braft 完全指南：从零掌握分布式一致性编程

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# Ubuntu/Debian
sudo apt-get update
sudo apt-get install -y build-essential cmake git
sudo apt-get install -y libssl-dev libprotobuf-dev protobuf-compiler
sudo apt-get install -y libgflags-dev libgoogle-glog-dev

# 安装 brpc（braft 依赖）
git clone https://github.com/apache/brpc.git
cd brpc && mkdir build && cd build
cmake .. && make -j$(nproc) && sudo make install

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# 克隆源码
git clone https://github.com/baidu/braft.git
cd braft

# 编译
mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
make -j$(nproc)

# 安装
sudo make install

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#include <braft/raft.h>
#include <braft/util.h>
#include <braft/storage.h>

// 操作类型
enum OpType {
    OP_INCREMENT = 1,
    OP_DECREMENT = 2,
    OP_SET = 3
};

// 操作日志
struct CounterOp {
    OpType type;
    int64_t value;

    // 序列化
    std::string serialize() const {
        return std::to_string(type) + ":" + std::to_string(value);
    }

    // 反序列化
    static CounterOp deserialize(const std::string& data) {
        size_t pos = data.find(':');
        CounterOp op;
        op.type = static_cast<OpType>(std::stoi(data.substr(0, pos)));
        op.value = std::stoll(data.substr(pos + 1));
        return op;
    }
};

// 状态机实现
class CounterStateMachine : public braft::StateMachine {
public:
    CounterStateMachine() : _counter(0) {}

    // 应用日志到状态机
    void on_apply(braft::Iterator& iter) override {
        for (; iter.valid(); iter.next()) {
            braft::AsyncClosureGuard closure_guard(iter.done());

            if (iter.done()) {
                // 这是来自客户端的请求
                CounterOp op = CounterOp::deserialize(iter.data().to_string());
                int64_t old_value = _counter;

                switch (op.type) {
                    case OP_INCREMENT:
                        _counter += op.value;
                        break;
                    case OP_DECREMENT:
                        _counter -= op.value;
                        break;
                    case OP_SET:
                        _counter = op.value;
                        break;
                }

                LOG(INFO) << "Applied operation: " << op.serialize()
                         << ", counter: " << old_value << " -> " << _counter;

                // 返回结果给客户端
                if (iter.done()) {
                    static_cast<CounterClosure*>(iter.done())->set_result(_counter);
                }
            } else {
                // 这是从快照恢复或日志回放
                CounterOp op = CounterOp::deserialize(iter.data().to_string());
                switch (op.type) {
                    case OP_INCREMENT: _counter += op.value; break;
                    case OP_DECREMENT: _counter -= op.value; break;
                    case OP_SET: _counter = op.value; break;
                }
            }
        }
    }

    // 保存快照
    void on_snapshot_save(braft::SnapshotWriter* writer, braft::Closure* done) override {
        brpc::ClosureGuard done_guard(done);

        // 保存计数器值到快照
        std::string snapshot_path = writer->get_path() + "/counter";
        std::ofstream file(snapshot_path);
        if (!file.is_open()) {
            LOG(ERROR) << "Failed to open snapshot file: " << snapshot_path;
            done->status().set_error(EIO, "Failed to save snapshot");
            return;
        }

        file << _counter;
        file.close();

        // 添加文件到快照
        if (writer->add_file("counter") != 0) {
            LOG(ERROR) << "Failed to add file to snapshot";
            done->status().set_error(EIO, "Failed to add file to snapshot");
            return;
        }

        LOG(INFO) << "Saved snapshot with counter: " << _counter;
    }

    // 加载快照
    int on_snapshot_load(braft::SnapshotReader* reader) override {
        if (!reader->list_files().count("counter")) {
            LOG(ERROR) << "Counter file not found in snapshot";
            return -1;
        }

        std::string snapshot_path = reader->get_path() + "/counter";
        std::ifstream file(snapshot_path);
        if (!file.is_open()) {
            LOG(ERROR) << "Failed to open snapshot file: " << snapshot_path;
            return -1;
        }

        file >> _counter;
        file.close();

        LOG(INFO) << "Loaded snapshot with counter: " << _counter;
        return 0;
    }

    // 处理 Leader 变更
    void on_leader_start(int64_t term) override {
        LOG(INFO) << "Became leader at term: " << term;
    }

    void on_leader_stop(const butil::Status& status) override {
        LOG(INFO) << "Stepped down as leader: " << status;
    }

