C++Linux进阶项目分析-仿写Redis之Qedis

为什么要学这个项目

传统的webserver已经烂大街了，只有一个webserver项目大概率是找不到工作的，今天给大家分享一个C++Linux进阶项目-仿写Redis之Qedis，Redis是C++ Linux开发必备的核心知识，通过学习Qedis开源项目，不仅可以深入理解redis，也更能提升自己的编程能力，比如C++11任意函数作为任务的线程池，Reactor网络模型的C++封装，时间轮定时器，Redis数据结构的实现等。

视频讲解：C++Linux进阶项目分析-仿写Redis之Qedis

1.项目介绍

Qedis网上很多编译方式是错误的。

C++后台开发偏基础服务，比如分布式存储相关的岗位，基本上都是使用c++。

校招的时候如果想从事分布式存储相关的岗位，则需要深入掌握MySQL/Redis，而且即使不是做分布式存储，C++后台开发也是必须掌握Redis，所以建议大家可以参考Qedis项目仿写Redis，这样和其他人写webserver就有区分度。

Qedis 是一个基于 C++11 实现的 Redis 服务器，支持集群功能，并使用 LevelDB 作为持久化存储。该项目旨在提供一个高性能、可扩展的内存数据库解决方案，适用于需要快速数据访问和处理的应用场景。

Qedis 可以广泛应用于需要高性能数据存储和访问的场景，例如：

• 实时数据分析：Qedis 的高性能和低延迟特性使其成为实时数据分析的理想选择。
• 缓存系统：Qedis 可以作为缓存层，加速应用程序的数据访问速度。
• 消息队列：结合 Redis 的发布/订阅功能，Qedis 可以用于构建高效的消息队列系统

2 项目快速启动

确保系统已安装 C++11 编译器。

2.1 安装 LevelDB 库

2.1.0 leveldb介绍

LevelDB是一种快速的键-值存储库，由Google开发，用于提供高性能的数据持久性存储。它通常被用作支持各种应用程序的底层数据库引擎，包括分布式数据库、区块链、分布式文件系统等。

2.1.1 下载Level

git clone https://gitclone.com/github.com/google/leveldb

2.1.2 下载编译leveldb需要的googletest、benchmark

1、进入下载好的leveldb

cd leveldb

2、进入third_party目录

cd third_party

3、下载

git clone https://gitclone.com/github.com/google/googletest
git clone https://gitclone.com/github.com/google/benchmark

2.1.3 编译安装

回到leveldb目录

cd ../
mkdir build && cd build
# 步骤4: 使用CMake生成构建文件，这里以Debug模式为例
cmake -DCMAKE_BUILD_TYPE=Debug -DBUILD_SHARED_LIBS=1 ..
make
sudo make install

2.1.4 刷新环境

sudo ldconfig

2.1.5 c++测试范例

测试leveldb，文件名为hello.cc，内容如下所示：

#include <assert.h>
#include <string.h>
#include <leveldb/db.h>
#include <iostream>
using namespace leveldb;

int main(){
    leveldb::DB* db;
    leveldb::Options options;
    options.create_if_missing = true;

// 打开一个数据库，不存在就创建
    leveldb::Status status = leveldb::DB::Open(options, "/tmp/testdb", &db);
    assert(status.ok());

// 插入一个键值对
    status = db->Put(leveldb::WriteOptions(), "hello", "LevelDB");
    assert(status.ok());

// 读取键值对
   std::string value;
   status = db->Get(leveldb::ReadOptions(), "hello", &value);

   assert(status.ok());
   std::cout << value << std::endl;

   delete db;
    return 0;
}

编译代码：

g++ hello.cc -o hello -lpthread -lleveldb

执行程序：

./hello

显示：

LevelDB

2.2 下载和编译Qedis

git clone https://github.com/loveyacper/Qedis.git
cd Qedis

mkdir build
cd build
# 以debug模式编译目的是为了方便后续debug源码
cmake -DCMAKE_BUILD_TYPE=Debug ..
make

编译后的执行文件在Qedis/bin目录，所以需要切换目录：

lqf@ubuntu:~/long/Qedis/build$ cd ../bin/

2.3 启动Qedis和测试

需要确保之前已经安装过redis，因为测试我们需要redis-cli，但redis-server不要启动。

2.3.1 默认方式启动Qedis

lqf@ubuntu:~/long/Qedis/bin$ ./qedis_server 

打印：

  _____     _____   _____   _   _____ 
 /  _  \   | ____| |  _  \ | | /  ___/
 | | | |   | |__   | | | | | | | |___    Qedis(1.0.0) 64 bits, another redis written in C++11
 | | | |   |  __|  | | | | | | \___  \   Port: 6379
 | |_| |_  | |___  | |_| | | |  ___| |   Author: Bert Young
 \_______| |_____| |_____/ |_| /_____/   https://github.com/loveyacper/Qedis
​
​
start log thread
2024-11-27[14:49:20.419][USR]:Success: listen on (127.0.0.1:6379)

通过redis-cli控制台进行测试：

# 启动redis-cli控制台
lqf@ubuntu:~/long/Qedis/bin$ redis-cli 
# 设置key
127.0.0.1:6379> set key qedis
OK
# 获取key，测试正常
127.0.0.1:6379> get key
"qedis"
127.0.0.1:6379> 

2.3.2 通过配置文件启动Qedis

如果需要使用leveldb做持久化，需要修改配置文件Qedis/qedis.conf ，将backend 设置为1：

然后重新启动qedis_server，注意你配置文件路径

./qedis_server ~/long/Qedis/qedis.conf

打印：

Load libqedismodule.dylib failed because runtime error Load libnotexist.dylib failed because runtime error

/ _ \ | | | _ \ | | / ___/ | | | | | |__ | | | | | | | |___ Qedis(1.0.0) 64 bits, another redis written in C++11 | | | | | | | | | | | | _ \ Port: 6379 | || | | |_ | |_| | | | _| | Author: Bert Young ___| |_| |_/ |_| /_/ https://github.com/loveyacper/Qedis start log thread 2024-11-2818:32:21.938:Success: listen on (127.0.0.1:6379) 2024-11-2818:32:21.946:Open leveldb dump0 2024-11-2818:32:21.951:Open leveldb dump1 2024-11-2818:32:21.957:Open leveldb dump2 2024-11-2818:32:21.961:Open leveldb dump3 2024-11-2818:32:21.967:Open leveldb dump4 2024-11-2818:32:21.971:Open leveldb dump5 2024-11-2818:32:21.976:Open leveldb dump6 2024-11-2818:32:21.980:Open leveldb dump7 2024-11-2818:32:21.984:Open leveldb dump8 2024-11-2818:32:21.989:Open leveldb dump9 2024-11-2818:32:21.994:Open leveldb dump10 2024-11-2818:32:21.999:Open leveldb dump11 2024-11-2818:32:22.004:Open leveldb dump12 2024-11-2818:32:22.009:Open leveldb dump13 2024-11-2818:32:22.014:Open leveldb dump14 2024-11-2818:32:22.019:Open leveldb dump15

