Database Pool

CMakeLists.txt

@@ -40,6 +40,7 @@ message("Compile options: " ${COMPILE_OPTIONS_STRING})
 find_package(nlohmann_json REQUIRED)
 find_package(FCGI REQUIRED)
 find_package(Argon2 REQUIRED)
+find_package(Threads REQUIRED)
 
 add_executable(${PROJECT_NAME} main.cpp)
 target_include_directories(${PROJECT_NAME} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
@@ -63,6 +64,7 @@ target_link_libraries(${PROJECT_NAME} PRIVATE
     FCGI::FCGI++
     nlohmann_json::nlohmann_json
     Argon2::Argon2
+    Threads::Threads
 )
 
 install(TARGETS ${PROJECT_NAME} RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})

database/CMakeLists.txt

@@ -1,11 +1,15 @@
 set(HEADERS
-    dbinterface.h
+    interface.h
     exceptions.h
+    pool.h
+    resource.h
 )
 
 set(SOURCES
-    dbinterface.cpp
+    interface.cpp
     exceptions.cpp
+    pool.cpp
+    resource.cpp
 )
 
 target_sources(${PROJECT_NAME} PRIVATE ${SOURCES})

database/exceptions.cpp

@@ -3,18 +3,18 @@
 
 #include "exceptions.h"
 
-DBInterface::Duplicate::Duplicate(const std::string& text):
+DB::Duplicate::Duplicate(const std::string& text):
     std::runtime_error(text)
 {}
 
-DBInterface::DuplicateLogin::DuplicateLogin(const std::string& text):
+DB::DuplicateLogin::DuplicateLogin(const std::string& text):
     Duplicate(text)
 {}
 
-DBInterface::EmptyResult::EmptyResult(const std::string& text):
+DB::EmptyResult::EmptyResult(const std::string& text):
     std::runtime_error(text)
 {}
 
-DBInterface::NoLogin::NoLogin(const std::string& text):
+DB::NoLogin::NoLogin(const std::string& text):
     EmptyResult(text)
 {}

database/exceptions.h

@@ -3,24 +3,27 @@
 
 #pragma once
 
-#include "dbinterface.h"
+#include <string>
+#include <stdexcept>
 
-class DBInterface::Duplicate : public std::runtime_error {
+namespace DB {
+class Duplicate : public std::runtime_error {
 public:
     explicit Duplicate(const std::string& text);
 };
 
-class DBInterface::DuplicateLogin : public DBInterface::Duplicate {
+class DuplicateLogin : public Duplicate {
 public:
     explicit DuplicateLogin(const std::string& text);
 };
 
-class DBInterface::EmptyResult : public std::runtime_error {
+class EmptyResult : public std::runtime_error {
 public:
     explicit EmptyResult(const std::string& text);
 };
 
-class DBInterface::NoLogin : public DBInterface::EmptyResult {
+class NoLogin : public EmptyResult {
 public:
     explicit NoLogin(const std::string& text);
 };
+}

database/interface.cpp

@@ -1,18 +1,18 @@
 //  SPDX-FileCopyrightText: 2023 Yury Gubich <blue@macaw.me>
 //  SPDX-License-Identifier: GPL-3.0-or-later
 
-#include "dbinterface.h"
+#include "interface.h"
 
 #include "mysql/mysql.h"
 
-DBInterface::DBInterface(Type type):
+DB::Interface::Interface(Type type):
     type(type),
     state(State::disconnected)
 {}
 
-DBInterface::~DBInterface() {}
+DB::Interface::~Interface() {}
 
-std::unique_ptr<DBInterface> DBInterface::create(Type type) {
+std::unique_ptr<DB::Interface> DB::Interface::create(Type type) {
     switch (type) {
         case Type::mysql:
             return std::make_unique<MySQL>();
@@ -21,6 +21,6 @@ std::unique_ptr<DBInterface> DBInterface::create(Type type) {
     throw std::runtime_error("Unexpected database type: " + std::to_string((uint8_t)type));
 }
 
