Flume NG源码分析(五)使用ThriftSource通过RPC方式收集日志
上一篇说了利用ExecSource从本地日志文件异步的收集日志,这篇说说采用RPC方式同步收集日志的方式。笔者对Thrift比较熟悉,所以用ThriftSource来介绍RPC的日志收集方式。
整体的结构图如下:
1. ThriftSource包含了一个Thrift Server,以及一个Thrift Service服务的实现。这里的Thrift Service是由ThriftSourceProtocol定义
2. 应用程序调用Thrift Service的客户端,以RPC的方式将日志发送到ThriftSource的Thrfit Service的服务端,完成应用层序日志的收集
先来看下ThriftSourceProtocol定义的Thrfit服务。Thrift服务定义在flume-ng-sdk工程的flume.thrift中
1. 定义了ThriftFlumeEvent数据结构,日志封装成Event来Flume NG中传递
2. 定义了ThriftSourceProtocol服务,有两个接口,append和appendBatch
- namespace java org.apache.flume.thrift
-
- struct ThriftFlumeEvent {
- 1: required map <string, string> headers,
- 2: required binary body,
- }
-
- enum Status {
- OK,
- FAILED,
- ERROR,
- UNKNOWN
- }
-
- service ThriftSourceProtocol {
- Status append(1: ThriftFlumeEvent event),
- Status appendBatch(1: list<ThriftFlumeEvent> events),
- }
Thrift生成的中间文件是ThrfitSourceProtocol,由服务器端和客户端共享
- public class ThriftSourceProtocol {
-
- public interface Iface {
-
- public Status append(ThriftFlumeEvent event) throws org.apache.thrift.TException;
-
- public Status appendBatch(List<ThriftFlumeEvent> events) throws org.apache.thrift.TException;
-
- }
-
- 。。。。。。
- }
ThrfitSource中的ThriftSourceHandler私有类实现了ThrfitSourceProtocol这个服务,append接口的实现逻辑如下
1. 把ThriftFlumeEvent转化成SimpleEvent
2. 修改计数器
3. 把SimpleEvent交给ChannelProcessor来处理,传递到下游的Channel中去
可以看到ThriftSouceHandler的实现逻辑和ExecRunnable的逻辑基本是一样的
- private class ThriftSourceHandler implements ThriftSourceProtocol.Iface {
-
- @Override
- public Status append(ThriftFlumeEvent event) throws TException {
- Event flumeEvent = EventBuilder.withBody(event.getBody(),
- event.getHeaders());
-
- sourceCounter.incrementAppendReceivedCount();
- sourceCounter.incrementEventReceivedCount();
-
- try {
- getChannelProcessor().processEvent(flumeEvent);
- } catch (ChannelException ex) {
- logger.warn("Thrift source " + getName() + " could not append events " +
- "to the channel.", ex);
- return Status.FAILED;
- }
- sourceCounter.incrementAppendAcceptedCount();
- sourceCounter.incrementEventAcceptedCount();
- return Status.OK;
- }
-
- @Override
- public Status appendBatch(List<ThriftFlumeEvent> events) throws TException {
- sourceCounter.incrementAppendBatchReceivedCount();
- sourceCounter.addToEventReceivedCount(events.size());
-
- List<Event> flumeEvents = Lists.newArrayList();
- for(ThriftFlumeEvent event : events) {
- flumeEvents.add(EventBuilder.withBody(event.getBody(),
- event.getHeaders()));
- }
-
- try {
- getChannelProcessor().processEventBatch(flumeEvents);
- } catch (ChannelException ex) {
- logger.warn("Thrift source %s could not append events to the " +
- "channel.", getName());
- return Status.FAILED;
- }
-
- sourceCounter.incrementAppendBatchAcceptedCount();
- sourceCounter.addToEventAcceptedCount(events.size());
- return Status.OK;
- }
- }
-
- }
