| /* |
| * Copyright (c) 2011 Yahoo! Inc. All rights reserved. |
| * |
| * Licensed 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. See accompanying LICENSE file. |
| */ |
| package org.apache.s4.base; |
| |
| import java.util.Map; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import com.google.common.collect.Maps; |
| |
| /** |
| * The base event class in S4. The base class supports generic key/value pairs which us useful for rapid prototyping and |
| * for inter-application communication. For greater efficiency and type safety, extend this class to create custom event |
| * types. |
| * |
| * @author leo |
| * |
| */ |
| public class Event { |
| |
| private static final Logger logger = LoggerFactory.getLogger(Event.class); |
| |
| final private long time; |
| private int streamId; |
| private int appId; |
| private Map<String, Data<?>> map; |
| |
| /** Default constructor sets time using system time. */ |
| public Event() { |
| this.time = System.currentTimeMillis(); |
| } |
| |
| /** |
| * This constructor explicitly sets the time. Event that need to explicitly set the time must call {super(time)} |
| */ |
| public Event(long time) { |
| this.time = time; |
| } |
| |
| /** |
| * @return the create time |
| */ |
| public long getTime() { |
| return time; |
| } |
| |
| /** |
| * The stream id is used to identify streams uniquely in a cluster configuration. It is not required to operate in |
| * local mode. |
| * |
| * @return the target stream id |
| */ |
| public int getStreamId() { |
| return streamId; |
| } |
| |
| /** |
| * The stream id is used to identify streams uniquely in a cluster configuration. It is not required to operate in |
| * local mode. |
| * |
| * @param targetStreamId |
| */ |
| public void setStreamId(int streamId) { |
| this.streamId = streamId; |
| } |
| |
| /** |
| * All events must be assigned the unique App ID of the App that owns the stream to which this event is injected. |
| * The assignment must be done automatically by the stream that receives the event. Each application has a unique |
| * ID. We use the app ID in combination with the stream ID to identify stream instances in a cluster. |
| * |
| * |
| * @return the unique application ID. |
| */ |
| public int getAppId() { |
| return appId; |
| } |
| |
| /** |
| * All events must be assigned the unique App ID of the App that owns the stream to which this event is injected. |
| * The assignment must be done automatically by the stream that receives the event. Each application has a unique |
| * ID. We use the app ID in combination with the stream ID to identify stream instances in a cluster. |
| * |
| * @param appId |
| * a unique application identifier, typically assigned by the deployment system. |
| */ |
| public void setAppId(int appId) { |
| this.appId = appId; |
| } |
| |
| /** |
| * Put an arbitrary key-value pair in the event. The type of the value is T. |
| * |
| * @param type |
| * the type of the value |
| * @param key |
| * the key |
| * @param value |
| * the value |
| */ |
| public <T> void put(String key, Class<T> type, T value) { |
| |
| if (map == null) { |
| map = Maps.newHashMap(); |
| } |
| |
| map.put(key, new Data<T>(type, value)); |
| } |
| |
| /** |
| * Get value for key. The caller must know the type of the value. |
| * |
| * @param key |
| * @return the value |
| */ |
| @SuppressWarnings("unchecked") |
| public <T> T get(String key, Class<T> type) { |
| |
| Data<?> data = map.get(key); |
| |
| if (type != data.type) { |
| logger.error("Trying to get a value of type {} for an attribute of type {}.", type, data.type); |
| return null; |
| } |
| |
| return (T) data.value; |
| } |
| |
| /** |
| * Returns the value for key as a String. |
| * |
| * @param key |
| * @return the value as a string. |
| */ |
| public String get(String key) { |
| |
| Data<?> data = map.get(key); |
| |
| return String.valueOf(data.value); |
| } |
| |
| public boolean hasAttributes() { |
| |
| return map != null; |
| } |
| |
| public boolean containsKey(String key) { |
| return map.containsKey(key); |
| } |
| |
| public Map<String, String> getAttributesAsMap() { |
| |
| Map<String, String> amap = Maps.newHashMap(); |
| |
| for (Map.Entry<String, Data<?>> entry : map.entrySet()) { |
| String key = entry.getKey(); |
| String value = String.valueOf(entry.getValue().value); |
| amap.put(key, value); |
| } |
| return amap; |
| } |
| |
| /* Helper data object. */ |
| private class Data<T> { |
| |
| private T value; |
| private Class<T> type; |
| |
| private Data(Class<T> type, T value) { |
| this.value = value; |
| this.type = type; |
| } |
| |
| } |
| } |