Java tutorial
/* * Copyright 2015 Flipkart Internet, pvt ltd. * * 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. */ package com.flipkart.poseidon.serviceclients; import com.flipkart.phantom.task.spi.TaskResult; import com.flipkart.poseidon.serviceclients.batch.ResponseMerger; import flipkart.lego.concurrency.api.Promise; import flipkart.lego.concurrency.api.PromiseListener; import flipkart.lego.concurrency.exceptions.PromiseBrokenException; import org.apache.commons.lang3.exception.ExceptionUtils; import java.util.ArrayList; import java.util.List; import java.util.Map; import java.util.Optional; import java.util.concurrent.*; /** * Created by mohan.pandian on 18/03/15. * <p/> * A Promise that wraps a Future <TaskResult>, typically returned by TaskContext.executeAsyncCommand() * and eventually delivers the data from TaskResult (DomainObject) */ public class FutureTaskResultToDomainObjectPromiseWrapper<DomainObject> implements Promise<DomainObject> { private final List<Future<TaskResult>> futureList = new ArrayList<>(); private PromiseBrokenException promiseBrokenException; private ResponseMerger<DomainObject> responseMerger; public FutureTaskResultToDomainObjectPromiseWrapper(Future<TaskResult> future) { futureList.add(future); } public FutureTaskResultToDomainObjectPromiseWrapper(ResponseMerger<DomainObject> responseMerger) { this.responseMerger = responseMerger; } @Override public boolean isRealized() { for (Future<TaskResult> future : futureList) { if (!future.isDone()) { return false; } } return true; } @Override public boolean isFullfilled() throws IllegalStateException { for (Future<TaskResult> future : futureList) { if (future.isCancelled()) { return false; } } return true; } @Override public boolean isBroken() throws IllegalStateException { for (Future<TaskResult> future : futureList) { if (future.isCancelled()) { return true; } } return false; } @Override public void await() throws InterruptedException { try { for (Future<TaskResult> future : futureList) { future.get(); } } catch (ExecutionException exception) { promiseBrokenException = new PromiseBrokenException(exception); throw new InterruptedException(exception.getMessage()); } catch (CancellationException exception) { promiseBrokenException = new PromiseBrokenException(exception); } } @Override public void await(long timeout, TimeUnit timeUnit) throws InterruptedException { try { for (Future<TaskResult> future : futureList) { future.get(timeout, timeUnit); } } catch (ExecutionException exception) { promiseBrokenException = new PromiseBrokenException(exception); throw new InterruptedException(exception.getMessage()); } catch (CancellationException exception) { promiseBrokenException = new PromiseBrokenException(exception); } catch (TimeoutException ignored) { } } @Override public DomainObject get() throws PromiseBrokenException, InterruptedException { try { ServiceResponse<DomainObject> serviceResponse = new ServiceResponse<>(); for (Future<TaskResult> futureResult : futureList) { TaskResult result = futureResult.get(); if (result == null) { throw new PromiseBrokenException("Task result is null"); } ServiceResponse<DomainObject> response = (ServiceResponse<DomainObject>) result.getData(); if (!response.getIsSuccess()) throw response.getException(); serviceResponse.addData(response.getDataList()); } if (responseMerger != null) { return responseMerger.mergeResponse(serviceResponse.getDataList()); } else { return serviceResponse.getDataList().get(0); } } catch (ExecutionException exception) { checkAndThrowServiceClientException(exception); promiseBrokenException = new PromiseBrokenException(exception); throw new InterruptedException(exception.getMessage()); } catch (CancellationException exception) { promiseBrokenException = new PromiseBrokenException(exception); throw new PromiseBrokenException(promiseBrokenException); } } @Override public DomainObject get(long timeout, TimeUnit timeUnit) throws PromiseBrokenException, TimeoutException, InterruptedException { try { ServiceResponse<DomainObject> serviceResponse = new ServiceResponse<>(); for (Future<TaskResult> futureResult : futureList) { TaskResult result = futureResult.get(timeout, timeUnit); if (result == null) { throw new PromiseBrokenException("Task result is null"); } ServiceResponse<DomainObject> response = (ServiceResponse<DomainObject>) result.getData(); if (!response.getIsSuccess()) throw response.getException(); serviceResponse.addData(response.getDataList()); } if (responseMerger != null) { return responseMerger.mergeResponse(serviceResponse.getDataList()); } else { return serviceResponse.getDataList().get(0); } } catch (ExecutionException exception) { checkAndThrowServiceClientException(exception); promiseBrokenException = new PromiseBrokenException(exception); throw new InterruptedException(exception.getMessage()); } catch (CancellationException exception) { promiseBrokenException = new PromiseBrokenException(exception); throw new PromiseBrokenException(promiseBrokenException); } } public Map<String, String> getHeaders() throws PromiseBrokenException, InterruptedException { try { TaskResult taskResult; taskResult = futureList.get(0).get(); if (taskResult == null) { throw new PromiseBrokenException("Task result is null"); } ServiceResponse<DomainObject> response = (ServiceResponse<DomainObject>) taskResult.getData(); return response.getHeaders(); } catch (ExecutionException exception) { checkAndThrowServiceClientException(exception); promiseBrokenException = new PromiseBrokenException(exception); throw new InterruptedException(exception.getMessage()); } catch (CancellationException exception) { promiseBrokenException = new PromiseBrokenException(exception); throw new PromiseBrokenException(promiseBrokenException); } } @Override public synchronized void addListener(PromiseListener promiseListener) { throw new UnsupportedOperationException("Adding listeners is not supported"); } public void addFutureForTask(Future<TaskResult> future) { futureList.add(future); } public void addFutureForTask(List<Future<TaskResult>> future) { futureList.addAll(future); } public List<Future<TaskResult>> getFutureList() { return futureList; } /** * If root cause of ExecutionException is ServiceClientException, just throw it. * Ex: ServiceResponseDecoder throwing ServiceClientException for 5xx responses. * * @param exception * @throws PromiseBrokenException */ private void checkAndThrowServiceClientException(ExecutionException exception) throws ServiceClientException { Throwable generatedException = Optional.ofNullable(ExceptionUtils.getRootCause(exception)) .orElse(exception); if (generatedException instanceof ServiceClientException) { throw (ServiceClientException) generatedException; } } }