    // 获取当前计数器值
    int64_t get_counter() const { return _counter; }

private:
    int64_t _counter;
};

// 异步回调
class CounterClosure : public braft::Closure {
public:
    CounterClosure() : _result(0) {}

    void Run() override {
        if (status().ok()) {
            LOG(INFO) << "Operation succeeded, result: " << _result;
        } else {
            LOG(ERROR) << "Operation failed: " << status();
        }
        delete this;
    }

    void set_result(int64_t result) { _result = result; }
    int64_t get_result() const { return _result; }

private:
    int64_t _result;
};

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class CounterServer {
public:
    CounterServer() : _node(nullptr), _state_machine(new CounterStateMachine()) {}

    ~CounterServer() {
        if (_node) {
            _node->shutdown(nullptr);
            _node->join();
            delete _node;
        }
        delete _state_machine;
    }

    // 启动节点
    int start(const std::string& listen_addr,
              const std::string& raft_addr,
              const std::string& peers,
              const std::string& data_dir) {

        // 创建 RPC 服务器
        if (_server.Start(listen_addr.c_str(), nullptr) != 0) {
            LOG(ERROR) << "Failed to start RPC server";
            return -1;
        }

        // 配置 Raft 节点
        braft::NodeOptions node_options;

        // 设置状态机
        node_options.fsm = _state_machine;

        // 设置存储路径
        node_options.log_uri = data_dir + "/log";
        node_options.raft_meta_uri = data_dir + "/raft_meta";
        node_options.snapshot_uri = data_dir + "/snapshot";

        // 设置选举超时（毫秒）
        node_options.election_timeout_ms = 5000;

        // 设置快照间隔
        node_options.snapshot_interval_s = 30;

        // 禁用 CLI（命令行接口），生产环境中通常启用
        node_options.disable_cli = false;

        // 创建 Raft 节点
        _node = new braft::Node("counter_group", braft::PeerId(raft_addr));

        if (_node->init(node_options) != 0) {
            LOG(ERROR) << "Failed to init raft node";
            return -1;
        }

        // 如果指定了 peers，则作为集群成员启动
        if (!peers.empty()) {
            std::vector<braft::PeerId> peer_list;
            butil::StringSplitter sp(peers.c_str(), ',');
            for (; sp; ++sp) {
                braft::PeerId peer(sp.field(), sp.length());
                peer_list.push_back(peer);
            }

            braft::Configuration conf(peer_list);
            if (_node->bootstrap(conf) != 0) {
                LOG(ERROR) << "Failed to bootstrap raft node";
                return -1;
            }
        }

        LOG(INFO) << "Counter server started at " << listen_addr
                  << ", raft at " << raft_addr;
        return 0;
    }

    // 执行操作
    void execute_operation(const CounterOp& op, CounterClosure* closure) {
        if (!_node->is_leader()) {
            closure->status().set_error(EPERM, "Not leader");
            closure->Run();
            return;
        }

        // 构造日志条目
        butil::IOBuf log_data;
        log_data.append(op.serialize());

        // 提交到 Raft
        braft::Task task;
        task.data = &log_data;
        task.done = closure;

        _node->apply(task);
    }

    // 获取当前值（强一致性读）
    int64_t get_counter_consistent() {
        if (!_node->is_leader()) {
            return -1;  // 只有 Leader 才能提供强一致性读
        }

        // 通过 read_index 实现线性一致性读
        braft::ReadIndexClosure* read_closure =
            new braft::ReadIndexClosure([this](const braft::ReadIndexStatus& status) {
                if (status.status.ok()) {
                    // 读取状态机数据
                    return _state_machine->get_counter();
                }
                return (int64_t)-1;
            });

        _node->read_index(butil::IOBuf(), read_closure);
        // 注意：实际应用中需要等待回调完成
        return _state_machine->get_counter();
    }

    // 获取当前值（非强一致性读）
    int64_t get_counter_local() {
        return _state_machine->get_counter();
    }

    // 检查是否为 Leader
    bool is_leader() const {
        return _node && _node->is_leader();
    }

    // 获取 Leader 信息
    braft::PeerId get_leader() const {
        if (_node) {
            return _node->leader_id();
        }
        return braft::PeerId();
    }

private:
    brpc::Server _server;
    braft::Node* _node;
    CounterStateMachine* _state_machine;
};

