Netty自娛自樂之類Dubbo RPC 框架設計構想 【上篇】
之前在前一篇的《Netty自娛自樂之協議棧設計》,菜鳥我已經自娛自樂了設計協議棧,gitHub地址為https://github.com/vOoT/ncustomer-protocal。先這一篇中,準備接著自娛去實現一個RPC框架,現在公司共的是Dubbo,那麽先不看其代碼,先自行實現一下吧。
dubbo 包括 註冊和服務調用,細節我們先不管,然後,我先先實現一個如下的簡單模型
哈哈哈,第一個版本就是這麽簡單,粗暴。說到自定義配置,首先想到的是Spring 自定義標簽,利用標簽進行配置服務。而我設計的標簽頁非常的簡單,使用如下:
<rpc:provider id="helloServiceImpl" class="com.qee.rpc.HelloServiceImpl"/>
<rpc:cumsumer id="helloService" interface="com.qee.rpc.HelloService"/>
看到了沒,非常像dubbo,那麽如何實現一個自定義標簽呢,從網上可以了解搜索的到,現在我就簡單說明一下,如何編寫和測試自己自定義的Spring 標簽。
一、 定義xsd 文件,該文件是xml文件的 schema 定義。從上面的例子中,我們知道xsd文件裏面應該有2個節點,1個provider節點和1個cumsumer節點定義。然後制定provider節點有id 和classs屬性,而cumsumer節點有 id和 interface屬性。定義文件如下(該文件名為light-weight-rpc.xsd):
<?xml version="1.0" encoding="UTF-8"?> <xsd:schema xmlns="http://www.qee.com/schema/rpc" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:beans="http://www.springframework.org/schema/beans" targetNamespace="http://www.qee.com/schema/rpc" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xsd:import namespace="http://www.springframework.org/schema/beans"/> <xsd:element name="provider" type="rpc-provider-type"></xsd:element><xsd:element name="cumsumer" type="rpc-cumsumer-type"></xsd:element> <xsd:complexType name="rpc-provider-type"> <xsd:attribute name="id" type="xsd:string" use="required"></xsd:attribute> <xsd:attribute name="class" type="xsd:string" use="required"></xsd:attribute> </xsd:complexType> <xsd:complexType name="rpc-cumsumer-type"> <xsd:attribute name="id" type="xsd:string" use="required"></xsd:attribute> <xsd:attribute name="interface" type="xsd:string" use="required"></xsd:attribute> </xsd:complexType> </xsd:schema>
上面,畫上紅線的地方需要註意和主要的關註點,首先需要說明這個文件的name space 為 xmlns="http://www.qee.com/schema/rpc 。其他的具體如何寫可以到網上搜索。有了這個文件,我們需要在xml的文件引入他,比如如下test.xml文件如何引用該文件
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:rpc="http://www.qee.com/schema/rpc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.qee.com/schema/rpc http://www.qee.com/schema/rpc/light-weight-rpc.xsd"> <rpc:provider id="helloServiceImpl" class="com.qee.rpc.HelloServiceImpl"/> <rpc:cumsumer id="helloService" interface="com.qee.rpc.HelloService"/> </beans>
上面就是一個spring xml 文件,主要關註的是花黃線的部分,這樣就可以使用<rpc:provider> 和<rpc:cumsumer>。
二、組織文件,即要把文件放到合適的地方,讓Spring能夠識別。第一步,需要把light-weight-rpc.xsd文件放到META-INF的文件夾下,然後在META-INF文件創建2個新的文件,名字固定。
文件1:spring.schemes ,該文件裏面直有一行數據,如下
http\://www.qee.com/schema/rpc/light-weight-rpc.xsd=META-INF/light-weight-rpc.xsd
該行告訴Spring容器,http://www.qee.com/schema/rpc/light-weight-rpc.xsd ,之前定義命名空間的light-weight-rpc.xsd文件是META-INF下的light-weight-rpc.xsd
文件2:spring.handlers,該文件裏面也只有一行數據,如下
http\://www.qee.com/schema/rpc=com.qee.rpc.config.support.LightWeightRpcNamespaceHandlerSupport
該行告訴Spring容器,命名空間http://www.qee.com/schema/rpc的解析處理器是 com.qee.rpc.config.support.LightWeightRpcNamespaceHandlerSupport。這個例子的目錄如下
好了到現在我們基本把文件的位置放置正確了。之後就是需要編寫com.qee.rpc.config.support.LightWeightRpcNamespaceHandlerSupport。
三、編寫com.qee.rpc.config.support.LightWeightRpcNamespaceHandlerSupport,該類需要繼承NamespaceHandlerSupport,重寫init()方法。主要的目的就是註冊,節點解析處理器。
代碼如下:
