EventLoop.cpp

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/*
 * SNode.C - a slim toolkit for network communication
 * Copyright (C) Volker Christian <me@vchrist.at>
 *               2020, 2021, 2022, 2023, 2024, 2025
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "core/EventLoop.h"
 
#include "core/DynamicLoader.h"
#include "core/EventMultiplexer.h"
 
#ifndef DOXYGEN_SHOULD_SKIP_THIS
 
#include "log/Logger.h"
#include "utils/Config.h"
#include "utils/Timeval.h"
#include "utils/system/signal.h"
 
#include <chrono>
#include <cstring>
 
#endif /* DOXYGEN_SHOULD_SKIP_THIS */
 
namespace core {
 
    int EventLoop::stopsig = 0;
    unsigned long EventLoop::tickCounter = 0;
    core::State EventLoop::eventLoopState = State::LOADED;
 
    static std::string getTickCounterAsString([[maybe_unused]] const el::LogMessage* logMessage) {
        std::string tick = std::to_string(EventLoop::getTickCounter());
 
        if (tick.length() < 13) {
            tick.insert(0, 13 - tick.length(), '0');
        }
 
        return tick;
    }
 
    EventLoop::EventLoop()
        : eventMultiplexer(::EventMultiplexer()) {
    }
 
    EventLoop& EventLoop::instance() {
        static EventLoop eventLoop;
 
        return eventLoop;
    }
 
    unsigned long EventLoop::getTickCounter() {
        return tickCounter;
    }
 
    EventMultiplexer& EventLoop::getEventMultiplexer() {
        return eventMultiplexer;
    }
 
    State EventLoop::getEventLoopState() {
        return eventLoopState;
    }
 
    // NOLINTNEXTLINE(cppcoreguidelines-avoid-c-arrays, hicpp-avoid-c-arrays, modernize-avoid-c-arrays)
    bool EventLoop::init(int argc, char* argv[]) {
        struct sigaction sact{};
        sigemptyset(&sact.sa_mask);
        sact.sa_flags = 0;
        sact.sa_handler = SIG_IGN;
 
        struct sigaction oldPipeAct{};
        sigaction(SIGPIPE, &sact, &oldPipeAct);
 
        struct sigaction oldIntAct{};
        sigaction(SIGINT, &sact, &oldIntAct);
 
        struct sigaction oldTermAct{};
        sigaction(SIGTERM, &sact, &oldTermAct);
 
        struct sigaction oldAlarmAct{};
        sigaction(SIGALRM, &sact, &oldAlarmAct);
 
        struct sigaction oldHupAct{};
        sigaction(SIGHUP, &sact, &oldHupAct);
 
        logger::Logger::setCustomFormatSpec("%tick", core::getTickCounterAsString);
 
        if (utils::Config::init(argc, argv)) {
            eventLoopState = State::INITIALIZED;
 
            LOG(TRACE) << "SNode.C: Starting ... HELLO";
        }
 
        sigaction(SIGPIPE, &oldPipeAct, nullptr);
        sigaction(SIGINT, &oldIntAct, nullptr);
        sigaction(SIGTERM, &oldTermAct, nullptr);
        sigaction(SIGALRM, &oldAlarmAct, nullptr);
        sigaction(SIGHUP, &oldHupAct, nullptr);
 
        return eventLoopState == State::INITIALIZED;
    }
 
    TickStatus EventLoop::_tick(const utils::Timeval& tickTimeOut) {
        TickStatus tickStatus = TickStatus::SUCCESS;
 
        tickCounter++;
 
        sigset_t newSet{};
        sigaddset(&newSet, SIGINT);
        sigaddset(&newSet, SIGTERM);
        sigaddset(&newSet, SIGALRM);
        sigaddset(&newSet, SIGHUP);
 
        sigset_t oldSet{};
        sigprocmask(SIG_BLOCK, &newSet, &oldSet);
 
        if (eventLoopState == State::RUNNING || eventLoopState == State::STOPPING) {
            tickStatus = eventMultiplexer.tick(tickTimeOut, oldSet);
        }
 
        sigprocmask(SIG_SETMASK, &oldSet, nullptr);
 
        return tickStatus;
    }
 
    TickStatus EventLoop::tick(const utils::Timeval& timeOut) {
        TickStatus tickStatus = TickStatus::TRACE;
 
        if (eventLoopState == State::INITIALIZED) {
            struct sigaction sact{};
            sigemptyset(&sact.sa_mask);
            sact.sa_flags = 0;
            sact.sa_handler = SIG_IGN;
 
            struct sigaction oldPipeAct{};
            sigaction(SIGPIPE, &sact, &oldPipeAct);
 
            tickStatus = EventLoop::instance()._tick(timeOut);
 
            sigaction(SIGPIPE, &oldPipeAct, nullptr);
        } else {
            EventLoop::instance().eventMultiplexer.clearEventQueue();
            free();
 
