hydra/src/libhydra/db.hh

#pragma once

#include <pqxx/pqxx>

#include "util.hh"


struct Connection : pqxx::connection
{
    Connection() : pqxx::connection(getFlags()) { };

    std::string getFlags()
    {
        using namespace nix;
        auto s = getEnv("HYDRA_DBI", "dbi:Pg:dbname=hydra;");
        std::string prefix = "dbi:Pg:";
        if (std::string(s, 0, prefix.size()) != prefix)
            throw Error("$HYDRA_DBI does not denote a PostgreSQL database");
        return concatStringsSep(" ", tokenizeString<Strings>(string(s, prefix.size()), ";"));
    }
};


class receiver : public pqxx::notification_receiver
{
    std::experimental::optional<std::string> status;

public:

    receiver(pqxx::connection_base & c, const std::string & channel)
        : pqxx::notification_receiver(c, channel) { }

    void operator() (const std::string & payload, int pid) override
    {
        status = payload;
    };

    std::experimental::optional<std::string> get() {
        auto s = status;
        status = std::experimental::nullopt;
        return s;
    }
};