public class LightWeightRpcNamespaceHandlerSupport extends NamespaceHandlerSupport { @Override public void init() { //註冊用於解析<rpc>的解析器 registerBeanDefinitionParser("provider", new LightWeightRpcBeanDefinitionParser()); registerBeanDefinitionParser("cumsumer", new LightWeightRpcBeanDefinitionParser()); } }
從代碼上我們只要,就是把解析xml文件provider和cumsumer節點進行BeanDefinition轉化解析。
因為這2個節點非常的類型。所以我就只想用痛一個解析處理器,LightWeightRpcBeanDefinitionParser,該轉化器繼承org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser。具體代碼如下:
public class LightWeightRpcBeanDefinitionParser extends AbstractSingleBeanDefinitionParser { protected Class getBeanClass(Element element) { return LightWeightRPCElement.class; } protected void doParse(Element element, BeanDefinitionBuilder bean) { String interfaces = element.getAttribute("interface"); String clazz = element.getAttribute("class"); String id = element.getAttribute("id"); bean.addPropertyValue("id", id + "Config"); if (StringUtils.hasText(id)) { bean.addPropertyValue("beanName", id); } if (StringUtils.hasText(clazz)) { bean.addPropertyValue("clazz", clazz); } if (StringUtils.hasText(interfaces)) { bean.addPropertyValue("interfaces", interfaces); } } }
我們把xml的id 放到 bean 的beanName,把id+"Config"放到 id上,因為這個 BeanDefinitionBuilder 最終生成的對象是 LightWeightRPCElement,不是我們需要的代碼對象。
@Data @ToString public class LightWeightRPCElement {
private String id;
private String beanName;
private String clazz;
private String interfaces;
}
是不是非常的簡單,到目前為止,我們已經完成了所有的自定義標簽工作,下一步當然就是測試一下啦,代碼如下:
public class RPCTest { public static void main(String[] args) { ApplicationContext ctx = new ClassPathXmlApplicationContext("test.xml"); LightWeightRPCElement p1= (LightWeightRPCElement)ctx.getBean("helloServiceImplConfig"); LightWeightRPCElement p2= (LightWeightRPCElement)ctx.getBean("helloServiceConfig"); System.out.println(p1); System.out.println(p2); } }
執行結果是:
四、這一步的話,我們需要處理之前已經註冊到Spring的 LightWeightRPCElement 的對象,在上面的例子中,這兩個的Bean Id分別是helloServiceImplConfig、helloServiceConfig,之後我們需要通過這2個對象來產生我們需要代理對象。首先我們來看一下JDK的生成代理對象的方法:
public static Object newProxyInstance(ClassLoader loader, Class<?>[] interfaces,InvocationHandler invocationHandler);
從上面的代碼中,我們知道生產一個代理對象需要一個類加載器loader,和代理接口的字節碼interfaces,和代理處理具柄invocationHandler。那麽我程序定義了一個名為InterfaceProxyHandler的代理處理具柄,它繼承InvocationHandler。代碼如下:
@Data public class InterfaceProxyHandler implements InvocationHandler { private CallBackExcuteHandler excuteHandler; public InterfaceProxyHandler(CallBackExcuteHandler excuteHandler) { this.excuteHandler = excuteHandler; } @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { MessageCallback callback = ExcuteManager.invoke(excuteHandler); .......//這裏代碼還沒寫,其實就是處理返回結果,準備下章解決。 } }
從上面的代碼,我們知道,它具體的執行邏輯是invoke方法。具體內容就是通過一個ExcuteManager來處理邏輯,該ExcuteManager就是一個封裝了ExecutorService的線程池管理類。其意思是每個代理對象去執行方法時,都是通過線程池的一個線程去執行,而這個線程池管理類的執行方法invoke需要一個Callable任務,所以程序自定義了一個CallBackExcuteHandler類。代碼如下:
