server/filter/PluginServiceCheckManager.java

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

//---IMPORTS---
import java.io.*;
import java.util.*;

import uk.org.iscream.cms.server.util.*;
import uk.org.iscream.cms.server.componentmanager.*;
import uk.org.iscream.cms.server.core.*;

/**
 * This class setups up and manages Plugins for performing service
 * checks.  When asked to run some service checks it runs the checks
 * on the service check pipeline for that host.  If the pipleline does
 * not exist it creates a new one.
 *
 * This is a singleton class.
 *
 * ###
 * This does not fully manage the pipelines, it should check
 * if a host has not heartbeated for a while and thus remove 
 * the pipeline.  At the moment it does not.
 * A suggestions for doing this is to use the getCreated() 
 * method on the PluginServiceCheckPipeline.  This tells you when
 * according to the system time the pipeline was created.  You could
 * then have a thread that periodically checks to see if a host
 * has not run its pipeline in say two heartbeats, and thus
 * this indicates that it is no longer running.  The pipeline
 * could then be removed from the hashmap and thus be eligable
 * for gc.
 * ###
 *
 * @author  $Author: tdb1 $
 * @version $Id: PluginServiceCheckManager.java,v 1.5 2001/03/14 23:25:29 tdb1 Exp $
 */
class PluginServiceCheckManager {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.5 $";
    
    /**
     * file name suffix for plugin service check classes:
     */
    private final String _suffix = "__ServiceCheck";
    
//---STATIC METHODS---

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

//---CONSTRUCTORS---

    /**
     * Private Constructor - this part creates the filter pipeline
     * This is a singleton class, btw.
     */
    private PluginServiceCheckManager(){
        _logger.write(toString(), Logger.SYSINIT, "created");
    }

//---PUBLIC METHODS---

    /**
     * run all registered service checks on a given host,
     * returning XML data with information about the check.
     *
     * @param hostname the host to run service checks for
     * @return the xml output from the service checks
     */
    public String runServiceChecks(String hostname){
        if (!_hostPipelines.containsKey(hostname)) {
               _hostPipelines.put(hostname, new PluginServiceCheckPipeline(hostname, this));
        }
        return "<services>" + ((PluginServiceCheckPipeline) _hostPipelines.get(hostname)).runPipeline() + "</services>";
    }

    /**
     * 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.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---

    /**
     * Returns a reference to the specified service check.
     * This method takes the name of the class that contains
     * a service check implementation.  It then checks to see
     * if it has loaded that class before.  If it has it returns
     * a reference to it, if not, it loads it for the first time,
     * remembers it, then returns that.
     *
     * @param className the PluginServiceCheck to be loaded
     * @return the requested PluginServiceCheck
     */
    public synchronized PluginServiceCheck getServiceCheck(String className) {
         _logger.write(toString(), Logger.DEBUG, "got request for service check - " + className);
        // see if we've already got the service check loaded
        if(_loadedServiceChecks.containsKey(className)) {
            _logger.write(toString(), Logger.DEBUG, className + " already loaded - returning reference to it.");
            return (PluginServiceCheck) _loadedServiceChecks.get(className);
        }
        // otherwise we need to load it and return
        _logger.write(toString(), Logger.DEBUG, "attempting to load service check - " + className);
        
        // Create an instance of the specified PluginServiceCheck
        // then added it to the list of already loaded service checks
        PluginServiceCheck serviceCheck = null;
        try {
            serviceCheck = (PluginServiceCheck)ClassLoader.getSystemClassLoader().loadClass(className).newInstance();
            _loadedServiceChecks.put(className, serviceCheck);
            _logger.write(toString(), Logger.DEBUG, "loaded service check - "+className+" ("+serviceCheck.getDescription()+")");
        }
        catch (InstantiationException e){
            _logger.write(toString(), Logger.ERROR, "failed to instantiate - "+className);
            _logger.write(toString(), Logger.ERROR, e.getMessage());
        }
        catch (Exception e){
            _logger.write(toString(), Logger.ERROR, "failed to add - "+className);
            _logger.write(toString(), Logger.ERROR, e.toString());
        }
        
        return serviceCheck;
    }

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

//---ATTRIBUTES---
 
    /**
     * A hash map containing host pipelines
     */
    private HashMap _hostPipelines = new HashMap();
 
    /**
     * A hash map containing host pipelines
     */
    private HashMap _loadedServiceChecks = new HashMap();
 
    /**
     * 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();
    
    /**
     * A reference to the reference manager in use
     */
    private ReferenceManager _refman = ReferenceManager.getInstance();

