ObjectRecorder


1   /*
2    * ObjectRecorder, a class that takes records of an objects state using reflection.
3    * Copyright (C) 2002  Achim Westermann, Achim.Westermann@gmx.de.
4    *
5    *  This library is free software; you can redistribute it and/or
6    *  modify it under the terms of the GNU Lesser General Public
7    *  License as published by the Free Software Foundation; either
8    *  version 2.1 of the License, or (at your option) any later version.
9    * 
10   *  This library is distributed in the hope that it will be useful,
11   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   *  Lesser General Public License for more details.
14   * 
15   *  You should have received a copy of the GNU Lesser General Public
16   *  License along with this library; if not, write to the Free Software
17   *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
18   *
19   *  If you modify or optimize the code in a useful way please let me know.
20   *  Achim.Westermann@gmx.de
21   */
22  package info.monitorenter.reflection;
23  
24  import info.monitorenter.util.TimeStampedValue;
25  import info.monitorenter.util.collections.IRingBuffer;
26  import info.monitorenter.util.collections.RingBufferArrayFast;
27  
28  import java.lang.reflect.Field  ;
29  import java.lang.reflect.InvocationTargetException  ;
30  import java.lang.reflect.Method  ;
31  import java.util.LinkedList  ;
32  
33  import javax.naming.directory.NoSuchAttributeException  ;
34  import javax.swing.event.ChangeEvent  ;
35  import javax.swing.event.ChangeListener  ;
36  import javax.swing.event.EventListenerList  ;
37  
38  
39  /**
40   * The <code>ObjectRecorder</code> takes records(inspections) of an objects
41   * state using reflection and accessibility- framework.
42   * <p>
43   * 
44   * It's strategy is to: <br>
45   * 
46   * <pre>
47   *  - try to set any field accessible.
48   *  - try to get the value of the field.
49   *  - if not suceed: try to invoke a bean- conform getter.
50   *  - if NoSuchMethod, it's useless (no implementation of MagicClazz here).
51   *  </pre>
52   * 
53   * <p>
54   * 
55   * Furthermore the <code>ObjectRecorder</code> has a history - size (buffer)
56   * and an adjustable distance between each inspection.
57   * <p>
58   * 
59   * @author <a HREF='mailto:Achim.Westermann@gmx.de'>Achim Westermann </a>
60   * 
61   * @version $Revision: 1.1 $
62   */
63  public class ObjectRecorder extends Thread   {
64  
65    /**
66     * Data container for the inspection of the internal intance.
67     * <p>
68     * 
69     * @author <a HREF="mailto:Achim.Westermann@gmx.de">Achim Westermann </a>
70     * 
71     * 
72     * @version $Revision: 1.1 $
73     */
74    public final class ObjectInspection {
75      /** Timestamp of the inspection. */
76      protected long m_time;
77  
78      /** The values taken on the inspection. */
79      private LinkedList   m_values;
80  
81      /**
82       * Creates an instance linked to the outer recorder.
83       * <p>
84       * 
85       */
86      private ObjectInspection() {
87        this.m_time = new java.util.Date  ().getTime();
88        this.m_values = new LinkedList  ();
89      }
90  
91      /**
92       * Adds an inspected value to this inpsection.
93       * <p>
94       * 
95       * @param value
96       *          an inspected value of this inpsection.
97       */
98      private void add(final Object   value) {
99        this.m_values.add(value);
100     }
101 
102     /**
103      * Get the value for the attribute at the given index.
104      * <p>
105      * 
106      * @param index
107      *          the index of the inspected value according to the order it was
108      *          found on the instance by {@link Class#getDeclaredFields()}.
109      *          <p>
110      * 
111      * @return the value for the attribute at the given index.
112      */
113     public Object   get(final int index) {
114       return this.m_values.get(index);
115     }
116 
117     /**
118      * Returns the timestamp in ms of this inspection.
119      * <p>
120      * 
121      * @return the timestamp in ms of this inspection.
122      */
123     public long getTime() {
124       return this.m_time;
125     }
126 
127     /**
128      * Removes the inspected value from this inspection.
129      * <p>
130      * 
131      * The value is identified by means of
132      * {@link Object#equals(java.lang.Object)}.
133      * <p>
134      * 
135      * @param value
136      *          the inspected value from this inspection.
137      */
138     protected void remove(final Object   value) {
139       this.m_values.remove(value);
140     }
141 
142     /**
143      * Returns a pretty print of this inspection.
144      * <p>
145      * 
146      * @return a pretty print of this inspection.
147      * 
148      * @see java.lang.Object#toString()
149      */
150     public String   toString() {
151       StringBuffer   ret = new StringBuffer  ("\nObjectInspection:\n");
152       ret.append("-----------------\n");
153       ret.append("Inspected: ").append(ObjectRecorder.this.getInspected().toString()).append("\n");
154       ret.append("time:      ").append(this.m_time).append("\n");
155       for (int i = ObjectRecorder.this.m_fields.length - 1; i >= 0; i--) {
156         ret.append(ObjectRecorder.this.m_fields[i].getName()).append(": ").append(
157             this.m_values.get(i).toString()).append("\n");
158       }
159       return ret.toString();
160     }
161   }
162 
163   /** Verbosity constant. */
164   protected static final boolean VERBOSE = false;
165 
166   /** Fast buffer to store recorded fiels. */
167   protected IRingBuffer m_buffer = new RingBufferArrayFast(100);
168 
169   /** The listeners on this recorder. */
170   protected EventListenerList   m_changeListeners = new EventListenerList  ();
171 
172   /** The fields to inspect on the instance. */
173   protected Field  [] m_fields;
174 
175   /**
176    * The time - interval between to inspections of the Object.