-DBInterface::State DBInterface::currentState() const {
+DB::Interface::State DB::Interface::currentState() const {
     return state;
 }

database/interface.h

@@ -8,7 +8,8 @@
 #include <memory>
 #include <stdint.h>
 
-class DBInterface {
+namespace DB {
+class Interface {
 public:
     enum class Type {
         mysql
@@ -18,19 +19,14 @@ public:
         connecting,
         connected
     };
-    static std::unique_ptr<DBInterface> create(Type type);
+    static std::unique_ptr<Interface> create(Type type);
 
-    virtual ~DBInterface();
+    virtual ~Interface();
 
     State currentState() const;
 
     const Type type;
 
-    class Duplicate;
-    class DuplicateLogin;
-    class EmptyResult;
-    class NoLogin;
-
 public:
     virtual void connect(const std::string& path) = 0;
     virtual void disconnect() = 0;
@@ -46,8 +42,9 @@ public:
     virtual unsigned int createSession(const std::string& login, const std::string& access, const std::string& renew) = 0;
 
 protected:
-    DBInterface(Type type);
+    Interface(Type type);
 
 protected:
     State state;
 };
+}

database/mysql/mysql.cpp

@@ -23,8 +23,8 @@ constexpr const char* createSessionQuery = "INSERT INTO sessions (`owner`, `acce
 
 static const std::filesystem::path buildSQLPath = "database";
 
-MySQL::MySQL():
-    DBInterface(Type::mysql),
+DB::MySQL::MySQL():
+    Interface(Type::mysql),
     connection(),
     login(),
     password(),
@@ -33,11 +33,11 @@ MySQL::MySQL():
     mysql_init(&connection);
 }
 
-MySQL::~MySQL() {
+DB::MySQL::~MySQL() {
     mysql_close(&connection);
 }
 
-void MySQL::connect(const std::string& path) {
+void DB::MySQL::connect(const std::string& path) {
     if (state != State::disconnected)
         return;
 
@@ -59,7 +59,7 @@ void MySQL::connect(const std::string& path) {
     state = State::connected;
 }
 
-void MySQL::setCredentials(const std::string& login, const std::string& password) {
+void DB::MySQL::setCredentials(const std::string& login, const std::string& password) {
     if (MySQL::login == login && MySQL::password == password)
         return;
 
@@ -81,7 +81,7 @@ void MySQL::setCredentials(const std::string& login, const std::string& password
         throw std::runtime_error(std::string("Error changing credetials: ") + mysql_error(con));
 }
 
-void MySQL::setDatabase(const std::string& database) {
+void DB::MySQL::setDatabase(const std::string& database) {
     if (MySQL::database == database)
         return;
 
@@ -97,7 +97,7 @@ void MySQL::setDatabase(const std::string& database) {
         throw std::runtime_error(std::string("Error changing db: ") + mysql_error(con));
 }
 
-void MySQL::disconnect() {
+void DB::MySQL::disconnect() {
     if (state == State::disconnected)
         return;
 
@@ -106,7 +106,7 @@ void MySQL::disconnect() {
     mysql_init(con);            //this is ridiculous!
 }
 
-void MySQL::executeFile(const std::filesystem::path& relativePath) {
+void DB::MySQL::executeFile(const std::filesystem::path& relativePath) {
     MYSQL* con = &connection;
     std::filesystem::path path = sharedPath() / relativePath;
     if (!std::filesystem::exists(path))
@@ -138,7 +138,7 @@ void MySQL::executeFile(const std::filesystem::path& relativePath) {
     }
 }
 
-uint8_t MySQL::getVersion() {
+uint8_t DB::MySQL::getVersion() {
     MYSQL* con = &connection;
     int result = mysql_query(con, versionQuery);
 
@@ -161,14 +161,14 @@ uint8_t MySQL::getVersion() {
         return 0;
 }
 
-void MySQL::setVersion(uint8_t version) {
+void DB::MySQL::setVersion(uint8_t version) {
     std::string strVersion = std::to_string(version);
     Statement statement(&connection, updateQuery);
     statement.bind(strVersion.data(), MYSQL_TYPE_VAR_STRING);
     statement.execute();
 }
 
