Peter M. Groen / FlashMQ

/*
This file is part of FlashMQ (https://www.flashmq.org)
Copyright (C) 2021 Wiebe Cazemier

FlashMQ is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, version 3.

FlashMQ is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public
License along with FlashMQ. If not, see <https://www.gnu.org/licenses/>.
*/

#include "logger.h"
#include <ctime>
#include <sstream>
#include <iomanip>
#include <string.h>
#include <functional>

#include "exceptions.h"
#include "utils.h"

Logger *Logger::instance = nullptr;
std::string Logger::logPath = "";

LogLine::LogLine(std::string &&line, bool alsoToStdOut) :
    line(line),
    alsoToStdOut(alsoToStdOut)
{

}

LogLine::LogLine(const char *s, size_t len, bool alsoToStdOut) :
    line(s, len),
    alsoToStdOut(alsoToStdOut)
{

}

LogLine::LogLine() :
    alsoToStdOut(true)
{

}

const char *LogLine::c_str() const
{
    return line.c_str();
}

bool LogLine::alsoLogToStdOut() const
{
    return alsoToStdOut;
}

Logger::Logger()
{
    memset(&linesPending, 1, sizeof(sem_t));
    sem_init(&linesPending, 0, 0);

    auto f = std::bind(&Logger::writeLog, this);
    this->writerThread = std::thread(f, this);

    pthread_t native = this->writerThread.native_handle();
    pthread_setname_np(native, "LogWriter");
}

Logger::~Logger()
{
    if (file)
    {
        fclose(file);
        file = nullptr;
    }

    sem_close(&linesPending);
}

std::string Logger::getLogLevelString(int level) const
{
    switch (level)
    {
    case LOG_NONE:
        return "NONE";
    case LOG_INFO:
        return "INFO";
    case LOG_NOTICE:
        return "NOTICE";
    case LOG_WARNING:
        return "WARNING";
    case LOG_ERR:
        return "ERROR";
    case LOG_DEBUG:
        return "DEBUG";
    case LOG_SUBSCRIBE:
        return "SUBSCRIBE";
    case LOG_UNSUBSCRIBE:
        return "UNSUBSCRIBE";
    default:
        return "UNKNOWN LOG LEVEL";
    }
}

Logger *Logger::getInstance()
{
    if (instance == nullptr)
        instance = new Logger();
    return instance;
}

void Logger::logf(int level, const char *str, ...)
{
    va_list valist;
    va_start(valist, str);
    this->logf(level, str, valist);
    va_end(valist);
}

void Logger::queueReOpen()
{
    reload = true;
    sem_post(&linesPending);
}

void Logger::reOpen()
{
    if (file)
    {
        fclose(file);
        file = nullptr;
    }

    if (logPath.empty())
        return;

    if ((file = fopen(logPath.c_str(), "a")) == nullptr)
    {
        logf(LOG_ERR, "(Re)opening log file '%s' error: %s. Logging to stdout.", logPath.c_str(), strerror(errno));
    }
}

// I want all messages logged during app startup to also show on stdout/err, otherwise failure can look so silent. So, call this when the app started.
void Logger::noLongerLogToStd()
{
    if (!logPath.empty())
        logf(LOG_INFO, "Switching logging from stdout to logfile '%s'", logPath.c_str());
    alsoLogToStd = false;
}

void Logger::setLogPath(const std::string &path)
{
    Logger::logPath = path;
}

void Logger::setFlags(bool logDebug, bool logSubscriptions, bool quiet)
{
    curLogLevel = LOG_ERR | LOG_WARNING | LOG_NOTICE | LOG_INFO | LOG_SUBSCRIBE | LOG_UNSUBSCRIBE ;

    if (logDebug)
        curLogLevel |= LOG_DEBUG;
    else
        curLogLevel &= ~LOG_DEBUG;

    if (logSubscriptions)
        curLogLevel |= (LOG_UNSUBSCRIBE | LOG_SUBSCRIBE);
    else
        curLogLevel &= ~(LOG_UNSUBSCRIBE | LOG_SUBSCRIBE);

    if (!quiet)
        curLogLevel |= (LOG_NOTICE | LOG_INFO);
    else
        curLogLevel &= ~(LOG_NOTICE | LOG_INFO);
}

void Logger::quit()
{
    running = false;
    sem_post(&linesPending);
    writerThread.join();
}

void Logger::writeLog()
{
    LogLine line;
    while(running)
    {
        sem_wait(&linesPending);

        if (reload)
        {
            reOpen();
        }

        {
            std::lock_guard<std::mutex> locker(logMutex);

            if (lines.empty())
                continue;

            line = std::move(lines.front());
            lines.pop();
        }

        if (this->file)
        {
            if (fputs(line.c_str(), this->file) < 0 ||
                fputs("\n", this->file) < 0 ||
                fflush(this->file) != 0)
            {
                alsoLogToStd = true;
                fputs("Writing to log failed. Enabling stdout logger.", stderr);
            }
        }

        if (!this->file || line.alsoLogToStdOut())
        {
            FILE *output = stdout;
#ifdef TESTING
            output = stderr; // the stdout interfers with Qt test XML output, so using stderr.
#endif
            fputs(line.c_str(), output);
            fputs("\n", output);
            fflush(output);
        }
    }
}

void Logger::logf(int level, const char *str, va_list valist)
{
    if ((level & curLogLevel) == 0)
        return;

    time_t time = std::time(nullptr);
    struct tm tm = *std::localtime(&time);
    std::ostringstream oss;

    std::string str_(str);
    oss << "[" << std::put_time(&tm, "%Y-%m-%d %H:%M:%S") << "] [" << getLogLevelString(level) << "] " << str_;
    oss.flush();
    const std::string s = oss.str();
    const char *logfmtstring = s.c_str();

    char buf[512];

    va_list valist2;
    va_copy(valist2, valist);
    vsnprintf(buf, 512, logfmtstring, valist);
    size_t len = strlen(buf);
    LogLine line(buf, len, alsoLogToStd);
    va_end(valist2);

    {
        std::lock_guard<std::mutex> locker(logMutex);
        lines.push(std::move(line));
    }

    sem_post(&linesPending);
}

int logSslError(const char *str, size_t len, void *u)
{
    (void) len;
    (void) u;

    Logger *logger = Logger::getInstance();
    logger->logf(LOG_ERR, str);
    return 0;
}