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2021SC@SDUSC BRPC源码分析（十二）thrift

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2021SC@SDUSC BRPC源码分析（十二）thrift

目录

thrift

thrift介绍

thrift是应用较广的RPC框架，最初由Facebook发布，后交由Apache维护。为了和thrift服务互通，同时解决thrift原生方案在多线程安全、易用性、并发能力等方面的一系列问题，brpc实现并支持thrift在NonBlocking模式下的协议(FramedProtocol), 下文均直接称为thrift协议。

相比使用原生方案的优势有：

thrift编译

为了复用解析代码，brpc对thrift的支持仍需要依赖thrift库以及thrift生成的代码。

brpc默认不启用thrift支持也不需要thrift依赖。但如果需用thrift协议, 配置brpc环境的时候需加上–with-thrift或-DWITH_THRIFT=ON.

Linux下安装thrift依赖 先参考官方wiki安装好必备的依赖和工具，然后从官网下载thrift源代码，解压编译。

wget http://www.apache.org/dist/thrift/0.11.0/thrift-0.11.0.tar.gz
tar -xf thrift-0.11.0.tar.gz
cd thrift-0.11.0/
./configure --prefix=/usr --with-ruby=no --with-python=no --with-java=no --with-go=no --with-perl=no --with-php=no --with-csharp=no --with-erlang=no --with-lua=no --with-nodejs=no
make CPPFLAGS=-DFORCE_BOOST_SMART_PTR -j 4 -s
sudo make install

配置brpc支持thrift协议后make。编译完成后会生成libbrpc.a, 其中包含了支持thrift协议的扩展代码, 像正常使用brpc的代码一样链接即可。

# Ubuntu
sh config_brpc.sh --headers=/usr/include --libs=/usr/lib --with-thrift
# Fedora/CentOS
sh config_brpc.sh --headers=/usr/include --libs=/usr/lib64 --with-thrift
# Or use cmake
mkdir build && cd build && cmake ../ -DWITH_THRIFT=1

Client端访问thrift server

#include <brpc/channel.h>
#include <brpc/thrift_message.h>         // 定义了ThriftStub
...

DEFINE_string(server, "0.0.0.0:8019", "IP Address of thrift server");
DEFINE_string(load_balancer, "", "The algorithm for load balancing");
...
  
brpc::ChannelOptions options;
options.protocol = brpc::PROTOCOL_THRIFT;
brpc::Channel thrift_channel;
if (thrift_channel.Init(Flags_server.c_str(), FLAGS_load_balancer.c_str(), &options) != 0) {
   LOG(ERROR) << "Fail to initialize thrift channel";
   return -1;
}

brpc::ThriftStub stub(&thrift_channel);
...

// example::[EchoRequest/EchoResponse]是thrift生成的消息
example::EchoRequest req;
example::EchoResponse res;
req.data = "hello";

stub.CallMethod("Echo", &cntl, &req, &res, NULL);

if (cntl.Failed()) {
    LOG(ERROR) << "Fail to send thrift request, " << cntl.ErrorText();
    return -1;
}

代码分析

class ThriftService : public Describable {
public:
    ThriftService();
    virtual ~ThriftService();
    virtual void ProcessThriftFramedRequest(
        Controller* controller,
        ThriftFramedMessage* request,
        ThriftFramedMessage* response,
        ::google::protobuf::Closure* done) = 0;
    void Describe(std::ostream &os, const DescribeOptions&) const;

private:
DISALLOW_COPY_AND_ASSIGN(ThriftService);
friend class policy::ThriftClosure;
friend void policy::ProcessThriftRequest(InputMessageBase* msg_base);
friend class StatusService;
friend class Server;

private:
    void Expose(const butil::StringPiece& prefix);    
    MethodStatus* _status;
};
}

namespace brpc {

class ThriftStub;

static const int16_t THRIFT_INVALID_FID = -1;
static const int16_t THRIFT_REQUEST_FID = 1;
static const int16_t THRIFT_RESPONSE_FID = 0;

class ThriftMessageBase {
public:
……
略
……
};

class ThriftFramedMessage : public ::google::protobuf::Message {
friend class ThriftStub;
public:
    butil::IOBuf body;
    int16_t field_id;
    
private:
    bool _own_raw_instance;
    ThriftMessageBase* _raw_instance;

public:
   ……
略
……

protected:
……
略
……

private:
……
略
……
};

class ThriftStub {
public:
……
略
……

private:
    ChannelBase* _channel;
};

namespace details {

template <typename T>
class ThriftMessageWrapper final : public ThriftMessageBase {
public:
    ThriftMessageWrapper() : msg_ptr(NULL) {}
    ThriftMessageWrapper(T* msg2) : msg_ptr(msg2) {}
    virtual ~ThriftMessageWrapper() {}
    uint32_t Read(::apache::thrift::protocol::TProtocol* iprot) override final
    { return msg_ptr->T::read(iprot); }
    uint32_t Write(::apache::thrift::protocol::TProtocol* oprot) const override final
    { return msg_ptr->T::write(oprot); }
    T* msg_ptr;
};

template <typename T>
class ThriftMessageHolder final : public ThriftMessageBase {
public:
    virtual ~ThriftMessageHolder() {}
    uint32_t Read(::apache::thrift::protocol::TProtocol* iprot) override final
    { return msg.T::read(iprot); }
    uint32_t Write(::apache::thrift::protocol::TProtocol* oprot) const override final
    { return msg.T::write(oprot); }
    T msg;
};

template <typename RESPONSE>
class ThriftDoneWrapper : public ::google::protobuf::Closure {
public:
    explicit ThriftDoneWrapper(::google::protobuf::Closure* done)
        : _done(done) {}
    void Run() override {
        _done->Run();
        delete this;
    }
private:
    ::google::protobuf::Closure* _done;
public:
    ThriftMessageWrapper<RESPONSE> raw_response_wrapper;
    ThriftFramedMessage response;
};

} 

……
略
……

template <typename REQUEST, typename RESPONSE>
void ThriftStub::CallMethod(const char* method_name,
                            Controller* cntl,
                            const REQUEST* raw_request,
                            RESPONSE* raw_response,
                            ::google::protobuf::Closure* done) {
    cntl->_thrift_method_name.assign(method_name);

    details::ThriftMessageWrapper<REQUEST>
        raw_request_wrapper(const_cast<REQUEST*>(raw_request));
    ThriftFramedMessage request;
    request._raw_instance = &raw_request_wrapper;

    if (done == NULL) {
        ThriftFramedMessage response;
        details::ThriftMessageWrapper<RESPONSE> raw_response_wrapper(raw_response);
        response._raw_instance = &raw_response_wrapper;
        _channel->CallMethod(NULL, cntl, &request, &response, NULL);
    } else {
        details::ThriftDoneWrapper<RESPONSE>* new_done =
            new details::ThriftDoneWrapper<RESPONSE>(done);
        new_done->raw_response_wrapper.msg_ptr = raw_response;
        new_done->response._raw_instance = &new_done->raw_response_wrapper;
        _channel->CallMethod(NULL, cntl, &request, &new_done->response, new_done);
    }
}

标签：BRPC,2021SC,--,raw,brpc,源码,done,response,thrift
来源： https://blog.csdn.net/Lollo_HA/article/details/121880684