有了Thrfit服务实现后,ThrfitSource定义了Thrfit Server。默认是TThreadedSelectorServer,当TThreadedSelectorServer ClassNotFound后,创建TThreadPoolServer,还是没找到的话,那么ThriftSource启动失败。
关于Thrfit Server的更多介绍可以看这篇Thrift源码分析(七)-- TServer服务器分析
Thrift Server的创建和启动主要做了几件事情
1. 创建ServerSocket,这里是TNonblockingServerSocket,非阻塞的ServerSocket
2. 创建服务器参数类TNonblockingServer.AbstractNonblockingServerArgs,所有的服务器的属性设置都是在Args类里传递的
3. TThreadedSelectorServer是一个Reactor模式的服务器实现,需要传递一个线程池。这里是Executors.newFixedThreadPool(maxThreads, threadFactory);
4. 设置编解码协议,这里是TFastFramedTransport协议
5. 设置Thrift服务的实现类Processor,这里是上面定义的ThrfitSourceHandler类
6. 启动Thrift服务器,这里在单独的线程中启动了Thrift服务器。servingExecutor.submit(new Runnable() {public void run() {server.serve();}})
在单独的线程启动Thrift服务器主要的目的是在原来的线程中可以处理一下Thrfit服务器停止后的清理工作。
- Class<?> serverClass = null;
- Class<?> argsClass = null;
- TServer.AbstractServerArgs args = null;
- /*
- * Use reflection to determine if TThreadedSelectServer is available. If
- * it is not available, use TThreadPoolServer
- */
- try {
- serverClass = Class.forName("org.apache.thrift" +
- ".server.TThreadedSelectorServer");
-
- argsClass = Class.forName("org.apache.thrift" +
- ".server.TThreadedSelectorServer$Args");
-
- // Looks like TThreadedSelectorServer is available, so continue..
- ExecutorService sourceService;
- ThreadFactory threadFactory = new ThreadFactoryBuilder().setNameFormat(
- "Flume Thrift IPC Thread %d").build();
- if (maxThreads == 0) {
- sourceService = Executors.newCachedThreadPool(threadFactory);
- } else {
- sourceService = Executors.newFixedThreadPool(maxThreads, threadFactory);
- }
- serverTransport = new TNonblockingServerSocket(
- new InetSocketAddress(bindAddress, port));
- args = (TNonblockingServer.AbstractNonblockingServerArgs) argsClass
- .getConstructor(TNonblockingServerTransport.class)
- .newInstance(serverTransport);
- Method m = argsClass.getDeclaredMethod("executorService",
- ExecutorService.class);
- m.invoke(args, sourceService);
- }
-
-
- try {
-
- args.protocolFactory(new TCompactProtocol.Factory());
- args.inputTransportFactory(new TFastFramedTransport.Factory());
- args.outputTransportFactory(new TFastFramedTransport.Factory());
- args.processor(new ThriftSourceProtocol
- .Processor<ThriftSourceHandler>(new ThriftSourceHandler()));
-
- server = (TServer) serverClass.getConstructor(argsClass).newInstance
- (args);
- } catch (Throwable ex) {
- throw new FlumeException("Cannot start Thrift Source.", ex);
- }
-
-
- servingExecutor = Executors.newSingleThreadExecutor(new
- ThreadFactoryBuilder().setNameFormat("Flume Thrift Source I/O Boss")
- .build());
-
- /**
- * Start serving.
- */
- servingExecutor.submit(new Runnable() {
- @Override
- public void run() {
- server.serve();
- }
- });
总结一下,采用RPC的方式收集日志有几个步骤
1. 定义RPC服务来收集日志
2. 实现RPC服务,并提供客户端给应用程序。应用程序使用客户端来将日志封装成Event,通过RPC调用传递给RPC类型的Source
3. RPC类型的Source启动RPC Server,提供RPC服务,将接收到的Event传递给下游的Channel
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