3 如何仿写redis

1. 熟悉redis原理，但这个不是说一定要每行代码都看懂，推荐书籍：《Redis设计与实现》
2. 熟悉leveldb，也是不说一定要每行代码看懂，主要是先理解下leveldb如何使用，我这里有整理的leveldb相关的资料，大家可以加薇laoliao6668获取。
3. 熟悉Qedis源码，参考Qedis仿写redis，前期可以先照抄Qedis源码都可以，我这里主要梳理Qedis的流程。

4 Qedis框架流程

这里是服务器开源项目调试的经典流程，不只局限于qedis源码。

4.0 通过gdb启动服务程序

我们通过gdb的方式启动qedis_server

gdb ./qedis_server 

如果需要设置配置文件，则在gdb启动后，这样就能加载配置文件

(gdb) set args ../qedis.conf 

4.1 main函数在哪个文件

4.1.1 获取main函数所在源文件位置

在main函数打断点：

(gdb) b main
Breakpoint 1 at 0x5f60:file/home/lqf/long/Qedis/QedisSvr/Qedis.cc, line 447.

这样能快速定位main函数所在的文件，结合vscode，点击

自动跳转到main函数，是不是非常方便。

这里我们没有提供配置文件参数，默认是前台运行，前台运行更方便debug

4.1.2 r运行程序

我们输入r先运行到main函数再打其他断点，输入r然后回车：

Breakpoint 1 at 0x5f60: file /home/lqf/long/Qedis/QedisSvr/Qedis.cc, line 447.
(gdb) r
Starting program: /home/lqf/long/Qedis/bin/qedis_server 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
​
Breakpoint 1, main (ac=1, av=0x7fffffffe038) at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:447
447     {
(gdb) 

接下来我们就要根据tcp 服务的套路打断点：

4.2 qedis服务框架

设置断点

所有的tcp服务器都遵循

函数：

• bind
• listen
• accept
• epoll_wait
• epoll_ctl
• 发送 send或者write，不同的项目可能用的函数不一样，先断点send
• 接收recv或者read，不同的项目可能用的函数不一样，先断点recv

(gdb) b bind
Breakpoint 2 at 0x7ffff7b71380: file ../sysdeps/unix/syscall-template.S, line 78.
(gdb) b listen
Breakpoint 3 at 0x7ffff7b714e0: file ../sysdeps/unix/syscall-template.S, line 78.
(gdb) b accept
Breakpoint 4 at 0x7ffff798e4b0: accept. (2 locations)
(gdb) b epoll_wait
Breakpoint 5 at 0x7ffff7b70630: file ../sysdeps/unix/sysv/linux/epoll_wait.c, line 28.    
(gdb) b epoll_ctl
Breakpoint 6 at 0x7ffff7b70d10: file ../sysdeps/unix/syscall-template.S, line 78.
(gdb) b send
Breakpoint 7 at 0x7ffff798e770: send. (2 locations)
(gdb) b recv
Breakpoint 8 at 0x7ffff798e5f0: recv. (2 locations)

bind和listen查看调用栈

打好断点后，我们输入c继续运行程序：

Thread 1 "qedis_server" hit Breakpoint 2, bind () at ../sysdeps/unix/syscall-template.S:78
78      ../sysdeps/unix/syscall-template.S: No such file or directory.

通过查看堆栈的方式：

#0  bind () at ../sysdeps/unix/syscall-template.S:78
#1  0x00007ffff7f11289 in Internal::ListenSocket::Bind (this=this@entry=0x5555555759a0, addr=...)
    at /home/lqf/long/Qedis/QBase/ListenSocket.cc:48
#2  0x00007ffff7f1935a in Server::TCPBind (this=<optimized out>, addr=..., tag=1)
    at /home/lqf/long/Qedis/QBase/Server.cc:57
#3  0x000055555555a64e in Qedis::_Init (this=0x7fffffffde10) at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:290
#4  0x00007ffff7f18924 in Server::MainLoop (this=0x7fffffffde10, daemon=<optimized out>)
    at /home/lqf/long/Qedis/QBase/Server.cc:128
#5  0x0000555555559fc5 in main (ac=1, av=0x7fffffffe038) at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:464

可以清晰看到服务程序如何bind和listen

listen同理也是使用bt查看堆栈，

从这里63行也可以看出来这里是封装了NetThreadPool 网络线程池，查看源码是支持：

• recvThread_接收线程；
• sendThread_发送线程。

class NetThreadPool
{
    std::shared_ptr<RecvThread> recvThread_;
    std::shared_ptr<SendThread> sendThread_;
    ....
}

接收数据相关：

RecvThread::Run()

发送数据相关：

SendThread::Run( )

继续运行触发epoll_ctl

#0  epoll_ctl () at ../sysdeps/unix/syscall-template.S:78
#1  0x00007ffff7f10880 in Epoll::AddSocket (epfd=<optimized out>, socket=socket@entry=5, events=events@entry=1, 
    ptr=ptr@entry=0x5555555759a0) at /home/lqf/long/Qedis/QBase/EPoller.cc:28
#2  0x00007ffff7f108d1 in Epoller::AddSocket (this=0x555555573f50, sock=5, events=1, userPtr=0x5555555759a0)
    at /home/lqf/long/Qedis/QBase/EPoller.cc:75
#3  0x00007ffff7f118a8 in Internal::NetThread::_AddSocket (this=this@entry=0x555555573c20, 
    task=std::shared_ptr<Socket> (use count 2, weak count 1) = {...}, events=<optimized out>)
    at /home/lqf/long/Qedis/QBase/NetThreadPool.cc:73
#4  0x00007ffff7f126f5 in Internal::NetThread::_TryAddNewTasks (this=0x555555573c20)
    at /home/lqf/long/Qedis/QBase/NetThreadPool.cc:67
#5  0x00007ffff7f13348 in Internal::RecvThread::Run (this=0x555555573c20)
    at /home/lqf/long/Qedis/QBase/NetThreadPool.cc:93

