feat: mysql connection pool..

in progress

README.md

@@ -41,7 +41,7 @@ cmake --build build
 - Session: 개별 클라이언트 비동기 수신/송신 처리
 - PacketHandler: 패킷 ID별 로직 디스패칭
 - SessionManager: 글로벌 세션 관리 및 브로드캐스팅
-- DatabaseManager: 비동기 데이터베이스 작업 및 락 제어
+- DatabaseManager: 커넥션 풀을 통한 동기/비동기 데이터베이스 작업 관리
 - Packet: Protobuf 기반 직렬화 프로토콜 (proto/Protocol.proto)
 
 ## Python GUI 클라이언트

include/DatabaseManager.h

@@ -2,10 +2,13 @@
 
 #include <boost/asio.hpp>
 #include <boost/asio/awaitable.hpp>
+#include <boost/asio/ssl.hpp>
 #include <boost/mysql.hpp>
+#include <deque>
 #include <memory>
 #include <queue>
 #include <string>
+#include <vector>
 
 class DatabaseManager {
 public:
@@ -33,24 +36,60 @@ public:
     uint64_t myValue;
   };
 
+  class ConnectionProxy {
+  public:
+    ConnectionProxy(std::unique_ptr<boost::mysql::tcp_ssl_connection> conn,
+                    DatabaseManager &owner)
+        : conn_(std::move(conn)), owner_(owner) {}
+    ~ConnectionProxy();
+
+    // Move only
+    ConnectionProxy(ConnectionProxy &&other) noexcept
+        : conn_(std::move(other.conn_)), owner_(other.owner_) {}
+    ConnectionProxy &operator=(ConnectionProxy &&other) noexcept {
+      if (this != &other) {
+        conn_ = std::move(other.conn_);
+      }
+      return *this;
+    }
+    ConnectionProxy(const ConnectionProxy &) = delete;
+    ConnectionProxy &operator=(const ConnectionProxy &) = delete;
+
+    boost::mysql::tcp_ssl_connection *operator->() { return conn_.get(); }
+    boost::mysql::tcp_ssl_connection &operator*() { return *conn_; }
+
+  private:
+    std::unique_ptr<boost::mysql::tcp_ssl_connection> conn_;
+    DatabaseManager &owner_;
+  };
+
   boost::asio::awaitable<UserData> LoadUser(std::string nickname);
   boost::asio::awaitable<void> SaveUser(std::string nickname, uint64_t gold,
                                         uint32_t swordLevel);
   boost::asio::awaitable<RankingResult> GetRanking(int type,
                                                    std::string nickname);
 
+  boost::asio::awaitable<ConnectionProxy> GetConnection();
+
 private:
   DatabaseManager() = default;
 
-  // 비동기 Mutex 역할을 할 함수들
-  boost::asio::awaitable<void> Lock();
-  void Unlock();
+  void ReturnConnection(std::unique_ptr<boost::mysql::tcp_ssl_connection> conn);
+  boost::asio::awaitable<std::unique_ptr<boost::mysql::tcp_ssl_connection>>
+  CreateNewConnection();
 
-  std::unique_ptr<boost::mysql::tcp_ssl_connection> conn_;
+  std::deque<std::unique_ptr<boost::mysql::tcp_ssl_connection>> pool_;
+  std::queue<std::shared_ptr<boost::asio::steady_timer>> waiting_queue_;
+
+  boost::asio::io_context *io_context_ = nullptr;
   std::unique_ptr<boost::asio::strand<boost::asio::io_context::executor_type>>
       strand_;
 
-  // 비동기 락 시스템을 위한 상태 변수
-  bool is_locked_ = false;
-  std::queue<std::shared_ptr<boost::asio::steady_timer>> waiting_queue_;
+  boost::asio::ssl::context ssl_ctx_{boost::asio::ssl::context::tlsv12_client};
+
+  std::string host_, user_, password_, db_;
+  uint16_t port_;
+
+  uint32_t max_connections_ = 10;
+  uint32_t current_total_connections_ = 0;
 };

server/DatabaseManager.cpp

@@ -9,47 +9,84 @@ DatabaseManager &DatabaseManager::GetInstance() {
   return instance;
 }
 
+DatabaseManager::ConnectionProxy::~ConnectionProxy() {
+  if (conn_) {
+    owner_.ReturnConnection(std::move(conn_));
+  }
+}
+
 bool DatabaseManager::Init(boost::asio::io_context &io_context,
                            const std::string &host, uint16_t port,
                            const std::string &user, const std::string &password,
                            const std::string &db) {
   try {
+    io_context_ = &io_context;
     strand_ = std::make_unique<
         boost::asio::strand<boost::asio::io_context::executor_type>>(
         io_context.get_executor());
 
-    boost::asio::ip::tcp::resolver resolver(io_context.get_executor());
-    auto endpoints = resolver.resolve(host, std::to_string(port));
+    host_ = host;
+    port_ = port;
+    user_ = user;
+    password_ = password;
+    db_ = db;
 
