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 volatile 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                 Thread t = Thread.currentThread();
  47                 logger.info("Thread = {}", t);
  48                 t.setName("EventDispatcherImpl");
  49                 logger.info("Thread = {}", t);
  50                 while (true) {
  51                     AbstractEvent ev;
  52                     try {
  53                         ev = events.take();
  54                     } catch (InterruptedException e) {
  55                         logger.info("The event handler thread was interrupted, shutting down", e);
  56                         return;
  57                     }
  58                     try {
  59                         dispatchEvent(ev);
  60                     } catch (Exception e) {
  61                         logger.error("Exception in dispatching event "+ev.toString(), e);
  62                     }
  63                 }
  64             }
  65         });
  66         logger.debug("event dispatcher is started");
  67     }
  68
  69     void stop() {
  70         // stop accepting new tasks
  71         eventHandler.shutdown();
  72         try {
  73             // Wait a while for existing tasks to terminate
  74             if (!eventHandler.awaitTermination(10, TimeUnit.SECONDS)) {
  75                 eventHandler.shutdownNow();
  76                 // Wait a while for tasks to respond to being cancelled
  77                 if (!eventHandler.awaitTermination(10, TimeUnit.SECONDS))
  78                     logger.error("Dispatcher's event handler did not terminate");
  79             }
  80         } catch (InterruptedException e) {
  81             // (Re-)Cancel if current thread also interrupted
  82             eventHandler.shutdownNow();
  83             // Preserve interrupt status
  84             Thread.currentThread().interrupt();
  85         }
  86         logger.debug("event dispatcher is stopped");
  87     }
  88
  89     private void dispatchEvent(AbstractEvent ev) {
  90         AbstractHandler handler = handlers[ev.getHandlerType().ordinal()];
  91         if (handler == null) {
  92             logger.warn("event dispatcher found no handler for " + ev);
  93             return;
  94         }
  95
  96         logger.info("EventDispatcherImpl: dispatchEvent: {}", ev);
  97         handler.processEvent(ev);
  98     }
  99
 100     public void eventHandlerAdded(final ServiceReference ref, AbstractHandler handler){
 101         Long pid = (Long) ref.getProperty(org.osgi.framework.Constants.SERVICE_ID);
 102         Object handlerTypeObject = ref.getProperty(Constants.EVENT_HANDLER_TYPE_PROPERTY);
 103         if (!(handlerTypeObject instanceof AbstractEvent.HandlerType)){
 104             logger.error("Abstract handler reg failed to provide a valid handler type " + handlerTypeObject);
 105             return;
 106         }
 107         AbstractEvent.HandlerType handlerType = (AbstractEvent.HandlerType) handlerTypeObject;
 108         handlers[handlerType.ordinal()] = handler;
 109
 110         logger.debug("Event handler for type {} registered for {}, pid {}",
 111                      handlerType, handler.getClass().getName(), pid);
 112     }
 113
 114     public void eventHandlerRemoved(final ServiceReference ref){
 115         Long pid = (Long) ref.getProperty(org.osgi.framework.Constants.SERVICE_ID);
 116         Object handlerTypeObject = ref.getProperty(Constants.EVENT_HANDLER_TYPE_PROPERTY);
 117         if (!(handlerTypeObject instanceof AbstractEvent.HandlerType)){
 118             logger.error("Abstract handler unreg failed to provide a valid handler type " + handlerTypeObject);
 119             return;
 120         }
 121         AbstractEvent.HandlerType handlerType = (AbstractEvent.HandlerType) handlerTypeObject;
 122         handlers[handlerType.ordinal()] = null;
 123
 124         logger.debug("Event handler for type {} unregistered pid {}", handlerType, pid);
 125     }
 126
 127     /**
 128      * Enqueue the event.
 129      *
 130      * @param event the {@link org.opendaylight.ovsdb.openstack.netvirt.AbstractEvent} event to be handled.
 131      */
 132     @Override
 133     public void enqueueEvent(AbstractEvent event) {
 134         if (event == null) {
 135             logger.warn("enqueueEvent: event is null");
 136             return;
 137         }
 138
 139         try {
 140             logger.info("EventDispatcherImpl: enqueueEvent: {}", event);
 141             events.put(event);
 142         } catch (InterruptedException e) {
 143             logger.error("Thread was interrupted while trying to enqueue event ", e);
 144         }
 145     }
 146 }