openstack/net-virt/src/main/java/org/opendaylight/ovsdb/openstack/netvirt/impl/EventDispatcherImpl.java

   1 /*
   2  * Copyright (C) 2014 Red Hat, Inc.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  *
   8  * Authors : Dave Tucker, Flavio Fernandes
   9  */
  10
  11 package org.opendaylight.ovsdb.openstack.netvirt.impl;
  12
  13 import org.opendaylight.ovsdb.openstack.netvirt.AbstractEvent;
  14 import org.opendaylight.ovsdb.openstack.netvirt.AbstractHandler;
  15 import org.opendaylight.ovsdb.openstack.netvirt.api.Constants;
  16 import org.opendaylight.ovsdb.openstack.netvirt.api.EventDispatcher;
  17
  18 import org.osgi.framework.ServiceReference;
  19 import org.slf4j.Logger;
  20 import org.slf4j.LoggerFactory;
  21
  22 import java.util.concurrent.BlockingQueue;
  23 import java.util.concurrent.ExecutorService;
  24 import java.util.concurrent.Executors;
  25 import java.util.concurrent.LinkedBlockingQueue;
  26 import java.util.concurrent.TimeUnit;
  27
  28 public class EventDispatcherImpl implements EventDispatcher {
  29
  30     static final Logger logger = LoggerFactory.getLogger(EventDispatcher.class);
  31     private ExecutorService eventHandler;
  32     private BlockingQueue<AbstractEvent> events;
  33
  34     private AbstractHandler[] handlers;
  35
  36     void init() {
  37         eventHandler = Executors.newSingleThreadExecutor();
  38         this.events = new LinkedBlockingQueue<>();
  39         this.handlers = new AbstractHandler[AbstractEvent.HandlerType.size];
  40     }
  41
  42     void start() {
  43         eventHandler.submit(new Runnable()  {
  44             @Override
  45             public void run() {
  46                 while (true) {
  47                     AbstractEvent ev;
  48                     try {
  49                         ev = events.take();
  50                     } catch (InterruptedException e) {
  51                         logger.info("The event handler thread was interrupted, shutting down", e);
  52                         return;
  53                     }
  54                     dispatchEvent(ev);
  55                 }
  56             }
  57         });
  58         logger.debug("event dispatcher is started");
  59     }
  60
  61     void stop() {
  62         // stop accepting new tasks
  63         eventHandler.shutdown();
  64         try {
  65             // Wait a while for existing tasks to terminate
  66             if (!eventHandler.awaitTermination(10, TimeUnit.SECONDS)) {
  67                 eventHandler.shutdownNow();
  68                 // Wait a while for tasks to respond to being cancelled
  69                 if (!eventHandler.awaitTermination(10, TimeUnit.SECONDS))
  70                     logger.error("Dispatcher's event handler did not terminate");
  71             }
  72         } catch (InterruptedException e) {
  73             // (Re-)Cancel if current thread also interrupted
  74             eventHandler.shutdownNow();
  75             // Preserve interrupt status
  76             Thread.currentThread().interrupt();
  77         }
  78         logger.debug("event dispatcher is stopped");
  79     }
  80
  81     private void dispatchEvent(AbstractEvent ev) {
  82         AbstractHandler handler = handlers[ev.getHandlerType().ordinal()];
  83         if (handler == null) {
  84             logger.warn("event dispatcher found no handler for " + ev);
  85             return;
  86         }
  87
  88         handler.processEvent(ev);
  89     }
  90
  91     public void eventHandlerAdded(final ServiceReference ref, AbstractHandler handler){
  92         Long pid = (Long) ref.getProperty(org.osgi.framework.Constants.SERVICE_ID);
  93         Object handlerTypeObject = ref.getProperty(Constants.EVENT_HANDLER_TYPE_PROPERTY);
  94         if (!(handlerTypeObject instanceof AbstractEvent.HandlerType)){
  95             logger.error("Abstract handler reg failed to provide a valid handler type " + handlerTypeObject);
  96             return;
  97         }
  98         AbstractEvent.HandlerType handlerType = (AbstractEvent.HandlerType) handlerTypeObject;
  99         handlers[handlerType.ordinal()] = handler;
 100
 101         logger.debug("Event handler for type {} registered for {}, pid {}",
 102                      handlerType, handler.getClass().getName(), pid);
 103     }
 104
 105     public void eventHandlerRemoved(final ServiceReference ref){
 106         Long pid = (Long) ref.getProperty(org.osgi.framework.Constants.SERVICE_ID);
 107         Object handlerTypeObject = ref.getProperty(Constants.EVENT_HANDLER_TYPE_PROPERTY);
 108         if (!(handlerTypeObject instanceof AbstractEvent.HandlerType)){
 109             logger.error("Abstract handler unreg failed to provide a valid handler type " + handlerTypeObject);
 110             return;
 111         }
 112         AbstractEvent.HandlerType handlerType = (AbstractEvent.HandlerType) handlerTypeObject;
 113         handlers[handlerType.ordinal()] = null;
 114
 115         logger.debug("Event handler for type {} unregistered pid {}", handlerType, pid);
 116     }
 117
 118     /**
 119      * Enqueue the event.
 120      *
 121      * @param event the {@link org.opendaylight.ovsdb.openstack.netvirt.AbstractEvent} event to be handled.
 122      */
 123     @Override
 124     public void enqueueEvent(AbstractEvent event) {
 125         if (event == null) {
 126             return;
 127         }
 128
 129         try {
 130             events.put(event);
 131         } catch (InterruptedException e) {
 132             logger.error("Thread was interrupted while trying to enqueue event ", e);
 133         }
 134     }
 135 }