struct RequestOrResponse {
    RequestResponseHeader requestResponseHeader; // uint32 messageLength;
    SpecificRequestOrResponseHeader body; // 格式取决于具体的请求和响应，比如：RequestV1Header
}

struct RequestV1Header {
  int16 apiKey;
  int16 apiVersion;
  int32 correlationId;
  string clientId;
}

kubectl apply -f https://raw.githubusercontent.com/FoundationDB/fdb-kubernetes-operator/main/config/crd/bases/apps.foundationdb.org_foundationdbclusters.yaml
kubectl apply -f https://raw.githubusercontent.com/FoundationDB/fdb-kubernetes-operator/main/config/crd/bases/apps.foundationdb.org_foundationdbbackups.yaml
kubectl apply -f https://raw.githubusercontent.com/FoundationDB/fdb-kubernetes-operator/main/config/crd/bases/apps.foundationdb.org_foundationdbrestores.yaml

wget https://raw.githubusercontent.com/apache/doris-operator/master/config/operator/fdb-operator.yaml
kubectl apply -f fdb-operator.yaml

wget https://raw.githubusercontent.com/foundationdb/fdb-kubernetes-operator/main/config/samples/cluster.yaml -O fdb-cluster.yaml
kubectl apply -f fdb-cluster.yaml

# 查看集群状态
kubectl get fdb

# 预期输出（启动需要时间，需要等待几分钟）
NAME           GENERATION   RECONCILED   AVAILABLE   FULLREPLICATION   VERSION   AGE
test-cluster   1            1            true        true              7.1.26    3m30s

kubectl create -f https://raw.githubusercontent.com/apache/doris-operator/master/config/crd/bases/crds.yaml

wget https://raw.githubusercontent.com/apache/doris-operator/master/config/operator/disaggregated-operator.yaml -O disaggregated-operator.yaml
kubectl apply -f disaggregated-operator.yaml

# 查看部署状态
kubectl get pod -n doris

# 预期输出
NAME                              READY   STATUS    RESTARTS   AGE
doris-operator-5fd65d8d69-rgqlk   1/1     Running   0          79s

wget https://raw.githubusercontent.com/apache/doris-operator/master/doc/examples/disaggregated/cluster/ddc-sample.yaml -O ddc-sample.yaml

# 启动 3 个 standalone 模式的 ShardingSphere Proxy
                                          +-------+
                                          |  LB   |
                                          +-------+
                                              |
                                |-------------|--------------|
                                |             |              |
                            +-------+     +-------+       +-------+
                            | Node1 |     | Node2 |       | Node3 |
                            +-------+     +-------+       +-------+

$ pwd
/tmp/testconfig
$ ls -l
drwxr-xr-x  3 root root 4096 Oct 10 19:48 .
drwxr-xr-x 10 root root 4096 Oct 10 19:48 ..
drwxr-xr-x  1 root root   11 Oct 10 19:48 ..ver1
drwxr-xr-x  1 root root   11 Oct 10 19:48 ..ver2
lrwxr-xr-x  1 root root   11 Oct 10 19:48 ..data -> ..ver1
drwxr-xr-x  1 root root   11 Oct 10 19:48 data
$
$ ll -a data
drwxr-xr-x  3 root root 4096 Oct 10 19:48 .
drwxr-xr-x 10 root root 4096 Oct 10 19:48 ..
lrwxrwxrwx  1 root root   11 Oct 10 19:48 registry.yaml -> /tmp/testconfig/..data/registry.yaml

// redis-v7.2/src/eval.c#183

/* 初始化 lua 环境
 *
 * redis 首次启动时调用，此时 setup 为 1,
 * 这个函数也会在 redis 的其他生命周期中被调用，此时 setup 为 0，但是被简化为 scriptingReset 调用。
 */ 
void scriptingInit(int setup) {
    lua_State *lua = lua_open();

    if (setup) {
        // 首次启动时，初始化 lua 环境 和 ldb (Lua debugger) 的一些数据结构
        lctx.lua_client = NULL;
        server.script_disable_deny_script = 0;
        ldbInit();
    }

    /* 初始化 lua 脚本字典，用于存储 sha1 -> lua 脚本的映射
     * 用户使用 EVALSHA 命令时，从这个字典中查找对应的 lua 脚本。
     */
    lctx.lua_scripts = dictCreate(&shaScriptObjectDictType);
    lctx.lua_scripts_mem = 0;

    /* 注册 redis 的一些 api 到 lua 环境中 */
    luaRegisterRedisAPI(lua);

    /* 注册调试命令 */
    lua_getglobal(lua,"redis");

    /* redis.breakpoint */
    lua_pushstring(lua,"breakpoint");
    lua_pushcfunction(lua,luaRedisBreakpointCommand);
    lua_settable(lua, -3);
    /* redis.debug */
    lua_pushstring(lua,"debug");
    lua_pushcfunction(lua,luaRedisDebugCommand);
    lua_settable(lua,-3);
    /* redis.replicate_commands */
    lua_pushstring(lua, "replicate_commands");
    lua_pushcfunction(lua, luaRedisReplicateCommandsCommand);
    lua_settable(lua, -3);

    lua_setglobal(lua,"redis");

