Log.cpp

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/*
 * Copyright (C) 2019-2021 Tobias Flaig.
 *
 * This file is part of nawa.
 *
 * nawa is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License,
 * version 3, as published by the Free Software Foundation.
 *
 * nawa 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with nawa.  If not, see <https://www.gnu.org/licenses/>.
 */
 
#include <atomic>
#include <iomanip>
#include <mutex>
#include <nawa/Exception.h>
#include <nawa/oss.h>
#include <nawa/logging/Log.h>
 
using namespace nawa;
using namespace std;
 
namespace {
    struct DestructionDetector {
        bool destructed = false;
 
        ~DestructionDetector() { destructed = true; }
    } destructionDetector;
 
    bool locked = false;                                
    ostream* out;                                       
    ofstream logFile;                                   
    Log::Level outputLevel = Log::Level::INFORMATIONAL; 
    bool extendedFormat = false;                        
    unique_ptr<string> hostnameStr;
    pid_t pid = 0;
    atomic_uint instanceCount(0);
    mutex outLock;
}// namespace
 
struct Log::Data {
    std::string appname; 
    Level defaultLevel;  
    explicit Data(Level defaultLevel = Level::INFORMATIONAL) : defaultLevel(defaultLevel) {}
};
 
Log::Log() noexcept {
    data = make_unique<Data>(Level::INFORMATIONAL);
 
    if (instanceCount == 0) {
        out = &cerr;
 
        // get hostname
        hostnameStr = make_unique<string>(oss::getSystemHostname());
 
        // get pid
        pid = getpid();
    }
 
    // appname is nawa by default
    data->appname = "nawa";
 
    ++instanceCount;
}
 
Log::Log(string appname, Level level) noexcept : Log() {
    data->appname = move(appname);
    data->defaultLevel = level;
}
 
Log::Log(Level level) noexcept : Log() {
    data->defaultLevel = level;
}
 
Log::Log(Log const& other) noexcept {
    data = make_unique<Data>(*other.data);
    ++instanceCount;
}
 
Log& Log::operator=(Log const& other) noexcept {
    if (this != &other) {
        *data = *other.data;
        ++instanceCount;
    }
    return *this;
}
 
Log::~Log() {
    if (!destructionDetector.destructed) {
        --instanceCount;
        if (instanceCount == 0) {
            if (logFile.is_open()) {
                logFile.close();
            }
            locked = false;
        }
    } else {
        if (logFile.is_open()) {
            logFile.close();
        }
    }
}
 
void Log::setStream(ostream* os) noexcept {
    if (!locked) {
        out = os;
    }
}
 
void Log::setOutfile(string const& filename) {
    if (!locked) {
        if (logFile.is_open()) {
            logFile.close();
        }
        logFile.open(filename, ofstream::out | ofstream::app);
        if (!logFile) {
            throw Exception(__PRETTY_FUNCTION__, 1,
                            "Failed to open requested file for writing.");
        }
        out = &logFile;
    }
}
 
void Log::setOutputLevel(Level level) {
    if (!locked) {
        outputLevel = level;
    }
}
 
void Log::setExtendedFormat(bool useExtendedFormat) {
    if (!locked) {
        extendedFormat = useExtendedFormat;
    }
}
 
void Log::lockStream() noexcept {
    locked = true;
}
 
bool Log::isLocked() noexcept {
    return locked;
}
 
void Log::setAppname(string appname) noexcept {
    data->appname = move(appname);
}
 
void Log::setDefaultLogLevel(Level level) noexcept {
    data->defaultLevel = level;
}
 
void Log::write(string const& msg) {
    write(msg, data->defaultLevel);
}
 
void Log::write(string const& msg, Level level) {
    if (level <= outputLevel && outputLevel != Level::OFF && level != Level::OFF) {
        auto now = time(nullptr);
        lock_guard<mutex> l(outLock);
        if (extendedFormat) {
            *out << put_time(localtime(&now), "%b %d %H:%M:%S ") << *hostnameStr << ' '
                 << oss::getProgramInvocationName() << '[' << pid << "]: ";
        }
        cerr << "[" << data->appname << "] " << msg << endl;
        out->flush();
    }
}
 
void Log::operator()(string const& msg) {
    write(msg, data->defaultLevel);
}
 
void Log::operator()(string const& msg, Level level) {
    write(msg, level);
}