-void MySQL::migrate(uint8_t targetVersion) {
+void DB::MySQL::migrate(uint8_t targetVersion) {
     uint8_t currentVersion = getVersion();
 
     while (currentVersion < targetVersion) {
@@ -190,7 +190,7 @@ void MySQL::migrate(uint8_t targetVersion) {
     std::cout << "Database is now on actual version " << std::to_string(targetVersion) << std::endl;
 }
 
-std::optional<std::string> MySQL::getComment(std::string& string) {
+std::optional<std::string> DB::MySQL::getComment(std::string& string) {
     ltrim(string);
     if (string.length() < 2)
         return std::nullopt;
@@ -218,7 +218,7 @@ std::optional<std::string> MySQL::getComment(std::string& string) {
     return std::nullopt;
 }
 
-unsigned int MySQL::registerAccount(const std::string& login, const std::string& hash) {
+unsigned int DB::MySQL::registerAccount(const std::string& login, const std::string& hash) {
     //TODO validate filed lengths!
     MYSQL* con = &connection;
     MySQL::Transaction txn(con);
@@ -247,7 +247,7 @@ unsigned int MySQL::registerAccount(const std::string& login, const std::string&
     return id;
 }
 
-std::string MySQL::getAccountHash(const std::string& login) {
+std::string DB::MySQL::getAccountHash(const std::string& login) {
     std::string l = login;
     MYSQL* con = &connection;
 
@@ -265,7 +265,7 @@ std::string MySQL::getAccountHash(const std::string& login) {
     return std::any_cast<const std::string&>(result[0][0]);
 }
 
-unsigned int MySQL::createSession(const std::string& login, const std::string& access, const std::string& renew) {
+unsigned int DB::MySQL::createSession(const std::string& login, const std::string& access, const std::string& renew) {
     std::string l = login, a = access, r = renew;
     static std::string testingDevice("Testing...");
 
@@ -281,7 +281,7 @@ unsigned int MySQL::createSession(const std::string& login, const std::string& a
     return lastInsertedId();
 }
 
-unsigned int MySQL::lastInsertedId() {
+unsigned int DB::MySQL::lastInsertedId() {
     MYSQL* con = &connection;
     int result = mysql_query(con, lastIdQuery);
 

database/mysql/mysql.h

@@ -9,10 +9,11 @@
 
 #include <mysql.h>
 
-#include "database/dbinterface.h"
+#include "database/interface.h"
 #include "utils/helpers.h"
 
-class MySQL : public DBInterface {
+namespace DB {
+class MySQL : public Interface {
     class Statement;
     class Transaction;
 
@@ -51,3 +52,4 @@ struct ResDeleter {
     }
 };
 };
+}

database/mysql/statement.cpp

@@ -9,7 +9,7 @@
 
 static uint64_t TIME_LENGTH = sizeof(MYSQL_TIME);
 
-MySQL::Statement::Statement(MYSQL* connection, const char* statement):
+DB::MySQL::Statement::Statement(MYSQL* connection, const char* statement):
     stmt(mysql_stmt_init(connection)),
     param()
 {
@@ -18,7 +18,7 @@ MySQL::Statement::Statement(MYSQL* connection, const char* statement):
         throw std::runtime_error(std::string("Error preparing statement: ") + mysql_stmt_error(stmt.get()));
 }
 
-void MySQL::Statement::bind(void* value, enum_field_types type, bool usigned) {
+void DB::MySQL::Statement::bind(void* value, enum_field_types type, bool usigned) {
     MYSQL_BIND& result = param.emplace_back();
     std::memset(&result, 0, sizeof(result));
 
@@ -45,7 +45,7 @@ void MySQL::Statement::bind(void* value, enum_field_types type, bool usigned) {
     }
 }
 
-void MySQL::Statement::execute() {
+void DB::MySQL::Statement::execute() {
     MYSQL_STMT* raw = stmt.get();
     int result = mysql_stmt_bind_param(raw, param.data());
     if (result != 0)
@@ -64,7 +64,7 @@ void MySQL::Statement::execute() {
     }
 }
 
