/*
* 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.router;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.script.Bindings;
import javax.script.Compilable;
import javax.script.CompiledScript;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import com.alibaba.dubbo.common.Constants;
import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.rpc.Invocation;
import com.alibaba.dubbo.rpc.Invoker;
import com.alibaba.dubbo.rpc.RpcContext;
import com.alibaba.dubbo.rpc.RpcException;
import com.alibaba.dubbo.rpc.cluster.Router;
/**
* ScriptRouter
*
* @author william.liangf
*/
public class ScriptRouter implements Router {
private static final Logger logger = LoggerFactory.getLogger(ScriptRouter.class);
private static final Map<String, ScriptEngine> engines = new ConcurrentHashMap<String, ScriptEngine>();
private final ScriptEngine engine;
private final String rule;
public ScriptRouter(URL url) {
String type = url.getParameter(Constants.TYPE_KEY);
String rule = url.getParameterAndDecoded(Constants.RULE_KEY);
if (type == null || type.length() == 0){
type = Constants.DEFAULT_SCRIPT_TYPE_KEY;
}
if (rule == null || rule.length() == 0){
throw new IllegalStateException(new IllegalStateException("route rule can not be empty. rule:" + rule));
}
ScriptEngine engine = engines.get(type);
if (engine == null){
engine = new ScriptEngineManager().getEngineByName(type);
if (engine == null) {
throw new IllegalStateException(new IllegalStateException("Unsupported route rule type: " + type + ", rule: " + rule));
}
engines.put(type, engine);
}
this.engine = engine;
this.rule = rule;
}
@SuppressWarnings("unchecked")
public <T> List<Invoker<T>> route(List<Invoker<T>> invokers, Invocation invocation) throws RpcException {
try {
List<Invoker<T>> invokersCopy = new ArrayList<Invoker<T>>(invokers);
Compilable compilable = (Compilable) engine;
Bindings bindings = engine.createBindings();
bindings.put("invokers", invokersCopy);
bindings.put("invocation", invocation);
bindings.put("context", RpcContext.getContext());
CompiledScript function = compilable.compile(rule);
Object obj = function.eval(bindings);
if (obj instanceof Invoker[]) {
invokersCopy = Arrays.asList((Invoker<T>[]) obj);
} else if (obj instanceof Object[]) {
invokersCopy = new ArrayList<Invoker<T>>();
for (Object inv : (Object[]) obj) {
invokersCopy.add((Invoker<T>)inv);
}
} else {
invokersCopy = (List<Invoker<T>>) obj;
}
return invokersCopy;
} catch (ScriptException e) {
//fail then ignore rule .invokers.
logger.error("route error , rule has been ignored .rule :"+ rule + ",invocation:" + invocation + ",url :"+(RpcContext.getContext().getInvoker() == null ? "" : RpcContext.getContext().getInvoker().getUrl()), e);
return invokers;
}
}
}