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// 基于 brpc 的客户端
class CounterClient {
public:
    CounterClient() {}

    // 连接到服务器
    int connect(const std::string& server_addr) {
        brpc::ChannelOptions options;
        options.protocol = brpc::PROTOCOL_BAIDU_STD;
        options.timeout_ms = 1000;
        options.max_retry = 3;

        if (_channel.Init(server_addr.c_str(), &options) != 0) {
            LOG(ERROR) << "Failed to connect to " << server_addr;
            return -1;
        }

        return 0;
    }

    // 增加计数器
    bool increment(int64_t value) {
        CounterOp op{OP_INCREMENT, value};
        return execute_operation(op);
    }

    // 减少计数器
    bool decrement(int64_t value) {
        CounterOp op{OP_DECREMENT, value};
        return execute_operation(op);
    }

    // 设置计数器值
    bool set(int64_t value) {
        CounterOp op{OP_SET, value};
        return execute_operation(op);
    }

    // 获取计数器值
    int64_t get() {
        // 这里简化为直接调用服务端方法
        // 实际应用中需要通过 RPC 调用
        return 0;
    }

private:
    bool execute_operation(const CounterOp& op) {
        // 实际实现需要定义 protobuf 接口并通过 RPC 调用
        // 这里只是示例框架
        return true;
    }

private:
    brpc::Channel _channel;
};

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#include <iostream>
#include <signal.h>
#include <gflags/gflags.h>

DEFINE_string(listen_addr, "127.0.0.1:8080", "Listen address for RPC");
DEFINE_string(raft_addr, "127.0.0.1:8081", "Raft listen address");
DEFINE_string(peers, "", "Initial peers, separated by comma");
DEFINE_string(data_dir, "./data", "Data directory");

static CounterServer* g_server = nullptr;

void signal_handler(int sig) {
    if (g_server) {
        LOG(INFO) << "Received signal " << sig << ", shutting down...";
        delete g_server;
        g_server = nullptr;
        exit(0);
    }
}

int main(int argc, char* argv[]) {
    google::ParseCommandLineFlags(&argc, &argv, true);

    // 设置信号处理
    signal(SIGINT, signal_handler);
    signal(SIGTERM, signal_handler);

    // 创建数据目录
    if (system(("mkdir -p " + FLAGS_data_dir).c_str()) != 0) {
        LOG(ERROR) << "Failed to create data directory";
        return -1;
    }

    // 启动服务器
    g_server = new CounterServer();
    if (g_server->start(FLAGS_listen_addr, FLAGS_raft_addr,
                       FLAGS_peers, FLAGS_data_dir) != 0) {
        LOG(ERROR) << "Failed to start counter server";
        return -1;
    }

    // 等待用户输入
    std::string line;
    while (std::getline(std::cin, line)) {
        if (line == "quit" || line == "exit") {
            break;
        }

        if (line == "status") {
            std::cout << "Leader: " << g_server->is_leader() << std::endl;
            std::cout << "Counter: " << g_server->get_counter_local() << std::endl;
            std::cout << "Leader ID: " << g_server->get_leader() << std::endl;
        } else if (line.substr(0, 4) == "inc ") {
            int64_t value = std::stoll(line.substr(4));
            CounterClosure* closure = new CounterClosure();
            CounterOp op{OP_INCREMENT, value};
            g_server->execute_operation(op, closure);
        } else if (line.substr(0, 4) == "dec ") {
            int64_t value = std::stoll(line.substr(4));
            CounterClosure* closure = new CounterClosure();
            CounterOp op{OP_DECREMENT, value};
            g_server->execute_operation(op, closure);
        } else if (line.substr(0, 4) == "set ") {
            int64_t value = std::stoll(line.substr(4));
            CounterClosure* closure = new CounterClosure();
            CounterOp op{OP_SET, value};
            g_server->execute_operation(op, closure);
        } else {
            std::cout << "Commands: status, inc <value>, dec <value>, set <value>, quit" << std::endl;
        }
    }

    delete g_server;
    return 0;
}

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cmake_minimum_required(VERSION 3.10)
project(counter_example)

set(CMAKE_CXX_STANDARD 11)

find_package(PkgConfig REQUIRED)
find_package(Protobuf REQUIRED)
find_package(gflags REQUIRED)

