企业搜索引擎开发之连接器connector（二十四）
本人在上文中提到，连接器实现了两种事件依赖的机制 ，其一是我们手动操作连接器实例时；其二是由连接器的自动更新机制
上文中分析了连接器的自动更新机制，即定时器执行定时任务
那么，如果我们手动操作连接器实例时，是怎么发出事件更新连接器实例的呢
通过eclipse开发工具，追踪调用ChangeDetector接口的detect()方法的方法
ChangeDetectorTask类的run方法里面调用我们再上文中已经分析了，其他方法便是ConnectorCoordinatorImpl实例对象的方法
即ConnectorCoordinatorImpl实例对象的如下方法，分别调用了ChangeDetector接口的detect()方法
/** * 移除连接器实例 * Removes this {@link Connector} instance. Halts traversals, * removes the Connector instance from the known connectors, * and removes the Connector's on-disk representation. */ /* @Override */ public void removeConnector() { synchronized(this) { resetBatch(); if (instanceInfo != null) { instanceInfo.removeConnector(); } } // This must not be called while holding the lock. changeDetector.detect(); } /** * 重启遍历 * Retraverses the {@link Connector}'s content from scratch. * Halts any traversal in progress and removes any saved traversal state, * forcing the Connector to retraverse the Repository from its start. */ /* @Override */ public void restartConnectorTraversal() throws ConnectorNotFoundException { // To avoid deadlock, this method calls InstanceInfo's getters and setters, // rather than the local ones. synchronized(this) { resetBatch(); // Halt any traversal. getInstanceInfo().setConnectorState(null); // Discard the checkpoint. // If Schedule was 'run-once', re-enable it to run again. But watch out - // empty disabled Schedules could look a bit like a run-once Schedule. Schedule schedule = getInstanceInfo().getConnectorSchedule(); if (schedule != null && schedule.isDisabled() && schedule.getRetryDelayMillis() == -1 && schedule.nextScheduledInterval() != -1) { schedule.setDisabled(false); getInstanceInfo().setConnectorSchedule(schedule); } } // TODO: Remove this if we switch completely to JDBC PersistentStore. // FileStore doesn't notice the deletion of a file that did not exist. if (lister != null) { connectorCheckpointChanged(null); } // This must not be called while holding the lock. changeDetector.detect(); } /** * 设置配置信息 * Sets the {@link Configuration} for this {@link ConnectorCoordinator}. * If this {@link ConnectorCoordinator} supports persistence this will * persist the new Configuration. */ /* @Override */ public ConfigureResponse setConnectorConfiguration(TypeInfo newTypeInfo, Configuration configuration, Locale locale, boolean update) throws ConnectorNotFoundException, ConnectorExistsException, InstantiatorException { LOGGER.info("Configuring connector " + name); String typeName = newTypeInfo.getConnectorTypeName(); Preconditions.checkArgument(typeName.equals(configuration.getTypeName()), "TypeInfo must match Configuration type"); ConfigureResponse response = null; synchronized(this) { resetBatch(); if (instanceInfo != null) { if (!update) { throw new ConnectorExistsException(); } if (typeName.equals(typeInfo.getConnectorTypeName())) { configuration = new Configuration(configuration, getConnectorConfiguration()); response = resetConfig(instanceInfo.getConnectorDir(), typeInfo, configuration, locale); } else { // An existing connector is being given a new type - drop then add. // TODO: This shouldn't be called from within the synchronized block // because it will kick the change detector. removeConnector(); response = createNewConnector(newTypeInfo, configuration, locale); if (response != null) { // TODO: We need to restore original Connector config. This is // necessary once we allow update a Connector with new ConnectorType. // However, when doing so consider: createNewConnector could have // thrown InstantiatorException as well. Also, you need to kick // the changeDetector (but not in this synchronized block). LOGGER.severe("Failed to update Connector configuration."); // + " Restoring original Connector configuration."); } } } else { if (update) { throw new ConnectorNotFoundException(); } response = createNewConnector(newTypeInfo, configuration, locale); } } if (response == null) { // This must not be called while holding the lock. changeDetector.detect(); } else { return new ExtendedConfigureResponse(response, configuration.getXml()); } return response; } /** * 设置定时调度 * Sets the traversal {@link Schedule} for the {@link Connector}. * * @param connectorSchedule Schedule to store or null to unset any existing * Schedule. * @throws ConnectorNotFoundException if the connector is not found */ /* @Override */ public void setConnectorSchedule(Schedule connectorSchedule) throws ConnectorNotFoundException { synchronized(this) { // Persistently store the new schedule. getInstanceInfo().setConnectorSchedule(connectorSchedule); } // This must not be called while holding the lock. changeDetector.detect(); }
接下来ChangeDetector接口的detect()方法其实又调用了自身的实现ConnectorCoordinatorImpl实例对象的实现ChangeHandler接口的方法
ConnectorCoordinatorImpl-->ChangeDetector的detect()-->ChangeListener的相关方法-->ChangeHandler(ConnectorCoordinatorImpl实例对象)的相关方法
所以手动操作与自动更新机制实际上是殊途同归，最后都是调用了ChangeHandler(ConnectorCoordinatorImpl实例对象)的相关方法
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