从堆栈可以看出来此时是把当前的fd加入到epoll处理，我们也看看

Qedis/QBase/NetThreadPool.cc

void NetThread::_TryAddNewTasks()
{
    if (newCnt_ > 0 && mutex_.try_lock())
    { 
        NewTasks  tmp;
        newTasks_.swap(tmp);   //newTasks_是任务队列，可以跟踪下 是在哪里push任务
        newCnt_ = 0; 
        mutex_.unlock();
​
        auto iter(tmp.begin()),
             end (tmp.end());
​
        for (; iter != end; ++ iter) 
            _AddSocket(iter->first, iter->second); 
    }
}

当前文件搜索newTasks_关键字可以找到NetThread::AddSocket，可以增加断点NetThread::AddSocket

void NetThread::AddSocket(PSOCKET task, uint32_t events)
{
    std::lock_guard<std::mutex>    guard(mutex_);
    newTasks_.push_back(std::make_pair(task, events)); 
    ++ newCnt_;
​
    assert (newCnt_ == static_cast<int>(newTasks_.size()));
}

把socket任务加入到对应的线程进行处理，比如SendThread::Run函数里调用tcpSock->Send()发送数据给客户端。需要源码的朋友可以加薇laoliao6668获取

继续运行触发epoll_wait的调用

Thread 3 "qedis_server" hit Breakpoint 5, epoll_wait (epfd=3, events=0x5555555759f0, maxevents=maxevents@entry=1, 
    timeout=timeout@entry=1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:28
28      ../sysdeps/unix/sysv/linux/epoll_wait.c: No such file or directory.
(gdb) bt
#0  epoll_wait (epfd=3, events=0x5555555759f0, maxevents=maxevents@entry=1, timeout=timeout@entry=1)
    at ../sysdeps/unix/sysv/linux/epoll_wait.c:28
#1  0x00007ffff7f10c3a in Epoller::Poll (timeoutMs=<optimized out>, maxEvent=<optimized out>, events=..., 
    this=<optimized out>) at /usr/include/c++/10/bits/stl_vector.h:1043
#2  Epoller::Poll (this=0x555555573f50, events=std::vector of length 0, capacity 0, maxEvent=1, timeoutMs=1)
    at /home/lqf/long/Qedis/QBase/EPoller.cc:99
#3  0x00007ffff7f1339d in Internal::RecvThread::Run (this=0x555555573c20)

此时可以清晰看到RecvThread::Run 就是epoll_wait所在的线程。这里注意tasks_表示的是class Socket ，后续线程池获取到这个Socket再调用对应的函数做处理

void RecvThread::Run()
{
    // init log;
    g_logLevel = logALL;
    g_logDest  = logFILE;
    if (g_logLevel && g_logDest)
    {
        g_log = LogManager::Instance().CreateLog(g_logLevel, g_logDest, "recvthread_log");
    }

    std::deque<PSOCKET >::iterator it;

    int loopCount = 0;
    while (IsAlive())
    {
        _TryAddNewTasks();

        if (tasks_.empty())
        {
            std::this_thread::sleep_for(std::chrono::microseconds(100));
            continue;
        }

        const int nReady = poller_->Poll(firedEvents_, static_cast<int>(tasks_.size()), 1);
        for (int i = 0; i < nReady; ++ i)
        {
            assert (!(firedEvents_[i].events & EventTypeWrite));

            Socket* sock = (Socket* )firedEvents_[i].userdata;

            if (firedEvents_[i].events & EventTypeRead)     
            {
                if (!sock->OnReadable()) //处理新连接
                {
                    sock->OnError();
                }
            }

            if (firedEvents_[i].events & EventTypeError)
            {
                sock->OnError();
            }
        }
        
        if (nReady == 0)
            loopCount *= 2;
        
        if (++ loopCount < 100000)
            continue;

        loopCount = 0;

        for (auto it(tasks_.begin());       //遍历任务，判断socket任务是不是有效的
             it != tasks_.end();
             )
        {
            if ((*it)->Invalid())
            {
                NetThreadPool::Instance().DisableRead(*it); //禁止读事件
                RemoveSocket(*it, EventTypeRead);   //从epoll 移除socket fd
                it = tasks_.erase(it);      //如果是无效的从任务队列中移除
            }
            else
            {
                ++ it;
            }
        }
    }
}

知道epoll_wait在哪个线程后，可以先停止该函数的断点 。

然后继续运行，此时如果客户端不发消息，此时没有函数触发。

发送线程和接收线程是独立的。

redis-cli连接qedis触发accept

#0  __libc_accept (fd=5, addr=addr@entry=..., len=len@entry=0x7ffff7024b54) at ../sysdeps/unix/sysv/linux/accept.c:24
#1  0x00007ffff7f11591 in Internal::ListenSocket::_Accept (this=this@entry=0x5555555759a0)
    at /home/lqf/long/Qedis/QBase/ListenSocket.cc:78
#2  0x00007ffff7f115de in Internal::ListenSocket::OnReadable (this=0x5555555759a0)
    at /home/lqf/long/Qedis/QBase/ListenSocket.cc:85
#3  0x00007ffff7f133d3 in Internal::RecvThread::Run (this=0x555555573c20)
    at /home/lqf/long/Qedis/QBase/NetThreadPool.cc:110

即是：

bool ListenSocket::OnReadable()
{
    while (true)
    {
        int connfd = _Accept();
        if (connfd >= 0)
        {  //创建对象绑定新连接
            Server::Instance()->NewConnection(connfd, tag_);
        }

void Server::NewConnection(int sock, int tag, const std::function<void ()>& cb)
{
    if (sock == INVALID_SOCKET)
        return;
​
    auto conn = _OnNewConnection(sock, tag);
    
    if (!conn)
    {
        Socket::CloseSocket(sock);
        return;
    }
​
    conn->SetOnDisconnect(cb);
​
    if (NetThreadPool::Instance().AddSocket(conn, EventTypeRead | EventTypeWrite))  //先连接 加入可读 可写事件
        tasks_.AddTask(conn);  //加到队列
}

QBase/Server.cc代码需要花时间研究。重点函数：

erver::_RunLogic()

