lix/src/libutil/logging.cc

#include "logging.hh"
#include "util.hh"

#include <atomic>
#include <nlohmann/json.hpp>

namespace nix {

thread_local ActivityId curActivity = 0;

Logger * logger = makeDefaultLogger();

void Logger::warn(const std::string & msg)
{
    log(lvlInfo, ANSI_RED "warning:" ANSI_NORMAL " " + msg);
}

class SimpleLogger : public Logger
{
public:

    bool systemd, tty;

    SimpleLogger()
    {
        systemd = getEnv("IN_SYSTEMD") == "1";
        tty = isatty(STDERR_FILENO);
    }

    void log(Verbosity lvl, const FormatOrString & fs) override
    {
        if (lvl > verbosity) return;

        std::string prefix;

        if (systemd) {
            char c;
            switch (lvl) {
            case lvlError: c = '3'; break;
            case lvlInfo: c = '5'; break;
            case lvlTalkative: case lvlChatty: c = '6'; break;
            default: c = '7';
            }
            prefix = std::string("<") + c + ">";
        }

        writeToStderr(prefix + (tty ? fs.s : filterANSIEscapes(fs.s)) + "\n");
    }

    void startActivity(ActivityId act, Verbosity lvl, ActivityType type,
        const std::string & s, const Fields & fields, ActivityId parent)
    {
        if (lvl <= verbosity && !s.empty())
            log(lvl, s + "...");
    }
};

Verbosity verbosity = lvlInfo;

void warnOnce(bool & haveWarned, const FormatOrString & fs)
{
    if (!haveWarned) {
        warn(fs.s);
        haveWarned = true;
    }
}

void writeToStderr(const string & s)
{
    try {
        writeFull(STDERR_FILENO, s, false);
    } catch (SysError & e) {
        /* Ignore failing writes to stderr.  We need to ignore write
           errors to ensure that cleanup code that logs to stderr runs
           to completion if the other side of stderr has been closed
           unexpectedly. */
    }
}

Logger * makeDefaultLogger()
{
    return new SimpleLogger();
}

std::atomic<uint64_t> nextId{(uint64_t) getpid() << 32};

Activity::Activity(Logger & logger, Verbosity lvl, ActivityType type,
    const std::string & s, const Logger::Fields & fields, ActivityId parent)
    : logger(logger), id(nextId++)
{
    logger.startActivity(id, lvl, type, s, fields, parent);
}

struct JSONLogger : Logger
{
    Logger & prevLogger;

    JSONLogger(Logger & prevLogger) : prevLogger(prevLogger) { }

    void addFields(nlohmann::json & json, const Fields & fields)
    {
        if (fields.empty()) return;
        auto & arr = json["fields"] = nlohmann::json::array();
        for (auto & f : fields)
            if (f.type == Logger::Field::tInt)
                arr.push_back(f.i);
            else if (f.type == Logger::Field::tString)
                arr.push_back(f.s);
            else
                abort();
    }

    void write(const nlohmann::json & json)
    {
        prevLogger.log(lvlError, "@nix " + json.dump());
    }

    void log(Verbosity lvl, const FormatOrString & fs) override
    {
        nlohmann::json json;
        json["action"] = "msg";
        json["level"] = lvl;
        json["msg"] = fs.s;
        write(json);
    }

    void startActivity(ActivityId act, Verbosity lvl, ActivityType type,
        const std::string & s, const Fields & fields, ActivityId parent) override
    {
        nlohmann::json json;
        json["action"] = "start";
        json["id"] = act;
        json["level"] = lvl;
        json["type"] = type;
        json["text"] = s;
        addFields(json, fields);
        // FIXME: handle parent
        write(json);
    }

    void stopActivity(ActivityId act) override
    {
        nlohmann::json json;
        json["action"] = "stop";
        json["id"] = act;
        write(json);
    }

    void result(ActivityId act, ResultType type, const Fields & fields) override
    {
        nlohmann::json json;
        json["action"] = "result";
        json["id"] = act;
        json["type"] = type;
        addFields(json, fields);
        write(json);
    }
};

Logger * makeJSONLogger(Logger & prevLogger)
{
    return new JSONLogger(prevLogger);
}

static Logger::Fields getFields(nlohmann::json & json)
{
    Logger::Fields fields;
    for (auto & f : json) {
        if (f.type() == nlohmann::json::value_t::number_unsigned)
            fields.emplace_back(Logger::Field(f.get<uint64_t>()));
        else if (f.type() == nlohmann::json::value_t::string)
            fields.emplace_back(Logger::Field(f.get<std::string>()));
        else throw Error("unsupported JSON type %d", (int) f.type());
    }
    return fields;
}

bool handleJSONLogMessage(const std::string & msg,
    const Activity & act, std::map<ActivityId, Activity> & activities)
{
    if (!hasPrefix(msg, "@nix ")) return false;

    try {
        auto json = nlohmann::json::parse(std::string(msg, 5));

        std::string action = json["action"];

        if (action == "start") {
            auto type = (ActivityType) json["type"];
            if (type == actDownload || type == actUnknown)
                activities.emplace(std::piecewise_construct,
                    std::forward_as_tuple(json["id"]),
                    std::forward_as_tuple(*logger, (Verbosity) json["level"], type,
                        json["text"], getFields(json["fields"]), act.id));
        }

        else if (action == "stop")
            activities.erase((ActivityId) json["id"]);

        else if (action == "result") {
            auto i = activities.find((ActivityId) json["id"]);
            if (i != activities.end())
                i->second.result((ResultType) json["type"], getFields(json["fields"]));
        }

        else if (action == "setPhase") {
            std::string phase = json["phase"];
            act.result(resSetPhase, phase);
        }

        else if (action == "msg") {
            std::string msg = json["msg"];
            logger->log((Verbosity) json["level"], msg);
        }

    } catch (std::exception & e) {
        printError("bad log message from builder: %s", e.what());
    }

    return true;
}

}