org.argeo.cms/src/org/argeo/cms/internal/runtime/CmsSynchronousEventBusImpl.java

   1 package org.argeo.cms.internal.runtime;
   2
   3 import java.util.ArrayList;
   4 import java.util.Collections;
   5 import java.util.HashMap;
   6 import java.util.Iterator;
   7 import java.util.List;
   8 import java.util.Map;
   9
  10 import org.argeo.api.cms.CmsEventBus;
  11 import org.argeo.api.cms.CmsEventSubscriber;
  12 import org.argeo.api.cms.CmsLog;
  13
  14 /** A simple synchronous {@link CmsEventBus} implementation. */
  15 public class CmsSynchronousEventBusImpl implements CmsEventBus {
  16         private final static CmsLog log = CmsLog.getLog(CmsSynchronousEventBusImpl.class);
  17
  18         private final Map<String, List<CmsEventSubscriber>> subscribers;
  19
  20         public CmsSynchronousEventBusImpl() {
  21                 subscribers = Collections.synchronizedMap(new HashMap<>());
  22         }
  23
  24         @Override
  25         public void sendEvent(String topic, Map<String, Object> event) {
  26                 List<CmsEventSubscriber> subscribersOfTopic = subscribers.get(topic);
  27                 if (subscribersOfTopic == null) // no one cares
  28                         return;
  29                 synchronized (subscribersOfTopic) {
  30                         for (Iterator<CmsEventSubscriber> it = subscribersOfTopic.iterator(); it.hasNext();) {
  31                                 CmsEventSubscriber subscriber = it.next();
  32                                 try {
  33                                         subscriber.onEvent(topic, event);
  34                                 } catch (Throwable e) {
  35                                         log.error("Cannot process in topic " + topic + " the event " + event + " for subscriber "
  36                                                         + subscriber, e);
  37                                 }
  38                         }
  39                 }
  40                 log.trace(() -> "Dispatched event in topic " + topic + ": " + event);
  41         }
  42
  43         @Override
  44         public synchronized void addEventSubscriber(String topic, CmsEventSubscriber eventSubscriber) {
  45                 if (!subscribers.containsKey(topic)) {
  46                         subscribers.put(topic, new ArrayList<>());
  47                 }
  48                 subscribers.get(topic).add(eventSubscriber);
  49                 log.debug(() -> "Added subscriber " + eventSubscriber + " to topic " + topic);
  50         }
  51
  52         @Override
  53         public synchronized void removeEventSubscriber(String topic, CmsEventSubscriber eventSubscriber) {
  54                 List<CmsEventSubscriber> subscribersOfTopic = subscribers.get(topic);
  55                 assert subscribersOfTopic != null;
  56                 if (subscribersOfTopic != null) {
  57                         CmsEventSubscriber removedSubscriber = null;
  58                         synchronized (subscribersOfTopic) {
  59                                 subscribersOfTopic: for (Iterator<CmsEventSubscriber> it = subscribersOfTopic.iterator(); it
  60                                                 .hasNext();) {
  61                                         CmsEventSubscriber subscriber = it.next();
  62                                         if (subscriber == eventSubscriber) {
  63                                                 it.remove();
  64                                                 removedSubscriber = subscriber;
  65                                                 log.debug(() -> "Removed subscriber " + eventSubscriber + " from topic " + topic);
  66                                                 break subscribersOfTopic;
  67                                         }
  68                                 }
  69                         }
  70                         if (removedSubscriber == null)
  71                                 log.warn(() -> "Subscriber " + eventSubscriber + " not found (and therefore not removed) in topic "
  72                                                 + topic);
  73                 }
  74         }
  75
  76 }