MySQL C 客户端例子（使用Siren）

启动MySQL服务器

docker run --name mysql -e MYSQL_ROOT_PASSWORD=123456 -p 3306:3306 -d mysql

初始化数据库

docker exec -it mysql mysql -uroot -p123456

CREATE DATABASE test CHARACTER SET utf8 COLLATE utf8_general_ci;
use test

CREATE TABLE pairs (
    k VARCHAR(20) NOT NULL,
    v VARCHAR(20) NOT NULL
) ENGINE = InnoDB;

INSERT INTO pairs (k, v) VALUES ("foo", "bar");
quit

客户端代码（mysql_client.cc）

#include <cstdio>
#include <exception>
#include <string>
#include <vector>

#include <fcntl.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netdb.h>
#include <sys/poll.h>

#include <my_global.h>
#include <mysql.h>

#include <siren/async.h>
#include <siren/c_library.h>
#include <siren/elf_hook.h>
#include <siren/loop.h>
#include <siren/scope_guard.h>
#include <siren/utility.h>


#define MYSQLCLIENT_DL_FILE_NAME "libmysqlclient.so"


extern siren::Loop *siren_loop;
extern siren::Async *siren_async;

namespace {

auto elf_hooks = std::make_tuple(
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "open", siren_open),
    siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "read", maybe_siren_read),
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "write", maybe_siren_write),
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "readv", maybe_siren_readv),
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "writev", maybe_siren_writev),
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "lseek", siren_lseek),
    siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "close", maybe_siren_close),
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "usleep", siren_usleep),
    siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "socket", siren_socket),
    siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "getsockopt", siren_getsockopt),
    siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "setsockopt", siren_setsockopt),
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "accept", siren_accept),
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "accept4", siren_accept4),
    siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "connect", siren_connect),
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "recv", siren_recv),
    siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "send", siren_send),
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "recvfrom", siren_recvfrom),
    // siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "sendto", siren_sendto),
    siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "getaddrinfo", siren_getaddrinfo),
    siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "getnameinfo", siren_getnameinfo),
    siren::MakeELFHook(MYSQLCLIENT_DL_FILE_NAME, "poll", siren_poll)
);


class MySQLError
  : public std::exception
{
public:
    explicit MySQLError(MYSQL *mysql) {
        description_ = "MySQLError: ";
        description_ += mysql_error(mysql);
    }

    const char *what() const noexcept override {
        return description_.c_str();
    }

private:
    std::string description_;
};

}


int
real_main(int fiberID)
{
    char buf[1024];
    MYSQL mysql;
    mysql_init(&mysql);

    if (mysql_real_connect(&mysql, "192.168.11.101", "root", "123456", "test", 0, nullptr, 0)
        == nullptr) {
        throw MySQLError(&mysql);
    }

    int result = 1;

    auto scopeGuard = siren::MakeScopeGuard([&] () -> void {
        // 事务支持
        // if (result == 0) {
        //     mysql_commit(&mysql);
        // } else {
        //     mysql_rollback(&mysql);
        // }

        mysql_close(&mysql);
    });

    // 事务支持
    // if (mysql_autocommit(&mysql, 0)) {
    //     throw MySQLError(&mysql);
    // }

    auto query = [&] (const char *tag) -> void {
        // 查
        if (mysql_query(&mysql, "SELECT * FROM pairs")) {
            throw MySQLError(&mysql);
        }

        MYSQL_RES *result = mysql_store_result(&mysql);

        if (result == nullptr) {
            throw MySQLError(&mysql);
        }

        std::printf("[%d] %s: ", fiberID, tag);
        unsigned int numberOfFields = mysql_num_fields(result);

        for (;;) {
            MYSQL_ROW row = mysql_fetch_row(result);

            if (row == nullptr) {
                break;
            }

            for (unsigned int i = 0; i < numberOfFields; ++i) {
                std::printf("%s ", row[i]);
            }

            std::printf("| ");
        }

        std::putchar('\n');
    };

    // 增
    std::snprintf(buf, sizeof(buf), "INSERT INTO pairs (k, v) VALUES ('hello', 'world%d')", fiberID);
    if (mysql_query(&mysql, buf)) {
        throw MySQLError(&mysql);
    }

    query("AFTER INSERT");

    // 改
    std::snprintf(buf, sizeof(buf), "UPDATE pairs SET v = 'kitty%d' WHERE k = 'hello'", fiberID);
    if (mysql_query(&mysql, buf)) {
        throw MySQLError(&mysql);
    }

    query("AFTER UPDATE");

    // 删
    std::snprintf(buf, sizeof(buf), "DELETE FROM pairs WHERE k = 'hello'");
    if (mysql_query(&mysql, buf)) {
        throw MySQLError(&mysql);
    }

    query("AFTER DELETE");
    result = 0;
    return result;
}


int
main()
{
    siren::IterateTuple(elf_hooks, [] (auto &&elf_hook) { elf_hook.toggle(); });
    siren::Loop loop(16 * 1024);
    siren::Async async(&loop);
    siren_loop = &loop;
    siren_async = &async;
    int result;

    for (int i = 0; i < 10; ++i) {
        loop.createFiber([&, i(i)] () {
            result = real_main(i);
        });
    }

    try {
        loop.run();
    } catch (const std::exception &exception) {
        std::fprintf(stderr, "%s\n", exception.what());
        return 1;
    }

    return result;
}

编译运行

g++ -std=c++14 -DUSE_VALGRIND mysql_client.cc -lsiren -pthread -lmysqlclient -ldl && ./a.out