# 查找 brpc 和 braft
find_library(BRPC_LIB brpc)
find_library(BRAFT_LIB braft)

add_executable(counter_server
    counter_server.cpp
)

target_link_libraries(counter_server
    ${BRAFT_LIB}
    ${BRPC_LIB}
    ${Protobuf_LIBRARIES}
    gflags
    ssl
    crypto
    dl
    z
)

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# 编译
mkdir build && cd build
cmake .. && make

# 启动第一个节点（作为引导节点）
./counter_server --listen_addr=127.0.0.1:8080 --raft_addr=127.0.0.1:8081 \
                 --peers=127.0.0.1:8081,127.0.0.1:8082,127.0.0.1:8083 \
                 --data_dir=./node1

# 启动第二个节点
./counter_server --listen_addr=127.0.0.1:8090 --raft_addr=127.0.0.1:8082 \
                 --data_dir=./node2

# 启动第三个节点
./counter_server --listen_addr=127.0.0.1:8100 --raft_addr=127.0.0.1:8083 \
                 --data_dir=./node3

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class StateMachine {
public:
    // 应用日志条目到状态机
    virtual void on_apply(braft::Iterator& iter) = 0;

    // 保存快照
    virtual void on_snapshot_save(braft::SnapshotWriter* writer,
                                 braft::Closure* done) = 0;

    // 加载快照
    virtual int on_snapshot_load(braft::SnapshotReader* reader) = 0;

    // Leader 选举成功回调
    virtual void on_leader_start(int64_t term) {}

    // Leader 退位回调
    virtual void on_leader_stop(const butil::Status& status) {}

    // 启动回调
    virtual void on_start_following(const braft::LeaderChangeContext& ctx) {}

    // 停止 following 回调
    virtual void on_stop_following(const braft::LeaderChangeContext& ctx) {}

    // 配置变更回调
    virtual void on_configuration_committed(const braft::Configuration& conf,
                                           int64_t index) {}

    // 错误回调
    virtual void on_error(const braft::Error& e) {}
};

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// 支持多种操作的键值存储状态机
class KVStateMachine : public braft::StateMachine {
public:
    enum Operation {
        OP_PUT = 1,
        OP_DELETE = 2,
        OP_CAS = 3  // Compare-And-Swap
    };

    struct LogEntry {
        Operation op;
        std::string key;
        std::string value;
        std::string expected_value;  // for CAS

        std::string serialize() const {
            butil::IOBuf buf;
            buf.append(reinterpret_cast<const char*>(&op), sizeof(op));

            uint32_t key_len = key.length();
            buf.append(reinterpret_cast<const char*>(&key_len), sizeof(key_len));
            buf.append(key);

            uint32_t value_len = value.length();
            buf.append(reinterpret_cast<const char*>(&value_len), sizeof(value_len));
            buf.append(value);

            if (op == OP_CAS) {
                uint32_t expected_len = expected_value.length();
                buf.append(reinterpret_cast<const char*>(&expected_len), sizeof(expected_len));
                buf.append(expected_value);
            }

            return buf.to_string();
        }

        static LogEntry deserialize(const std::string& data) {
            LogEntry entry;
            const char* ptr = data.c_str();
            size_t offset = 0;

            // 读取操作类型
            entry.op = *reinterpret_cast<const Operation*>(ptr + offset);
            offset += sizeof(Operation);

            // 读取 key
            uint32_t key_len = *reinterpret_cast<const uint32_t*>(ptr + offset);
            offset += sizeof(uint32_t);
            entry.key = std::string(ptr + offset, key_len);
            offset += key_len;

            // 读取 value
            uint32_t value_len = *reinterpret_cast<const uint32_t*>(ptr + offset);
            offset += sizeof(uint32_t);
            entry.value = std::string(ptr + offset, value_len);
            offset += value_len;

            // 如果是 CAS 操作，读取期望值
            if (entry.op == OP_CAS && offset < data.length()) {
                uint32_t expected_len = *reinterpret_cast<const uint32_t*>(ptr + offset);
                offset += sizeof(uint32_t);
                entry.expected_value = std::string(ptr + offset, expected_len);
            }

            return entry;
        }
    };

private:
    std::unordered_map<std::string, std::string> _kv_store;
    mutable bthread::Mutex _mutex;
    std::atomic<int64_t> _applied_index{0};

public:
    void on_apply(braft::Iterator& iter) override {
        for (; iter.valid(); iter.next()) {
            braft::AsyncClosureGuard closure_guard(iter.done());