177    */
178   protected long m_interval;
179 
180   /** The instance to instpec. */
181   protected Object   m_toinspect;
182 
183   /**
184    * Creates an instance that will inspect the given Object in the given time
185    * interval.
186    * <p>
187    * 
188    * @param toinspect
189    *          the instance to inspect.
190    * 
191    * @param interval
192    *          the interval of inspection in ms.
193    */
194   public ObjectRecorder(final Object   toinspect, final long interval) {
195     this.m_interval = interval;
196     this.m_toinspect = toinspect;
197     // getting the fieldnames.
198     this.m_fields = toinspect.getClass().getDeclaredFields();
199     this.start();
200   }
201 
202   /**
203    * Adds a change listener that will be informed about new recordings of the
204    * inpected instances.
205    * <p>
206    * 
207    * @param x
208    *          the change listener that will be informed about new recordings of
209    *          the inpected instances.
210    */
211   public void addChangeListener(final ChangeListener   x) {
212     this.m_changeListeners.add(ChangeListener  .class, x);
213     // x.stateChanged(new ChangeEvent(this)); // Aufruf des neuen
214     // ChangeListeners um zu aktualisieren.
215   }
216 
217   /**
218    * Informs the listeners about a change of this instance.
219    * <p>
220    * 
221    */
222   protected void fireChange() {
223     ChangeEvent   ce = new ChangeEvent  (this);
224     Object  [] listeners = this.m_changeListeners.getListenerList();
225     for (int i = listeners.length - 1; i >= 0; i -= 2) {
226       ChangeListener   cl = (ChangeListener  ) listeners[i];
227       cl.stateChanged(ce);
228     }
229   }
230 
231   /**
232    * The History returned by this Method represents the past of the field
233    * specified by attributeName. It starts from low index with the newest values
234    * taken from the inspected Object and ends with the oldest.
235    * 
236    * @param attributeName
237    *          field name of the internal instance to inspect.
238    * 
239    * @return An array filled with TimeStampedValues that represent the past of
240    *         the last inspections of the field with attributeName.
241    * 
242    * @throws NoSuchAttributeException
243    *           if the attribute / field described by the given argument does not
244    *           exist on the internal Object to instpect.
245    * 
246    * @see ObjectRecorder#getInspected()
247    */
248   public TimeStampedValue[] getAttributeHistory(final String   attributeName)
249       throws NoSuchAttributeException   {
250     // search for the field
251     int attribindex = -1;
252     for (int i = this.m_fields.length - 1; i >= 0; i--) {
253       if (this.m_fields[i].getName().equals(attributeName)) {
254         attribindex = i;
255         break;
256       }
257     }
258     if (attribindex == -1) {
259       throw new NoSuchAttributeException  ("The Attribute with the name: " + attributeName
260           + " does not exist in " + this.m_toinspect.getClass().getName());
261     }
262     int stop = this.m_buffer.size();
263     TimeStampedValue[] ret = new TimeStampedValue[stop];
264     ObjectInspection tmp;
265     synchronized (this.m_buffer) {
266       java.util.Iterator   it = this.m_buffer.iteratorF2L();
267       int i = 0;
268       while (it.hasNext()) {
269         tmp = (ObjectInspection) it.next();
270         ret[i++] = new TimeStampedValue(tmp.getTime(), tmp.get(attribindex));
271       }
272     }
273     return ret;
274   }
275 
276   /**
277    * Returns the names of the fields to inspect.
278    * <p>
279    * 
280    * @return the names of the fields to inspect.
281    */
282   public String  [] getAttributeNames() {
283     String  [] ret = new String  [this.m_fields.length];
284     for (int i = 0; i < this.m_fields.length; i++) {
285       ret[i] = this.m_fields[i].getName();
286     }
287     return ret;
288 
289   }
290 
291   /**
292    * Returns the inspected instance.
293    * <p>
294    * 
295    * @return the inspected instance.
296    */
297   public Object   getInspected() {
298     return this.m_toinspect;
299   }
300 
301   /**
302    * Returns the last recoreded value taken from the given field along with the
303    * timestamp identifying the time this value was recored.
304    * <p>
305    * 
306    * @param fieldname
307    *          the field whose value was recorded.
308    * 
309    * @return the last recoreded value taken from the given field along with the
310    *         timestamp identifying the time this value was recored.
311    * 
312    * @throws NoSuchAttributeException
313    *           if no such field exists on the Object to inspect.
