Thrift 基礎(C++ rpc )

1、thrift簡介

thrift是Facebook開源的一套rpc框架，目前被許多公司使用
我理解的特色

1. 使用IDL語言生成多語言的實現代碼，程序員只須要實現本身的業務邏輯
2. 支持序列化和反序列化操做，底層封裝協議，傳輸模塊
3. 以同步rpc調用爲主，使用libevent evhttp支持http形式的異步調用
4. rpc服務端線程安全，客戶端大多數非線程安全
5. 相比protocol buffer效率差些，protocol buffer不支持rpc，須要本身實現rpc擴展，目前有grpc能夠使用

因爲thrift支持序列化和反序列化，而且支持rpc調用，其代碼風格較好而且使用方便，對效率要求不算過高的業務，以及須要rpc的場景，能夠選擇thrift做爲基礎庫

層次圖：

2、編譯(thrift for c++ && centos7)

一、官網獲取源碼包 thrift-0.11.0.tar.gz 解壓

tar zxvf thrift-0.11.0.tar.gz

二、安裝依賴

yum -y install automake libtool flex bison pkgconfig gcc-c++ boost-devel libevent-devel zlib-devel python-devel ruby-devel openssl-devel

三、編譯boost
使用boost_1_63_0.tar.gz

./bootstrap.sh
./b2

四、編譯thrift
源碼根目錄運行

./configure && make
sudo make install

五、驗證安裝

thrift -version
顯示 Thrift version 0.11.0

3、編寫使用IDL編寫.thrift文件

這裏給出一個thrift的IDL基本語法列表，詳細用法能夠去官網查找

namespace cpp thrift.Test
//typedef 用法
typedef i32 MyInt32;
typedef string MyString;
typedef i32 UserId;
//struct 結構定義
struct TypedefTestStruct
{
    1: MyInt32 field_MyInt32;
    2: MyString field_MyString;
    3: i32 field_Int32;
    4: string filed_string;
}
//enum 枚舉定義
enum Numberz
{
    ONE = 1,
    TWO,
    THREE,
    FIVE = 5,
    SIX,
    EIGHT = 8
}
//const 用法
const Numberz myNumberz = Numberz.ONE;
struct Bonk
{
    1: string message,
    2: i32 type
}
//類型嵌套
struct Xtruct
{
    1: string string_thing,
    2: i8 byte_thing,
    3: i32 i32_thing,
    4: i64 i64_thing
}
struct Xtruct2
{
    1: i8 byte_thing,
    2: Xtruct struct_thing,
    3: i32 i32_thing
}
//支持map list set類型分別對應C++中的 map = stl::map list = stl::vector set = stl::set
typedef map<string, Bonk> MapType
struct Insanity
{
    1: map<Numberz, UserId> userMap;
    2: list<Xtruct> xtructs;
}
struct CrazyNesting
{
    1: string string_field,
    2: optional set<Insanity> set_field;
    3: required list<map<set<i32>, map<i32,set<list<map<Insanity,string>>>>>> list_field,
    4: binary binary_field
}
//union用法
union SomeUnion
{
    1: map<NumberZ, UserId> map_thing,
    2: string string_thing,
    3: i32 i32_thing,
    4: Xtruct3 xtruct_thing,
    5: Insanity insanity_thing
}
//exception 異常
exception Xception
{
    1: i32 errorCode,
    2: string message
}
exception Xception2
{   
    1: i32 errorCode,
    2: Xtruct struct_thing
}
// empty struct
struct EmptyStruct{}
struct OneField
{
    1: EmptyStruct field;
}
//service 定義的一組rpc服務,通常是抽象出來的接口調用
service ThriftTest
{
    void testVoid(),
    string testString(1: string thing),
    bool testBool(1: bool thing),
    i8 testByte(1: i8 thing),
    i32 testI32(1: i32 thing),
    i64 testI64(1: i64 thing),
    Xtruct testStruct(1: Xtruct thing),
    Xtruct2 testNest(1: Xtruct2 thing),
    map<string, string> testStringMap(1: map<string, string> thing),
    set<i32> testSet(1: set<i32> thing),
    list<i32> testList(1: list<i32> thing),
    Numberz testEnum(1: Numberz thing),
    map<i32, map<i32,i32>> testMapMap(1: i32 hello),
    map<UserId, map<Numberz,Insanity>> testInsanity(1: Insanity argument),
    Xtruct testMulti(1: i8 arg0, 2: i32 arg1, 3: i64 arg2, 4: map<i16, string> arg3, 5: Numberz arg4, 6: UserId arg5),
    void testException(1: string arg) throws(1: Xception err1),
    Xtruct testMultiException(1: string arg0, 2: string arg1) throws(1: Xception err1, 2: Xception2 err2),
    oneway void testOneway(1:i32 secondsToSleep)
}