在哪里被调用，可以断点

并重点查看StreamSocket.h的class StreamSocket

分析哪里接收的客户端数据

recv函数没有触发，那要断点read，或者readv

StreamSocket::Recv()调用了readv

int StreamSocket::Recv()
{
    if (recvBuf_.Capacity() == 0)
    {
        recvBuf_.InitCapacity(64 * 1024); // First recv data, allocate buffer
    }
    
    BufferSequence  buffers;
    recvBuf_.GetSpace(buffers);
    if (buffers.count == 0)
    {
        WRN << "Recv buffer is full";
        return 0;
    }
​
    int ret = static_cast<int>(::readv(localSock_, buffers.buffers, static_cast<int>(buffers.count)));
    if (ret == ERRORSOCKET && (EAGAIN == errno || EWOULDBLOCK == errno))
        return 0;
​
    if (ret > 0)
        recvBuf_.AdjustWritePtr(ret);
​
    return (0 == ret) ? EOFSOCKET : ret;
}

，所以需要断点：StreamSocket::Recv

断点触发情况：

Thread 3 "qedis_server" hit Breakpoint 11, StreamSocket::Recv (this=this@entry=0x7ffff0001820)
    at /home/lqf/long/Qedis/QBase/StreamSocket.cc:46
46      {
(gdb) bt
#0  StreamSocket::Recv (this=this@entry=0x7ffff0001820) at /home/lqf/long/Qedis/QBase/StreamSocket.cc:46
#1  0x00007ffff7f1b0b4 in StreamSocket::OnReadable (this=0x7ffff0001820) at /home/lqf/long/Qedis/QBase/StreamSocket.cc:122
#2  0x00007ffff7f133d3 in Internal::RecvThread::Run (this=0x555555573c20)
    at /home/lqf/long/Qedis/QBase/NetThreadPool.cc:110

StreamSocket::Recv读取到的数据由StreamSocket::DoMsgParse函数处理，所以也要断点

#0  StreamSocket::DoMsgParse (this=0x7ffff0001820) at /home/lqf/long/Qedis/QBase/StreamSocket.cc:219
#1  0x00007ffff7f1cafb in Internal::TaskManager::DoMsgParse (this=0x7fffffffde20)
    at /home/lqf/long/Qedis/QBase/TaskManager.cc:99
#2  0x00007ffff7f18ace in Server::MainLoop (this=0x7fffffffde10, daemon=<optimized out>)
    at /home/lqf/long/Qedis/QBase/Server.cc:139
#3  0x0000555555559fc5 in main (ac=1, av=0x7fffffffe038) at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:464

可以看到是在main函数处理 redis的协议

StreamSocket::DoMsgParse

后续请继续跟踪：

QMigrateClient::_HandlePacket

分析哪里发送的客户端数据

send函数没有触发，那要断点write，或者writev

通过搜索源码找到

StreamSocket::_Send调用了writev

int StreamSocket::_Send(const BufferSequence& bf)
{
    auto  total = bf.TotalBytes();
    if (total == 0)
        return 0;
​
    int ret = static_cast<int>(::writev(localSock_, bf.buffers, static_cast<int>(bf.count)));
    if (ERRORSOCKET == ret && (EAGAIN == errno || EWOULDBLOCK == errno))
    {
        epollOut_ = true;
        ret = 0;
    }
    else if (ret > 0 && static_cast<size_t>(ret) < total)
    {
        epollOut_ = true;
    }
    else if (static_cast<size_t>(ret) == total)
    {
        epollOut_ = false;
    }
​
    return ret;
}

所以需要断点StreamSocket::_Send

#0  StreamSocket::_Send (this=this@entry=0x7ffff0001820, bf=...) at /home/lqf/long/Qedis/QBase/StreamSocket.cc:72
#1  0x00007ffff7f1a900 in StreamSocket::Send (this=this@entry=0x7ffff0001820)
    at /home/lqf/long/Qedis/QBase/StreamSocket.cc:148
#2  0x00007ffff7f1395c in Internal::SendThread::Run (this=0x555555573f80)

需要源码的朋友可以加薇laoliao6668获取

5 默认启动的线程

5.1 主线程

Thread 1 "qedis_server" received signal SIGINT, Interrupt.
0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7fffffffdd20, rem=rem@entry=0x7fffffffdd20) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
78      in ../sysdeps/unix/sysv/linux/clock_nanosleep.c
(gdb) thread 1
[Switching to thread 1 (Thread 0x7ffff7827780 (LWP 11433))]
#0  0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7fffffffdd20, rem=rem@entry=0x7fffffffdd20) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
78      in ../sysdeps/unix/sysv/linux/clock_nanosleep.c
(gdb) bt
#0  0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7fffffffdd20, rem=rem@entry=0x7fffffffdd20) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
#1  0x00007ffff7b33ec7 in __GI___nanosleep (requested_time=requested_time@entry=0x7fffffffdd20, 
    remaining=remaining@entry=0x7fffffffdd20) at nanosleep.c:27
#2  0x00007ffff7f18b15 in std::this_thread::sleep_for<long, std::ratio<1l, 1000000l> > (__rtime=..., __rtime=...)
    at /usr/include/c++/10/thread:401
#3  Server::MainLoop (this=0x7fffffffde10, daemon=<optimized out>) at /home/lqf/long/Qedis/QBase/Server.cc:140
#4  0x0000555555559fc5 in main (ac=1, av=0x7fffffffe038) at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:464

5.2 监控线程ThreadPool::_MonitorRoutine()

(gdb) thread 2
[Switching to thread 2 (Thread 0x7ffff7826700 (LWP 11775))]
#0  0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7ffff7825e20, rem=rem@entry=0x7ffff7825e20) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
78      in ../sysdeps/unix/sysv/linux/clock_nanosleep.c
(gdb) bt
#0  0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7ffff7825e20, rem=rem@entry=0x7ffff7825e20) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
#1  0x00007ffff7b33ec7 in __GI___nanosleep (requested_time=requested_time@entry=0x7ffff7825e20, 
    remaining=remaining@entry=0x7ffff7825e20) at nanosleep.c:27
#2  0x00007ffff7f2348d in std::this_thread::sleep_for<long, std::ratio<1l, 1l> > (__rtime=..., __rtime=...)
    at /usr/include/c++/10/thread:401
#3  ThreadPool::_MonitorRoutine (this=0x7ffff7f33600 <ThreadPool::Instance()::pool>)
    at /home/lqf/long/Qedis/QBase/Threads/ThreadPool.cc:94
#4  0x00007ffff7d4e793 in ?? () from /lib/x86_64-linux-gnu/libstdc++.so.6
#5  0x00007ffff7983609 in start_thread (arg=<optimized out>) at pthread_create.c:477
#6  0x00007ffff7b70353 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

