| /* |
| * 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.geode.cache.execute; |
| |
| import java.util.concurrent.TimeUnit; |
| |
| import org.apache.geode.distributed.DistributedMember; |
| |
| /** |
| * <p> |
| * Defines the interface for a container that gathers results from function execution.<br> |
| * GemFire provides a default implementation for ResultCollector. Applications can choose to |
| * implement their own custom ResultCollector. A custom ResultCollector facilitates result sorting |
| * or aggregation. Aggregation functions like sum, minimum, maximum and average can also be applied |
| * to the result using a custom ResultCollector. Results arrive as they are sent using the |
| * {@link ResultSender#sendResult(Object)} and can be used as they arrive. To indicate that all |
| * results have been received {@link #endResults()} is called. |
| * |
| * </p> |
| * Example: <br> |
| * |
| * <pre> |
| * Region region ; |
| * Set keySet = Collections.singleton("myKey"); |
| * Function multiGetFunction ; |
| * Object args ; |
| * ResultCollector rc = FunctionService.onRegion(region) |
| * .setArguments(args) |
| * .withFilter(keySet) |
| * .withCollector(new MyCustomResultCollector()) |
| * .execute(multiGetFunction.getId()); |
| * Application can do something else here before retrieving the result |
| * Or it can have some logic in {{@link #addResult(DistributedMember, Object)} to use the partial results. |
| * If it wants to see all the results it can use |
| * Object functionResult = rc.getResult(); |
| * or |
| * Object functionResult = rc.getResult(timeout,TimeUnit); |
| * depending on if it wants to wait for all the results or wait for a timeout period. |
| * </pre> |
| * |
| * GemFire provides default implementation of ResultCollector which collects results in Arraylist. |
| * There is no need to provide a synchronization mechanism in the user implementations of |
| * ResultCollector |
| * |
| * @since GemFire 6.0 |
| * |
| */ |
| public interface ResultCollector<T, S> { |
| |
| /** |
| * Method used to pull results from the ResultCollector. It returns the result of function |
| * execution, potentially blocking until {@link #endResults() all the results are available} has |
| * been called. |
| * |
| * @return the result |
| * @throws FunctionException if result retrieval fails |
| * @since GemFire 6.0 |
| */ |
| S getResult() throws FunctionException; |
| |
| /** |
| * Method used to pull results from the ResultCollector. It returns the result of function |
| * execution, blocking for the timeout period until {@link #endResults() all the results are |
| * available}. If all the results are not received in provided time a FunctionException is thrown. |
| * |
| * @param timeout the maximum time to wait |
| * @param unit the time unit of the timeout argument |
| * @return the result |
| * @throws FunctionException if result retrieval fails within timeout provided |
| * @throws InterruptedException if the current thread was interrupted while waiting |
| * @since GemFire 6.0 |
| * |
| */ |
| S getResult(long timeout, TimeUnit unit) throws FunctionException, InterruptedException; |
| |
| /** |
| * Method used to feed result to the ResultCollector. It adds a single function execution result |
| * to the ResultCollector It is invoked every time a result is sent using ResultSender. |
| * |
| * @since GemFire 6.0 |
| * @param memberID DistributedMember ID to which result belongs |
| */ |
| void addResult(DistributedMember memberID, T resultOfSingleExecution); |
| |
| /** |
| * GemFire will invoke this method when function execution has completed and all results for the |
| * execution have been obtained and {@link #addResult(DistributedMember, Object) added to the |
| * ResultCollector} Unless the {@link ResultCollector} has received |
| * {@link ResultSender#lastResult(Object) last result} from all the executing nodes, it keeps |
| * waiting for more results to come. |
| * |
| * @since GemFire 6.0 |
| * |
| * @see ResultSender#lastResult(Object) |
| */ |
| void endResults(); |
| |
| /** |
| * GemFire will invoke this method before re-executing function (in case of Function Execution |
| * HA). This is to clear the previous execution results from the result collector |
| * |
| * @since GemFire 6.5 |
| */ |
| void clearResults(); |
| |
| } |