| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more contributor license |
| * agreements. See the NOTICE file distributed with this work for additional information regarding |
| * copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance with the License. You may obtain a |
| * copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software distributed under the License |
| * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express |
| * or implied. See the License for the specific language governing permissions and limitations under |
| * the License. |
| */ |
| |
| package org.apache.fluo.api.observer; |
| |
| import org.apache.fluo.api.client.FluoClient; |
| import org.apache.fluo.api.client.TransactionBase; |
| import org.apache.fluo.api.config.FluoConfiguration; |
| import org.apache.fluo.api.config.SimpleConfiguration; |
| import org.apache.fluo.api.data.Bytes; |
| import org.apache.fluo.api.data.Column; |
| import org.apache.fluo.api.metrics.MetricsReporter; |
| |
| /** |
| * Implemented by users to a watch a {@link Column} and be notified of changes to the Column via the |
| * {@link #process(TransactionBase, Bytes, Column)} method. |
| * |
| * <p> |
| * In Fluo version 1.1.0 this was converted to a functional interface. This change along with the |
| * introduction of {@link ObserverProvider} allows Observers to be written as lambdas. |
| * |
| * @since 1.0.0 |
| */ |
| @FunctionalInterface |
| public interface Observer { |
| |
| /** |
| * @since 1.0.0 |
| */ |
| enum NotificationType { |
| WEAK, STRONG |
| } |
| |
| /** |
| * A {@link Column} and {@link NotificationType} pair |
| * |
| * @since 1.0.0 |
| * @deprecated since 1.1.0. The method that used this class was deprecated. |
| */ |
| @Deprecated |
| class ObservedColumn { |
| private final Column col; |
| private final NotificationType notificationType; |
| |
| public ObservedColumn(Column col, NotificationType notificationType) { |
| this.col = col; |
| this.notificationType = notificationType; |
| } |
| |
| public Column getColumn() { |
| return col; |
| } |
| |
| public NotificationType getType() { |
| return notificationType; |
| } |
| |
| /** |
| * @since 1.1.0 |
| */ |
| @Override |
| public String toString() { |
| return col + " " + notificationType; |
| } |
| } |
| |
| /** |
| * @since 1.0.0 |
| * |
| * @deprecated since 1.1.0. The method that used this interface was deprecated. |
| */ |
| @Deprecated |
| interface Context { |
| /** |
| * @return A configuration object with application configuration like that returned by |
| * {@link FluoClient#getAppConfiguration()} |
| */ |
| SimpleConfiguration getAppConfiguration(); |
| |
| /** |
| * @return The per observer configuration that's specific to this observer. |
| */ |
| SimpleConfiguration getObserverConfiguration(); |
| |
| /** |
| * @return A {@link MetricsReporter} to report application metrics from this observer |
| */ |
| MetricsReporter getMetricsReporter(); |
| } |
| |
| /** |
| * Implemented by user to initialize Observer. |
| * |
| * @param context Observer context |
| * |
| * @deprecated since 1.1.0. Fluo will no longer call this method when observers are configured by |
| * {@link FluoConfiguration#setObserverProvider(String)}. Its only called when |
| * observers are configured the old way by |
| * {@link FluoConfiguration#addObserver(org.apache.fluo.api.config.ObserverSpecification)} |
| */ |
| @Deprecated |
| default void init(Context context) throws Exception {} |
| |
| /** |
| * Implemented by users to process notifications on a {@link ObservedColumn}. If a notification |
| * occurs, this method passes the user a {@link TransactionBase} as well as the row and |
| * {@link Column} where the notification occurred. The user can use the {@link TransactionBase} to |
| * read and write to Fluo. After this method returns, {@link TransactionBase} will be committed |
| * and closed by Fluo. |
| */ |
| void process(TransactionBase tx, Bytes row, Column col) throws Exception; |
| |
| /** |
| * Implemented by user to return an {@link ObservedColumn} that will trigger this observer. During |
| * initialization, this information is stored in zookeeper so that workers have a consistent view. |
| * If a worker loads an Observer and the information returned differs from what is in zookeeper |
| * then an exception will be thrown. It is safe to assume that {@link #init(Context)} will be |
| * called before this method. If the return value of the method is derived from what is passed to |
| * {@link #init(Context)}, then the derivation process should be deterministic. |
| * |
| * @deprecated since 1.1.0 Fluo will no longer call this method when observers are configured by |
| * {@link FluoConfiguration#setObserverProvider(String)}. Its only called when |
| * observers are configured the old way by |
| * {@link FluoConfiguration#addObserver(org.apache.fluo.api.config.ObserverSpecification)} |
| */ |
| @Deprecated |
| default ObservedColumn getObservedColumn() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| /** |
| * Implemented by user to close resources used by Observer |
| * |
| * @deprecated since 1.1.0. Fluo will no longer call this method when observers are configured by |
| * {@link FluoConfiguration#setObserverProvider(String)}. Its only called when |
| * observers are configured the old way by |
| * {@link FluoConfiguration#addObserver(org.apache.fluo.api.config.ObserverSpecification)} |
| */ |
| @Deprecated |
| default void close() {} |
| } |