server/filter/FilterThread.java

//---PACKAGE DECLARATION---
package uk.ac.ukc.iscream.filter;

//---IMPORTS---
import java.io.*;
import java.net.*;
import java.util.*;
import uk.ac.ukc.iscream.core.*;
import uk.ac.ukc.iscream.filter.*;
import uk.ac.ukc.iscream.util.*;

/**
 * Handle an incoming packet as a separate thread.
 * Passes the data through various plugins, then 
 * passes it on to the parent filter.
 *
 * Now grabs data from a single queue, rather than
 * waiting to be contacted.
 *
 * @author  $Author: ajm4 $
 * @version $Id: FilterThread.java,v 1.14 2000/12/13 13:36:46 ajm4 Exp $
 */
public class FilterThread extends Thread{

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.14 $";
    
//---STATIC METHODS---

//---CONSTRUCTORS---
   
    /**
     * Class constructor.
     */
    public FilterThread(Queue queue, Filter parent){
        _parent = parent;
        _queue = queue;
        _logger.write(toString(), Logger.DEBUG, "created");
    }

//---PUBLIC METHODS---

    /**
     * Runs the thread
     */
    public void run(){
        // get a queue for ourselves
        int n = _queue.getQueue();
        // keep this out here, saves recreating the object
        String xml = null;
        while(true) {
            // get a String of xml
            try {
                xml = (String) _queue.get(n);
            }
            catch (InvalidQueueException e) {
                _logger.write(toString(), Logger.ERROR, "Queue error: "+e);
            }
            
            // Get a string without any null characters in it.
            //  -- maybe String.trim() would be better here ?
            if (xml.indexOf(0) != -1) {
                xml = xml.substring(0, xml.indexOf(0));
            }
            else {
                xml = xml.substring(0, xml.length());
            }
            
            // Use XMLPacketMaker to make an XMLPacket object.
            XMLPacketMaker xmlPacketMaker = new XMLPacketMaker(xml);
            XMLPacket packet = xmlPacketMaker.createXMLPacket();
                   
            if(packet != null && PluginFilterManager.getInstance().runFilters(packet)) {
                // packet is not null
                // packet was not dropped by a plugin
                // ... best pass it on !
                _parent.receiveXML(xml);
            }
            else {
                // either we had a null, or a plugin dropped it
                _logger.write(toString(), Logger.DEBUG, "An XML packet was sucessfully filtered from the system.");
            }
        }
    }

    /**
     * Overrides the {@link java.lang.Object#toString() Object.toString()}
     * method to provide clean logging (every class should have this).
     *
     * This uses the uk.ac.ukc.iscream.util.NameFormat class
     * to format the toString()
     *
     * @return the name of this class and its CVS revision
     */
    public String toString() {
        return FormatName.getName(
            _name,
            getClass().getName(),
            REVISION);
    }

//---PRIVATE METHODS---

//---ACCESSOR/MUTATOR METHODS---

//---ATTRIBUTES---

    /**
     * Our parent filter
     */
    Filter _parent;
    
    /**
     * The Queue object
     */
    Queue _queue;
    
    /**
     * This is the friendly identifier of the
     * component this class is running in.
     * eg, a Filter may be called "filter1",
     * If this class does not have an owning
     * component,  a name from the configuration
     * can be placed here.  This name could also
     * be changed to null for utility classes.
     */
    private String _name = FilterMain.NAME;

    /**
     * This holds a reference to the
     * system logger that is being used.
     */
    private Logger _logger = ReferenceManager.getInstance().getLogger();