5.3 发送线程SendThread::Run

其实这里是运行在线程池创建的线程里，但一直独占了线程池的一个线程。

(gdb) thread 3
[Switching to thread 3 (Thread 0x7ffff7025700 (LWP 11776))]
#0  0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7ffff7024c20, rem=rem@entry=0x7ffff7024c20) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
78      in ../sysdeps/unix/sysv/linux/clock_nanosleep.c
(gdb) bt
#0  0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7ffff7024c20, rem=rem@entry=0x7ffff7024c20) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
#1  0x00007ffff7b33ec7 in __GI___nanosleep (requested_time=requested_time@entry=0x7ffff7024c20, 
    remaining=remaining@entry=0x7ffff7024c20) at nanosleep.c:27
#2  0x00007ffff7f13a61 in std::this_thread::sleep_for<long, std::ratio<1l, 1000000l> > (__rtime=..., __rtime=...)
    at /usr/include/c++/10/thread:401
#3  Internal::SendThread::Run (this=0x555555573f80) at /home/lqf/long/Qedis/QBase/NetThreadPool.cc:194
。。。。。。
#27 ThreadPool::_WorkerRoutine (this=0x7ffff7f33600 <ThreadPool::Instance()::pool>)
    at /home/lqf/long/Qedis/QBase/Threads/ThreadPool.cc:83

5.4 接收线程RecvThread::Run

其实这里是运行在线程池创建的线程里，但一直独占了线程池的一个线程。

(gdb) thread 4
[Switching to thread 4 (Thread 0x7ffff6824700 (LWP 11777))]
#0  0x00007ffff7b7068e in epoll_wait (epfd=3, events=0x5555555759f0, maxevents=maxevents@entry=1, timeout=timeout@entry=1)
    at ../sysdeps/unix/sysv/linux/epoll_wait.c:30
30      ../sysdeps/unix/sysv/linux/epoll_wait.c: No such file or directory.
(gdb) bt
#0  0x00007ffff7b7068e in epoll_wait (epfd=3, events=0x5555555759f0, maxevents=maxevents@entry=1, timeout=timeout@entry=1)
    at ../sysdeps/unix/sysv/linux/epoll_wait.c:30
#1  0x00007ffff7f10c3a in Epoller::Poll (timeoutMs=<optimized out>, maxEvent=<optimized out>, events=..., 
    this=<optimized out>) at /usr/include/c++/10/bits/stl_vector.h:1043
#2  Epoller::Poll (this=0x555555573f50, events=std::vector of length 0, capacity 0, maxEvent=1, timeoutMs=1)
    at /home/lqf/long/Qedis/QBase/EPoller.cc:99
#3  0x00007ffff7f1339d in Internal::RecvThread::Run (this=0x555555573c20)
    at /home/lqf/long/Qedis/QBase/NetThreadPool.cc:101
。。。
    
#25 std::__future_base::_Task_state<std::_Bind<std::_Bind<void (Internal::RecvThread::*(std::shared_ptr<Internal::RecvThread>))()> ()>, std::allocator<int>, void ()>::_M_run() (this=0x555555574960) at /usr/include/c++/10/future:1459
#26 0x00007ffff7f2322a in std::function<void ()>::operator()() const (this=0x7ffff6823e10)
    at /usr/include/c++/10/bits/std_function.h:622
#27 ThreadPool::_WorkerRoutine (this=0x7ffff7f33600 <ThreadPool::Instance()::pool>)
    at /home/lqf/long/Qedis/QBase/Threads/ThreadPool.cc:83    

可以看到，发送/接收线程，其实都是线程池分配的线程运行的。

线程：

void   ThreadPool::_CreateWorker()
{
    std::thread  t([this]() { this->_WorkerRoutine(); } );
    workers_.push_back(std::move(t));
}

5.5 持久化线程AOFThread::Run

其实这里是运行在线程池创建的线程里，但一直独占了线程池的一个线程。

(gdb) thread 5
[Switching to thread 5 (Thread 0x7ffff5d7e700 (LWP 11778))]
#0  0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7ffff5d7daf0, rem=rem@entry=0x7ffff5d7daf0) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
78      ../sysdeps/unix/sysv/linux/clock_nanosleep.c: No such file or directory.
(gdb) bt
#0  0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7ffff5d7daf0, rem=rem@entry=0x7ffff5d7daf0) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
#1  0x00007ffff7b33ec7 in __GI___nanosleep (requested_time=requested_time@entry=0x7ffff5d7daf0, 
    remaining=remaining@entry=0x7ffff5d7daf0) at nanosleep.c:27
#2  0x00007ffff7f64db1 in std::this_thread::sleep_for<long, std::ratio<1l, 1000l> > (__rtime=..., __rtime=...)
    at /usr/include/c++/10/thread:401
#3  qedis::QAOFThreadController::AOFThread::Run (this=0x55555558c920) at /home/lqf/long/Qedis/QedisCore/QAOF.cc:167
#4  0x00007ffff7f66b53 in std::__invoke_impl<void, void (qedis::QAOFThreadController::AOFThread::*&)(), std::shared_ptr<qedis::QAOFThreadController::AOFThread>&> (__f=<optimized out>, __f=<optimized out>, __t=...)
    at /usr/include/c++/10/bits/invoke.h:73
#5  std::__invoke<void (qedis::QAOFThreadController::AOFThread::*&)(), std::shared_ptr<qedis::QAOFThreadController::AOFThread>&> (__fn=<optimized out>) at /usr/include/c++/10/bits/invoke.h:95
#6  std::_Bind<void (qedis::QAOFThreadController::AOFThread::*(std::shared_ptr<qedis::QAOFThreadController::AOFThread>))()>::__call<void, , 0ul>(std::tuple<>&&, std::_Index_tuple<0ul>) (__args=..., this=<optimized out>)
    at /usr/include/c++/10/functional:416
。。。。。。。
#31 0x00007ffff7f2322a in std::function<void ()>::operator()() const (this=0x7ffff5d7de10)
    at /usr/include/c++/10/bits/std_function.h:622
#32 ThreadPool::_WorkerRoutine (this=0x7ffff7f33600 <ThreadPool::Instance()::pool>)
    at /home/lqf/long/Qedis/QBase/Threads/ThreadPool.cc:83

