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root/i-scream/experimental/server/Queue/Queue.java
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Comparing experimental/server/Queue/Queue.java (file contents):
Revision 1.4 by tdb, Thu Jan 18 22:08:07 2001 UTC vs.
Revision 1.7 by tdb, Mon Feb 12 02:27:56 2001 UTC

# Line 1 | Line 1
1   //---PACKAGE DECLARATION---
2 < package uk.ac.ukc.iscream.util;
2 > //package uk.ac.ukc.iscream.util;
3  
4   //---IMPORTS---
5   import java.util.LinkedList;
6   import java.util.NoSuchElementException;
7 < import uk.ac.ukc.iscream.util.*;
7 > //import uk.ac.ukc.iscream.util.*;
8  
9   /**
10   * A Queue class designed to operate in a multi-threaded environment, with
# Line 62 | Line 62 | public class Queue {
62       * This method returns an object from the front of a given queue.
63       * It will block until data exists in the queue if required.
64       *
65 +     * @param The queue to retrieve data from.
66       * @return The object from the front of the queue.
67       * @throws InvalidQueueException if the queue does not exist.
68       */
# Line 88 | Line 89 | public class Queue {
89          }
90          return o;
91      }
92 <      
92 >    
93      /**
94 <     * This method returns a textual status of the queues. It
95 <     * is merely for observation, and would most likely be used
96 <     * by a larger "monitoring" component. Information returned
97 <     * includes the current size of each queue, and the total
97 <     * items passed through.
94 >     * This method releases a get() method that's currently
95 >     * waiting on an empty queue. This was designed for
96 >     * shutdown() type methods that may have problems closing
97 >     * if the thread of control is waiting on a queue.
98       *
99 <     * @return A String message containing status information.
99 >     * @param queue the queue to release.
100       */
101 <    public String status() {
102 <        String status = "";
101 >    public void releaseQueue(int queue) {
102 >        synchronized(((LinkedList) _lists.get(queue))) {
103 >                ((LinkedList) _lists.get(queue)).notifyAll();
104 >        }
105 >    }
106 >
107 >    /**
108 >     * This method erases the contents of a given queue. This
109 >     * method should be used with care. It can only empty one
110 >     * internal queue, not all of them. This must be called
111 >     * multiple times to empty all queues.
112 >     *
113 >     * @param queue the queue to empty.
114 >     */
115 >    public void clearQueue(int queue) {
116 >        synchronized(this) {
117 >            ((LinkedList) _lists.get(queue)).clear();
118 >        }
119 >    }
120 >    
121 >    /**
122 >     * This method returns an XML textual status of the queues.
123 >     * It is merely for observation, and would most likely be
124 >     * used by a larger "monitoring" component. Information
125 >     * returned includes the current size of each queue, and
126 >     * the total items passed through.
127 >     *
128 >     * @return A String message containing status information in XML format
129 >     */
130 >    public String xmlStatus() {
131 >        String status = "<queue ";
132          for(int i=0; i < _lists.size(); i++) {
133              // check for null entries
134              if(_lists.get(i) != null) {
135 <                status += "Queue number "+i+" contains "+((LinkedList) _lists.get(i)).size()+" elements";
107 <                status += "\n";
135 >                status += "queue"+i+"=\""+((LinkedList) _lists.get(i)).size()+"\" ";
136              }
137              else {
138 <                status += "Slot number "+i+" is currently empty";
111 <                status += "\n";
138 >                status += "queue"+i+"=\"null\" ";
139              }
140          }
141 <        status += "A total of "+_count+" elements have been added to the queues";
141 >        status += "total=\""+_count+"\"></queue>";
142          return status;
143      }
144      
# Line 122 | Line 149 | public class Queue {
149       *
150       * @param queue The queue number to query.
151       * @return the current size of the queue.
152 +     * @throws InvalidQueueException if the queue does not exist.
153       */
154      public int queueSize(int queue) throws InvalidQueueException {
155 <        if (queue >= _lists.size() || _lists.get(queue) == null) {
155 >        if (queue >= _lists.size() || _lists.get(queue) == null) {
156              throw new InvalidQueueException("Requested queue "+queue+" does not exist");
157          }
158 <        return ((LinkedList) _lists.get(queue)).size();
158 >        return ((LinkedList) _lists.get(queue)).size();
159      }
160      
161      /**
162       * Returns the total numer of elements to have passed
163       * through this queue (ie. a counter on the add method).
164       *
165 <     * @return the element-ometer
165 >     * @return the element-ometer.
166       */
167      public int elementCount() {
168 <        return _count;
168 >        return _count;
169      }
170      
171      /**
# Line 180 | Line 208 | public class Queue {
208      }
209      
210      /**
211 +     * Start a monitor on our own Queue. This will log XML
212 +     * statistics about our Queue to a given Queue (could be
213 +     * the one being monitored).
214 +     *
215 +     * @param interval The long interval, in milliseconds, at which to take samples
216 +     * @param destQueue The queue to monitor to
217 +     * @param name A name to identify this Queue with
218 +     * @return whether we succeeded
219 +     */
220 +    public boolean startMonitor(long interval, Queue destQueue, String name) {
221 +        if(_queueMon == null) {
222 +            // start a monitor
223 +            _queueMon = new QueueMonitor(this, destQueue, interval, name);
224 +            _queueMon.start();
225 +            return true;
226 +        }
227 +        else {
228 +            // already have a monitor running
229 +            return false;
230 +        }
231 +    }
232 +    
233 +    /**
234 +     * Start a monitor on our own Queue. This will log XML
235 +     * statistics about our Queue to this Queue.
236 +     *
237 +     * @param interval The long interval, in milliseconds, at which to take samples
238 +     * @param name A name to identify this Queue with
239 +     * @return whether we succeeded
240 +     */
241 +    public boolean startMonitor(long interval, String name) {
242 +        return startMonitor(interval, this, name);
243 +    }
244 +    
245 +    /**
246 +     * Stop a monitor on our Queue if we have on running.
247 +     *
248 +     * @return whether we succeeded
249 +     */
250 +    public boolean stopMonitor() {
251 +        if(_queueMon != null) {
252 +            // stop a monitor
253 +            _queueMon.shutdown();
254 +            _queueMon = null;
255 +            return true;
256 +        }
257 +        else {
258 +            // no monitor running
259 +            return false;
260 +        }
261 +    }
262 +    
263 +    /**
264       * Overrides the {@link java.lang.Object#toString() Object.toString()}
265       * method to provide clean logging (every class should have this).
266       *
267       * This uses the uk.ac.ukc.iscream.util.FormatName class
268       * to format the toString()
269       *
270 <     * @return the name of this class and its CVS revision
270 >     * @return the name of this class and its CVS revision.
271       */
272      public String toString() {
273          return FormatName.getName(
# Line 211 | Line 292 | public class Queue {
292       * passed through, for statistical purposes.
293       */
294      private int _count = 0;
295 +    
296 +    /**
297 +     * A reference to our QueueMonitor, if we have one.
298 +     */
299 +    private QueueMonitor _queueMon = null;
300      
301      /**
302       * This is the friendly identifier of the

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