server/componentmanager/ConfigurationProxy.java

//---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: tdb1 $
 * @version $Id: ConfigurationProxy.java,v 1.14 2001/03/26 12:10:42 tdb1 Exp $
 */
public class ConfigurationProxy extends Thread {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public static final String REVISION = "$Revision: 1.14 $";
    
    /**
     * 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:	1.15
Committed:	Tue May 29 17:02:34 2001 UTC (22 years, 11 months ago) by tdb
Branch:	MAIN
Branch point for:	SERVER_PIRCBOT
Changes since 1.14:	+7 -7 lines
Log Message:	Major change in the java package naming. This has been held off for some time now, but it really needed doing. The future packaging of all i-scream products will be; uk.org.iscream.<product>.<subpart>.* In the case of the central monitoring system server this will be; uk.org.iscream.cms.server.* The whole server has been changed to follow this structure, and tested to a smallish extent. Further changes in other parts of the CMS will follow.
#	User	Rev	Content
1	ajm	1.1	//---PACKAGE DECLARATION---
2	tdb	1.15	package uk.org.iscream.cms.server.componentmanager;
3	ajm	1.1
4			//---IMPORTS---
5			import java.util.*;
6	tdb	1.15	import uk.org.iscream.cms.server.core.*;
7			import uk.org.iscream.cms.server.util.*;
8	ajm	1.1
9			/**
10			* A Configuration Proxy hold configurations caches and
11			* maintains configurations obtained from the Configuration
12			* Manager.
13			*
14	ajm	1.13	* 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	tdb	1.15	* @author $Author: tdb1 $
24			* @version $Id: ConfigurationProxy.java,v 1.14 2001/03/26 12:10:42 tdb1 Exp $
25	ajm	1.1	*/
26			public class ConfigurationProxy extends Thread {
27
28			//---FINAL ATTRIBUTES---
29
30			/**
31			* The current CVS revision of this class
32			*/
33	tdb	1.15	public static final String REVISION = "$Revision: 1.14 $";
34	ajm	1.1
35	ajm	1.13	/**
36			* The default time to refresh the
37			* configurations - 60 seconds.
38	tdb	1.14	*/
39	ajm	1.1	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	tdb	1.11	public synchronized static ConfigurationProxy getInstance() {
48	ajm	1.1	if (_instance == null){
49			_instance = new ConfigurationProxy();
50			}
51			return _instance;
52			}
53
54			//---CONSTRUCTORS---
55
56			/**
57			* Construct a ConfigurationProxy
58	ajm	1.13	* Then starts the auto-updating part (the thread) running.
59	ajm	1.1	*/
60			private ConfigurationProxy() {
61	tdb	1.7	// set the Thread name
62			setName("componentmanager.ConfigurationProxy");
63	ajm	1.1	start();
64			}
65
66			//---PUBLIC METHODS---
67
68	ajm	1.13	/**
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	ajm	1.1	public void run() {
77			// periodic checks for config changes here
78
79			while(_running) {
80			int refreshTime = 0;
81			try {
82	ajm	1.3	refreshTime = Integer.parseInt(getProperty("ConfigurationProxy", "ConfigurationProxy.updateTime"));
83	ajm	1.1	} catch (NumberFormatException e) {
84			refreshTime = DEFAULT_REFRESH_TIME;
85	ajm	1.3	_logger.write(toString(), Logger.WARNING, "Erronous ConfigurationProxy.updateTime value in configuration using default of " + refreshTime + " seconds");
86	tdb	1.5	} catch (PropertyNotFoundException e) {
87	ajm	1.1	refreshTime = DEFAULT_REFRESH_TIME;
88	ajm	1.3	_logger.write(toString(), Logger.WARNING, "ConfigurationProxy.updateTime value unavailable using default of " + refreshTime + " seconds");
89	ajm	1.1	}
90
91			try {
92			Thread.sleep(refreshTime * 1000);
93			} catch (InterruptedException e) {
94			}
95	ajm	1.6	// 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	tdb	1.9	// disconnect the old Configuration object from the ORB
103			cc.getConfig().disconnect();
104			// get the updated Configuration from the manager
105	ajm	1.6	cc.setConfig(_confman.getConfiguration(configName));
106			cc.setPropertyCache(new HashMap());
107			}
108	ajm	1.1	}
109			}
110			}
111			}
112
113	ajm	1.13	/**
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	tdb	1.5	public String getProperty(String configName, String propertyName) throws PropertyNotFoundException {
125	ajm	1.6	// 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	tdb	1.12	// IMPORTANT - make sure we cache the fact something doesn't exist
140			propertyCache.put(propertyName, null);
141	ajm	1.6	}
142	ajm	1.4	}
143	tdb	1.12	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	ajm	1.1	}
151			}
152	tdb	1.8
153	ajm	1.13	/**
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	tdb	1.8	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	ajm	1.13	/**
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	tdb	1.8	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	ajm	1.1	/**
196			* Overrides the {@link java.lang.Object#toString() Object.toString()}
197			* method to provide clean logging (every class should have this).
198			*
199	tdb	1.15	* This uses the uk.org.iscream.cms.server.util.FormatName class
200	ajm	1.1	* 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	ajm	1.13	/**
246			* Holds a list of configuration cache's for every configuration that
247			* has been requested of this proxy.
248			*/
249	ajm	1.1	private HashMap _configCache = new HashMap();
250
251	ajm	1.13	/**
252			* Holds the current state of the configuration proxy's thread
253			*/
254	ajm	1.1	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			}