//---STATIC ATTRIBUTES---

}
Revision:	1.15
Committed:	Fri Jan 12 00:45:25 2001 UTC (23 years, 4 months ago) by tdb
Branch:	MAIN
Changes since 1.14:	+48 -44 lines
Log Message:	A structural change to the Filter. The old setup looked like this; UDPReader ------> FilterThread (thread) --> (parent) TCPReader ------> FilterThread (thread) --> (parent) FilterServant --> FilterThread (thread) --> (parent) Seeing this from a threaded point of view, each time a packet came in (through whatever means - UDP, TCP or CORBA), a FilterThread instance was created to deal with it. If the link to the parent was slow this resulting in a build-up of FilterThreads all waiting to talk to the parent - and there is only one actual parent object, with a synchronised thread, so they have to queue up anyway. As a result of this, the following change has been made. UDPReader -------\ TCPReader ----------> Queue (single) >-- FilterThread --> (parent) FilterServant ---/ In this setup, each of the three objects that generate packets only see the single instance of a Queue. They all add their data to this Queue, and then carry on with the task of listening. The FilterThread (having it's role changed slightly) now acts as a consumer of the Queue, in that it grabs data from the Queue and deals with passing it on to the parent. This setup should be more efficient in the long run, especially under a high load situation. The only problem could be the Queue growing to an unlimited size, but this is a Queue design issue.
#	User	Rev	Content
1	tdb	1.8	//---PACKAGE DECLARATION---
2			package uk.ac.ukc.iscream.filter;
3
4			//---IMPORTS---
5	pjm2	1.1	import java.io.*;
6			import java.net.*;
7			import java.util.*;
8	pjm2	1.6	import uk.ac.ukc.iscream.core.*;
9	tdb	1.2	import uk.ac.ukc.iscream.filter.*;
10	ajm	1.11	import uk.ac.ukc.iscream.util.*;
11	pjm2	1.1
12	tdb	1.8	/**
13	ajm	1.14	* Handle an incoming packet as a separate thread.
14			* Passes the data through various plugins, then
15			* passes it on to the parent filter.
16	tdb	1.8	*
17	tdb	1.15	* Now grabs data from a single queue, rather than
18			* waiting to be contacted.
19			*
20			* @author $Author: ajm4 $
21			* @version $Id: FilterThread.java,v 1.14 2000/12/13 13:36:46 ajm4 Exp $
22	tdb	1.8	*/
23	tdb	1.2	public class FilterThread extends Thread{
24	pjm2	1.1
25	tdb	1.8	//---FINAL ATTRIBUTES---
26
27			/**
28			* The current CVS revision of this class
29			*/
30	tdb	1.15	public final String REVISION = "$Revision: 1.14 $";
31	tdb	1.8
32			//---STATIC METHODS---
33
34			//---CONSTRUCTORS---
35	tdb	1.15
36	ajm	1.14	/**
37	tdb	1.15	* Class constructor.
38	ajm	1.14	*/
39	tdb	1.15	public FilterThread(Queue queue, Filter parent){
40	tdb	1.10	_parent = parent;
41	tdb	1.15	_queue = queue;
42	ajm	1.14	_logger.write(toString(), Logger.DEBUG, "created");
43	pjm2	1.1	}
44	tdb	1.8
45			//---PUBLIC METHODS---
46
47	ajm	1.14	/**
48			* Runs the thread
49			*/
50	pjm2	1.1	public void run(){
51	tdb	1.15	// get a queue for ourselves
52			int n = _queue.getQueue();
53			// keep this out here, saves recreating the object
54			String xml = null;
55			while(true) {
56			// get a String of xml
57			try {
58			xml = (String) _queue.get(n);
59			}
60			catch (InvalidQueueException e) {
61			_logger.write(toString(), Logger.ERROR, "Queue error: "+e);
62			}
63
64			// Get a string without any null characters in it.
65			// -- maybe String.trim() would be better here ?
66			if (xml.indexOf(0) != -1) {
67			xml = xml.substring(0, xml.indexOf(0));
68			}
69			else {
70			xml = xml.substring(0, xml.length());
71			}
72
73			// Use XMLPacketMaker to make an XMLPacket object.
74			XMLPacketMaker xmlPacketMaker = new XMLPacketMaker(xml);
75			XMLPacket packet = xmlPacketMaker.createXMLPacket();
76
77			if(packet != null && PluginFilterManager.getInstance().runFilters(packet)) {
78			// packet is not null
79			// packet was not dropped by a plugin
80			// ... best pass it on !
81			_parent.receiveXML(xml);
82			}
83			else {
84			// either we had a null, or a plugin dropped it
85			_logger.write(toString(), Logger.DEBUG, "An XML packet was sucessfully filtered from the system.");
86			}
87	pjm2	1.1	}
88			}
89	tdb	1.8
90			/**
91			* Overrides the {@link java.lang.Object#toString() Object.toString()}
92			* method to provide clean logging (every class should have this).
93			*
94	ajm	1.14	* This uses the uk.ac.ukc.iscream.util.NameFormat class
95			* to format the toString()
96			*
97	tdb	1.8	* @return the name of this class and its CVS revision
98			*/
99			public String toString() {
100	ajm	1.14	return FormatName.getName(
101			_name,
102			getClass().getName(),
103			REVISION);
104	tdb	1.8	}
105
106			//---PRIVATE METHODS---
107
108			//---ACCESSOR/MUTATOR METHODS---
109
110			//---ATTRIBUTES---
111
112	ajm	1.14	/**
113			* Our parent filter
114			*/
115	tdb	1.10	Filter _parent;
116	ajm	1.14
117			/**
118	tdb	1.15	* The Queue object
119	ajm	1.14	*/
120	tdb	1.15	Queue _queue;
121	ajm	1.14
122			/**
123			* This is the friendly identifier of the
124			* component this class is running in.
125			* eg, a Filter may be called "filter1",
126			* If this class does not have an owning
127			* component, a name from the configuration
128			* can be placed here. This name could also
129			* be changed to null for utility classes.
130			*/
131			private String _name = FilterMain.NAME;
132
133			/**
134			* This holds a reference to the
135			* system logger that is being used.
136			*/
137			private Logger _logger = ReferenceManager.getInstance().getLogger();
138	tdb	1.8
139			//---STATIC ATTRIBUTES---
140
141	pjm2	1.1	}