server/componentmanager/ConfigurationProxy.java

/* 
 * i-scream central monitoring system
 * http://www.i-scream.org.uk
 * Copyright (C) 2000-2002 i-scream
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

//---PACKAGE DECLARATION---
package uk.org.iscream.cms.server.componentmanager;

//---IMPORTS---
import java.util.*;
import uk.org.iscream.cms.server.core.*;
import uk.org.iscream.cms.server.util.*;

/**
 * A Configuration Proxy hold configurations caches and
 * maintains configurations obtained from the Configuration
 * Manager.
 *
 * It also has support for checking for updates in configurations,
 * if a change is detected, it reloads all the changed configurations.
 * This is done by a thread which runs every ConfigurationProxy.updateTime
 * seconds.
 *
 * This is a singleton class, and should be used by all classes
 * that wish to gain a configuration from the server, as it then
 * allows them to be dynamically reconfigured.
 *
 * @author  $Author: tdb $
 * @version $Id: ConfigurationProxy.java,v 1.16 2002/05/18 18:16:01 tdb Exp $
 */
public class ConfigurationProxy extends Thread {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public static final String REVISION = "$Revision: 1.16 $";
    
    /**
     * The default time to refresh the
     * configurations - 60 seconds.
     */
    public final int DEFAULT_REFRESH_TIME = 60;

//---STATIC METHODS---

    /**
     * Return a reference to the single class.
     * Construct it if it does not already exist, otherwise just return the reference.
     */
    public synchronized static ConfigurationProxy getInstance() {
        if (_instance == null){
            _instance = new ConfigurationProxy();
        }
        return _instance;
    }

//---CONSTRUCTORS---
    
    /**
     * Construct a ConfigurationProxy
     * Then starts the auto-updating part (the thread) running.
     */
    private ConfigurationProxy() {
        // set the Thread name
        setName("componentmanager.ConfigurationProxy");
        start();    
    }

//---PUBLIC METHODS---

    /**
     * This method runs and waits for a period defined by
     * ConfigurationProxy.updateTime.  Each time it checks all the 
     * configuratons it has loaded to see if their configurations have
     * changed.  If they have, it refreshes the cache with the new configuration
     * and then instructs the old one to be disconnected from the ORB so that it
     * can be garbage collected.
     */
    public void run() {
        // periodic checks for config changes here
        
        while(_running) {
            int refreshTime = 0;
            try {
                refreshTime = Integer.parseInt(getProperty("ConfigurationProxy", "ConfigurationProxy.updateTime"));
            } catch (NumberFormatException e) {
                refreshTime = DEFAULT_REFRESH_TIME;
                _logger.write(toString(), Logger.WARNING, "Erronous ConfigurationProxy.updateTime value in configuration using default of " + refreshTime + " seconds");
            } catch (PropertyNotFoundException e) {
                refreshTime = DEFAULT_REFRESH_TIME;
                _logger.write(toString(), Logger.WARNING, "ConfigurationProxy.updateTime value unavailable using default of " + refreshTime + " seconds");
            }
        
            try {
                Thread.sleep(refreshTime * 1000);
            } catch (InterruptedException e) {
            }
            // ensures we update the list independently of the getProperty method
            synchronized (this) {
                Iterator i = _configCache.keySet().iterator();
                while(i.hasNext()) {
                    String configName = (String) i.next();
                    ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
                    if (_confman.isModified(cc.getConfig().getFileList(), cc.getConfig().getLastModified())) {
                        // disconnect the old Configuration object from the ORB
                        cc.getConfig().disconnect();
                        // get the updated Configuration from the manager
                        cc.setConfig(_confman.getConfiguration(configName));
                        cc.setPropertyCache(new HashMap());
                    }
                }
            }
        }
    }