-std::vector<std::vector<std::any>> MySQL::Statement::fetchResult() {
+std::vector<std::vector<std::any>> DB::MySQL::Statement::fetchResult() {
     MYSQL_STMT* raw = stmt.get();
     if (mysql_stmt_store_result(raw) != 0)
         throw std::runtime_error(std::string("Error fetching statement result: ") + mysql_stmt_error(raw));   //TODO not sure if it's valid here

database/mysql/statement.h

@@ -10,6 +10,7 @@
 
 #include "mysql.h"
 
+namespace DB {
 class MySQL::Statement {
     struct STMTDeleter {
         void operator () (MYSQL_STMT* stmt) {
@@ -27,3 +28,4 @@ private:
     std::unique_ptr<MYSQL_STMT, STMTDeleter> stmt;
     std::vector<MYSQL_BIND> param;
 };
+}

database/mysql/transaction.cpp

@@ -3,7 +3,7 @@
 
 #include "transaction.h"
 
-MySQL::Transaction::Transaction(MYSQL* connection):
+DB::MySQL::Transaction::Transaction(MYSQL* connection):
     con(connection),
     opened(false)
 {
@@ -13,12 +13,12 @@ MySQL::Transaction::Transaction(MYSQL* connection):
     opened = true;
 }
 
-MySQL::Transaction::~Transaction() {
+DB::MySQL::Transaction::~Transaction() {
     if (opened)
         abort();
 }
 
-void MySQL::Transaction::commit() {
+void DB::MySQL::Transaction::commit() {
     if (mysql_commit(con) != 0)
         throw std::runtime_error(std::string("Failed to commit transaction") + mysql_error(con));
 
@@ -27,7 +27,7 @@ void MySQL::Transaction::commit() {
         throw std::runtime_error(std::string("Failed to return autocommit") + mysql_error(con));
 }
 
-void MySQL::Transaction::abort() {
+void DB::MySQL::Transaction::abort() {
     opened = false;
     if (mysql_rollback(con) != 0)
         throw std::runtime_error(std::string("Failed to rollback transaction") + mysql_error(con));

database/mysql/transaction.h

@@ -5,6 +5,7 @@
 
 #include "mysql.h"
 
+namespace DB {
 class MySQL::Transaction {
 public:
     Transaction(MYSQL* connection);
@@ -17,3 +18,4 @@ private:
     MYSQL* con;
     bool opened;
 };
+}

database/pool.cpp

@@ -0,0 +1,57 @@
+//  SPDX-FileCopyrightText: 2023 Yury Gubich <blue@macaw.me>
+//  SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "pool.h"
+
+DB::Pool::Pool (Private):
+    std::enable_shared_from_this<Pool>(),
+    mutex(),
+    conditional(),
+    interfaces()
+{}
+
+DB::Pool::~Pool () {
+}
+
+std::shared_ptr<DB::Pool> DB::Pool::create () {
+    return std::make_shared<Pool>(Private());
+}
+
+void DB::Pool::addInterfaces (
+    Interface::Type type,
+    std::size_t amount,
+    const std::string & login,
+    const std::string & password,
+    const std::string & database,
+    const std::string& path
+) {
+    std::unique_lock lock(mutex);
+    for (std::size_t i = 0; i < amount; ++i) {
+        const std::unique_ptr<Interface>& ref = interfaces.emplace(Interface::create(type));
+        ref->setCredentials(login, password);
+        ref->setDatabase(database);
+        ref->connect(path);
+    }
+
+    lock.unlock();
+    conditional.notify_all();
+}
+
+DB::Resource DB::Pool::request () {
+    std::unique_lock lock(mutex);
+    while (interfaces.empty())
+        conditional.wait(lock);
+
+    std::unique_ptr<Interface> interface = std::move(interfaces.front());
+    interfaces.pop();
+    return Resource(std::move(interface), shared_from_this());
+}
+
+void DB::Pool::free (std::unique_ptr<Interface> interface) {
+    std::unique_lock lock(mutex);
+
+    interfaces.push(std::move(interface));
+
+    lock.unlock();
+    conditional.notify_one();
+}

