CAmSocketHandler.cpp

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#include <cassert>
#include <sys/fcntl.h>
#include <sys/errno.h>
#include <sys/poll.h>
#include <time.h>
#include <algorithm>
#include <features.h>
#include <csignal>
#include <unistd.h>

#include "CAmDltWrapper.h"
#include "CAmSocketHandler.h"

#ifdef WITH_TIMERFD
#include <sys/timerfd.h>
#endif

namespace am
{

CAmSocketHandler::CAmSocketHandler() :
        mPipe(), //
                mDispatchDone(true), //
                mSetPollKeys(MAX_POLLHANDLE), //
                mListPoll(), //
                mSetTimerKeys(MAX_TIMERHANDLE),
                mListTimer(), //
                mListActiveTimer(), //
                mSetSignalhandlerKeys(MAX_POLLHANDLE), //
                mSignalHandlers(), //
                mRecreatePollfds(true),
                mInternalCodes(internal_codes_e::NO_ERROR),
                mSignalFdHandle(0)
#ifndef WITH_TIMERFD
,mStartTime() //
#endif
{
    if (pipe(mPipe) == -1)
    {
        mInternalCodes = internal_codes_e::PIPE_ERROR;
        logError("Sockethandler could not create pipe!");
    }

    //add the pipe to the poll - nothing needs to be processed here we just need the pipe to trigger the ppoll
    short event = 0;
    sh_pollHandle_t handle;
    event |= POLLIN;
    if (addFDPoll(mPipe[0], event, NULL,
                [](const pollfd, const sh_pollHandle_t, void*){},
                [](const sh_pollHandle_t, void*) { return (false); },
            NULL, NULL, handle) != E_OK)
    {
        mInternalCodes |= internal_codes_e::FD_ERROR;
    }
}

CAmSocketHandler::~CAmSocketHandler()
{
    for (auto it : mListPoll)
    {
        close(it.pollfdValue.fd);
    }
    close(mPipe[0]);
    close(mPipe[1]);
}

//todo: maybe have some: give me more time returned?
void CAmSocketHandler::start_listenting()
{
    mDispatchDone = false;
    int16_t pollStatus;

#ifndef WITH_TIMERFD 
    clock_gettime(CLOCK_MONOTONIC, &mStartTime);
#endif    
    timespec buffertime;
    
    VectorListPoll_t cloneListPoll;
    VectorListPoll_t::iterator listmPollIt;
    VectorListPollfd_t fdPollingArray; 
    
    auto preparePollfd = [&](const sh_poll_s& row)
    {
        CAmSocketHandler::prepare((sh_poll_s&)row);
        pollfd temp = row.pollfdValue;
        temp.revents = 0;
        fdPollingArray.push_back(temp);
    };

    while (!mDispatchDone)
    {
        if (mRecreatePollfds)
        {
            fdPollingArray.clear();
            //freeze mListPoll by copying it - otherwise we get problems when we want to manipulate it during the next lines
            cloneListPoll = mListPoll;
            //there was a change in the setup, so we need to recreate the fdarray from the list
            std::for_each(cloneListPoll.begin(), cloneListPoll.end(), preparePollfd);
            mRecreatePollfds = false;
        }
        else
        {
            //first we go through the registered filedescriptors and check if someone needs preparation:
            std::for_each(cloneListPoll.begin(), cloneListPoll.end(), CAmSocketHandler::prepare);
        }

#ifndef WITH_TIMERFD
        timerCorrection();
#endif
        //block until something is on a filedescriptor

        if ((pollStatus = ppoll(&fdPollingArray[0], fdPollingArray.size(), insertTime(buffertime), NULL)) < 0)
        {
            if (errno == EINTR)
            {
                //a signal was received, that means it's time to go...
                pollStatus = 0;
            }
            else
            {
                logError("SocketHandler::start_listenting ppoll returned with error", errno);
                throw std::runtime_error(std::string("SocketHandler::start_listenting ppoll returned with error."));
            }
        }

        if (pollStatus != 0) //only check filedescriptors if there was a change
        {
            std::list<sh_poll_s> listPoll;
            //todo: here could be a timer that makes sure naughty plugins return!
            //stage 0+1, call firedCB
            listmPollIt = cloneListPoll.begin();
            for (auto it : fdPollingArray)
            {
                if (CAmSocketHandler::eventFired(it))
                {
                    listmPollIt->pollfdValue.revents = it.revents;
                    listPoll.push_back(*listmPollIt);
                    CAmSocketHandler::fire(*listmPollIt);
                }
                else
                {
                    listmPollIt->pollfdValue.revents = 0;
                }
                listmPollIt++;
            }
            
            //stage 2, lets ask around if some dispatching is necessary, the ones who need stay on the list
            listPoll.remove_if(CAmSocketHandler::noDispatching);

            //stage 3, the ones left need to dispatch, we do this as long as there is something to dispatch..
            do
            {
                listPoll.remove_if(CAmSocketHandler::dispatchingFinished);
            } while (!listPoll.empty());