    /**
     * This method obtains the configuration from the configuration
     * cache, if the configuration isn't in the cache, it adds it.
     * It then asks the configuration for the requested property
     * name, and then returns that to the caller.
     *
     * @param configName the name of the configuration
     * @param propertyName the name of the property to obtain
     *
     * @return the value of the requested property
     */
    public String getProperty(String configName, String propertyName) throws PropertyNotFoundException {
        // ensures the run method can update the cache if needed.
        synchronized (this) {
            if (!_configCache.containsKey(configName)) {
                _configCache.put(configName, new ConfigurationCache(_confman.getConfiguration(configName), new HashMap()));
            }
            ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
            HashMap propertyCache = cc.getPropertyCache();
            Configuration config = cc.getConfig();
            if(!propertyCache.containsKey(propertyName)) {
                // try and get the config 
                // if we can't throw an exception
                try {
                    propertyCache.put(propertyName, config.getProperty(propertyName));
                } catch (org.omg.CORBA.MARSHAL e) {
                    // IMPORTANT - make sure we cache the fact something doesn't exist
                    propertyCache.put(propertyName, null);    
                }
            }
            String property = (String) propertyCache.get(propertyName);
            if(property == null) {
                // the property cannot be found, so we throw back
                // a PropertyNotFoundException and give up.
                throw new PropertyNotFoundException("Could not locate the property \""+propertyName+"\" in the configuration \""+configName+"\"");
            }
            return property;
        }
    }
    
    /**
     * This method obtains the configuration from the configuration
     * cache, if the configuration isn't in the cache, it adds it.
     * It then returns the file list used to build that configuration.
     *
     * @param configName the name of the configuration
     *
     * @return the semi-coma separated list of filenames
     */
    public String getFileList(String configName) {
        // ensures the run method can update the cache if needed.
        synchronized (this) {
            if (!_configCache.containsKey(configName)) {
                _configCache.put(configName, new ConfigurationCache(_confman.getConfiguration(configName), new HashMap()));
            }
            ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
            return cc.getConfig().getFileList();
        }
    }
    
    /**
     * This method obtains the configuration from the configuration
     * cache, if the configuration isn't in the cache, it adds it.
     * It then returns the time in milliseconds of the most last
     * modified date of the most recently modified file in the configurations
     * file list. 
     *
     * @param configName the name of the configuration
     *
     * @return the time in millis
     */
    public long getLastModified(String configName) {
        // ensures the run method can update the cache if needed.
        synchronized (this) {
            if (!_configCache.containsKey(configName)) {
                _configCache.put(configName, new ConfigurationCache(_confman.getConfiguration(configName), new HashMap()));
            }
            ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
            return cc.getConfig().getLastModified();
        }
    }
    
    /**
     * Overrides the {@link java.lang.Object#toString() Object.toString()}
     * method to provide clean logging (every class should have this).
     *
     * This uses the uk.org.iscream.cms.server.util.FormatName 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---

    /**
     * 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 = null;
    
    /**
     * This holds a reference to the
     * system logger that is being used.
     */
    private Logger _logger = ReferenceManager.getInstance().getLogger();
    
    /**
     * A reference to the reference manager in use
     */
    private ReferenceManager _refman = ReferenceManager.getInstance();
    
    /**
     * This holds a reference to the configuration
     * manager
     */
    private ConfigurationManager _confman = ReferenceManager.getInstance().getCM();
    
    /**
     * Holds a list of configuration cache's for every configuration that
     * has been requested of this proxy.
     */
    private HashMap _configCache = new HashMap();
    
    /**
     * Holds the current state of the configuration proxy's thread
     */
    private boolean _running = true;

//---STATIC ATTRIBUTES---

    /**
     * A reference to the single instance of this class
     */
    private static ConfigurationProxy _instance;