5.6 日志线程LogThread::Run

其实这里是运行在线程池创建的线程里，但一直独占了线程池的一个线程。

(gdb) thread 6
[Switching to thread 6 (Thread 0x7ffff557d700 (LWP 11779))]
#0  0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7ffff557cc30, rem=rem@entry=0x7ffff557cc30) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
78      in ../sysdeps/unix/sysv/linux/clock_nanosleep.c
(gdb) bt
#0  0x00007ffff7b2e23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, 
    req=req@entry=0x7ffff557cc30, rem=rem@entry=0x7ffff557cc30) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
#1  0x00007ffff7b33ec7 in __GI___nanosleep (requested_time=requested_time@entry=0x7ffff557cc30, 
    remaining=remaining@entry=0x7ffff557cc30) at nanosleep.c:27
#2  0x00007ffff7f208fd in std::this_thread::sleep_for<long, std::ratio<1l, 1000l> > (__rtime=..., __rtime=...)
    at /usr/include/c++/10/thread:401
#3  LogManager::LogThread::Run (this=0x555555573320) at /home/lqf/long/Qedis/QBase/Log/Logger.cc:662
#4  0x00007ffff7f20dc3 in std::__invoke_impl<void, void (LogManager::LogThread::*&)(), std::shared_ptr<LogManager::LogThread>&> (__f=<optimized out>, __f=<optimized out>, __t=...) at /usr/include/c++/10/bits/invoke.h:73
#5  std::__invoke<void (LogManager::LogThread::*&)(), std::shared_ptr<LogManager::LogThread>&> (__fn=<optimized out>)
    at /usr/include/c++/10/bits/invoke.h:95
#6  std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))()>::__call<void, , 0ul>(std::tuple<>&&, std::_Index_tuple<0ul>) (__args=..., this=<optimized out>) at /usr/include/c++/10/functional:416
#7  std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))()>::operator()<, void>() (
    this=<optimized out>) at /usr/include/c++/10/functional:499
#8  std::__invoke_impl<void, std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))()>&>(std::__invoke_other, std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))()>&) (__f=...)
    at /usr/include/c++/10/bits/invoke.h:60
#9  std::__invoke<std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))()>&>(std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))()>&) (__fn=...) at /usr/include/c++/10/bits/invoke.h:95
#10 std::_Bind<std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))()> ()>::__call<void>(std::tuple<>&&, std::_Index_tuple<>) (__args=..., this=<optimized out>) at /usr/include/c++/10/functional:416
#11 std::_Bind<std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))()> ()>::operator()<, void>() (this=<optimized out>) at /usr/include/c++/10/functional:499
#12 std::__invoke_impl<void, std::_Bind<std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))
​
。。。。
#30 std::_Function_handler<void (), ThreadPool::ExecuteTask<std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))()>>(std::_Bind<void (LogManager::LogThread::*(std::shared_ptr<LogManager::LogThread>))()>&&)::{lambda()#1}>::_M_invoke(std::_Any_data const&) (__functor=...) at /usr/include/c++/10/bits/std_function.h:291
#31 0x00007ffff7f2322a in std::function<void ()>::operator()() const (this=0x7ffff557ce10)
    at /usr/include/c++/10/bits/std_function.h:622
#32 ThreadPool::_WorkerRoutine (this=0x7ffff7f33600 <ThreadPool::Instance()::pool>)
--Type <RET> for more, q to quit, c to continue without paging--
    at /home/lqf/long/Qedis/QBase/Threads/ThreadPool.cc:83

6 命令执行操作level-db

操作leveldb

redis命令和leveldb封装映射

#0  qedis::QCommandTable::AliasCommand (aliases=std::map with 0 elements)
    at /home/lqf/long/Qedis/QedisCore/QCommand.cc:208
#1  0x000055555555a6f1 in Qedis::_Init (this=0x7fffffffde10)
    at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:297
#2  0x00007ffff7f18924 in Server::MainLoop (this=0x7fffffffde10, daemon=<optimized out>)
    at /home/lqf/long/Qedis/QBase/Server.cc:128
#3  0x0000555555559fc5 in main (ac=1, av=0x7fffffffe038)
    at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:464

初始化db

#0  0x0000555555559930 in qedis::QStore::Init(int)@plt ()
#1  0x000055555555a704 in Qedis::_Init (this=0x7fffffffde10)
    at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:298
#2  0x00007ffff7f18924 in Server::MainLoop (this=0x7fffffffde10, daemon=<optimized out>)
    at /home/lqf/long/Qedis/QBase/Server.cc:128
#3  0x0000555555559fc5 in main (ac=1, av=0x7fffffffe038)
    at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:464

my_hash作用

Thread 1 "qedis_server" hit Breakpoint 6, qedis::dictGenHashFunction (key=0x55555558d710, len=4)
    at /home/lqf/long/Qedis/QedisCore/QHelper.cc:26
26      unsigned int dictGenHashFunction(const void* key, int len) {
(gdb) bt
#0  qedis::dictGenHashFunction (key=0x55555558d710, len=4) at /home/lqf/long/Qedis/QedisCore/QHelper.cc:26
#1  0x00007ffff7f7b206 in qedis::my_hash::operator() (this=this@entry=0x555555578a90, str="key2")
    at /home/lqf/long/Qedis/QedisCore/QHelper.cc:71

        at /usr/include/c++/10/bits/unordered_map.h:985
#5  qedis::QStore::SetValue (this=this@entry=0x7ffff7fc66c0 <qedis::QStore::Instance()::store>, key="key2", 
    value=...) at /home/lqf/long/Qedis/QedisCore/QStore.cc:612
#6  0x00007ffff7fa4488 in qedis::SetValue (key="key2", value="d", exclusive=<optimized out>)
    at /home/lqf/long/Qedis/QedisCore/QString.cc:82
#7  0x00007ffff7fa4a7a in qedis::set (params=..., reply=0x7ffff0001730)
    at /home/lqf/long/Qedis/QedisCore/QString.cc:89
#8  0x00007ffff7f69e45 in qedis::QClient::_HandlePacket (this=0x7ffff00015c0, 
    start=0x7ffff0011960 "*3\r\n$3\r\nset\r\n$4\r\nkey2\r\n$1\r\nd\r\n", bytes=<optimized out>)
    at /home/lqf/long/Qedis/QedisCore/QClient.h:48
#9  0x00007ffff7f1a680 in StreamSocket::DoMsgParse (this=0x7ffff00015c0)
--Type <RET> for more, q to quit, c to continue without paging--
    at /home/lqf/long/Qedis/QBase/StreamSocket.cc:227
#10 0x00007ffff7f1cafb in Internal::TaskManager::DoMsgParse (this=0x7fffffffde20)
    at /home/lqf/long/Qedis/QBase/TaskManager.cc:99
#11 0x00007ffff7f18ace in Server::MainLoop (this=this@entry=0x7fffffffde10, daemon=<optimized out>)
    at /home/lqf/long/Qedis/QBase/Server.cc:139
#12 0x0000555555559fc5 in main (ac=1, av=0x7fffffffe038) at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:464