database/pool.h

@@ -0,0 +1,47 @@
+//  SPDX-FileCopyrightText: 2023 Yury Gubich <blue@macaw.me>
+//  SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <string>
+#include <memory>
+#include <queue>
+#include <mutex>
+#include <condition_variable>
+
+#include "interface.h"
+#include "resource.h"
+
+namespace DB {
+class Pool : public std::enable_shared_from_this<Pool> {
+    struct Private {};
+    friend class Resource;
+
+    void free(std::unique_ptr<Interface> interface);
+
+public:
+    Pool(Private);
+    Pool(const Pool&) = delete;
+    Pool(Pool&&) = delete;
+    ~Pool();
+    Pool& operator = (const Pool&) = delete;
+    Pool& operator = (Pool&&) = delete;
+
+    static std::shared_ptr<Pool> create();
+    Resource request();
+    void addInterfaces(
+        Interface::Type type,
+        std::size_t amount,
+        const std::string& login,
+        const std::string& password,
+        const std::string& database,
+        const std::string& path
+    );
+
+private:
+    std::mutex mutex;
+    std::condition_variable conditional;
+    std::queue<std::unique_ptr<Interface>> interfaces;
+
+};
+}

database/resource.cpp

@@ -0,0 +1,38 @@
+//  SPDX-FileCopyrightText: 2023 Yury Gubich <blue@macaw.me>
+//  SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "resource.h"
+
+#include "pool.h"
+
+DB::Resource::Resource (
+    std::unique_ptr<Interface> interface,
+    std::weak_ptr<Pool> parent
+):
+    parent(parent),
+    interface(std::move(interface))
+{}
+
+DB::Resource::Resource(Resource&& other):
+    parent(other.parent),
+    interface(std::move(other.interface))
+{}
+
+DB::Resource::~Resource() {
+    if (!interface)
+        return;
+
+    if (std::shared_ptr<Pool> p = parent.lock())
+        p->free(std::move(interface));
+}
+
+DB::Resource& DB::Resource::operator = (Resource&& other) {
+    parent = other.parent;
+    interface = std::move(other.interface);
+
+    return *this;
+}
+
+DB::Interface* DB::Resource::operator -> () {
+    return interface.get();
+}

database/resource.h

@@ -0,0 +1,31 @@
+//  SPDX-FileCopyrightText: 2023 Yury Gubich <blue@macaw.me>
+//  SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <memory>
+
+#include "interface.h"
+
+namespace DB {
+class Pool;
+
+class Resource {
+    friend class Pool;
+    Resource(std::unique_ptr<Interface> interface, std::weak_ptr<Pool> parent);
+
+public:
+    Resource(const Resource&) = delete;
+    Resource(Resource&& other);
+    ~Resource();
+
+    Resource& operator = (const Resource&) = delete;
+    Resource& operator = (Resource&& other);
+
+    Interface* operator -> ();
+
+private:
+    std::weak_ptr<Pool> parent;
+    std::unique_ptr<Interface> interface;
+};
+}

handler/login.cpp

@@ -32,7 +32,7 @@ void Handler::Login::handle(Request& request) {
     bool success = false;
     try {
         success = server->validatePassword(login, password);
-    } catch (const DBInterface::NoLogin& e) {
+    } catch (const DB::NoLogin& e) {
         std::cerr << "Exception on logging in:\n\t" << e.what() << std::endl;
         return error(request, Result::wrongCredentials, Response::Status::badRequest);
     } catch (const std::exception& e) {

handler/register.cpp

@@ -35,7 +35,7 @@ void Handler::Register::handle(Request& request) {
 
     try {
         server->registerAccount(login, password);
-    } catch (const DBInterface::DuplicateLogin& e) {
+    } catch (const DB::DuplicateLogin& e) {
         std::cerr << "Exception on registration:\n\t" << e.what() << std::endl;
         return error(request, Result::loginExists, Response::Status::conflict);
     } catch (const std::exception& e) {