            _applied_index.store(iter.index());

            LogEntry entry = LogEntry::deserialize(iter.data().to_string());
            bool success = false;
            std::string old_value;

            {
                std::unique_lock<bthread::Mutex> lock(_mutex);

                switch (entry.op) {
                    case OP_PUT:
                        old_value = _kv_store[entry.key];
                        _kv_store[entry.key] = entry.value;
                        success = true;
                        break;

                    case OP_DELETE:
                        if (_kv_store.count(entry.key)) {
                            old_value = _kv_store[entry.key];
                            _kv_store.erase(entry.key);
                            success = true;
                        }
                        break;

                    case OP_CAS:
                        if (_kv_store.count(entry.key) &&
                            _kv_store[entry.key] == entry.expected_value) {
                            old_value = _kv_store[entry.key];
                            _kv_store[entry.key] = entry.value;
                            success = true;
                        }
                        break;
                }
            }

            LOG(INFO) << "Applied " << entry.key << ": " << old_value
                     << " -> " << entry.value << ", success: " << success;

            // 返回结果给客户端
            if (iter.done()) {
                KVClosure* kv_closure = dynamic_cast<KVClosure*>(iter.done());
                if (kv_closure) {
                    kv_closure->set_result(success, old_value);
                }
            }
        }
    }

    void on_snapshot_save(braft::SnapshotWriter* writer, braft::Closure* done) override {
        brpc::ClosureGuard done_guard(done);

        std::string snapshot_path = writer->get_path() + "/kv_data";
        std::ofstream file(snapshot_path, std::ios::binary);
        if (!file.is_open()) {
            LOG(ERROR) << "Failed to open snapshot file";
            done->status().set_error(EIO, "Failed to save snapshot");
            return;
        }

        {
            std::unique_lock<bthread::Mutex> lock(_mutex);

            // 保存当前应用的索引
            file.write(reinterpret_cast<const char*>(&_applied_index), sizeof(_applied_index));

            // 保存键值对数量
            uint64_t count = _kv_store.size();
            file.write(reinterpret_cast<const char*>(&count), sizeof(count));

            // 保存所有键值对
            for (const auto& pair : _kv_store) {
                uint32_t key_len = pair.first.length();
                file.write(reinterpret_cast<const char*>(&key_len), sizeof(key_len));
                file.write(pair.first.c_str(), key_len);

                uint32_t value_len = pair.second.length();
                file.write(reinterpret_cast<const char*>(&value_len), sizeof(value_len));
                file.write(pair.second.c_str(), value_len);
            }
        }

        file.close();

        if (writer->add_file("kv_data") != 0) {
            LOG(ERROR) << "Failed to add file to snapshot";
            done->status().set_error(EIO, "Failed to add file");
            return;
        }

        LOG(INFO) << "Saved snapshot with " << _kv_store.size()
                 << " keys at index " << _applied_index.load();
    }

    int on_snapshot_load(braft::SnapshotReader* reader) override {
        if (!reader->list_files().count("kv_data")) {
            LOG(ERROR) << "kv_data not found in snapshot";
            return -1;
        }

        std::string snapshot_path = reader->get_path() + "/kv_data";
        std::ifstream file(snapshot_path, std::ios::binary);
        if (!file.is_open()) {
            LOG(ERROR) << "Failed to open snapshot file";
            return -1;
        }

        {
            std::unique_lock<bthread::Mutex> lock(_mutex);
            _kv_store.clear();

            // 读取应用索引
            int64_t applied_index;
            file.read(reinterpret_cast<char*>(&applied_index), sizeof(applied_index));
            _applied_index.store(applied_index);

            // 读取键值对数量
            uint64_t count;
            file.read(reinterpret_cast<char*>(&count), sizeof(count));

            // 读取所有键值对
            for (uint64_t i = 0; i < count; ++i) {
                uint32_t key_len;
                file.read(reinterpret_cast<char*>(&key_len), sizeof(key_len));
                std::string key(key_len, '\0');
                file.read(&key[0], key_len);

                uint32_t value_len;
                file.read(reinterpret_cast<char*>(&value_len), sizeof(value_len));
                std::string value(value_len, '\0');
                file.read(&value[0], value_len);

                _kv_store[key] = value;
            }
        }

        file.close();