设置hash的目的是什么？为什么这里要抽象一层出来？这里貌似是如果不需要持久化存储时，就不用到leveldb

什么时候才会初始化 leveldb

需要配置文件开启持久化才行

#0  qedis::QStore::InitDumpBackends (this=0x7ffff7fc66c0 <qedis::QStore::Instance()::store>)
    at /home/lqf/long/Qedis/QedisCore/QStore.cc:787
#1  0x000055555555a738 in Qedis::_Init (this=0x7fffffffe410) at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:302
#2  0x00007ffff7f18924 in Server::MainLoop (this=0x7fffffffe410, daemon=<optimized out>)
    at /home/lqf/long/Qedis/QBase/Server.cc:128
#3  0x0000555555559fc5 in main (ac=2, av=0x7fffffffe638) at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:464

void QStore::InitDumpBackends()
{
    assert (waitSyncKeys_.empty());
​
    if (g_config.backend == BackEndNone) //默认是不需要持久化
        return;
​
    if (g_config.backend == BackEndLeveldb)
    {
        waitSyncKeys_.resize(store_.size());
        for (size_t i = 0; i < store_.size(); ++ i)
        {
            std::unique_ptr<QLeveldb> db(new QLeveldb);
            QString dbpath = g_config.backendPath + std::to_string(i);
            if (!db->Open(dbpath.data()))
                assert(false);
            else
                USR << "Open leveldb " << dbpath;
​
            backends_.push_back(std::move(db));
        }
    }
    else 
    {
        // ERROR: unsupport backend
        return;
    }
        
    for (int i = 0; i < static_cast<int>(backends_.size()); ++ i)
    {
        auto timer = TimerManager::Instance().CreateTimer();
        timer->Init(1000 / g_config.backendHz);
        timer->SetCallback([&, i] () {
                int oldDb = QSTORE.SelectDB(i);
                QSTORE.DumpToBackends(i);
                QSTORE.SelectDB(oldDb);
        });
​
        TimerManager::Instance().AddTimer(timer);
    }
}

如何持久化

通过定时器定时刷新

(gdb) bt
#0  qedis::QLeveldb::Put (this=0x55555558cec0, key="key", obj=..., absttl=-1)
    at /home/lqf/long/Qedis/QedisCore/QLeveldb.cc:74
#1  0x00007ffff7f9f665 in qedis::QStore::DumpToBackends (
    this=0x7ffff7fc66c0 <qedis::QStore::Instance()::store>, dbno=<optimized out>)
    at /home/lqf/long/Qedis/QedisCore/QStore.cc:850
#2  0x00007ffff7f9f8dd in operator() (__closure=0x5555556dcc30)
    at /home/lqf/long/Qedis/QedisCore/QStore.cc:820
#3  std::__invoke_impl<void, const qedis::QStore::InitDumpBackends()::<lambda()>&> (__f=...)
    at /usr/include/c++/10/bits/invoke.h:60
#4  std::__invoke<const qedis::QStore::InitDumpBackends()::<lambda()>&> (__fn=...)
    at /usr/include/c++/10/bits/invoke.h:95
#5  std::_Bind<qedis::QStore::InitDumpBackends()::<lambda()>()>::__call_c<void> (__args=..., 
    this=0x5555556dcc30) at /usr/include/c++/10/functional:427
#6  std::_Bind<qedis::QStore::InitDumpBackends()::<lambda()>()>::operator()<> (this=0x5555556dcc30)
    at /usr/include/c++/10/functional:511
#7  operator() (this=0x5555556dcc30) at /home/lqf/long/Qedis/QBase/Timer.h:61
#8  std::__invoke_impl<void, Timer::SetCallback<qedis::QStore::InitDumpBackends()::<lambda()>, {}>::<lambda()>&> (__f=...) at /usr/include/c++/10/bits/invoke.h:60
#9  std::__invoke_r<void, Timer::SetCallback<qedis::QStore::InitDumpBackends()::<lambda()>, {}>::<lambda()>&>
    (__fn=...) at /usr/include/c++/10/bits/invoke.h:153
#10 std::_Function_handler<void(), Timer::SetCallback<qedis::QStore::InitDumpBackends()::<lambda()>, {}>::<lambda()> >::_M_invoke(const std::_Any_data &) (__functor=...) at /usr/include/c++/10/bits/std_function.h:291
#11 0x00007ffff7f1d7ca in std::function<void ()>::operator()() const (this=0x5555556dcc30)
    at /usr/include/c++/10/bits/std_function.h:622
#12 Timer::OnTimer (this=0x5555556dcc30) at /home/lqf/long/Qedis/QBase/Timer.cc:201
#13 Timer::OnTimer (this=0x5555556dcc30) at /home/lqf/long/Qedis/QBase/Timer.cc:193
--Type <RET> for more, q to quit, c to continue without paging--
#14 0x00007ffff7f1e181 in TimerManager::UpdateTimers (this=0x7ffff7f31a60 <TimerManager::Instance()::mgr>, 
    now=...) at /home/lqf/long/Qedis/QBase/Timer.cc:330
#15 0x000055555555b7c3 in Qedis::_RunLogic (this=0x7fffffffdde0)
    at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:431
#16 0x00007ffff7f18ace in Server::MainLoop (this=0x7fffffffdde0, daemon=<optimized out>)
    at /home/lqf/long/Qedis/QBase/Server.cc:139
#17 0x0000555555559fc5 in main (ac=2, av=0x7fffffffe008) at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:464