-    boost::mysql::handshake_params params(user, password, db);
-    static boost::asio::ssl::context ssl_ctx(
-        boost::asio::ssl::context::tlsv12_client);
+    current_total_connections_ = 0;
+    pool_.clear();
 
-    conn_ = std::make_unique<boost::mysql::tcp_ssl_connection>(
-        io_context.get_executor(), ssl_ctx);
-    conn_->connect(*endpoints.begin(), params);
-
-    Logger::Log("Database 연결 성공 (AsyncLock 적용): ", host, ":", port);
+    Logger::Log("Database Dynamic Pool 초기화 완료 (Max: ", max_connections_,
+                "): ", host, ":", port);
     return true;
   } catch (const std::exception &e) {
-    Logger::Log("Database 연결 실패: ", e.what());
+    Logger::Log("Database Pool 초기화 실패: ", e.what());
     return false;
   }
 }
 
-// 비동기 락 획득 (이미 락이 걸려있으면 대기열에 들어감)
-boost::asio::awaitable<void> DatabaseManager::Lock() {
-  auto executor = co_await boost::asio::this_coro::executor;
+boost::asio::awaitable<std::unique_ptr<boost::mysql::tcp_ssl_connection>>
+DatabaseManager::CreateNewConnection() {
+  auto conn = std::make_unique<boost::mysql::tcp_ssl_connection>(
+      io_context_->get_executor(), ssl_ctx_);
 
+  boost::asio::ip::tcp::resolver resolver(io_context_->get_executor());
+  auto endpoints = co_await resolver.async_resolve(host_, std::to_string(port_),
+                                                   boost::asio::use_awaitable);
+
+  boost::mysql::handshake_params params(user_, password_, db_);
+  co_await conn->async_connect(*endpoints.begin(), params,
+                               boost::asio::use_awaitable);
+
+  co_return conn;
+}
+
+boost::asio::awaitable<DatabaseManager::ConnectionProxy>
+DatabaseManager::GetConnection() {
+  while (true) {
     co_await boost::asio::post(
         boost::asio::bind_executor(*strand_, boost::asio::use_awaitable));
 
-  if (!is_locked_) {
-    is_locked_ = true;
-    co_return;
+    if (!pool_.empty()) {
+      auto conn = std::move(pool_.front());
+      pool_.pop_front();
+      co_return ConnectionProxy(std::move(conn), *this);
     }
 
-  // 이미 잠겨있으면 타이머를 만들어서 대기열에 추가 (비동기 대기)
+    if (current_total_connections_ < max_connections_) {
+      current_total_connections_++;
+      try {
+        Logger::Log("새로운 DB 커넥션 생성 중... (현재: ",
+                    current_total_connections_, ")");
+        auto conn = co_await CreateNewConnection();
+        Logger::Log("새로운 DB 커넥션 생성 완료");
+        co_return ConnectionProxy(std::move(conn), *this);
+      } catch (const std::exception &e) {
+        Logger::Log("DB 커넥션 생성 실패: ", e.what());
+        current_total_connections_--;
+        throw;
+      }
+    }
+
+    auto executor = co_await boost::asio::this_coro::executor;
     auto timer = std::make_shared<boost::asio::steady_timer>(
         executor, std::chrono::steady_clock::time_point::max());
     waiting_queue_.push(timer);
@@ -57,53 +94,53 @@ boost::asio::awaitable<void> DatabaseManager::Lock() {
     try {
       co_await timer->async_wait(boost::asio::use_awaitable);
     } catch (...) {
-    // 타이머 취소(Unlock에서 호출함)되면 성공적으로 락을 획득한 것으로 간주
     }
-  co_return;
+  }
 }
 
-// 비동기 락 해제 (대기열에 다음 사람이 있으면 깨워줌)
-void DatabaseManager::Unlock() {
+void DatabaseManager::ReturnConnection(
+    std::unique_ptr<boost::mysql::tcp_ssl_connection> conn) {
+  if (!conn) {
     boost::asio::dispatch(*strand_, [this]() {
-    if (waiting_queue_.empty()) {
-      is_locked_ = false;
-    } else {
-      auto next = waiting_queue_.front();
+      if (current_total_connections_ > 0) {
+        current_total_connections_--;
+      }
+    });
+    return;
+  }
+
+  boost::asio::dispatch(*strand_, [this, conn = std::move(conn)]() mutable {
+    pool_.push_back(std::move(conn));
+    if (!waiting_queue_.empty()) {
+      auto timer = waiting_queue_.front();
       waiting_queue_.pop();
-      next->cancel();
+      timer->cancel();
     }
   });
 }
 
 boost::asio::awaitable<DatabaseManager::UserData>
 DatabaseManager::LoadUser(std::string nickname) {
-  co_await Lock();
-
   try {
-    if (!conn_) {
-      Unlock();
-      co_return UserData{nickname, 10000, 0};
-    }
+    auto conn = co_await GetConnection();
 