            PLOG(FATAL) << "Core: not initialized: No events will be processed\nCall SNodeC::init(argc, argv) before SNodeC::tick().";
        }
 
        return tickStatus;
    }
 
    int EventLoop::start(const utils::Timeval& timeOut) {
        struct sigaction sact{};
        sigemptyset(&sact.sa_mask);
        sact.sa_flags = 0;
        sact.sa_handler = SIG_IGN;
 
        struct sigaction oldPipeAct{};
        sigaction(SIGPIPE, &sact, &oldPipeAct);
 
        sact.sa_handler = EventLoop::stoponsig;
 
        struct sigaction oldIntAct{};
        sigaction(SIGINT, &sact, &oldIntAct);
 
        struct sigaction oldTermAct{};
        sigaction(SIGTERM, &sact, &oldTermAct);
 
        struct sigaction oldAlarmAct{};
        sigaction(SIGALRM, &sact, &oldAlarmAct);
 
        struct sigaction oldHupAct{};
        sigaction(SIGHUP, &sact, &oldHupAct);
 
        if (eventLoopState == State::INITIALIZED && utils::Config::bootstrap()) {
            eventLoopState = State::RUNNING;
            core::TickStatus tickStatus = TickStatus::SUCCESS;
 
            LOG(TRACE) << "Core::EventLoop: started";
 
            do {
                tickStatus = EventLoop::instance()._tick(timeOut);
            } while ((tickStatus == TickStatus::SUCCESS || tickStatus == TickStatus::INTERRUPTED) && eventLoopState == State::RUNNING);
 
            switch (tickStatus) {
                case TickStatus::SUCCESS:
                    LOG(TRACE) << "Core::EventLoop: Stopped";
                    break;
                case TickStatus::NOOBSERVER:
                    LOG(TRACE) << "Core::EventLoop: No Observer";
                    break;
                case TickStatus::INTERRUPTED:
                    LOG(TRACE) << "Core::EventLoop: Interrupted";
                    break;
                case TickStatus::TRACE:
                    PLOG(FATAL) << "Core::EventLoop: _tick()";
                    break;
            }
        }
 
        sigaction(SIGPIPE, &oldPipeAct, nullptr);
        sigaction(SIGTERM, &oldTermAct, nullptr);
        sigaction(SIGALRM, &oldAlarmAct, nullptr);
        sigaction(SIGHUP, &oldHupAct, nullptr);
 
        free();
 
        sigaction(SIGINT, &oldIntAct, nullptr);
 
        return stopsig;
    }
 
    void EventLoop::stop() {
        eventLoopState = State::STOPPING;
    }
 
    void EventLoop::free() {
        std::string signal = "SIG" + utils::system::sigabbrev_np(stopsig);
 
        if (signal == "SIGUNKNOWN") {
            signal = std::to_string(stopsig);
        }
 
        if (stopsig != 0) {
            LOG(TRACE) << "Core: Sending signal " << signal << " to all DescriptorEventReceivers";
 
            EventLoop::instance().eventMultiplexer.signal(stopsig);
        }
 
        eventLoopState = State::STOPPING;
 
        utils::Timeval timeout = 2;
 
        core::TickStatus tickStatus = TickStatus::SUCCESS;
        do {
            auto t1 = std::chrono::system_clock::now();
            const utils::Timeval timeoutOp = timeout;
 
            tickStatus = EventLoop::instance()._tick(timeoutOp);
 
            auto t2 = std::chrono::system_clock::now();
            const std::chrono::duration<double> seconds = t2 - t1;
 
            timeout -= seconds.count();
        } while (timeout > 0 && (tickStatus == TickStatus::SUCCESS));
 
        LOG(TRACE) << "Core: Terminate all stalled DescriptorEventReceivers";
 
        EventLoop::instance().eventMultiplexer.terminate();
 
        LOG(TRACE) << "Core: Close all libraries opened during runtime";
 
        DynamicLoader::execDlCloseAll();
 
        LOG(TRACE) << "Core:: Clean up the filesystem";
 
        utils::Config::terminate();
 
        LOG(TRACE) << "Core:: All resources released";
 
        LOG(TRACE) << "SNode.C: Ended ... BYE";
    }
 
    void EventLoop::stoponsig(int sig) {
        LOG(TRACE) << "Core: Received signal '" << strsignal(sig) << "' (SIG" << utils::system::sigabbrev_np(sig) << " = " << sig << ")";
        stopsig = sig;
        stop();
    }
 
} // namespace core