4、使用thrift文件生成C++代碼

一、生成同步調用的C++代碼

thrift -r --gen cpp xxx.thrift

二、生成異步調用的C++代碼(同時同步調用的代碼也被生成)

thrift --gen cpp:cob_style xxx.thrift

5、thrfit同步調用

一、StressTest.thrift文件

namespace cpp test.stress
service Service {
  void echoVoid(),
  i8 echoByte(1: i8 arg),
  i32 echoI32(1: i32 arg),
  i64 echoI64(1: i64 arg),
  string echoString(1: string arg),
  list<i8>  echoList(1: list<i8> arg),
  set<i8>  echoSet(1: set<i8> arg),
  map<i8, i8>  echoMap(1: map<i8, i8> arg),
}

二、使用thrift -r --gen cpp StressTest.thrift 生成代碼
gen-cpp目錄有

StressTest_types.h StressTest_types.cpp StressTest_constants.h StressTest_constants.cpp Service.h Service.cpp Service_server.skeleton.cpp

生成
StressTest_types.h StressTest_constants.h 爲相關類型定義文件
Service_server.skeleton爲服務端須要的實現文件

三、代碼實現
服務端:

#include <thrift/concurrency/ThreadManager.h>
#include <thrift/concurrency/PlatformThreadFactory.h>
#include <thrift/concurrency/Thread.h>
#include <thrift/protocol/TBinaryProtocol.h>
#include <thrift/server/TSimpleServer.h>
#include <thrift/server/TNonblockingServer.h>
#include <thrift/transport/TServerSocket.h>
#include <thrift/transport/TNonblockingServerSocket.h>
#include <thrift/transport/TNonblockingServerTransport.h>
#include <thrift/transport/TBufferTransports.h>
#include "Service.h"
using namespace ::apache::thrift;
using namespace ::apache::thrift::protocol;
using namespace ::apache::thrift::transport;
using namespace ::apache::thrift::server;
using namespace  ::test::stress;
class ServiceHandler : virtual public ServiceIf {
 public:
  ServiceHandler() {
  }
  void echoVoid() {
    // Your implementation goes here
    printf("echoVoid\n");
  }
  int8_t echoByte(const int8_t arg) {
    printf("echoByte %c\n", arg);
    return arg;
  }
  int32_t echoI32(const int32_t arg) {
    printf("echoI32\n");
    return arg;
  }
  int64_t echoI64(const int64_t arg) {
    printf("echoI64\n");
    return arg;
  }
  void echoString(std::string& _return, const std::string& arg) {
    printf("echoString\n");
  }
  void echoList(std::vector<int8_t> & _return, const std::vector<int8_t> & arg) {
    printf("echoList\n");
  }
  void echoSet(std::set<int8_t> & _return, const std::set<int8_t> & arg) {
    printf("echoSet\n");
  }
  void echoMap(std::map<int8_t, int8_t> & _return, const std::map<int8_t, int8_t> & arg) {
    printf("echoMap\n");
  }
};

int main(int argc, char **argv) {
  int port = 9090;
  stdcxx::shared_ptr<ServiceHandler> handler(new ServiceHandler());
  stdcxx::shared_ptr<TProcessor> processor(new ServiceProcessor(handler));
  stdcxx::shared_ptr<TProtocolFactory> protocolFactory(new TBinaryProtocolFactory());
  stdcxx::shared_ptr<TNonblockingServerTransport> serverTransport(new TNonblockingServerSocket(port));
  stdcxx::shared_ptr<PlatformThreadFactory> threadFactory = std::shared_ptr<PlatformThreadFactory>(new PlatformThreadFactory());
  stdcxx::shared_ptr<ThreadManager> threadManager = ThreadManager::newSimpleThreadManager(10);