314    * 
315    */
316   public TimeStampedValue getLastValue(final String   fieldname) throws NoSuchAttributeException   {
317     // search for the field
318     int attribindex = -1;
319     for (int i = this.m_fields.length - 1; i >= 0; i--) {
320       if (this.m_fields[i].getName().equals(fieldname)) {
321         attribindex = i;
322         break;
323       }
324     }
325     if (attribindex == -1) {
326       throw new NoSuchAttributeException  ("The Attribute with the name: " + fieldname
327           + " does not exist in " + this.m_toinspect.getClass().getName());
328     }
329     ObjectInspection tmp = (ObjectInspection) this.m_buffer.getYoungest();
330     return new TimeStampedValue(tmp.getTime(), tmp.get(attribindex));
331   }
332 
333   /**
334    * Returns the internal fifo buffer that stores the
335    * {@link ObjectRecorder.ObjectInspection} instances that have been done.
336    * <p>
337    * 
338    * @return the internal fifo buffer that stores the
339    *         {@link ObjectRecorder.ObjectInspection} instances that have been
340    *         done.
341    */
342   public IRingBuffer getRingBuffer() {
343     return this.m_buffer;
344   }
345 
346   /**
347    * Makes a record of the state of the object specified in the constructor. The
348    * new record is stored in a RingBuffer and contains all retrieveable values
349    * of the Object specified in the constructor. Reflection is used to get the
350    * values. If a field is private it's value is tried to be taken from the
351    * Object by invoking a getter - method conform with the bean - specification:
352    * The name of the method has to be "get" followed by the name of the field
353    * with first letter uppercase.
354    */
355   public void inspect() {
356     ObjectInspection newentry = new ObjectInspection();
357     for (int i = 0; i < this.m_fields.length; i++) {
358       if (ObjectRecorder.VERBOSE) {
359         System.out.println(this.getClass().getName() + " inpspecting " + this.m_fields[i].getName()
360             + " of " + this.m_toinspect.getClass().getName() + ".");
361       }
362       try {
363         this.m_fields[i].setAccessible(true);
364         newentry.add(this.m_fields[i].get(this.m_toinspect));
365       } catch (IllegalAccessException   e) {
366         if (ObjectRecorder.VERBOSE) {
367           System.err.println(this.getClass().getName() + ".inspect(): No public access to "
368               + this.m_fields[i].getName() + " of " + this.m_toinspect.getClass().getName());
369         }
370         // Try to invoke bean- conform getter method.
371         String   fieldname = this.m_fields[i].getName();
372         char[] fieldnm = fieldname.toCharArray();
373         fieldnm[0] = Character.toUpperCase(fieldnm[0]);
374         fieldname = new String  (fieldnm);
375         String   methodname = new StringBuffer  ("get").append(fieldname).toString();
376         // name of method constructed. Now invoke it.
377         try {
378           Method   toinvoke = this.m_toinspect.getClass().getDeclaredMethod(methodname,
379               new Class  [] {});
380           newentry.add(toinvoke.invoke(this.m_toinspect, new Object  [] {}));
381 
382         } catch (NoSuchMethodException   f) {
383           if (ObjectRecorder.VERBOSE) {
384             System.err.println(this.getClass().getName() + ".inspect(): Failure at getting field "
385                 + this.m_fields[i].getName() + " by trying to invoke a method: " + methodname);
386           }
387         } catch (SecurityException   g) {
388           g.printStackTrace();
389         } catch (IllegalAccessException   h) {
390           h.printStackTrace();
391         } catch (InvocationTargetException   l) {
392           l.printStackTrace();
393         }
394       }
395     }
396     this.m_buffer.add(newentry);
397     this.fireChange();
398   }
399 
400   /**
401    * Removes the given listener for changes of the inpsected instance.
402    * <p>
403    * 
404    * @param x
405    *          the listener to remove.
406    */
407   public void removeChangeListener(final ChangeListener   x) {
408     this.m_changeListeners.remove(ChangeListener  .class, x);
409   }
410 
411   /**
412    * 
413    * @see java.lang.Runnable#run()
414    */
415   public void run() {
416     while (true) {
417       try {
418         sleep(this.m_interval);
419       } catch (InterruptedException   e) {
420         // nop
421       }
422       this.inspect();
423     }
424   }
425 
426   /**
427    * Define the amount of recorded states of the Object to inspect that remain
428    * in memory.
429    * <p>
430    * 
431    * Default value is 100.
432    * <p>
433    * 
434    * @param length
435    *          the amount of recorded states of the Object to inspect that remain
436    *          in memory.
437    */
438   public void setHistoryLength(final int length) {
439     this.m_buffer.setBufferSize(length);
440   }
441 
442   /**
443    * Sets the interval for inpection of the instance to inspect in ms.
444    * <p>
445    * 
446    * @param sleeptime
447    *          the interval for inpection of the instance to inspect in ms.
448    * 
449    * @see ObjectRecorder#ObjectRecorder(Object, long)
450    */
451   public void setInterval(final long sleeptime) {
452     this.m_interval = sleeptime;
453   }
454 
455   /**
456    * @see java.lang.Object#toString()
457    */
458   public String   toString() {
459     return this.m_buffer.toString();
460   }
461 }
462
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