public class CallBackExcuteHandler implements Callable<MessageCallback> { private String beanName; private List<InetSocketAddress> remoteAddresses; private LoadBalancedStrategy loadBalancedStrategy; public CallBackExcuteHandler(String beanName) { this.beanName = beanName; } public CallBackExcuteHandler(String beanName, List<InetSocketAddress> remoteAddresses) { this.beanName = beanName; this.remoteAddresses = remoteAddresses; } public CallBackExcuteHandler(String beanName, List<InetSocketAddress> remoteAddresses, LoadBalancedStrategy loadBalancedStrategy) { this.beanName = beanName; this.remoteAddresses = remoteAddresses; this.loadBalancedStrategy = loadBalancedStrategy; } public CallBackExcuteHandler() { } /** * 線程執行 * * @return * @throws Exception */ @Override public MessageCallback call() throws Exception { if (CollectionUtils.isEmpty(remoteAddresses)) { List<ServiceAddressConfig> remoteUrls = ServiceRemoteUrlContext.getInstance().getRemoteUrls(beanName); if (CollectionUtils.isEmpty(remoteUrls)) { throw new RuntimeException("服務 [" + beanName + " ]遠程地址錯誤"); } } int size = remoteAddresses.size(); int idx = loadBalancedStrategy.strategy(size); InetSocketAddress inetSocketAddress = remoteAddresses.get(idx); System.out.println("返回的地址" + inetSocketAddress + " idx=" + idx); MessageCallback messageCallback = new MessageCallback(); return messageCallback; } }
具體邏輯就是看call,這裏就是處理的具體邏輯,這個邏輯其實就是處理Netty網絡通信的內容,等下章開始講解,這一章主要通過搭建具體的框架,之後補充細節。這裏遠程地址為空的話,去遠程地址管理上下文獲取,接著通過一個負載均衡策略對象,返回其中一個地址的index。通過這種方式實現負載均衡調用。
遠程地址管理上下文對象代碼如下:
public class ServiceRemoteUrlContext { private Map<String, List<ServiceAddressConfig>> remoteUrls; private volatile static ServiceRemoteUrlContext context; private ServiceRemoteUrlContext() { } public static ServiceRemoteUrlContext getInstance() { if (context == null) { synchronized (ServiceRemoteUrlContext.class) { if (context == null) { context = new ServiceRemoteUrlContext(); context.remoteUrls = new HashMap<>(); } } } return context; } /** * 添加一個遠程地址,地址從service-url.properties 獲取 * * @param beanName * @param serviceAddressConfig * @return */ public boolean addServiceAddress(String beanName, ServiceAddressConfig serviceAddressConfig) { if (StringUtils.isEmpty(beanName) || serviceAddressConfig == null) { return false; } synchronized (remoteUrls) { if (remoteUrls.get(beanName) == null) { List<ServiceAddressConfig> remoteAddress = new ArrayList<>(); remoteAddress.add(serviceAddressConfig); remoteUrls.put(beanName, remoteAddress); } else { List<ServiceAddressConfig> serviceAddressConfigs = remoteUrls.get(beanName); if (serviceAddressConfigs.contains(serviceAddressConfig)) { return false; } serviceAddressConfigs.add(serviceAddressConfig); return true; } } return false; } /** * 獲取一個服務的遠程地址 ,beanName like "com.qee.rpc.config.test.HelloService" * * @param beanName * @return */ public List<ServiceAddressConfig> getRemoteUrls(String beanName) { return remoteUrls.get(beanName); } }
負載均衡的接口,代碼如下:
public interface LoadBalancedStrategy { /** * 從 0 -size-1 獲取一個值 * * @param size * @return */ int strategy(int size); }
現在只實現了1中,輪詢方法,之後可以寫成可配置,代碼如下:
public class RollPolingStrategy implements LoadBalancedStrategy { private int currentValue = 0; private Class<?> clazz; public RollPolingStrategy(Class<?> clazz) { this.clazz = clazz; } @Override public int strategy(int size) { synchronized (clazz) { int nextValue = (currentValue + 1) % size; currentValue = nextValue; if (currentValue > size) { nextValue = 0; } return currentValue; } } }
接著,我們需要看一下簡單的ExcuteManager類,代碼如下:
public class ExcuteManager { /** * 默認是200個線程 */ private static final int DEFAULT_THRED_NUM = 200; /** * 超時時間為1秒 */ private static final int DEFAULT_TIME_OUT_TIME = 1000; private static ExecutorService executorService = Executors.newFixedThreadPool(DEFAULT_THRED_NUM); public static MessageCallback invoke(Callable<MessageCallback> call) { Future<MessageCallback> submit = executorService.submit(call); try { return submit.get(DEFAULT_TIME_OUT_TIME, TimeUnit.MILLISECONDS); } catch (InterruptedException e) { submit.cancel(true); throw new RuntimeException("the method is interupted ", e); } catch (ExecutionException e) { submit.cancel(true); throw new RuntimeException("the method cal excute exception", e); } catch (TimeoutException e) { System.out.println(Thread.currentThread().getName()); submit.cancel(true); throw new RuntimeException("the method call is time out ", e); } } public static void shutdown() { executorService.shutdown(); } public static void shutdownNow() { executorService.shutdownNow(); } }
這些參數,在後面都做成可配置的。
最後一步了,就是需要生產一個代理對象,並把代理對象註冊到Spring容器裏面。那麽Spring的 BeanPostProcessor可以為我們解決問題,看代碼如下:
@Component public class RegisterRpcProxyBeanProcessor implements BeanPostProcessor, BeanFactoryAware { private BeanFactory beanFactory; @Override public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { return bean; } @Override public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { Object target = bean; if (bean instanceof LightWeightRPCElement) { //如果是LightWeightRPCElement,則強轉,否則不處理 LightWeightRPCElement rpcElement = (LightWeightRPCElement) bean; // 接著就是獲取 之前XML 的屬性值 Class<?> clazz = null; if (!StringUtils.isEmpty(rpcElement.getInterfaces())) { try { clazz = Class.forName(rpcElement.getInterfaces()); } catch (ClassNotFoundException e) { throw new RuntimeException("獲取 [" + rpcElement.getInterfaces() + " ] class字節碼失敗"); } } //通過ServiceRemoteUrlContext得到這個接口的遠程端口和地址 List<ServiceAddressConfig> remoteUrls = ServiceRemoteUrlContext.getInstance().getRemoteUrls(rpcElement.getInterfaces()); List<InetSocketAddress> remoteAddressList = ExtractUtil.extractList(remoteUrls, "remoteAddress", ServiceAddressConfig.class); CallBackExcuteHandler callBackExcuteHandler = new CallBackExcuteHandler(rpcElement.getInterfaces(), remoteAddressList,new RollPolingStrategy(clazz)); InterfaceProxyHandler interfaceProxyHandler = new InterfaceProxyHandler(callBackExcuteHandler); //這裏之後可以優化為各種方式產生動態代理,如cglib等 target = Proxy.newProxyInstance(bean.getClass().getClassLoader(), new Class[]{clazz}, interfaceProxyHandler); if (beanFactory instanceof DefaultListableBeanFactory) { //這裏就是動態註冊對象,把動態代理對象註冊到Spring上 DefaultListableBeanFactory defaultFactory = (DefaultListableBeanFactory) beanFactory; defaultFactory.registerSingleton(rpcElement.getBeanName(), target); } } return target; } @Override public void setBeanFactory(BeanFactory beanFactory) throws BeansException { this.beanFactory = beanFactory; }
從上面的註釋大家應該也非常的清楚了,現在只剩下最後一步了,如何獲取該接口的遠程服務地址和端口,dubbo是通過註冊中心zookeeper,而這裏的簡單的采用配置,例子如下:
com.qee.rpc.config.test.HelloService 127.0.0.1:8888,127.0.0.1:7777,127.0.0.1:9999
對,就是在一個properties文件上 通過服務接口全稱 和指定遠程服務主機和端口。之後可以改為有註冊中心的方式。現在我們來看一下讀取這個配置的類,代碼如下:
@Component public class ServiceRemoteUrlsInit implements InitializingBean { /** * 遠程服務配置地址路徑,默認 */ @Value("${remote-urls-path:classpath:service-urls.properties}") private String remoteUrlsPropertyPath; @Override public void afterPropertiesSet() throws Exception { Properties pps = new Properties(); if (!remoteUrlsPropertyPath.startsWith("classpath")) { throw new RuntimeException(remoteUrlsPropertyPath + "不存在"); } String[] filePath = remoteUrlsPropertyPath.split(":"); if (filePath == null || filePath.length != 2) { throw new RuntimeException(remoteUrlsPropertyPath + "內容配置錯誤"); } ClassPathResource resource = new ClassPathResource(filePath[1]); InputStream in = new BufferedInputStream(resource.getInputStream()); pps.load(in); Enumeration en = pps.propertyNames(); while (en.hasMoreElements()) { String beanName = (String) en.nextElement(); String strRemoteUrls = pps.getProperty(beanName); String[] remoteUrls = strRemoteUrls.split(","); if (remoteUrls == null || remoteUrls.length == 0) { break; } for (String remoteUrl : remoteUrls) { String[] hostPort = remoteUrl.split(":"); if (hostPort == null || hostPort.length != 2) { throw new RuntimeException(remoteUrlsPropertyPath + " 配置內容錯誤"); } ServiceAddressConfig serviceAddressConfig = new ServiceAddressConfig(); serviceAddressConfig.setBeanName(beanName); serviceAddressConfig.setHostName(hostPort[0]); serviceAddressConfig.setRemotePort(Integer.valueOf(hostPort[1])); InetSocketAddress socketAddress = new InetSocketAddress(serviceAddressConfig.getHostName(), serviceAddressConfig.getRemotePort()); serviceAddressConfig.setRemoteAddress(socketAddress); ServiceRemoteUrlContext.getInstance().addServiceAddress(beanName, serviceAddressConfig); } } } }
代碼比較簡單,就是實現 InitializingBean這個Spring接口,Spring啟動在Bean創建後,初始化 afterPropertiesSet()這個配置,在這個方法裏面讀取類路徑的配置文件。最後我們來運行一個例子。還是HelloService.我們有一個Invoker類,需要註入HelloService 對象調用。代碼如下:
@Component public class Invoker { @Autowired private HelloService helloService; @Resource(name = "helloService") private HelloService helloService2; public void print() { helloService.hello("123"); helloService2.hello("122344"); } }
然後通過SpringBoot 啟動測試:
@ComponentScan(basePackages = "com.qee.rpc") @EnableAutoConfiguration public class App { private static ExecutorService executorService = Executors.newCachedThreadPool(); private static final CountDownLatch cd = new CountDownLatch(1); public static void main(String[] args) { try { SpringApplication.run(App.class, args); System.out.println("the main Thread :" + Thread.currentThread().getName()); final Invoker invoker = (Invoker) ApplicationContextUtils.getBean("invoker"); for (int i = 0; i < 300; i++) { executorService.execute(new Runnable() { @Override public void run() { try { cd.await(); } catch (InterruptedException e) { e.printStackTrace(); } invoker.print(); } }); } cd.countDown(); Thread.sleep(100000); } catch (InterruptedException e) { e.printStackTrace(); } finally { ExcuteManager.shutdown(); executorService.shutdown(); } }
有300個線程去調這個 invoker.print();修改一下 InterfaceProxyHandler的invoke方法,因為我們底層的通信還沒完成。所以以
System.out.println("在InterfaceProxyHandler上調用invoke方法,參數是=" + args[0]);
以這個語句來測試一下代碼,其中這個大致框架已經上傳到gitHub:https://github.com/vOoT/light-weight-rpc, 有什麽建議和問題,大家一起討論吧。最後貼一下執行結果:
哈哈哈,這樣我們是不是就是可以通過Spring註解 @Autowired 和 @Resource 來註入動態對象。
Netty自娛自樂之類Dubbo RPC 框架設計構想 【上篇】