request/CMakeLists.txt

@@ -1,10 +1,13 @@
 set(HEADERS
     request.h
+    redirect.h
+
     redirectable.h
 )
 
 set(SOURCES
     request.cpp
+    redirect.cpp
 )
 
 target_sources(pica PRIVATE ${SOURCES})

request/accepting.h

@@ -9,5 +9,6 @@
 
 class Accepting {
 public:
+    virtual ~Accepting() {};
     virtual void accept(std::unique_ptr<Request> request) = 0;
 };

server/server.cpp

@@ -13,6 +13,11 @@
 #include "handler/login.h"
 
 constexpr const char* pepper = "well, not much of a secret, huh?";
+constexpr const char* dbLogin = "pica";
+constexpr const char* dbPassword = "pica";
+constexpr const char* dbName = "pica";
+constexpr const char* dbPath = "/run/mysqld/mysqld.sock";
+constexpr uint8_t dbConnectionsCount = 4;
 
 constexpr const char* randomChars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
 constexpr uint8_t saltSize = 16;
@@ -28,18 +33,22 @@ Server::Server():
     requestCount(0),
     serverName(std::nullopt),
     router(),
-    db(),
+    pool(DB::Pool::create()),
     sessions()
 {
     std::cout << "Startig pica..." << std::endl;
-
-    db = DBInterface::create(DBInterface::Type::mysql);
     std::cout << "Database type: MySQL" << std::endl;
+    pool->addInterfaces(
+        DB::Interface::Type::mysql,
+        dbConnectionsCount,
+        dbLogin,
+        dbPassword,
+        dbName,
+        dbPath
+    );
 
-    db->setCredentials("pica", "pica");
-    db->setDatabase("pica");
+    DB::Resource db = pool->request();
 
-    db->connect("/run/mysqld/mysqld.sock");
     db->migrate(currentDbVesion);
 
     router.addRoute(std::make_unique<Handler::Info>());
@@ -112,10 +121,12 @@ unsigned int Server::registerAccount(const std::string& login, const std::string
     if (result != ARGON2_OK)
         throw std::runtime_error(std::string("Hashing failed: ") + argon2_error_message(result));
 
+    DB::Resource db = pool->request();
     return db->registerAccount(login, hash);
 }
 
 bool Server::validatePassword(const std::string& login, const std::string& password) {
+    DB::Resource db = pool->request();
     std::string hash = db->getAccountHash(login);
 
     std::string spiced = password + pepper;
@@ -139,9 +150,10 @@ Session& Server::openSession(const std::string& login) {
         try {
             accessToken = generateRandomString(32);
             renewToken = generateRandomString(32);
+            DB::Resource db = pool->request();
             sessionId = db->createSession(login, accessToken, renewToken);
             break;
-        } catch (const DBInterface::Duplicate& e) {
+        } catch (const DB::Duplicate& e) {
             std::cout << "Duplicate on creating session, trying again with different tokens";
         }
     } while (--counter != 0);

server/server.h

@@ -22,7 +22,7 @@
 #include "response/response.h"
 #include "router.h"
 #include "session.h"
-#include "database/dbinterface.h"
+#include "database/pool.h"
 #include "utils/helpers.h"
 #include "config.h"
 
@@ -49,6 +49,6 @@ private:
     uint64_t requestCount;
     std::optional<std::string> serverName;
     Router router;
-    std::unique_ptr<DBInterface> db;
+    std::shared_ptr<DB::Pool> pool;
     Sessions sessions;
 };

server/session.h

@@ -10,6 +10,10 @@
 class Session : public Accepting {
 public:
     Session(unsigned int id, const std::string& access, const std::string& renew);
+    Session(const Session&) = delete;
+    Session(Session&& other);
+    Session& operator = (const Session&) = delete;
+    Session& operator = (Session&& other);
 
     std::string getAccessToken() const;
     std::string getRenewToken() const;