        LOG(INFO) << "Loaded snapshot with " << _kv_store.size()
                 << " keys at index " << _applied_index.load();
        return 0;
    }

    // 获取值
    bool get(const std::string& key, std::string* value) const {
        std::unique_lock<bthread::Mutex> lock(_mutex);
        auto it = _kv_store.find(key);
        if (it != _kv_store.end()) {
            *value = it->second;
            return true;
        }
        return false;
    }

    // 获取所有键
    std::vector<std::string> list_keys() const {
        std::unique_lock<bthread::Mutex> lock(_mutex);
        std::vector<std::string> keys;
        for (const auto& pair : _kv_store) {
            keys.push_back(pair.first);
        }
        return keys;
    }

    size_t size() const {
        std::unique_lock<bthread::Mutex> lock(_mutex);
        return _kv_store.size();
    }
};

// KV 操作的回调
class KVClosure : public braft::Closure {
public:
    void Run() override {
        if (status().ok()) {
            LOG(INFO) << "KV operation succeeded, result: " << _success
                     << ", old_value: " << _old_value;
        } else {
            LOG(ERROR) << "KV operation failed: " << status();
        }
        delete this;
    }

    void set_result(bool success, const std::string& old_value) {
        _success = success;
        _old_value = old_value;
    }

    bool get_success() const { return _success; }
    const std::string& get_old_value() const { return _old_value; }

private:
    bool _success = false;
    std::string _old_value;
};

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class ConfigurationManager {
public:
    // 添加节点
    static void add_peer(braft::Node* node, const std::string& peer_addr,
                        braft::Closure* done) {
        braft::Configuration new_conf;
        node->list_peers(&new_conf);

        braft::PeerId peer_id(peer_addr);
        new_conf.add_peer(peer_id);

        LOG(INFO) << "Adding peer: " << peer_addr;
        node->change_peers(new_conf, done);
    }

    // 移除节点
    static void remove_peer(braft::Node* node, const std::string& peer_addr,
                           braft::Closure* done) {
        braft::Configuration new_conf;
        node->list_peers(&new_conf);

        braft::PeerId peer_id(peer_addr);
        new_conf.remove_peer(peer_id);

        LOG(INFO) << "Removing peer: " << peer_addr;
        node->change_peers(new_conf, done);
    }

    // 查看当前配置
    static std::vector<std::string> list_peers(braft::Node* node) {
        braft::Configuration conf;
        node->list_peers(&conf);

        std::vector<std::string> peers;
        for (auto it = conf.begin(); it != conf.end(); ++it) {
            peers.push_back(it->to_string());
        }
        return peers;
    }

    // 安全的配置变更（逐个添加/删除）
    static void safe_change_peers(braft::Node* node,
                                 const std::vector<std::string>& target_peers,
                                 braft::Closure* final_done) {
        // 获取当前配置
        braft::Configuration current_conf;
        node->list_peers(&current_conf);

        std::set<std::string> current_peers;
        for (auto it = current_conf.begin(); it != current_conf.end(); ++it) {
            current_peers.insert(it->to_string());
        }

        std::set<std::string> target_set(target_peers.begin(), target_peers.end());

        // 找出需要添加和删除的节点
        std::vector<std::string> to_add, to_remove;

        for (const auto& peer : target_set) {
            if (current_peers.find(peer) == current_peers.end()) {
                to_add.push_back(peer);
            }
        }

        for (const auto& peer : current_peers) {
            if (target_set.find(peer) == target_set.end()) {
                to_remove.push_back(peer);
            }
        }

        // 创建批量变更管理器
        BatchConfigChange* batch = new BatchConfigChange(node, to_add, to_remove, final_done);
        batch->start();
    }

private:
    // 批量配置变更管理器
    class BatchConfigChange {
    public:
        BatchConfigChange(braft::Node* node,
                         const std::vector<std::string>& to_add,
                         const std::vector<std::string>& to_remove,
                         braft::Closure* done)
            : _node(node), _to_add(to_add), _to_remove(to_remove),
              _final_done(done), _current_index(0) {}

        void start() {
            if (!_to_add.empty()) {
                process_add();
            } else if (!_to_remove.empty()) {
                process_remove();
            } else {
                finish();
            }
        }

    private:
        void process_add() {
            if (_current_index >= _to_add.size()) {
                _current_index = 0;
                process_remove();
                return;
            }

