server/componentmanager/ConfigurationProxy.java

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

//---IMPORTS---
import java.util.*;
import uk.org.iscream.core.*;
import uk.org.iscream.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: ajm4 $
 * @version $Id: ConfigurationProxy.java,v 1.13 2001/03/26 01:39:41 ajm4 Exp $
 */
public class ConfigurationProxy extends Thread {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public static final String REVISION = "$Revision: 1.13 $";
    
    /**
     * 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.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:	1.14
Committed:	Mon Mar 26 12:10:42 2001 UTC (23 years, 1 month ago) by tdb
Branch:	MAIN
CVS Tags:	PROJECT_COMPLETION
Changes since 1.13:	+4 -3 lines
Log Message:	Closing the javadoc tag helps...
#	Content
1	//---PACKAGE DECLARATION---
2	package uk.org.iscream.componentmanager;
3
4	//---IMPORTS---
5	import java.util.*;
6	import uk.org.iscream.core.*;
7	import uk.org.iscream.util.*;
8
9	/**
10	* A Configuration Proxy hold configurations caches and
11	* maintains configurations obtained from the Configuration
12	* Manager.
13	*
14	* It also has support for checking for updates in configurations,
15	* if a change is detected, it reloads all the changed configurations.
16	* This is done by a thread which runs every ConfigurationProxy.updateTime
17	* seconds.
18	*
19	* This is a singleton class, and should be used by all classes
20	* that wish to gain a configuration from the server, as it then
21	* allows them to be dynamically reconfigured.
22	*
23	* @author $Author: ajm4 $
24	* @version $Id: ConfigurationProxy.java,v 1.13 2001/03/26 01:39:41 ajm4 Exp $
25	*/
26	public class ConfigurationProxy extends Thread {
27
28	//---FINAL ATTRIBUTES---
29
30	/**
31	* The current CVS revision of this class
32	*/
33	public static final String REVISION = "$Revision: 1.13 $";
34
35	/**
36	* The default time to refresh the
37	* configurations - 60 seconds.
38	*/
39	public final int DEFAULT_REFRESH_TIME = 60;
40
41	//---STATIC METHODS---
42
43	/**
44	* Return a reference to the single class.
45	* Construct it if it does not already exist, otherwise just return the reference.
46	*/
47	public synchronized static ConfigurationProxy getInstance() {
48	if (_instance == null){
49	_instance = new ConfigurationProxy();
50	}
51	return _instance;
52	}
53
54	//---CONSTRUCTORS---
55
56	/**
57	* Construct a ConfigurationProxy
58	* Then starts the auto-updating part (the thread) running.
59	*/
60	private ConfigurationProxy() {
61	// set the Thread name
62	setName("componentmanager.ConfigurationProxy");
63	start();
64	}
65
66	//---PUBLIC METHODS---
67
68	/**
69	* This method runs and waits for a period defined by
70	* ConfigurationProxy.updateTime. Each time it checks all the
71	* configuratons it has loaded to see if their configurations have
72	* changed. If they have, it refreshes the cache with the new configuration
73	* and then instructs the old one to be disconnected from the ORB so that it
74	* can be garbage collected.
75	*/
76	public void run() {
77	// periodic checks for config changes here
78
79	while(_running) {
80	int refreshTime = 0;
81	try {
82	refreshTime = Integer.parseInt(getProperty("ConfigurationProxy", "ConfigurationProxy.updateTime"));
83	} catch (NumberFormatException e) {
84	refreshTime = DEFAULT_REFRESH_TIME;
85	_logger.write(toString(), Logger.WARNING, "Erronous ConfigurationProxy.updateTime value in configuration using default of " + refreshTime + " seconds");
86	} catch (PropertyNotFoundException e) {
87	refreshTime = DEFAULT_REFRESH_TIME;
88	_logger.write(toString(), Logger.WARNING, "ConfigurationProxy.updateTime value unavailable using default of " + refreshTime + " seconds");
89	}
90
91	try {
92	Thread.sleep(refreshTime * 1000);
93	} catch (InterruptedException e) {
94	}
95	// ensures we update the list independently of the getProperty method
96	synchronized (this) {
97	Iterator i = _configCache.keySet().iterator();
98	while(i.hasNext()) {
99	String configName = (String) i.next();
100	ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
101	if (_confman.isModified(cc.getConfig().getFileList(), cc.getConfig().getLastModified())) {
102	// disconnect the old Configuration object from the ORB
103	cc.getConfig().disconnect();
104	// get the updated Configuration from the manager
105	cc.setConfig(_confman.getConfiguration(configName));
106	cc.setPropertyCache(new HashMap());
107	}
108	}
109	}
110	}
111	}
112
113	/**
114	* This method obtains the configuration from the configuration
115	* cache, if the configuration isn't in the cache, it adds it.
116	* It then asks the configuration for the requested property
117	* name, and then returns that to the caller.
118	*