}
Revision:	1.17
Committed:	Tue May 21 16:47:17 2002 UTC (22 years ago) by tdb
Branch:	MAIN
Changes since 1.16:	+3 -2 lines
Log Message:	Added URL to GPL headers.
#	Content
1	/*
2	* i-scream central monitoring system
3	* http://www.i-scream.org.uk
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.org.iscream.cms.server.componentmanager;
23
24	//---IMPORTS---
25	import java.util.*;
26	import uk.org.iscream.cms.server.core.*;
27	import uk.org.iscream.cms.server.util.*;
28
29	/**
30	* A Configuration Proxy hold configurations caches and
31	* maintains configurations obtained from the Configuration
32	* Manager.
33	*
34	* It also has support for checking for updates in configurations,
35	* if a change is detected, it reloads all the changed configurations.
36	* This is done by a thread which runs every ConfigurationProxy.updateTime
37	* seconds.
38	*
39	* This is a singleton class, and should be used by all classes
40	* that wish to gain a configuration from the server, as it then
41	* allows them to be dynamically reconfigured.
42	*
43	* @author $Author: tdb $
44	* @version $Id: ConfigurationProxy.java,v 1.16 2002/05/18 18:16:01 tdb Exp $
45	*/
46	public class ConfigurationProxy extends Thread {
47
48	//---FINAL ATTRIBUTES---
49
50	/**
51	* The current CVS revision of this class
52	*/
53	public static final String REVISION = "$Revision: 1.16 $";
54
55	/**
56	* The default time to refresh the
57	* configurations - 60 seconds.
58	*/
59	public final int DEFAULT_REFRESH_TIME = 60;
60
61	//---STATIC METHODS---
62
63	/**
64	* Return a reference to the single class.
65	* Construct it if it does not already exist, otherwise just return the reference.
66	*/
67	public synchronized static ConfigurationProxy getInstance() {
68	if (_instance == null){
69	_instance = new ConfigurationProxy();
70	}
71	return _instance;
72	}
73
74	//---CONSTRUCTORS---
75
76	/**
77	* Construct a ConfigurationProxy
78	* Then starts the auto-updating part (the thread) running.
79	*/
80	private ConfigurationProxy() {
81	// set the Thread name
82	setName("componentmanager.ConfigurationProxy");
83	start();
84	}
85
86	//---PUBLIC METHODS---
87
88	/**
89	* This method runs and waits for a period defined by
90	* ConfigurationProxy.updateTime. Each time it checks all the
91	* configuratons it has loaded to see if their configurations have
92	* changed. If they have, it refreshes the cache with the new configuration
93	* and then instructs the old one to be disconnected from the ORB so that it
94	* can be garbage collected.
95	*/
96	public void run() {
97	// periodic checks for config changes here
98
99	while(_running) {
100	int refreshTime = 0;
101	try {
102	refreshTime = Integer.parseInt(getProperty("ConfigurationProxy", "ConfigurationProxy.updateTime"));
103	} catch (NumberFormatException e) {
104	refreshTime = DEFAULT_REFRESH_TIME;
105	_logger.write(toString(), Logger.WARNING, "Erronous ConfigurationProxy.updateTime value in configuration using default of " + refreshTime + " seconds");
106	} catch (PropertyNotFoundException e) {
107	refreshTime = DEFAULT_REFRESH_TIME;
108	_logger.write(toString(), Logger.WARNING, "ConfigurationProxy.updateTime value unavailable using default of " + refreshTime + " seconds");
109	}
110
111	try {
112	Thread.sleep(refreshTime * 1000);
113	} catch (InterruptedException e) {
114	}
115	// ensures we update the list independently of the getProperty method
116	synchronized (this) {
117	Iterator i = _configCache.keySet().iterator();
118	while(i.hasNext()) {
119	String configName = (String) i.next();
120	ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
121	if (_confman.isModified(cc.getConfig().getFileList(), cc.getConfig().getLastModified())) {
122	// disconnect the old Configuration object from the ORB
123	cc.getConfig().disconnect();
124	// get the updated Configuration from the manager
125	cc.setConfig(_confman.getConfiguration(configName));
126	cc.setPropertyCache(new HashMap());
127	}
128	}
129	}
130	}
131	}
132
133	/**
134	* This method obtains the configuration from the configuration
135	* cache, if the configuration isn't in the cache, it adds it.
136	* It then asks the configuration for the requested property
137	* name, and then returns that to the caller.
138	*
139	* @param configName the name of the configuration
140	* @param propertyName the name of the property to obtain
141	*
142	* @return the value of the requested property
143	*/
144	public String getProperty(String configName, String propertyName) throws PropertyNotFoundException {
145	// ensures the run method can update the cache if needed.