     boost::mysql::results result;
-    boost::mysql::statement stmt = co_await conn_->async_prepare_statement(
+    boost::mysql::statement stmt = co_await conn->async_prepare_statement(
         "SELECT username, gold, sword_level, max_sword_level FROM users WHERE "
         "username = ?",
         boost::asio::use_awaitable);
-    co_await conn_->async_execute(stmt.bind(nickname), result,
+    co_await conn->async_execute(stmt.bind(nickname), result,
                                  boost::asio::use_awaitable);
 
     if (result.rows().empty()) {
-      boost::mysql::statement ins_stmt =
-          co_await conn_->async_prepare_statement(
+      boost::mysql::statement ins_stmt = co_await conn->async_prepare_statement(
           "INSERT INTO users (username, gold, sword_level) VALUES (?, "
           "10000, 0)",
           boost::asio::use_awaitable);
-      co_await conn_->async_execute(ins_stmt.bind(nickname), result,
+      co_await conn->async_execute(ins_stmt.bind(nickname), result,
                                    boost::asio::use_awaitable);
       Logger::Log("새로운 유저 탄생 (DB): ", nickname);
-      Unlock();
-      co_return UserData{nickname, 10000, 0};
+      co_return UserData{nickname, 10000, 0, 0};
     } else {
       auto row = result.rows().at(0);
       UserData data;
@@ -111,56 +148,42 @@ DatabaseManager::LoadUser(std::string nickname) {
       data.gold = row.at(1).as_uint64();
       data.swordLevel = (uint32_t)row.at(2).as_int64();
       data.maxSwordLevel = (uint32_t)row.at(3).as_int64();
-      Unlock();
       co_return data;
     }
   } catch (const std::exception &e) {
     Logger::Log("LoadUser 에러: ", e.what());
-    Unlock();
-    co_return UserData{nickname, 10000, 0};
+    co_return UserData{nickname, 10000, 0, 0};
   }
 }
 
 boost::asio::awaitable<void> DatabaseManager::SaveUser(std::string nickname,
                                                        uint64_t gold,
                                                        uint32_t swordLevel) {
-  co_await Lock();
-
   try {
-    if (!conn_) {
-      Unlock();
-      co_return;
-    }
+    auto conn = co_await GetConnection();
 
     boost::mysql::results result;
-    boost::mysql::statement stmt = co_await conn_->async_prepare_statement(
+    boost::mysql::statement stmt = co_await conn->async_prepare_statement(
         "UPDATE users SET gold = ?, sword_level = ?, max_sword_level = "
         "GREATEST(max_sword_level, ?) WHERE username = ?",
         boost::asio::use_awaitable);
-    co_await conn_->async_execute(
+    co_await conn->async_execute(
         stmt.bind(gold, (int64_t)swordLevel, (int64_t)swordLevel, nickname),
         result, boost::asio::use_awaitable);
   } catch (const std::exception &e) {
     Logger::Log("SaveUser 에러: ", e.what());
   }
-
-  Unlock();
   co_return;
 }
 
 boost::asio::awaitable<DatabaseManager::RankingResult>
 DatabaseManager::GetRanking(int type, std::string nickname) {
-  co_await Lock();
-
   RankingResult res;
   res.myRank = -1;
   res.myValue = 0;
 
   try {
-    if (!conn_) {
-      Unlock();
-      co_return res;
-    }
+    auto conn = co_await GetConnection();
 
     std::string columnName = (type == 0) ? "max_sword_level" : "gold";
 
@@ -168,7 +191,7 @@ DatabaseManager::GetRanking(int type, std::string nickname) {
     std::string topQuery = "SELECT username, " + columnName +
                            " FROM users ORDER BY " + columnName +
                            " DESC LIMIT 10";
-    co_await conn_->async_execute(topQuery, topResult,
+    co_await conn->async_execute(topQuery, topResult,
                                  boost::asio::use_awaitable);
 
     uint32_t rank = 1;
@@ -176,7 +199,6 @@ DatabaseManager::GetRanking(int type, std::string nickname) {
       RankingResult::Entry entry;
       entry.rank = rank++;
       entry.nickname = row.at(0).as_string();
-      // DB 타입이 달라 분기처리..
       if (type == 0) {
         entry.value = (uint64_t)row.at(1).as_int64();
       } else {
@@ -190,9 +212,9 @@ DatabaseManager::GetRanking(int type, std::string nickname) {
         "SELECT " + columnName + ", (SELECT COUNT(*) + 1 FROM users WHERE " +
         columnName + " > u." + columnName + ") FROM users u WHERE username = ?";
 
-    boost::mysql::statement stmt = co_await conn_->async_prepare_statement(
+    boost::mysql::statement stmt = co_await conn->async_prepare_statement(
         myQuery, boost::asio::use_awaitable);
-    co_await conn_->async_execute(stmt.bind(nickname), myResult,
+    co_await conn->async_execute(stmt.bind(nickname), myResult,
                                  boost::asio::use_awaitable);
 
     if (!myResult.rows().empty()) {
@@ -207,7 +229,5 @@ DatabaseManager::GetRanking(int type, std::string nickname) {
   } catch (const std::exception &e) {
     Logger::Log("GetRanking 에러: ", e.what());
   }
-
-  Unlock();
   co_return res;
 }