119	* @param configName the name of the configuration
120	* @param propertyName the name of the property to obtain
121	*
122	* @return the value of the requested property
123	*/
124	public String getProperty(String configName, String propertyName) throws PropertyNotFoundException {
125	// ensures the run method can update the cache if needed.
126	synchronized (this) {
127	if (!_configCache.containsKey(configName)) {
128	_configCache.put(configName, new ConfigurationCache(_confman.getConfiguration(configName), new HashMap()));
129	}
130	ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
131	HashMap propertyCache = cc.getPropertyCache();
132	Configuration config = cc.getConfig();
133	if(!propertyCache.containsKey(propertyName)) {
134	// try and get the config
135	// if we can't throw an exception
136	try {
137	propertyCache.put(propertyName, config.getProperty(propertyName));
138	} catch (org.omg.CORBA.MARSHAL e) {
139	// IMPORTANT - make sure we cache the fact something doesn't exist
140	propertyCache.put(propertyName, null);
141	}
142	}
143	String property = (String) propertyCache.get(propertyName);
144	if(property == null) {
145	// the property cannot be found, so we throw back
146	// a PropertyNotFoundException and give up.
147	throw new PropertyNotFoundException("Could not locate the property \""+propertyName+"\" in the configuration \""+configName+"\"");
148	}
149	return property;
150	}
151	}
152
153	/**
154	* This method obtains the configuration from the configuration
155	* cache, if the configuration isn't in the cache, it adds it.
156	* It then returns the file list used to build that configuration.
157	*
158	* @param configName the name of the configuration
159	*
160	* @return the semi-coma separated list of filenames
161	*/
162	public String getFileList(String configName) {
163	// ensures the run method can update the cache if needed.
164	synchronized (this) {
165	if (!_configCache.containsKey(configName)) {
166	_configCache.put(configName, new ConfigurationCache(_confman.getConfiguration(configName), new HashMap()));
167	}
168	ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
169	return cc.getConfig().getFileList();
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 time in milliseconds of the most last
177	* modified date of the most recently modified file in the configurations
178	* file list.
179	*
180	* @param configName the name of the configuration
181	*
182	* @return the time in millis
183	*/
184	public long getLastModified(String configName) {
185	// ensures the run method can update the cache if needed.
186	synchronized (this) {
187	if (!_configCache.containsKey(configName)) {
188	_configCache.put(configName, new ConfigurationCache(_confman.getConfiguration(configName), new HashMap()));
189	}
190	ConfigurationCache cc = (ConfigurationCache) _configCache.get(configName);
191	return cc.getConfig().getLastModified();
192	}
193	}
194
195	/**
196	* Overrides the {@link java.lang.Object#toString() Object.toString()}
197	* method to provide clean logging (every class should have this).
198	*
199	* This uses the uk.org.iscream.util.FormatName class
200	* to format the toString()
201	*
202	* @return the name of this class and its CVS revision
203	*/
204	public String toString() {
205	return FormatName.getName(
206	_name,
207	getClass().getName(),
208	REVISION);
209	}
210
211	//---PRIVATE METHODS---
212
213	//---ACCESSOR/MUTATOR METHODS---
214
215	//---ATTRIBUTES---
216
217	/**
218	* This is the friendly identifier of the
219	* component this class is running in.
220	* eg, a Filter may be called "filter1",
221	* If this class does not have an owning
222	* component, a name from the configuration
223	* can be placed here. This name could also
224	* be changed to null for utility classes.
225	*/
226	private String _name = null;
227
228	/**
229	* This holds a reference to the
230	* system logger that is being used.
231	*/
232	private Logger _logger = ReferenceManager.getInstance().getLogger();
233
234	/**
235	* A reference to the reference manager in use
236	*/
237	private ReferenceManager _refman = ReferenceManager.getInstance();
238
239	/**
240	* This holds a reference to the configuration
241	* manager
242	*/
243	private ConfigurationManager _confman = ReferenceManager.getInstance().getCM();
244
245	/**
246	* Holds a list of configuration cache's for every configuration that
247	* has been requested of this proxy.
248	*/
249	private HashMap _configCache = new HashMap();
250
251	/**
252	* Holds the current state of the configuration proxy's thread
253	*/
254	private boolean _running = true;
255
256	//---STATIC ATTRIBUTES---
257
258	/**
259	* A reference to the single instance of this class
260	*/
261	private static ConfigurationProxy _instance;
262
263	}