  threadManager->threadFactory(threadFactory);
  threadManager->start();

  stdcxx::shared_ptr<TNonblockingServer> server(new TNonblockingServer(processor, protocolFactory, serverTransport, threadManager));

  server->serve();
  
  return 0;
}

咱們須要實現ServiceHandler繼承ServiceIf的相關接口，ServiceHandler是負責相關rpc調用業務的功能實現，
thrift服務器模型基本模型有四種、SimpleServer ThreadedServer ThreadPoolServer NoBlockingServer
SimpleServer 簡單的單線程模型
ThreadedServer 一個線程一個鏈接
ThreadPoolServer 線程池
NoBlockingServer 基於libevent的IO複用模型 libevent在linux平臺是基於epoll的reactor模型
還有一個異步Server模型TEvhttpServer 基於libevent的evhttp
這裏服務端使用了非阻塞epoll實現的thrift服務端模型

客戶端:

#include <iostream>
#include <string>
#include <thrift/transport/TTransportUtils.h>
#include <thrift/transport/TSocket.h>
#include <thrift/protocol/TBinaryProtocol.h>
#include "Service.h"

using namespace  ::test::stress;
using namespace apache::thrift;
using namespace apache::thrift::protocol;
using namespace apache::thrift::transport;

int main()
{
    ::apache::thrift::stdcxx::shared_ptr<TSocket> socket(new TSocket("localhost", 9090));
    ::apache::thrift::stdcxx::shared_ptr<TTransport> transport(new TFramedTransport(socket));
    ::apache::thrift::stdcxx::shared_ptr<TProtocol> protocol(new TBinaryProtocol(transport));
    ServiceClient client(protocol);
    transport->open();
    std::cout << "client echoByte byte=" << client.echoByte('A') << std::endl;
    std::cout << "send_echoByte('B')" << std::endl;
    client.send_echoByte('B');
    std::cout << "send_echoByte('C')" << std::endl;
    client.send_echoByte('C');
    std::cout << "recv_echoByte()" << client.recv_echoByte() << std::endl;
    std::cout << "recv_echoByte()" << client.recv_echoByte() << std::endl;
    transport->close();
    return 0;
}

客戶端使用則比較簡單，Service.h定義了相關接口，ServiceClient則是rpc客戶類
TTransport new TFramedTransport(socket) 這裏建立基於socket的傳輸層
TProtocol 協議層，序列化後的數據存儲方式，這裏以TBinaryProtocol 二進制存儲

6、thrift異步調用

一、thrift文件同同步調用一致
二、使用thrift --gen cpp:cob_style StressTest.thrift 生成代碼

StressTest_types.h StressTest_types.cpp StressTest_constants.h StressTest_constants.cpp Service.h Service.cpp Service_server.skeleton.cpp Service_async_server.skeleton.cpp

Service_server.skeleton.cpp 同步代碼用不到
Service_async_server.skeleton.cpp則爲http的異步實現
服務端：

#include <thrift/protocol/TBinaryProtocol.h>
#include <thrift/async/TAsyncProtocolProcessor.h>
#include <thrift/async/TEvhttpServer.h>
#include <event.h>
#include <evhttp.h>
#include <iostream>
#include "Service.h"

using namespace ::apache::thrift;
using namespace ::apache::thrift::protocol;
using namespace ::apache::thrift::transport;
using namespace ::apache::thrift::async;

using namespace  ::test::stress;

class ServiceHandler : virtual public ServiceIf {
public:
    ServiceHandler() {
    }

    void echoVoid() {
        printf("echoVoid\n");
    }

    int8_t echoByte(const int8_t arg) {
        printf("echoByte %c\n", arg);
        return arg;
    }

    int32_t echoI32(const int32_t arg) {
        printf("echoI32\n");
        return arg;
    }

    int64_t echoI64(const int64_t arg) {
        printf("echoI64\n");
        return arg;
    }

    void echoString(std::string& _return, const std::string& arg) {
        printf("echoString %s\n", arg.c_str());
        _return = arg;
    }

    void echoList(std::vector<int8_t> & _return, const std::vector<int8_t> & arg) {
        printf("echoList\n");
    }

    void echoSet(std::set<int8_t> & _return, const std::set<int8_t> & arg) {
        printf("echoSet\n");
    }

    void echoMap(std::map<int8_t, int8_t> & _return, const std::map<int8_t, int8_t> & arg) {
        printf("echoMap\n");
    }