//---STATIC ATTRIBUTES---

    /**
     * A reference to the single instance of this class
     */
    private static PluginServiceCheckManager _instance;
}
Revision:	1.6
Committed:	Tue May 29 17:02:35 2001 UTC (22 years, 11 months ago) by tdb
Branch:	MAIN
Branch point for:	SERVER_PIRCBOT
Changes since 1.5:	+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.
#	Content
1	//---PACKAGE DECLARATION---
2	package uk.org.iscream.cms.server.filter;
3
4	//---IMPORTS---
5	import java.io.*;
6	import java.util.*;
7
8	import uk.org.iscream.cms.server.util.*;
9	import uk.org.iscream.cms.server.componentmanager.*;
10	import uk.org.iscream.cms.server.core.*;
11
12	/**
13	* This class setups up and manages Plugins for performing service
14	* checks. When asked to run some service checks it runs the checks
15	* on the service check pipeline for that host. If the pipleline does
16	* not exist it creates a new one.
17	*
18	* This is a singleton class.
19	*
20	* ###
21	* This does not fully manage the pipelines, it should check
22	* if a host has not heartbeated for a while and thus remove
23	* the pipeline. At the moment it does not.
24	* A suggestions for doing this is to use the getCreated()
25	* method on the PluginServiceCheckPipeline. This tells you when
26	* according to the system time the pipeline was created. You could
27	* then have a thread that periodically checks to see if a host
28	* has not run its pipeline in say two heartbeats, and thus
29	* this indicates that it is no longer running. The pipeline
30	* could then be removed from the hashmap and thus be eligable
31	* for gc.
32	* ###
33	*
34	* @author $Author: tdb1 $
35	* @version $Id: PluginServiceCheckManager.java,v 1.5 2001/03/14 23:25:29 tdb1 Exp $
36	*/
37	class PluginServiceCheckManager {
38
39	//---FINAL ATTRIBUTES---
40
41	/**
42	* The current CVS revision of this class
43	*/
44	public final String REVISION = "$Revision: 1.5 $";
45
46	/**
47	* file name suffix for plugin service check classes:
48	*/
49	private final String _suffix = "__ServiceCheck";
50
51	//---STATIC METHODS---
52
53	/**
54	* Return a reference to the singleton class.
55	* Construct it if it does not already exist, otherwise just return the reference.
56	*/
57	public static PluginServiceCheckManager getInstance() {
58	if (_instance == null){
59	_instance = new PluginServiceCheckManager();
60	}
61	return _instance;
62	}
63
64	//---CONSTRUCTORS---
65
66	/**
67	* Private Constructor - this part creates the filter pipeline
68	* This is a singleton class, btw.
69	*/
70	private PluginServiceCheckManager(){
71	_logger.write(toString(), Logger.SYSINIT, "created");
72	}
73
74	//---PUBLIC METHODS---
75
76	/**
77	* run all registered service checks on a given host,
78	* returning XML data with information about the check.
79	*
80	* @param hostname the host to run service checks for
81	* @return the xml output from the service checks
82	*/
83	public String runServiceChecks(String hostname){
84	if (!_hostPipelines.containsKey(hostname)) {
85	_hostPipelines.put(hostname, new PluginServiceCheckPipeline(hostname, this));
86	}
87	return "<services>" + ((PluginServiceCheckPipeline) _hostPipelines.get(hostname)).runPipeline() + "</services>";
88	}
89
90	/**
91	* Overrides the {@link java.lang.Object#toString() Object.toString()}
92	* method to provide clean logging (every class should have this).
93	*
94	* This uses the uk.org.iscream.cms.server.util.NameFormat class
95	* to format the toString()
96	*
97	* @return the name of this class and its CVS revision
98	*/
99	public String toString() {
100	return FormatName.getName(
101	_name,
102	getClass().getName(),
103	REVISION);
104	}
105
106	//---PRIVATE METHODS---
107
108	/**
109	* Returns a reference to the specified service check.
110	* This method takes the name of the class that contains
111	* a service check implementation. It then checks to see
112	* if it has loaded that class before. If it has it returns
113	* a reference to it, if not, it loads it for the first time,
114	* remembers it, then returns that.
115	*
116	* @param className the PluginServiceCheck to be loaded
117	* @return the requested PluginServiceCheck
118	*/
119	public synchronized PluginServiceCheck getServiceCheck(String className) {
120	_logger.write(toString(), Logger.DEBUG, "got request for service check - " + className);
121	// see if we've already got the service check loaded
122	if(_loadedServiceChecks.containsKey(className)) {
123	_logger.write(toString(), Logger.DEBUG, className + " already loaded - returning reference to it.");
124	return (PluginServiceCheck) _loadedServiceChecks.get(className);
125	}
126	// otherwise we need to load it and return
127	_logger.write(toString(), Logger.DEBUG, "attempting to load service check - " + className);
128
129	// Create an instance of the specified PluginServiceCheck
130	// then added it to the list of already loaded service checks
131	PluginServiceCheck serviceCheck = null;
132	try {
133	serviceCheck = (PluginServiceCheck)ClassLoader.getSystemClassLoader().loadClass(className).newInstance();
134	_loadedServiceChecks.put(className, serviceCheck);
135	_logger.write(toString(), Logger.DEBUG, "loaded service check - "+className+" ("+serviceCheck.getDescription()+")");
136	}
137	catch (InstantiationException e){
138	_logger.write(toString(), Logger.ERROR, "failed to instantiate - "+className);
139	_logger.write(toString(), Logger.ERROR, e.getMessage());
140	}
141	catch (Exception e){
142	_logger.write(toString(), Logger.ERROR, "failed to add - "+className);
143	_logger.write(toString(), Logger.ERROR, e.toString());
144	}
145
146	return serviceCheck;
147	}
148
149	//---ACCESSOR/MUTATOR METHODS---
150
151	//---ATTRIBUTES---
152
153	/**
154	* A hash map containing host pipelines
155	*/
156	private HashMap _hostPipelines = new HashMap();
157
158	/**
159	* A hash map containing host pipelines
160	*/
161	private HashMap _loadedServiceChecks = new HashMap();
162
163	/**
164	* This is the friendly identifier of the
165	* component this class is running in.
166	* eg, a Filter may be called "filter1",
167	* If this class does not have an owning
168	* component, a name from the configuration
169	* can be placed here. This name could also
170	* be changed to null for utility classes.
171	*/
172	private String _name = FilterMain.NAME;
173
174	/**
175	* This holds a reference to the
176	* system logger that is being used.
177	*/
178	private Logger _logger = ReferenceManager.getInstance().getLogger();
179
180	/**
181	* A reference to the reference manager in use
182	*/
183	private ReferenceManager _refman = ReferenceManager.getInstance();
184
185	//---STATIC ATTRIBUTES---
186
187	/**
188	* A reference to the single instance of this class
189	*/
190	private static PluginServiceCheckManager _instance;
191	}