            braft::Closure* done = new braft::NewCallback(this, &BatchConfigChange::on_add_done);
            add_peer(_node, _to_add[_current_index], done);
        }

        void process_remove() {
            if (_current_index >= _to_remove.size()) {
                finish();
                return;
            }

            braft::Closure* done = new braft::NewCallback(this, &BatchConfigChange::on_remove_done);
            remove_peer(_node, _to_remove[_current_index], done);
        }

        void on_add_done() {
            ++_current_index;
            process_add();
        }

        void on_remove_done() {
            ++_current_index;
            process_remove();
        }

        void finish() {
            if (_final_done) {
                _final_done->Run();
            }
            delete this;
        }

        braft::Node* _node;
        std::vector<std::string> _to_add;
        std::vector<std::string> _to_remove;
        braft::Closure* _final_done;
        size_t _current_index;
    };
};

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class SmartSnapshotManager {
public:
    struct SnapshotOptions {
        int64_t max_log_size = 100 * 1024 * 1024;  // 100MB
        int64_t max_log_entries = 100000;          // 10万条
        int32_t snapshot_interval_s = 3600;        // 1小时
        int32_t min_snapshot_interval_s = 300;     // 最小5分钟
        double log_growth_threshold = 2.0;         // 日志增长2倍触发快照
    };

    SmartSnapshotManager(braft::Node* node, const SnapshotOptions& options)
        : _node(node), _options(options), _last_snapshot_time(0),
          _last_snapshot_log_size(0) {}

    // 检查是否需要创建快照
    bool should_create_snapshot() {
        time_t now = time(nullptr);

        // 获取当前日志信息
        int64_t current_log_size = get_log_size();
        int64_t current_log_entries = get_log_entries();

        // 检查时间间隔
        if (now - _last_snapshot_time >= _options.snapshot_interval_s) {
            LOG(INFO) << "Snapshot triggered by time interval";
            return true;
        }

        // 检查日志大小
        if (current_log_size >= _options.max_log_size) {
            LOG(INFO) << "Snapshot triggered by log size: " << current_log_size;
            return true;
        }

        // 检查日志条目数
        if (current_log_entries >= _options.max_log_entries) {
            LOG(INFO) << "Snapshot triggered by log entries: " << current_log_entries;
            return true;
        }

        // 检查日志增长率
        if (_last_snapshot_log_size > 0 &&
            current_log_size >= _last_snapshot_log_size * _options.log_growth_threshold &&
            now - _last_snapshot_time >= _options.min_snapshot_interval_s) {
            LOG(INFO) << "Snapshot triggered by log growth: "
                     << _last_snapshot_log_size << " -> " << current_log_size;
            return true;
        }

        return false;
    }

    // 创建快照
    void create_snapshot() {
        if (_creating_snapshot.load()) {
            LOG(WARNING) << "Snapshot creation already in progress";
            return;
        }

        _creating_snapshot.store(true);

        SnapshotClosure* done = new SnapshotClosure([this](bool success) {
            _creating_snapshot.store(false);
            if (success) {
                _last_snapshot_time = time(nullptr);
                _last_snapshot_log_size = get_log_size();
                LOG(INFO) << "Snapshot created successfully";
            } else {
                LOG(ERROR) << "Failed to create snapshot";
            }
        });

        _node->snapshot(done);
    }

    // 定期检查（应该在单独线程中调用）
    void periodic_check() {
        while (!_stopped.load()) {
            if (should_create_snapshot()) {
                create_snapshot();
            }
            bthread_usleep(60 * 1000 * 1000);  // 每分钟检查一次
        }
    }

    void stop() {
        _stopped.store(true);
    }

private:
    int64_t get_log_size() {
        // 实际实现需要从 braft 获取日志大小
        // 这里返回估算值
        return 0;
    }

    int64_t get_log_entries() {
        // 实际实现需要从 braft 获取日志条目数
        return 0;
    }

    class SnapshotClosure : public braft::Closure {
    public:
        SnapshotClosure(std::function<void(bool)> callback)
            : _callback(callback) {}

        void Run() override {
            _callback(status().ok());
            delete this;
        }

    private:
        std::function<void(bool)> _callback;
    };

    braft::Node* _node;
    SnapshotOptions _options;
    std::atomic<bool> _creating_snapshot{false};
    std::atomic<bool> _stopped{false};
    time_t _last_snapshot_time;
    int64_t _last_snapshot_log_size;
};