Thrift笔记(五)--Thrift server源码分析

从(四)server代码跟进

public static void simple(MultiplicationService.Processor processor) {
        try {
            TServerTransport serverTransport = new TServerSocket(9090);
            TServer server = new TSimpleServer(new Args(serverTransport).processor(processor));

            System.out.println("Starting the simple server...");
            server.serve();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

跟进server.serve()

public void serve() {
    try {
      serverTransport_.listen();
    } catch (TTransportException ttx) {
      LOGGER.error("Error occurred during listening.", ttx);
      return;
    }

    // Run the preServe event
    if (eventHandler_ != null) {
      eventHandler_.preServe();
    }

    setServing(true);

    while (!stopped_) {
      TTransport client = null;
      TProcessor processor = null;
      TTransport inputTransport = null;
      TTransport outputTransport = null;
      TProtocol inputProtocol = null;
      TProtocol outputProtocol = null;
      ServerContext connectionContext = null;
      try {
        client = serverTransport_.accept();
        if (client != null) {
          processor = processorFactory_.getProcessor(client);
          inputTransport = inputTransportFactory_.getTransport(client);
          outputTransport = outputTransportFactory_.getTransport(client);
          inputProtocol = inputProtocolFactory_.getProtocol(inputTransport);
          outputProtocol = outputProtocolFactory_.getProtocol(outputTransport);
          if (eventHandler_ != null) {
            connectionContext = eventHandler_.createContext(inputProtocol, outputProtocol);
          }
          while (true) {
            if (eventHandler_ != null) {
              eventHandler_.processContext(connectionContext, inputTransport, outputTransport);
            }
            if(!processor.process(inputProtocol, outputProtocol)) {
              break;
            }
          }
        }
      } catch (TTransportException ttx) {
        // Client died, just move on
      } catch (TException tx) {
        if (!stopped_) {
          LOGGER.error("Thrift error occurred during processing of message.", tx);
        }
      } catch (Exception x) {
        if (!stopped_) {
          LOGGER.error("Error occurred during processing of message.", x);
        }
      }

      if (eventHandler_ != null) {
        eventHandler_.deleteContext(connectionContext, inputProtocol, outputProtocol);
      }

      if (inputTransport != null) {
        inputTransport.close();
      }

      if (outputTransport != null) {
        outputTransport.close();
      }

    }
    setServing(false);
  }

跟进accept方法

protected TSocket acceptImpl() throws TTransportException {
    if (serverSocket_ == null) {
      throw new TTransportException(TTransportException.NOT_OPEN, "No underlying server socket.");
    }
    try {
      Socket result = serverSocket_.accept();
      TSocket result2 = new TSocket(result);
      result2.setTimeout(clientTimeout_);
      return result2;
    } catch (IOException iox) {
      throw new TTransportException(iox);
    }
  }

由于(四)使用的是阻塞IO， 代码也可以看到阻塞直到有客户端连接

跟进process()方法

public boolean process(TProtocol in, TProtocol out) throws TException {
    TMessage msg = in.readMessageBegin();
    ProcessFunction fn = processMap.get(msg.name);
    if (fn == null) {
      TProtocolUtil.skip(in, TType.STRUCT);
      in.readMessageEnd();
      TApplicationException x = new TApplicationException(TApplicationException.UNKNOWN_METHOD, "Invalid method name: '"+msg.name+"'");
      out.writeMessageBegin(new TMessage(msg.name, TMessageType.EXCEPTION, msg.seqid));
      x.write(out);
      out.writeMessageEnd();
      out.getTransport().flush();
      return true;
    }
    fn.process(msg.seqid, in, out, iface);
    return true;
  }

整体流程，readMessageBegin读客户端请求方法。请求方法在服务端没有注册，返回异常给客户端。如果有方法，对应方法处理。跟进process方法

public final void process(int seqid, TProtocol iprot, TProtocol oprot, I iface) throws TException {
    T args = getEmptyArgsInstance();
    try {
      args.read(iprot);
    } catch (TProtocolException e) {
      iprot.readMessageEnd();
      TApplicationException x = new TApplicationException(TApplicationException.PROTOCOL_ERROR, e.getMessage());
      oprot.writeMessageBegin(new TMessage(getMethodName(), TMessageType.EXCEPTION, seqid));
      x.write(oprot);
      oprot.writeMessageEnd();
      oprot.getTransport().flush();
      return;
    }
    iprot.readMessageEnd();
    TSerializable result = null;
    byte msgType = TMessageType.REPLY;

    try {
      result = getResult(iface, args);
    } catch (TTransportException ex) {
      LOGGER.error("Transport error while processing " + getMethodName(), ex);
      throw ex;
    } catch (TApplicationException ex) {
      LOGGER.error("Internal application error processing " + getMethodName(), ex);
      result = ex;
      msgType = TMessageType.EXCEPTION;
    } catch (Exception ex) {
      LOGGER.error("Internal error processing " + getMethodName(), ex);
      if(!isOneway()) {
        result = new TApplicationException(TApplicationException.INTERNAL_ERROR,
            "Internal error processing " + getMethodName());
        msgType = TMessageType.EXCEPTION;
      }
    }

    if(!isOneway()) {
      oprot.writeMessageBegin(new TMessage(getMethodName(), msgType, seqid));
      result.write(oprot);
      oprot.writeMessageEnd();
      oprot.getTransport().flush();
    }
  }

跟进读取参数方法

public void read(org.apache.thrift.protocol.TProtocol iprot, multiply_args struct) throws org.apache.thrift.TException {
        org.apache.thrift.protocol.TField schemeField;
        iprot.readStructBegin();
        while (true)
        {
          schemeField = iprot.readFieldBegin();
          if (schemeField.type == org.apache.thrift.protocol.TType.STOP) { 
            break;
          }
          switch (schemeField.id) {
            case 1: // N1
              if (schemeField.type == org.apache.thrift.protocol.TType.I32) {
                struct.n1 = iprot.readI32();
                struct.setN1IsSet(true);
              } else { 
                org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
              }
              break;
            case 2: // N2
              if (schemeField.type == org.apache.thrift.protocol.TType.I32) {
                struct.n2 = iprot.readI32();
                struct.setN2IsSet(true);
              } else { 
                org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
              }
              break;
            default:
              org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
          }
          iprot.readFieldEnd();
        }
        iprot.readStructEnd();

        // check for required fields of primitive type, which can't be checked in the validate method
        struct.validate();
      }

服务端跟进处理

result = getResult(iface, args);

继续跟进

public multiply_result getResult(I iface, multiply_args args) throws org.apache.thrift.TException {
        multiply_result result = new multiply_result();
        result.success = iface.multiply(args.n1, args.n2);
        result.setSuccessIsSet(true);
        return result;
      }

这里拿到结果， 最后写回给客户端

if(!isOneway()) {
      oprot.writeMessageBegin(new TMessage(getMethodName(), msgType, seqid));
      result.write(oprot);
      oprot.writeMessageEnd();
      oprot.getTransport().flush();
    }

这是最简单的一种方式，使用阻塞io， 二进制协议序列化。还有分阻塞， 压缩协议等。