| /** |
| * 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.apex.malhar.lib.appdata.query; |
| |
| import com.google.common.base.Preconditions; |
| |
| import com.datatorrent.api.Component; |
| import com.datatorrent.api.Context.OperatorContext; |
| |
| /** |
| * The QueryManagerSynchronous is a simple container for a {@link QueryExecutor} and a {@link QueueManager}. |
| * It encapsulates the functionality of enqueueing a query and returning a result synchronously. |
| * <br/> |
| * <br/> |
| * <b>Note:</b> Use {@link #newInstance} to create an instance of query processor. |
| * It reduces the boilerplate code with respect to generics. |
| * |
| * @param <QUERY_TYPE> The type of the query. |
| * @param <META_QUERY> The type of any query meta data. |
| * @param <QUEUE_CONTEXT> The type of any context information used by the queue. |
| * @param <RESULT> The type of the result returned by the {@link QueryExecutor}. |
| * @since 3.0.0 |
| */ |
| public class QueryManagerSynchronous<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT> implements Component<OperatorContext> |
| { |
| /** |
| * The {@link QueryExecutor} used to execute queries. |
| */ |
| private QueryExecutor<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT> queryExecutor; |
| /** |
| * The {@link QueueManager} used to queue queries. |
| */ |
| private QueueManager<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT> queryQueueManager; |
| |
| /** |
| * |
| * @param queryComputer |
| */ |
| private QueryManagerSynchronous(QueryExecutor<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT> queryComputer) |
| { |
| setQueryExecutor(queryComputer); |
| queryQueueManager = new SimpleQueueManager<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT>(); |
| } |
| |
| private QueryManagerSynchronous(QueryExecutor<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT> queryComputer, |
| QueueManager<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT> queryQueueManager) |
| { |
| setQueryExecutor(queryComputer); |
| setQueryQueueManager(queryQueueManager); |
| } |
| |
| /** |
| * A helper method to set a {@link QueryExecutor}. |
| * @param queryExecutor The {@link QueryExecutor} to set on the {@link QueryManagerSynchronous}. |
| */ |
| private void setQueryExecutor(QueryExecutor<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT> queryExecutor) |
| { |
| this.queryExecutor = Preconditions.checkNotNull(queryExecutor); |
| } |
| |
| /** |
| * A helper method to set a {@link QueueManager}. |
| * @param queryQueueManager The {@link QueueManager} to set on the {@link QueryManagerSynchronous}. |
| */ |
| private void setQueryQueueManager(QueueManager<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT> queryQueueManager) |
| { |
| this.queryQueueManager = Preconditions.checkNotNull(queryQueueManager); |
| } |
| |
| /** |
| * This method enqueues the given query with the corresponding meta data. |
| * @param query The query to enqueue . |
| * @param metaQuery Any additional query meta data required to execute the query. |
| * @param queueContext The queue context information required to queue the query. |
| * @return True if the query was successfully enqueued and false otherwise. |
| */ |
| public boolean enqueue(QUERY_TYPE query, META_QUERY metaQuery, QUEUE_CONTEXT queueContext) |
| { |
| return queryQueueManager.enqueue(query, metaQuery, queueContext); |
| } |
| |
| /** |
| * This method returns a result for the next query in the queue for which there is a result. If |
| * there are no more queries with results in the queue, then this method will return null. |
| * @return The result for the next query in the queue for which there is a result. |
| */ |
| public RESULT process() |
| { |
| RESULT result = null; |
| |
| do { |
| QueryBundle<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT> queryBundle = queryQueueManager.dequeue(); |
| |
| if (queryBundle == null) { |
| return null; |
| } |
| |
| result = queryExecutor.executeQuery(queryBundle.getQuery(), queryBundle.getMetaQuery(), |
| queryBundle.getQueueContext()); |
| } |
| while (result == null); |
| |
| return result; |
| } |
| |
| /** |
| * This method should be called from the {@link com.datatorrent.api.Operator#setup} method so that the |
| QueryManagerSynchronous can correctly initialize its internal state. |
| * @param context The operator context. |
| */ |
| @Override |
| public void setup(OperatorContext context) |
| { |
| queryQueueManager.setup(context); |
| } |
| |
| /** |
| * This method should be called from the {@link com.datatorrent.api.Operator#beginWindow} method so that the |
| QueryManagerSynchronous can correctly initialize/reset its internal state at the beginning of each window. |
| * @param windowId The windowId of the current window. |
| */ |
| public void beginWindow(long windowId) |
| { |
| queryQueueManager.beginWindow(windowId); |
| } |
| |
| /** |
| * This method should be called from the {@link com.datatorrent.api.Operator#endWindow} method so that the |
| QueryManagerSynchronous can correctly initialize/reset its internal state at the end of each window. |
| */ |
| public void endWindow() |
| { |
| queryQueueManager.endWindow(); |
| } |
| |
| /** |
| * This method should be called from the {@link com.datatorrent.api.Operator#teardown} method so that the |
| QueryManagerSynchronous can correctly initialize its internal state. |
| */ |
| @Override |
| public void teardown() |
| { |
| queryQueueManager.teardown(); |
| } |
| |
| /** |
| * Creates a new instance of a QueryManagerSynchronous. |
| * @param <QUERY_TYPE> The type of the query. |
| * @param <META_QUERY> The type of any meta data associated with the query. |
| * @param <QUEUE_CONTEXT> The type of any additional meta data required to manage queueing the query. |
| * @param <RESULT> The type of any query results. |
| * @param queryExecutor The {@link QueryExecutor} the queryExecutor used to execute queries. |
| * @return A new instance of QueryManagerSynchronous. |
| */ |
| public static <QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT> QueryManagerSynchronous<QUERY_TYPE, META_QUERY, |
| QUEUE_CONTEXT, RESULT> newInstance(QueryExecutor<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT> queryExecutor) |
| { |
| return new QueryManagerSynchronous<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT>(queryExecutor); |
| } |
| |
| /** |
| * Creates a new instance of a QueryManagerSynchronous. |
| * @param <QUERY_TYPE> The type of the query. |
| * @param <META_QUERY> The type of any meta data associated with the query. |
| * @param <QUEUE_CONTEXT> The type of any additional meta data required to manage queueing the query. |
| * @param <RESULT> The type of any query results. |
| * @param queryExecutor The {@link QueryExecutor} used to execute queries. |
| * @param queryQueueManager The {@link QueueManager} used to queue queries. |
| * @return A new instance of QueryManagerSynchronous. |
| */ |
| public static <QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT> QueryManagerSynchronous<QUERY_TYPE, META_QUERY, |
| QUEUE_CONTEXT, RESULT> newInstance(QueryExecutor<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT> queryExecutor, |
| QueueManager<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT> queryQueueManager) |
| { |
| return new QueryManagerSynchronous<QUERY_TYPE, META_QUERY, QUEUE_CONTEXT, RESULT>(queryExecutor, |
| queryQueueManager); |
| } |
| } |