1、路由规则的更新
路由配置信息有变动，通知RegistryDirectory#notify(List urls)，下面以Zookeeper为例讲解。
public synchronized void notify(List<URL> urls) {
...
List<URL> routerUrls = new ArrayList<URL>();
...
for (URL url : urls) {
String protocol = url.getProtocol();
String category = url.getParameter(Constants.CATEGORY_KEY, Constants.DEFAULT_CATEGORY);
if (Constants.ROUTERS_CATEGORY.equals(category)
|| Constants.ROUTE_PROTOCOL.equals(protocol)) {
routerUrls.add(url);
}
...
}
...
// routers
if (routerUrls != null && !routerUrls.isEmpty()) {
// 获取路由
// 下面详细讲解
List<Router> routers = toRouters(routerUrls);
if (routers != null) {
// null - do nothing
// 设置路由
setRouters(routers);
}
}
...
}
取出有变动的url -> 获取路由 -> 设置路由。下面详细讲解一下“获取路由”的过程。
// RegistryDirectory#toRouters(List<URL>)
private List<Router> toRouters(List<URL> urls) {
List<Router> routers = new ArrayList<Router>();
if (urls == null || urls.isEmpty()) {
return routers;
}
if (urls != null && !urls.isEmpty()) {
for (URL url : urls) {
if (Constants.EMPTY_PROTOCOL.equals(url.getProtocol())) {
continue;
}
String routerType = url.getParameter(Constants.ROUTER_KEY);
if (routerType != null && routerType.length() > 0) {
url = url.setProtocol(routerType);
}
try {
// RouterFactory是一个@SPI类，getRouter(URL)方法是@Adaptive("protocol")修饰的，所以通过url.protocol决定实现类
Router router = routerFactory.getRouter(url);
if (!routers.contains(router))
routers.add(router);
} catch (Throwable t) {
logger.error("convert router url to router error, url: " + url, t);
}
}
}
return routers;
}
2、路由规则的使用
在获取Invokers列表时，首先会通过Directory选出当前可用的Invokers列表，然后通过Router接口的route(List<Invoker>, URL, Invocation)过滤不符合路由规则的Invokers。下面看看具体实现。
2.1 使用路由规则对Invokers的过滤
// AbstractDirectory#list(Invocation invocation)
public List<Invoker<T>> list(Invocation invocation) throws RpcException {
...
// 通过Directory选出当前可用的Invokers列表
List<Invoker<T>> invokers = doList(invocation);
// 路由过滤
List<Router> localRouters = this.routers; // local reference
if (localRouters != null && !localRouters.isEmpty()) {
for (Router router : localRouters) {
try {
if (router.getUrl() == null || router.getUrl().getParameter(Constants.RUNTIME_KEY, false)) {
invokers = router.route(invokers, getConsumerUrl(), invocation);
}
} catch (Throwable t) {
logger.error("Failed to execute router: " + getUrl() + ", cause: " + t.getMessage(), t);
}
}
}
return invokers;
}
2.2 第一种实现路由过滤：ConditionRouter#route(List<Invoker>, URL, Invocation)
// ConditionRouter#route(List<Invoker<T>>, URL, Invocation)
public <T> List<Invoker<T>> route(List<Invoker<T>> invokers, URL url, Invocation invocation)
throws RpcException {
if (invokers == null || invokers.isEmpty()) {
return invokers;
}
try {
// 匹配规则：host = 10.99.1.109 => host = 10.20.3.3，就是消费者ip为10.99.1.109的，转向提供者ip为10.20.3.3的服务器
// when: => 的前半部分，也就是 host = 10.99.1.109
if (!matchWhen(url, invocation)) {
return invokers;
}
List<Invoker<T>> result = new ArrayList<Invoker<T>>();
if (thenCondition == null) {
logger.warn("The current consumer in the service blacklist. consumer: " + NetUtils.getLocalHost() + ", service: " + url.getServiceKey());
return result;
}
for (Invoker<T> invoker : invokers) {
// 匹配then条件
// then: => 的后半部分，也就是 host = 10.20.3.3
if (matchThen(invoker.getUrl(), url)) {
result.add(invoker);
}
}
if (!result.isEmpty()) {
return result;
} else if (force) {
logger.warn("The route result is empty and force execute. consumer: " + NetUtils.getLocalHost() + ", service: " + url.getServiceKey() + ", router: " + url.getParameterAndDecoded(Constants.RULE_KEY));
return result;
}
} catch (Throwable t) {
logger.error("Failed to execute condition router rule: " + getUrl() + ", invokers: " + invokers + ", cause: " + t.getMessage(), t);
}
return invokers;
}
ConditionRouter是按配置的条件进行过滤，下面是ScriptRouter按脚本进行过滤的方式。
2.2 第二种实现路由过滤：ScriptRouter#route(List<Invoker>, URL, Invocation)
// ScriptRouter#route(List<Invoker<T>>, URL, Invocation)
public <T> List<Invoker<T>> route(List<Invoker<T>> invokers, URL url, Invocation invocation) throws RpcException {
try {
List<Invoker<T>> invokersCopy = new ArrayList<Invoker<T>>(invokers);
// 脚本引擎engine = new ScriptEngineManager()
Compilable compilable = (Compilable) engine;
Bindings bindings = engine.createBindings();
bindings.put("invokers", invokersCopy);
bindings.put("invocation", invocation);
bindings.put("context", RpcContext.getContext());
// 编译规则
// rule是在FileRouterFactory#getRouter()中赋值的
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 + ", method:" + invocation.getMethodName() + ", url: " + RpcContext.getContext().getUrl(), e);
return invokers;
}
}
FileRouterFactory通过File读取规则脚本，新建一个脚本引擎ScriptEngineManager读取上面的脚本，获取Invokers列表。下面详细讲解一下FileRouterFactory读取脚本的过程。
// FileRouterFactory#getRouter(URL url)
public Router getRouter(URL url) {
try {
// Transform File URL into Script Route URL, and Load
// file:///d:/path/to/route.js?router=script ==> script:///d:/path/to/route.js?type=js&rule=<file-content>
String protocol = url.getParameter(Constants.ROUTER_KEY, ScriptRouterFactory.NAME); // Replace original protocol (maybe 'file') with 'script'
String type = null; // Use file suffix to config script type, e.g., js, groovy ...
// 获取url的path属性
// TODO 这个path是怎么赋值的
String path = url.getPath();
if (path != null) {
int i = path.lastIndexOf('.');
if (i > 0) {
type = path.substring(i + 1);
}
}
// 获取过滤规则
String rule = IOUtils.read(new FileReader(new File(url.getAbsolutePath())));
boolean runtime = url.getParameter(Constants.RUNTIME_KEY, false);
// 设置rule属性到url对象中
URL script = url.setProtocol(protocol).addParameter(Constants.TYPE_KEY, type).addParameter(Constants.RUNTIME_KEY, runtime).addParameterAndEncoded(Constants.RULE_KEY, rule);
// 获取ScriptRouter的实例
return routerFactory.getRouter(script);
} catch (IOException e) {
throw new IllegalStateException(e.getMessage(), e);
}
}