opposite lookups.
73	+	*/
74	+	public static final String[] algorithms = {"RANDOM", "FIRST", "LAST", "DROP"};
75	+
76		//---STATIC METHODS---
77
78		//---CONSTRUCTORS---
#	Line 89 | Line 113 | public class Queue {
113		for(int i=0; i < _lists.size(); i++) {
114		// skip over any gaps left in the list
115		if(_lists.get(i) != null) {
116	<	// get size before adding to the Queue
117	<	int s = ((LinkedList) _lists.get(i)).size();
118	<	// check whether we need to remove an item from the current Queue
119	<	if(_maxSize!=-1 && s==_maxSize && _removeAlgorithm!=DROP) {
120	<	// we need to remove an item
121	<	removeQueueItem((LinkedList) _lists.get(i));
122	<	}
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);
116	>	synchronized(((LinkedList) _lists.get(i))) {
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		}
124	<	}
125	<	// if the queue was empty before the add it is possible
126	<	// that a consumer is waiting... so we notify them
127	<	if (s == 0) {
128	<	synchronized(((LinkedList) _lists.get(i))) {
129	<	((LinkedList) _lists.get(i)).notifyAll();
124	>	// check if we should add (not if Queue full, and using DROP algorithm)
125	>	if(!(s>=_maxSize && _removeAlgorithm==DROP)) {
126	>	// add the next item, ensuring we lock
127	>	synchronized(this) {
128	>	// LinkedList.add() does the same thing, but this ensures behaviour
129	>	((LinkedList) _lists.get(i)).addLast(o);
130	>	}
131	>	// if the queue was empty before the add it is possible
132	>	// that a consumer is waiting... so we notify them
133	>	//synchronized(((LinkedList) _lists.get(i))) {
134	>	((LinkedList) _lists.get(i)).notifyAll();
135	>	//}
136		}
137		}
138		}
#	Line 131 | Line 155 | public class Queue {
155		throw new InvalidQueueException("Requested queue "+queue+" does not exist");
156		}
157		// block if the queue is empty
158	<	if (((LinkedList) _lists.get(queue)).size() == 0) {
159	<	synchronized(((LinkedList) _lists.get(queue))) {
158	>	synchronized(((LinkedList) _lists.get(queue))) {
159	>	if (((LinkedList) _lists.get(queue)).size() == 0) {
160		try { ((LinkedList) _lists.get(queue)).wait(); } catch(Exception e) {}
161		}
162		}
#	Line 201 | Line 225 | public class Queue {
225		if(_maxSize != -1) {
226		status += " maxSize=\""+_maxSize+"\"";
227		}
228	<	status += "</queue>";
228	>	status += "></queue>";
229		return status;
230		}
231
#	Line 223 | Line 247 | public class Queue {
247
248		/**
249		* Returns the total numer of elements to have passed
250	<	* through this queue (ie. a counter on the add method).
250	>	* through this queue. This is essentially a counter
251	>	* on the add method.
252		*
253		* @return the element-ometer.
254		*/
#	Line 242 | Line 267 | public class Queue {
267		*
268		* @return An integer to be passed to the get() method.
269		*/
270	<	public int getQueue() {
270	>	public synchronized int getQueue() {
271		int pos = -1;
272		for(int i=0; i < _lists.size(); i++) {
273		if(_lists.get(i) == null) {
#	Line 266 | Line 291 | public class Queue {
291		*
292		* @param queue The integer identifier for the queue, given by getQueue().
293		*/
294	<	public void removeQueue(int queue) {
294	>	public synchronized void removeQueue(int queue) {
295		_lists.set(queue, null);
296		}
297
#	Line 327 | Line 352 | public class Queue {
352		* Overrides the {@link java.lang.Object#toString() Object.toString()}
353		* method to provide clean logging (every class should have this).
354		*
355	<	* This uses the uk.ac.ukc.iscream.util.FormatName class
355	>	* This uses the uk.org.iscream.cms.server.util.FormatName class
356		* to format the toString()
357		*
358		* @return the name of this class and its CVS revision.

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