--- CircuitBreaker/src/dk/thoerup/curcuitbreaker/CircuitBreaker.java	2009/10/05 19:44:40	393
+++ miscJava/CircuitBreaker/src/main/java/dk/thoerup/circuitbreaker/CircuitBreaker.java	2015/06/09 09:28:14	2572
@@ -1,11 +1,23 @@
-package dk.thoerup.curcuitbreaker;
+package dk.thoerup.circuitbreaker;
 
-import java.util.logging.Logger;
 
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 
+import dk.thoerup.circuitbreaker.config.BreakerConfig;
+import dk.thoerup.circuitbreaker.config.StaticConfig;
+import dk.thoerup.circuitbreaker.notification.NotiferHelper;
+import dk.thoerup.circuitbreaker.notification.Notifier;
+import dk.thoerup.circuitbreaker.notification.NullNotifier;
+import dk.thoerup.circuitbreaker.statistics.NullStatistics;
+import dk.thoerup.circuitbreaker.statistics.Statistics;
+
+/* Simple CircuitBreaker implementation - snipped from http://www.jroller.com/kenwdelong/entry/circuit_breaker_in_java
+ * 
+ *  example of how it can be used
 
-/* example of how it can be used
-protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+ private CircuitBreaker cb = new CircuitBreaker("test", 5, 10000);
+ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 		class TestInvocation implements CircuitInvocation {
 			String url;
 			public TestInvocation(String url) {
@@ -27,7 +39,7 @@
 		try {
 			String s = (String) cb.invoke(new TestInvocation("http://rafiki/test"));
 			response.getWriter().print(s);
-		} catch (Throwable e) {
+		} catch (Exception e) {
 			logger.warning( e.getMessage() );
 			response.sendError(500);
 			return;
@@ -38,29 +50,45 @@
 
 
 public class CircuitBreaker{
-	Logger logger = Logger.getLogger(CircuitBreaker.class.getName());
-
 	
-	private CircuitBreakerState currentState;
+	private volatile CircuitBreakerState currentState;
 	
-	private OpenState open = new OpenState();
-	private HalfOpenState halfOpen = new HalfOpenState();
-	private ClosedState closed = new ClosedState();
+	private final OpenState open = new OpenState();
+	private final HalfOpenState halfOpen = new HalfOpenState();
+	private final ClosedState closed = new ClosedState();
 	
 	private String name;
 	
-	public CircuitBreaker(String name, int threshold, long timeoutMS) {
-		closed.setThreshold(threshold);
-		open.setTimeout(timeoutMS);
+	private ExecutorService executor = null;	
+	private Notifier notifier = new NullNotifier();
+	private Statistics stats = new NullStatistics();
+	
+	@Deprecated
+	public CircuitBreaker(String name, int threshold, int timeoutMS) {
+		this(name, new StaticConfig(threshold, timeoutMS) );
+	}
+	
+	public CircuitBreaker(String name, BreakerConfig config) {
+		closed.setThreshold(config);
+		open.setTimeout(config);
 		
 		this.name = name;
-		
-		reset();
+	
+		//set correct intial state
+		internalReset();
+	}
+	
+	public synchronized void shutdown() {
+		if (executor != null) {
+			executor.shutdown();
+		}
 	}
 	
 	
-    public Object invoke(CircuitInvocation invocation) throws Throwable
+    public Object invoke(CircuitInvocation invocation) throws Exception
     {
+    	stats.addStatistics(Event.Invocation);
+    	
     	Object result = null;
         try
         {
@@ -68,43 +96,141 @@
             result = invocation.proceed();
             getState().postInvoke(this);
         }
-        catch(Throwable t)
-        {
-            getState().onError(this, t);
-            throw t;
+        catch(Exception e)
+        {        	
+			if (e instanceof CircuitBreakerException) {
+				stats.addStatistics(Event.InvocationBlocked);
+			} else {
+				stats.addStatistics(Event.InvocationFailure);
+			}
+        	
+            getState().onError(this, e);
+            throw e;
         }
         return result;
     }
     
     public void tripBreaker() {
-    	synchronized(this) {
-    		currentState = open;
-    		open.trip();
-    		
-    		logger.warning("Circuitbreaker tripBreaker - " + name);
-    	}
+    	commonTripBreaker(Event.BreakerTripped);
+    }
     
+	//a re-trip should basically do the same as a normal trip, but it is here just to differentiate the two different events
+    public void retripBreaker() {
+    	commonTripBreaker(Event.BreakerRetripped);
     }
     
+    private void commonTripBreaker(Event event) {
+       	synchronized(this) {
+    		if (currentState != open) { // TODO:Is this conditional necessary ??
+    			open.trip();
+    			currentState = open;
+    		
+    			notifier.sendNotification(this, event);
+    			stats.addStatistics(event);
+    		}
+    	}   	
+    }
+
     public void attemptReset() {
     	synchronized(this) {
-    		currentState = halfOpen;
-    		
-    		logger.warning("Circuitbreaker attemptReset - " + name);
+    		if (currentState != halfOpen) { // TODO:Is this conditional necessary ??
+    			currentState = halfOpen;
+    			notifier.sendNotification(this, Event.BreakerAttemptReset);
+    			stats.addStatistics(Event.BreakerAttemptReset);
+    		}
     	}
+    	
     }
     
     public void reset() {
     	synchronized(this) {
-    		currentState = closed;
-    		
-    		logger.warning("Circuitbreaker reset - " + name);
+    		if (currentState != closed) { // TODO: Is this conditional necessary ??
+    			internalReset();
+    			notifier.sendNotification(this, Event.BreakerReset);
+    			stats.addStatistics(Event.BreakerReset);
+    		}
     	}
     }
     
+    //This one actually sets the correct closed/reset state 
+    private void internalReset() {
+		closed.resetFailureCount();
+		currentState = closed;    	
+    }
+    
+    
     private CircuitBreakerState getState() {
     	synchronized(this) {
     		return currentState;
     	}
     }
+    
+    public boolean isClosed() {
+    	return (getState() == closed); 
+    }
+    
+    public boolean isOpen() {
+    	return (getState() == open); 
+    }
+    
+    public String getName() {
+    	return name;
+    }
+    
+    public String getStateName() {
+    	return getState().getName();
+    }
+    
+    public int getThreshold() {
+    	return closed.getThreshold();
+    }
+    
+    public int getTimeout() {
+    	return (int)open.getTimeout();
+    }
+    
+    public int getFailureCount() {
+    	if (getState() == closed) {
+    		return closed.getFailureCount();
+    	} else {
+    		return -1;
+    	}
+    }
+    
+    public long getElapsed() {
+    	if (getState() == open) {
+    		return open.getElapsed();
+    	} else {
+    		return -1;
+    	}
+    }
+    
+    public void setNotifier(Notifier notifier) {
+    	synchronized(this) {
+    		this.notifier = notifier;
+    	}
+    }
+    
+    public String getNotifierName() { 
+    	return NotiferHelper.getName(notifier);
+    }
+    
+    public void setStatistics(Statistics newStats) {
+    	this.stats = newStats;
+    }
+    
+    public Statistics getStatistics() {
+    	return this.stats;
+    }
+    
+    public synchronized ExecutorService getExecutor() {
+    	
+    	if (executor == null) {
+    		executor = Executors.newFixedThreadPool(1);
+    	}
+    	
+    	return executor;
+    	
+    }
+ 
 }