};

class ServiceAsyncHandler : public ServiceCobSvIf {
 public:
  ServiceAsyncHandler() {
    syncHandler_ = std::auto_ptr<ServiceHandler>(new ServiceHandler);
    // Your initialization goes here
  }
  virtual ~ServiceAsyncHandler(){}

  void echoVoid(::apache::thrift::stdcxx::function<void()> cob) {
    syncHandler_->echoVoid();
    return cob();
  }

  void echoByte(::apache::thrift::stdcxx::function<void(int8_t const& _return)> cob, const int8_t arg) {
    int8_t _return = 0;
    _return = syncHandler_->echoByte(arg);
    return cob(_return);
  }

  void echoI32(::apache::thrift::stdcxx::function<void(int32_t const& _return)> cob, const int32_t arg) {
    int32_t _return = 0;
    _return = syncHandler_->echoI32(arg);
    return cob(_return);
  }

  void echoI64(::apache::thrift::stdcxx::function<void(int64_t const& _return)> cob, const int64_t arg) {
    int64_t _return = 0;
    _return = syncHandler_->echoI64(arg);
    return cob(_return);
  }

  void echoString(::apache::thrift::stdcxx::function<void(std::string const& _return)> cob, const std::string& arg) {
    std::string _return;
    syncHandler_->echoString(_return, arg);
    return cob(_return);
  }

  void echoList(::apache::thrift::stdcxx::function<void(std::vector<int8_t>  const& _return)> cob, const std::vector<int8_t> & arg) {
    std::vector<int8_t>  _return;
    syncHandler_->echoList(_return, arg);
    return cob(_return);
  }

  void echoSet(::apache::thrift::stdcxx::function<void(std::set<int8_t>  const& _return)> cob, const std::set<int8_t> & arg) {
    std::set<int8_t>  _return;
    syncHandler_->echoSet(_return, arg);
    return cob(_return);
  }

  void echoMap(::apache::thrift::stdcxx::function<void(std::map<int8_t, int8_t>  const& _return)> cob, const std::map<int8_t, int8_t> & arg) {
    std::map<int8_t, int8_t>  _return;
    syncHandler_->echoMap(_return, arg);
    return cob(_return);
  }
  
 protected:
  std::auto_ptr<ServiceHandler> syncHandler_;
};

int main()
{
    ::apache::thrift::stdcxx::shared_ptr<ServiceAsyncProcessor> asynProcessor(new ServiceAsyncProcessor(
                            ::apache::thrift::stdcxx::shared_ptr<ServiceCobSvIf>(new ServiceAsyncHandler())));

    ::apache::thrift::stdcxx::shared_ptr<TAsyncProtocolProcessor> asynProtocolProcessor(new TAsyncProtocolProcessor(asynProcessor,
                            ::apache::thrift::stdcxx::shared_ptr<TProtocolFactory>(new TBinaryProtocolFactory())));

    TEvhttpServer server(asynProtocolProcessor, 9999);
    server.serve();
    
    return 0;
}

這裏實現ServiceHandler的相關業務接口便可實現rpc服務端的相關功能

客戶端：

#include "Service.h"
#include <string>
#include <iostream>
#include <unistd.h>
#include <thrift/concurrency/ThreadManager.h>
#include <thrift/concurrency/PlatformThreadFactory.h>
#include <thrift/concurrency/Thread.h>
#include <thrift/async/TAsyncChannel.h>
#include <thrift/async/TEvhttpClientChannel.h>
#include <thrift/transport/TSocket.h>
#include <thrift/transport/TTransportUtils.h>
#include <thrift/transport/TBufferTransports.h>
#include <thrift/protocol/TBinaryProtocol.h>
#include <thrift/protocol/TProtocol.h>
#include <event.h>

using namespace  ::apache::thrift;
using namespace  ::apache::thrift::transport;
using namespace  ::apache::thrift::protocol;
using namespace  ::apache::thrift::async;
using namespace  ::apache::thrift::concurrency;
using namespace  ::test::stress;

class MyClient : public ServiceCobClient
{
public:
    MyClient(stdcxx::shared_ptr<TAsyncChannel> channel, TProtocolFactory* protocolFactory)
        : ServiceCobClient(channel, protocolFactory)
    {