持久化最终由 QStore::DumpToBackends函数负责，不管是删除还是添加。需要源码的朋友可以加薇laoliao6668获取

哪个线程执行具体的k-v操作

是主线程执行k-v操作

断点

b ExecuteCmd

然后redis-cli执行set get命令操作

(gdb) bt
#0  qedis::QCommandTable::ExecuteCmd (params=std::vector of length 3, capacity 4 = {...}, 
    info=0x7ffff7fc4d90 <qedis::QCommandTable::s_info+1872>, reply=0x7ffff0001730)
    at /home/lqf/long/Qedis/QedisCore/QCommand.cc:249
#1  0x00007ffff7f69e45 in qedis::QClient::_HandlePacket (this=0x7ffff00015c0, 
    start=0x7ffff00119a4 "*3\r\n$3\r\nset\r\n$3\r\nkey\r\n$1\r\nd\r\n", 
    bytes=<optimized out>) at /home/lqf/long/Qedis/QedisCore/QClient.h:48
#2  0x00007ffff7f1a680 in StreamSocket::DoMsgParse (this=0x7ffff00015c0)
    at /home/lqf/long/Qedis/QBase/StreamSocket.cc:227
#3  0x00007ffff7f1cafb in Internal::TaskManager::DoMsgParse (this=0x7fffffffde20)
    at /home/lqf/long/Qedis/QBase/TaskManager.cc:99
#4  0x00007ffff7f18ace in Server::MainLoop (this=0x7fffffffde10, daemon=<optimized out>)
    at /home/lqf/long/Qedis/QBase/Server.cc:139
#5  0x0000555555559fc5 in main (ac=1, av=0x7fffffffe038)
    at /home/lqf/long/Qedis/QedisSvr/Qedis.cc:464

QError QCommandTable::ExecuteCmd(const std::vector<QString>& params, const QCommandInfo* info, UnboundedBuffer* reply)
{
    if (params.empty())
    {
        ReplyError(QError_param, reply);
        return QError_param;
    }
​
    if (!info)
    {
        ReplyError(QError_unknowCmd, reply);
        return QError_unknowCmd;
    }
​
    if (!info->CheckParamsCount(static_cast<int>(params.size())))
    {
        ReplyError(QError_param, reply);
        return QError_param;
    }
​
    return info->handler(params, reply);    //执行这里，看看进入哪个函数
}

set get是是字符串操作，触发QedisCore/QString.cc相关函数的调用

QError set(const std::vector<QString>& params, UnboundedBuffer* reply)
{
    SetValue(params[1], params[2]); //存储kv
    FormatOK(reply);
    return QError_ok;
}

k-v设置都是在主线程处理？

具体操作levedb的封装

QedisCore/QLeveldb.h

QedisCore/QLeveldb.cc

断点

QLeveldb::Put

7 性能测试

需要注意的是这个Qedis项目，新版本的redis-benchmark并不支持，是下载的redis 3.2的版本，我也把源码包一起打包了。

./redis-benchmark -t set,get -n 1000000 -c 1

刚开始时，性能比较差，所以使用tcpdump 分析客户端的请求和响应

sudo tcpdump -A -i lo host 127.0.0.1 and port 6379

10:59:39.162891 IP localhost.55876 > localhost.6379: Flags [P.], seq 13951:13996, ack 1551, win 512, options [nop,nop,TS val 3294051496 ecr 3294051496], length 45: RESP "SET" "key:rand_int" "xxx" E..a.6@.@._^.........D....}..........U..... .W<..W<.*3 $3 SET $16 key:rand_int $3 xxx 10:59:39.192597 29毫秒才收到回复 IP localhost.6379 > localhost.55876: Flags [P.], seq 1551:1556, ack 13996, win 16384, options [nop,nop,TS val 3294051526 ecr 3294051496], length 5: RESP "OK" E..9F.@.@..............D......~...@..-..... .W<..W<.+OK <font style="color:#DF2A3F;"></font> 10:59:39.192741 0.14毫秒又继续发送请求了 IP localhost.55876 > localhost.6379: Flags [P.], seq 13996:14041, ack 1556, win 512, options [nop,nop,TS val 3294051526 ecr 3294051526], length 45: RESP "SET" "key:rand_int" "xxx" E..a.7@.@._].........D....~..........U..... .W<..W<.*3 $3 SET $16 key:rand_int $3 xxx 10:59:39.207409 IP 14.6毫秒才收到回复，localhost.6379 > localhost.55876: Flags [P.], seq 1556:1561, ack 14041, win 16384, options [nop,nop,TS val 3294051541 ecr 3294051526], length 5: RESP "OK" E..9F.@.@..............D......~9..@..-..... .W<..W<.+OK 10:59:39.207589 0.18毫秒又继续发送请求了 IP localhost.55876 > localhost.6379: Flags [P.], seq 14041:14086, ack 1561, win 512, options [nop,nop,TS val 3294051541 ecr 3294051541], length 45: RESP "SET" "key:rand_int" "xxx" E..a.8@.@._.........D....~9.........U..... .W<..W<.*3 $3 SET $16 key:rand_int $3 xxx 10:59:39.222298 14.8毫秒才收到回复 IP localhost.6379 > localhost.55876: Flags [P.], seq 1561:1566, ack 14086, win 16384, options [nop,nop,TS val 3294051555 ecr 3294051541], length 5: RESP "OK" E..9F.@.@..............D......~f..@..-..... .W<..W<.+OK 10:59:39.222530 IP localhost.55876 > localhost.6379: Flags [P.], seq 14086:14131, ack 1566, win 512, options [nop,nop,TS val 3294051556 ecr 3294051555], length 45: RESP "SET" "key:rand_int" "xxx" E..a.9@.@._[.........D....~f.........U..... .W<..W<.*3 $3 SET $16 key:rand_int $3 xxx 10:59:39.230025 IP localhost.55876 > localhost.6379: Flags [F.], seq 14131, ack 1566, win 512, options [nop,nop,TS val 3294051563 ecr 3294051555], length 0 E..4.:@.@._..........D....~..........(..... .W<..W<. 10:59:39.237170 IP localhost.6379 > localhost.55876: Flags [P.], seq 1566:1571, ack 14132, win 16384, options [nop,nop,TS val 3294051570 ecr 3294051556], length 5: RESP "OK" E..9F.@.@..............D......~...@..-..... .W<..W<.+OK 10:59:39.237296 IP localhost.55876 > localhost.6379: Flags [R], seq 2914614932, win 0, length 0 E..(..@.@.<..........D....~.....P....`..

./redis-benchmark -t set,get -n 1000000 -c 1 -P 100

pipe line模式，性能有提升到1万qps，但此模式下redis-server能到50万qps

E...m.@.@............H..k.r....p..O........
.T8..T8.*3
$3
SET
$16
key:__rand_int__
$3
xxx
*3
$3
SET
$16

其他参数，参考redis-benchmark的使用。