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/*
* Copyright 1999-2011 Alibaba Group.
*
* 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.alibaba.dubbo.rpc.cluster.support;
import java.util.ArrayList;
import java.util.List;
import com.alibaba.dubbo.common.Constants;
import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.common.Version;
import com.alibaba.dubbo.common.extension.ExtensionLoader;
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.common.utils.NetUtils;
import com.alibaba.dubbo.rpc.Invocation;
import com.alibaba.dubbo.rpc.Invoker;
import com.alibaba.dubbo.rpc.Result;
import com.alibaba.dubbo.rpc.RpcException;
import com.alibaba.dubbo.rpc.cluster.Directory;
import com.alibaba.dubbo.rpc.cluster.LoadBalance;
import com.alibaba.dubbo.rpc.support.RpcUtils;
/**
* AbstractClusterInvoker
*
* @author william.liangf
* @author chao.liuc
*/
public abstract class AbstractClusterInvoker implements Invoker {
private static final Logger logger = LoggerFactory
.getLogger(AbstractClusterInvoker.class);
protected final Directory directory;
protected final boolean availablecheck;
private volatile boolean destroyed = false;
private volatile Invoker stickyInvoker = null;
public AbstractClusterInvoker(Directory directory) {
this(directory, directory.getUrl());
}
public AbstractClusterInvoker(Directory directory, URL url) {
if (directory == null)
throw new IllegalArgumentException("service directory == null");
this.directory = directory ;
//sticky 需要检测 avaliablecheck
this.availablecheck = url.getParameter(Constants.CLUSTER_AVAILABLE_CHECK_KEY, Constants.DEFAULT_CLUSTER_AVAILABLE_CHECK) ;
}
public Class getInterface() {
return directory.getInterface();
}
public URL getUrl() {
return directory.getUrl();
}
public boolean isAvailable() {
Invoker invoker = stickyInvoker;
if (invoker != null) {
return invoker.isAvailable();
}
return directory.isAvailable();
}
public void destroy() {
directory.destroy();
destroyed = true;
}
/**
* 使用loadbalance选择invoker.
* a)先lb选择，如果在selected列表中 或者 不可用且做检验时，进入下一步(重选),否则直接返回
* b)重选验证规则：selected > available .保证重选出的结果尽量不在select中，并且是可用的
*
* @param availablecheck 如果设置true，在选择的时候先选invoker.available == true
* @param selected 已选过的invoker.注意：输入保证不重复
*
*/
protected Invoker select(LoadBalance loadbalance, Invocation invocation, List> invokers, List> selected) throws RpcException {
if (invokers == null || invokers.size() == 0)
return null;
String methodName = invocation == null ? "" : invocation.getMethodName();
boolean sticky = invokers.get(0).getUrl().getMethodParameter(methodName,Constants.CLUSTER_STICKY_KEY, Constants.DEFAULT_CLUSTER_STICKY) ;
{
//ignore overloaded method
if ( stickyInvoker != null && !invokers.contains(stickyInvoker) ){
stickyInvoker = null;
}
//ignore cucurrent problem
if (sticky && stickyInvoker != null && (selected == null || !selected.contains(stickyInvoker))){
if (availablecheck && stickyInvoker.isAvailable()){
return stickyInvoker;
}
}
}
Invoker invoker = doselect(loadbalance, invocation, invokers, selected);
if (sticky){
stickyInvoker = invoker;
}
return invoker;
}
private Invoker doselect(LoadBalance loadbalance, Invocation invocation, List> invokers, List> selected) throws RpcException {
if (invokers == null || invokers.size() == 0)
return null;
if (invokers.size() == 1)
return invokers.get(0);
// 如果只有两个invoker，退化成轮循
if (invokers.size() == 2 && selected != null && selected.size() > 0) {
return selected.get(0) == invokers.get(0) ? invokers.get(1) : invokers.get(0);
}
Invoker invoker = loadbalance.select(invokers, getUrl(), invocation);
//如果 selected中包含（优先判断） 或者 不可用&&availablecheck=true 则重试.
if( (selected != null && selected.contains(invoker))
||(!invoker.isAvailable() && getUrl()!=null && availablecheck)){
try{
Invoker rinvoker = reselect(loadbalance, invocation, invokers, selected, availablecheck);
if(rinvoker != null){
invoker = rinvoker;
}else{
//看下第一次选的位置，如果不是最后，选+1位置.
int index = invokers.indexOf(invoker);
try{
//最后在避免碰撞
invoker = index reselect(LoadBalance loadbalance,Invocation invocation,
List> invokers, List> selected ,boolean availablecheck)
throws RpcException {
//预先分配一个，这个列表是一定会用到的.
List> reselectInvokers = new ArrayList>(invokers.size()>1?(invokers.size()-1):invokers.size());
//先从非select中选
if( availablecheck ){ //选isAvailable 的非select
for(Invoker invoker : invokers){
if(invoker.isAvailable()){
if(selected ==null || !selected.contains(invoker)){
reselectInvokers.add(invoker);
}
}
}
if(reselectInvokers.size()>0){
return loadbalance.select(reselectInvokers, getUrl(), invocation);
}
}else{ //选全部非select
for(Invoker invoker : invokers){
if(selected ==null || !selected.contains(invoker)){
reselectInvokers.add(invoker);
}
}
if(reselectInvokers.size()>0){
return loadbalance.select(reselectInvokers, getUrl(), invocation);
}
}
//最后从select中选可用的.
{
if(selected != null){
for(Invoker invoker : selected){
if((invoker.isAvailable()) //优先选available
&& !reselectInvokers.contains(invoker)){
reselectInvokers.add(invoker);
}
}
}
if(reselectInvokers.size()>0){
return loadbalance.select(reselectInvokers, getUrl(), invocation);
}
}
return null;
}
public Result invoke(final Invocation invocation) throws RpcException {
checkWheatherDestoried();
LoadBalance loadbalance;
List> invokers = list(invocation);
if (invokers != null && invokers.size() > 0) {
loadbalance = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(invokers.get(0).getUrl()
.getMethodParameter(invocation.getMethodName(),Constants.LOADBALANCE_KEY, Constants.DEFAULT_LOADBALANCE));
} else {
loadbalance = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(Constants.DEFAULT_LOADBALANCE);
}
RpcUtils.attachInvocationIdIfAsync(getUrl(), invocation);
return doInvoke(invocation, invokers, loadbalance);
}
protected void checkWheatherDestoried() {
if(destroyed){
throw new RpcException("Rpc cluster invoker for " + getInterface() + " on consumer " + NetUtils.getLocalHost()
+ " use dubbo version " + Version.getVersion()
+ " is now destroyed! Can not invoke any more.");
}
}
@Override
public String toString() {
return getInterface() + " -> " + getUrl().toString();
}
protected void checkInvokers(List> invokers, Invocation invocation) {
if (invokers == null || invokers.size() == 0) {
throw new RpcException("Failed to invoke the method "
+ invocation.getMethodName() + " in the service " + getInterface().getName()
+ ". No provider available for the service " + directory.getUrl().getServiceKey()
+ " from registry " + directory.getUrl().getAddress()
+ " on the consumer " + NetUtils.getLocalHost()
+ " using the dubbo version " + Version.getVersion()
+ ". Please check if the providers have been started and registered.");
}
}
protected abstract Result doInvoke(Invocation invocation, List> invokers,
LoadBalance loadbalance) throws RpcException;
protected List> list(Invocation invocation) throws RpcException {
List> invokers = directory.list(invocation);
return invokers;
}
}