146	synchronized (this) {
147	if (!_configCache.containsKey(configName)) {
148	_configCache.put(configName, new ConfigurationCache(_confman.getConfiguration(configName), new HashMap()));
149	}
150	ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
151	HashMap propertyCache = cc.getPropertyCache();
152	Configuration config = cc.getConfig();
153	if(!propertyCache.containsKey(propertyName)) {
154	// try and get the config
155	// if we can't throw an exception
156	try {
157	propertyCache.put(propertyName, config.getProperty(propertyName));
158	} catch (org.omg.CORBA.MARSHAL e) {
159	// IMPORTANT - make sure we cache the fact something doesn't exist
160	propertyCache.put(propertyName, null);
161	}
162	}
163	String property = (String) propertyCache.get(propertyName);
164	if(property == null) {
165	// the property cannot be found, so we throw back
166	// a PropertyNotFoundException and give up.
167	throw new PropertyNotFoundException("Could not locate the property \""+propertyName+"\" in the configuration \""+configName+"\"");
168	}
169	return property;
170	}
171	}
172
173	/**
174	* This method obtains the configuration from the configuration
175	* cache, if the configuration isn't in the cache, it adds it.
176	* It then returns the file list used to build that configuration.
177	*
178	* @param configName the name of the configuration
179	*
180	* @return the semi-coma separated list of filenames
181	*/
182	public String getFileList(String configName) {
183	// ensures the run method can update the cache if needed.
184	synchronized (this) {
185	if (!_configCache.containsKey(configName)) {
186	_configCache.put(configName, new ConfigurationCache(_confman.getConfiguration(configName), new HashMap()));
187	}
188	ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
189	return cc.getConfig().getFileList();
190	}
191	}
192
193	/**
194	* This method obtains the configuration from the configuration
195	* cache, if the configuration isn't in the cache, it adds it.
196	* It then returns the time in milliseconds of the most last
197	* modified date of the most recently modified file in the configurations
198	* file list.
199	*
200	* @param configName the name of the configuration
201	*
202	* @return the time in millis
203	*/
204	public long getLastModified(String configName) {
205	// ensures the run method can update the cache if needed.
206	synchronized (this) {
207	if (!_configCache.containsKey(configName)) {
208	_configCache.put(configName, new ConfigurationCache(_confman.getConfiguration(configName), new HashMap()));
209	}
210	ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
211	return cc.getConfig().getLastModified();
212	}
213	}
214
215	/**
216	* Overrides the {@link java.lang.Object#toString() Object.toString()}
217	* method to provide clean logging (every class should have this).
218	*
219	* This uses the uk.org.iscream.cms.server.util.FormatName class
220	* to format the toString()
221	*
222	* @return the name of this class and its CVS revision
223	*/
224	public String toString() {
225	return FormatName.getName(
226	_name,
227	getClass().getName(),
228	REVISION);
229	}
230
231	//---PRIVATE METHODS---
232
233	//---ACCESSOR/MUTATOR METHODS---
234
235	//---ATTRIBUTES---
236
237	/**
238	* This is the friendly identifier of the
239	* component this class is running in.
240	* eg, a Filter may be called "filter1",
241	* If this class does not have an owning
242	* component, a name from the configuration
243	* can be placed here. This name could also
244	* be changed to null for utility classes.
245	*/
246	private String _name = null;
247
248	/**
249	* This holds a reference to the
250	* system logger that is being used.
251	*/
252	private Logger _logger = ReferenceManager.getInstance().getLogger();
253
254	/**
255	* A reference to the reference manager in use
256	*/
257	private ReferenceManager _refman = ReferenceManager.getInstance();
258
259	/**
260	* This holds a reference to the configuration
261	* manager
262	*/
263	private ConfigurationManager _confman = ReferenceManager.getInstance().getCM();
264
265	/**
266	* Holds a list of configuration cache's for every configuration that
267	* has been requested of this proxy.
268	*/
269	private HashMap _configCache = new HashMap();
270
271	/**
272	* Holds the current state of the configuration proxy's thread
273	*/
274	private boolean _running = true;
275
276	//---STATIC ATTRIBUTES---
277
278	/**
279	* A reference to the single instance of this class
280	*/
281	private static ConfigurationProxy _instance;
282
283	}