org.eclipse.linuxtools.tmf/src/org/eclipse/linuxtools/tmf/signal/TmfSignalManager.java

   1 /*******************************************************************************
   2  * Copyright (c) 2009 Ericsson
   3  *
   4  * All rights reserved. This program and the accompanying materials are
   5  * made available under the terms of the Eclipse Public License v1.0 which
   6  * accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *   Francois Chouinard - Initial API and implementation
  11  *******************************************************************************/
  12
  13 package org.eclipse.linuxtools.tmf.signal;
  14
  15 import java.lang.reflect.InvocationTargetException;
  16 import java.lang.reflect.Method;
  17 import java.util.ArrayList;
  18 import java.util.HashMap;
  19 import java.util.List;
  20 import java.util.Map;
  21
  22 /**
  23  * <b><u>TmfSignalHandler</u></b>
  24  * <p>
  25  * This class manages the set of signal listeners and the signals they are
  26  * interested in. When a signal is broadcasted, the appropriate listeners
  27  * signal handlers are invoked.
  28  * <p>
  29  */
  30 public class TmfSignalManager {
  31
  32         // The set of event listeners and their corresponding handler methods.
  33         // Note: listeners could be restricted to ITmfComponents but there is no
  34         // harm in letting anyone use this
  35         static private Map<Object, Method[]> fListeners = new HashMap<Object, Method[]>();
  36
  37         // If requested, add universal signal tracer
  38         // TODO: to be revisited...
  39         private static boolean fTraceIsActive = false;
  40         private static TmfSignalTracer fSignalTracer;
  41         static {
  42                 if (fTraceIsActive) {
  43                         fSignalTracer = TmfSignalTracer.getInstance();
  44                         addListener(fSignalTracer);
  45                 }
  46         }
  47
  48         public static synchronized void addListener(Object listener) {
  49                 Method[] methods = getSignalHandlerMethods(listener);
  50                 if (methods.length > 0)
  51                         fListeners.put(listener, methods);
  52         }
  53
  54         public static synchronized void removeListener(Object listener) {
  55                 fListeners.remove(listener);
  56         }
  57
  58         /**
  59          * Returns the list of signal handlers in the listener. Signal handler name
  60          * is irrelevant; only the annotation (@TmfSignalHandler) is important.
  61          *
  62          * @param listener
  63          * @return
  64          */
  65         static private Method[] getSignalHandlerMethods(Object listener) {
  66                 List<Method> handlers = new ArrayList<Method>();
  67                 Method[] methods = listener.getClass().getMethods();
  68                 for (Method method : methods) {
  69                         if (method.isAnnotationPresent(TmfSignalHandler.class)) {
  70                                 handlers.add(method);
  71                         }
  72                 }
  73                 return handlers.toArray(new Method[handlers.size()]);
  74         }
  75
  76         /**
  77          * Invokes the handling methods that listens to signals of a given type.
  78          *
  79          * The list of handlers is built on-the-fly to allow for the dynamic
  80          * creation/deletion of signal handlers. Since the number of signal
  81          * handlers shouldn't be too high, this is not a big performance issue
  82          * to pay for the flexibility.
  83          *
  84          * @param signal
  85          */
  86         static public synchronized void dispatchSignal(TmfSignal signal) {
  87
  88                 // Build the list of listener methods that are registered for this signal
  89                 Class<?> signalClass = signal.getClass();
  90                 Map<Object, List<Method>> listeners = new HashMap<Object, List<Method>>();
  91                 listeners.clear();
  92                 for (Map.Entry<Object, Method[]> entry : fListeners.entrySet()) {
  93                         List<Method> matchingMethods = new ArrayList<Method>();
  94                         for (Method method : entry.getValue()) {
  95                                 if (method.getParameterTypes()[0].isAssignableFrom(signalClass)) {
  96                                         matchingMethods.add(method);
  97                                 }
  98                         }
  99                         if (!matchingMethods.isEmpty()) {
 100                                 listeners.put(entry.getKey(), matchingMethods);
 101                         }
 102                 }
 103
 104                 // Call the signal handlers
 105                 for (Map.Entry<Object, List<Method>> entry : listeners.entrySet()) {
 106                         for (Method method : entry.getValue()) {
 107                                 try {
 108                                         method.invoke(entry.getKey(), new Object[] { signal });
 109                                 } catch (IllegalArgumentException e) {
 110                                         // TODO Auto-generated catch block
 111                                 } catch (IllegalAccessException e) {
 112                                         // TODO Auto-generated catch block
 113                                 } catch (InvocationTargetException e) {
 114                                         // TODO Auto-generated catch block
 115                                 }
 116                         }
 117                 }
 118         }
 119
 120 }