coyote/hiredis_wrapper.h

#pragma once

#include <mutex>
#include <string>
#include <memory>
#include <optional>
#include <exception>

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpragmas"
#pragma GCC diagnostic ignored "-Wc99-extensions"
#pragma GCC diagnostic ignored "-Wconversion"
#pragma GCC diagnostic ignored "-Wpedantic"
#include <hiredis.h>
#pragma GCC diagnostic pop

class RedisException : public std::exception {
public:
    RedisException(const char* error_) : error(error_) {}
    RedisException(const char* error_, size_t length) : error(error_, length) {}

    const char* what() const noexcept {
        return this->error.c_str();
    }

    std::string error;
};

using RedisReply = std::unique_ptr<redisReply, decltype(&freeReplyObject)>;

class Redis {
public:
    Redis(const Redis&) = delete;
    Redis operator=(const Redis&) = delete;

    Redis(const std::string& address, int port);
    Redis(const std::string& unix);
    ~Redis();

    template<typename... Args>
    RedisReply command(const char* format, Args... args) {
        std::lock_guard<std::mutex> guard(this->_mutex);
        redisReply* raw_reply = static_cast<redisReply*>(redisCommand(this->_context, format, args...));
        if (!raw_reply) {
            throw RedisException(this->_context->errstr);
        }

        RedisReply reply(raw_reply, freeReplyObject);
        if (reply->type == REDIS_REPLY_ERROR) {
            throw RedisException(reply->str, reply->len);
        }
        return reply;
    }

    void auth(const std::string& username, const std::string& password);
    void auth(const std::string& password);

    time_t ttl(const std::string& key);
    bool expire(const std::string& key, time_t expiry);
    bool expire_nx(const std::string& key, time_t expiry);

    std::optional<std::string> get(const std::string& key);
    void set(const std::string& key, const std::string& value, time_t expiry);

    std::optional<std::string> hget(const std::string& key, const std::string& field);
    void hset(const std::string& key, const std::string& field, const std::string& value);

private:
    redisContext* _context;
    std::mutex _mutex;

    bool _fake_expire_nx = false;
};

extern std::optional<Redis> redis;
void init_redis();