    }
    virtual ~MyClient(){}

    virtual void completed__(bool success)
    {
        if (success)
        {
            std::cout << "completed" << std::endl;
        }
        else
        {
            std::cout << "completed failed" << std::endl;
        }
    }

    void my_send_byte()
    {
        std::cout << "begin my_send_byte" << std::endl;
        stdcxx::function<void(ServiceCobClient*)> cob = stdcxx::bind(&MyClient::recv_byte_callback, this, stdcxx::placeholders::_1);
        echoByte(cob, 'A');
        std::cout << "end my_send_byte" << std::endl;
    }

    void my_send_string()
    {
        std::cout << "begin my_send_string" << std::endl;
        stdcxx::function<void(ServiceCobClient*)> cob = stdcxx::bind(&MyClient::recv_string_callback, this, stdcxx::placeholders::_1);
        echoString(cob, "test asynclient");
        std::cout << "end my_send_string" << std::endl;
    }

    void recv_byte_callback(ServiceCobClient* client)
    {
        std::cout << "recv_byte_callback" << std::endl;
        _res_byte = recv_echoByte();
        std::cout << "_res_byte =" << _res_byte << std::endl;
    }

    void recv_string_callback(ServiceCobClient* client)
    {
        std::cout << "recv_string_callback" << std::endl;
        recv_echoString(_res_string);
        std::cout << "_res_string=" << _res_string << std::endl;
    }
private:
    char _res_byte;
    std::string _res_string;
};

class ClientThread : public Runnable
{
public:
    ClientThread(event_base* base, std::string & host, int port)
        : _base(base), _host(host), _port(port)
    {
    }
    virtual ~ClientThread(){}
    virtual void run()
    {
        stdcxx::shared_ptr<TAsyncChannel>  channel1(new TEvhttpClientChannel(_host, "/", _host.c_str(), _port, _base));
        stdcxx::shared_ptr<TAsyncChannel>  channel2(new TEvhttpClientChannel(_host, "/", _host.c_str(), _port, _base));

        MyClient client1(channel1, new TBinaryProtocolFactory());
        MyClient client2(channel2, new TBinaryProtocolFactory());

        client1.my_send_byte();
        client1.my_send_string();

        client2.my_send_byte();
        client2.my_send_string();

        while (1)
        {
            client1.my_send_byte();
            sleep(1);
        }
    }
protected:
private:
    event_base* _base;
    std::string _host;
    int _port;
};

int main()
{
    std::string host = "192.168.119.129";
    int port = 9999;

    event_base* base = event_base_new();

    stdcxx::shared_ptr<PlatformThreadFactory> threadFactory = std::shared_ptr<PlatformThreadFactory>(new PlatformThreadFactory());
    stdcxx::shared_ptr<ThreadManager> threadManager = ThreadManager::newSimpleThreadManager(10);

    threadManager->threadFactory(threadFactory);
    threadManager->start();

    stdcxx::shared_ptr<Thread> thread = threadFactory->newThread(std::shared_ptr<ClientThread>(new ClientThread(base, host, port)));
    thread->start();

    event_base_dispatch(base);
    event_base_free(base);

    return 0;
}

客戶端則實現了MyClient，MyClient繼承公共的rpc服務接口，提供了異步回調的recv_byte_callback，recv_string_callback函數， ClientThread的線程函數的實現則對MyClient異步客戶端進了測試

7、簡單總結

經過這兩天的學習，簡單總結一下這個庫
一、thrift的C++代碼實現很漂亮，很規範，適合學習閱讀
二、thrift能夠知足不少基本的rpc調用場景
三、本文只是簡單寫了thrift的用法，想深刻了解這個庫的，其內部實現仍是須要花時間好好研究

做者 [@karllen][3] 2018 年 09月 15日 QQ羣: 347769318