        }
#ifndef WITH_TIMERFD
        else //Timerevent
        {
            //this was a timer event, we need to take care about the timers
            //find out the timedifference to starttime
            timerUp();
        }
#endif
    }
}

void CAmSocketHandler::stop_listening()
{
    mDispatchDone = true;
#ifndef WITH_TIMERFD
    //this is for all running timers only - we need to handle the additional offset here
    if (!mListActiveTimer.empty())
    {
        timespec currentTime, correctionTime;
        clock_gettime(CLOCK_MONOTONIC, &currentTime);
        correctionTime = timespecSub(currentTime, mStartTime);
        std::for_each(mListActiveTimer.begin(), mListActiveTimer.end(), [&correctionTime](sh_timer_s& t)
                {   t.countdown = timespecSub(t.countdown, correctionTime);});
    }
#endif
}

void CAmSocketHandler::exit_mainloop()
{
    //end the while loop
    stop_listening();

    //fire the ending filedescriptor
    int p(1);
    ssize_t result = write(mPipe[1], &p, sizeof(p));
}

bool CAmSocketHandler::fatalErrorOccurred() 
{ 
    return ((mInternalCodes&internal_codes_e::PIPE_ERROR)>0)||((mInternalCodes&internal_codes_e::FD_ERROR)>0); 
}

am_Error_e CAmSocketHandler::getFDPollData(const sh_pollHandle_t handle, sh_poll_s & outPollData)
{
    VectorListPoll_t::iterator iterator = mListPoll.begin();
    for (; iterator != mListPoll.end(); ++iterator)
    {
        if (iterator->handle == handle)
        {
            outPollData = *iterator;
            return (E_OK);
        }
    }
    return (E_UNKNOWN);
}

am_Error_e CAmSocketHandler::listenToSignals(const std::vector<uint8_t> & listSignals)
{
    int fdErr;
    uint8_t addedSignals = 0;
    sigset_t sigset;
    
    if(0==listSignals.size())
    {
        logWarning("Empty signal list!");
        return (E_NOT_POSSIBLE);
    }
    
    /* Create a sigset of all the signals that we're interested in */
    fdErr = sigemptyset(&sigset);
    if (fdErr != 0)
    {
        logError("Could not create sigset!");
        return (E_NOT_POSSIBLE);
    }
    
    for(uint8_t itSignal : listSignals)
    {
        fdErr = sigaddset(&sigset, itSignal);
        if (fdErr != 0)
            logWarning("Could not add", itSignal);
        else
          addedSignals++;
    }
    
    if(0==addedSignals)
    {
        logWarning("None of the signals were added!");
        return (E_NOT_POSSIBLE);
    }

    /* We must block the signals in order for signalfd to receive them */
    fdErr = sigprocmask(SIG_BLOCK, &sigset, NULL);
    if (fdErr != 0)
    {
        logError("Could not block signals! They must be blocked in order to receive them!");
        return (E_NOT_POSSIBLE);
    }

    int signalHandlerFd;
    if(mSignalFdHandle)
    {
      sh_poll_s sgPollData;
      if(E_OK!=getFDPollData(mSignalFdHandle, sgPollData))
      {
         removeFDPoll(mSignalFdHandle);
         mSignalFdHandle = 0;
      }
      else 
      {
        int signalHandlerFd = signalfd(sgPollData.pollfdValue.fd, &sigset, 0);
        if (signalHandlerFd == -1)
        {
            logError("Could not update signal fd!");
            return (E_NOT_POSSIBLE);
        }
        return E_OK;
      }
    }
    
    if(0==mSignalFdHandle)
    {
      /* Create the signalfd */
      signalHandlerFd = signalfd(-1, &sigset, 0);
      if (signalHandlerFd == -1)
      {
          logError("Could not open signal fd!");
          return (E_NOT_POSSIBLE);
      }

      auto actionPoll = [this](const pollfd pollfd, const sh_pollHandle_t, void*)
      {
          const VectorSignalHandlers_t & signalHandlers = mSignalHandlers;
          /* We have a valid signal, read the info from the fd */
          struct signalfd_siginfo info;
          ssize_t bytes = read(pollfd.fd, &info, sizeof(info));
          assert(bytes == sizeof(info));

          /* Notify all listeners */
          for(auto it: signalHandlers)
          it.callback(it.handle, info, it.userData);
      };
      /* We're going to add the signal fd through addFDPoll. At this point we don't have any signal listeners. */
      am_Error_e shFdError = addFDPoll(signalHandlerFd, POLLIN | POLLERR | POLLHUP, NULL, actionPoll, [](const sh_pollHandle_t, void*)
                                        {   return (false);}, NULL, NULL, mSignalFdHandle);
      return shFdError;
    }    
}

am_Error_e CAmSocketHandler::addFDPoll(const int fd, const short event, std::function<void(const sh_pollHandle_t handle, void* userData)> prepare,
        std::function<void(const pollfd pollfd, const sh_pollHandle_t handle, void* userData)> fired, std::function<bool(const sh_pollHandle_t handle, void* userData)> check,
        std::function<bool(const sh_pollHandle_t handle, void* userData)> dispatch, void* userData, sh_pollHandle_t& handle)
{
    if (!fdIsValid(fd))
        return (E_NON_EXISTENT);

