/*
* Copyright 1999-2015 dangdang.com.
* <p>
* 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.
* </p>
*/
package com.dangdang.ddframe.rdb.sharding.executor;
import com.dangdang.ddframe.rdb.sharding.config.ShardingProperties;
import com.dangdang.ddframe.rdb.sharding.config.ShardingPropertiesConstant;
import com.dangdang.ddframe.rdb.sharding.exception.ShardingJdbcException;
import com.google.common.collect.Lists;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import lombok.extern.slf4j.Slf4j;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
/**
* 多线程执行框架.
*
* @author gaohongtao
*/
@Slf4j
public final class ExecutorEngine {
private final ListeningExecutorService executorService;
public ExecutorEngine(final ShardingProperties shardingProperties) {
int executorSize = shardingProperties.getValue(ShardingPropertiesConstant.EXECUTOR_SIZE);
executorService = MoreExecutors.listeningDecorator(new ThreadPoolExecutor(executorSize, executorSize, 0, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(), new ThreadFactoryBuilder()
.setDaemon(true).setNameFormat("ShardingJDBC-%d").build()));
MoreExecutors.addDelayedShutdownHook(executorService, 60, TimeUnit.SECONDS);
}
/**
* 多线程执行任务.
* 一组任务中,将第一个任务放在当前线程中执行,其余的任务放到线程池中运行.
*
*
* @param inputs 输入参数
* @param executeUnit 执行单元
* @param <I> 入参类型
* @param <O> 出参类型
* @return 执行结果
*/
public <I, O> List<O> execute(final Collection<I> inputs, final ExecuteUnit<I, O> executeUnit) {
Iterator<I> iterator = inputs.iterator();
if (!iterator.hasNext()) {
return Collections.emptyList();
}
I firstInput = iterator.next();
ListenableFuture<List<O>> restListFuture = asyncRun(Lists.newArrayList(iterator), executeUnit);
O firstOutput;
List<O> restOutputs;
try {
firstOutput = executeUnit.execute(firstInput);
restOutputs = restListFuture.get();
//CHECKSTYLE:OFF
} catch (final Exception ex) {
//CHECKSTYLE:ON
ExecutorExceptionHandler.handleException(ex);
return null;
}
List<O> result = Lists.newLinkedList(restOutputs);
result.add(0, firstOutput);
return result;
}
/**
* 多线程执行任务并归并结果.
*
* @param inputs 执行入参
* @param executeUnit 执行单元
* @param mergeUnit 合并结果单元
* @param <I> 入参类型
* @param <M> 中间结果类型
* @param <O> 最终结果类型
* @return 执行结果
*/
public <I, M, O> O execute(final Collection<I> inputs, final ExecuteUnit<I, M> executeUnit, final MergeUnit<M, O> mergeUnit) {
return mergeUnit.merge(execute(inputs, executeUnit));
}
private <I, O> ListenableFuture<List<O>> asyncRun(final Collection<I> inputs, final ExecuteUnit<I, O> executeUnit) {
List<ListenableFuture<O>> result = new ArrayList<>(inputs.size());
for (final I each : inputs) {
result.add(executorService.submit(new Callable<O>() {
@Override
public O call() throws Exception {
return executeUnit.execute(each);
}
}));
}
return Futures.allAsList(result);
}
/**
* 安全关闭执行器,并释放线程.
*/
public void shutdown() {
executorService.shutdownNow();
try {
executorService.awaitTermination(5, TimeUnit.SECONDS);
} catch (final InterruptedException ignored) {
}
if (!executorService.isTerminated()) {
throw new ShardingJdbcException("ExecutorEngine can not been terminated");
}
}
}