    /* 注册一个错误处理函数，用于在 lua 脚本执行出错时，打印出错信息。
     * 需要注意的是，当错误发生在 C 函数中时，我们需要打印出错的 lua 脚本的信息，
     * 这样才能帮助用户调试 lua 脚本。
     */
    {
        char *errh_func =       "local dbg = debug\n"
                                "debug = nil\n"
                                "function __redis__err__handler(err)\n"
                                "  local i = dbg.getinfo(2,'nSl')\n"
                                "  if i and i.what == 'C' then\n"
                                "    i = dbg.getinfo(3,'nSl')\n"
                                "  end\n"
                                "  if type(err) ~= 'table' then\n"
                                "    err = {err='ERR ' .. tostring(err)}"
                                "  end"
                                "  if i then\n"
                                "    err['source'] = i.source\n"
                                "    err['line'] = i.currentline\n"
                                "  end"
                                "  return err\n"
                                "end\n";
        luaL_loadbuffer(lua,errh_func,strlen(errh_func),"@err_handler_def");
        lua_pcall(lua,0,0,0);
    }

    /* 创建一个 lua client (没有网络连接)，用于在 lua 环境中执行 redis 命令。
     * 这个客户端没必要在 scriptingReset() 调用时重新创建。
     */
    if (lctx.lua_client == NULL) {
        lctx.lua_client = createClient(NULL);
        lctx.lua_client->flags |= CLIENT_SCRIPT;

        /* We do not want to allow blocking commands inside Lua */
        lctx.lua_client->flags |= CLIENT_DENY_BLOCKING;
    }

    /* Lock the global table from any changes */
    lua_pushvalue(lua, LUA_GLOBALSINDEX);
    luaSetErrorMetatable(lua);
    /* Recursively lock all tables that can be reached from the global table */
    luaSetTableProtectionRecursively(lua);
    lua_pop(lua, 1);

    lctx.lua = lua;
}

type gracefulTcpServer struct {
	listener     *net.TCPListener
	shutdownChan chan struct{}
	conns        map[net.Conn]struct{}

	servingConnCount atomic.Int32
	serveRunning     atomic.Bool
}


// 普通启动方式
func start(port int) (*gracefulTcpServer, error) {
	ln, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
    // handle error ignored

	s := &gracefulTcpServer{
		listener:         ln.(*net.TCPListener),
		shutdownChan:     make(chan struct{}, 1),
		conns:            make(map[net.Conn]struct{}, 16),
		servingConnCount: atomic.Int32{},
		serveRunning:     atomic.Bool{},
	}

	return s, nil
}

// 优雅重启启动方式
func startFromFork() (*gracefulTcpServer, error) {
    // ... ignored code

    // 从环境变量中获取 父进程的处理的连接数，用来恢复连接
	if nfdStr := os.Getenv(__GRACE_ENV_NFDS); nfdStr == "" {
		panic("not nfds env")
	} else if nfd, err = strconv.Atoi(nfdStr); err != nil {
		panic(err)
	}

	// restore conn fds, 0, 1, 2 has been used by os.Stdin, os.Stdout, os.Stderr
	lfd := os.NewFile(3, filepath.Join(tmpdir, "graceful"))
	ln, err := net.FileListener(lfd)
	// handle error ignored

	s := &gracefulTcpServer{
		listener:         ln.(*net.TCPListener),
		shutdownChan:     make(chan struct{}, 1),
		conns:            make(map[net.Conn]struct{}, 16),
		servingConnCount: atomic.Int32{},
		serveRunning:     atomic.Bool{},
	}

    // 从父进程继承的套接字中恢复连接
	for i := 0; i < nfd; i++ {
		fd := os.NewFile(uintptr(4+i), filepath.Join(tmpdir, strconv.Itoa(4+i)))
		conn, err := net.FileConn(fd)
		// handle error ignored
		go s.handleConn(conn)
	}

	return s, nil
}

func (s *gracefulTcpServer) gracefulRestart() {
	_ = s.listener.SetDeadline(time.Now())
	lfd, err := s.listener.File()

    // 给子进程设置 优雅重启 相关的环境变量
	os.Setenv(__GRACE_ENV_FLAG, "true")
	os.Setenv(__GRACE_ENV_NFDS, strconv.Itoa(len(s.conns)))

    // 将父进程的监听套接字传递给子进程
	files := make([]uintptr, 4, 3+1+len(s.conns))
	copy(files[:4], []uintptr{
		os.Stdin.Fd(),
		os.Stdout.Fd(),
		os.Stderr.Fd(),
		lfd.Fd(),
	})
    // 将父进程的套接字传递给子进程 
	for conn := range s.conns {
		connFd, _ := conn.(*net.TCPConn).File()
		files = append(files, connFd.Fd())
	}
	procAttr := &syscall.ProcAttr{
		Env:   os.Environ(),
		Files: files,
		Sys:   nil,
	}

    // 执行 fork + exec 调用
	childPid, err := syscall.ForkExec(os.Args[0], os.Args, procAttr)
}


func main() {
    // ...
    
    // 根据环境变量判断是 fork 还是新启动
	if v := os.Getenv(__GRACE_ENV_FLAG); v != "" {
		s, err = startFromFork()
	} else {
		s, err = start(*port)
	}

	go s.serve()

    // 处理信号，如果是 SIGHUP 信号，则执行 gracefulRestart 方法后再退出
	s.waitForSignals()
}

$ cloudflared -v
cloudflared version 2023.7.3 (built 2023-07-25T20:51:49Z)

$ cloudflared login