    //create a new handle for the poll
    if (!nextHandle(mSetPollKeys))
    {
        logError("Could not create new polls, too many open!");
        return (E_NOT_POSSIBLE);
    }

    sh_poll_s pollData;
    pollData.pollfdValue.fd = fd;
    pollData.handle = mSetPollKeys.lastUsedID;
    pollData.pollfdValue.events = event;
    pollData.pollfdValue.revents = 0;
    pollData.prepareCB = prepare;
    pollData.firedCB = fired;
    pollData.checkCB = check;
    pollData.dispatchCB = dispatch;
    pollData.userData = userData;
    //add new data to the list
    mListPoll.push_back(pollData);

    mRecreatePollfds = true;

    handle = pollData.handle;
    return (E_OK);

}

am::am_Error_e CAmSocketHandler::addFDPoll(const int fd, const short event, IAmShPollPrepare *prepare, IAmShPollFired *fired, IAmShPollCheck *check, IAmShPollDispatch *dispatch, void *userData, sh_pollHandle_t & handle)
{

    std::function<void(const sh_pollHandle_t handle, void* userData)> prepareCB; //preperation callback
    std::function<void(const pollfd poll, const sh_pollHandle_t handle, void* userData)> firedCB; //fired callback
    std::function<bool(const sh_pollHandle_t handle, void* userData)> checkCB; //check callback
    std::function<bool(const sh_pollHandle_t handle, void* userData)> dispatchCB; //check callback

    if (prepare)
        prepareCB = std::bind(&IAmShPollPrepare::Call, prepare, std::placeholders::_1, std::placeholders::_2);
    if (fired)
        firedCB = std::bind(&IAmShPollFired::Call, fired, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3);
    if (check)
        checkCB = std::bind(&IAmShPollCheck::Call, check, std::placeholders::_1, std::placeholders::_2);
    if (dispatch)
        dispatchCB = std::bind(&IAmShPollDispatch::Call, dispatch, std::placeholders::_1, std::placeholders::_2);

    return addFDPoll(fd, event, prepareCB, firedCB, checkCB, dispatchCB, userData, handle);
}

am_Error_e CAmSocketHandler::removeFDPoll(const sh_pollHandle_t handle)
{
    VectorListPoll_t::iterator iterator = mListPoll.begin();

    for (; iterator != mListPoll.end(); ++iterator)
    {
        if (iterator->handle == handle)
        {
            iterator = mListPoll.erase(iterator);
            mSetPollKeys.pollHandles.erase(handle);
            mRecreatePollfds = true;
            return (E_OK);
        }
    }
    return (E_UNKNOWN);
}

am_Error_e CAmSocketHandler::addSignalHandler(std::function<void(const sh_pollHandle_t handle, const signalfd_siginfo & info, void* userData)> callback, sh_pollHandle_t& handle, void * userData)
{
    if (!nextHandle(mSetSignalhandlerKeys))
    {
        logError("Could not create new polls, too many open!");
        return (E_NOT_POSSIBLE);
    }

    mSignalHandlers.emplace_back();
    mSignalHandlers.back().callback = callback;
    mSignalHandlers.back().handle = mSetSignalhandlerKeys.lastUsedID;
    mSignalHandlers.back().userData = userData;
    handle = mSetSignalhandlerKeys.lastUsedID;

    return E_OK;
}

am_Error_e CAmSocketHandler::removeSignalHandler(const sh_pollHandle_t handle)
{
    VectorSignalHandlers_t::iterator it(mSignalHandlers.begin());
    for (; it != mSignalHandlers.end(); ++it)
    {
        if (it->handle == handle)
        {
            it = mSignalHandlers.erase(it);
            mSetSignalhandlerKeys.pollHandles.erase(handle);
            return (E_OK);
        }
    }
    return (E_UNKNOWN);
}

am_Error_e CAmSocketHandler::addTimer(const timespec & timeouts, IAmShTimerCallBack* callback, sh_timerHandle_t& handle, void * userData, const bool repeats)
{
    assert(callback!=NULL);

    std::function<void(const sh_timerHandle_t handle, void* userData)> callbackFunc;
    callbackFunc = std::bind(&IAmShTimerCallBack::Call, callback, std::placeholders::_1, std::placeholders::_2);

    return addTimer(timeouts, callbackFunc, handle, userData, repeats);
}

am_Error_e CAmSocketHandler::addTimer(const timespec & timeouts, std::function<void(const sh_timerHandle_t handle, void* userData)> callback, sh_timerHandle_t& handle, void * userData, const bool repeats)
{
    assert(!((timeouts.tv_sec == 0) && (timeouts.tv_nsec == 0)));

    mListTimer.emplace_back();
    sh_timer_s & timerItem = mListTimer.back();

#ifndef WITH_TIMERFD 
    //create a new handle for the timer
    if (!nextHandle(mSetTimerKeys))
    {
        logError("Could not create new timers, too many open!");
        mListTimer.pop_back();
        return (E_NOT_POSSIBLE);
    }
    //create a new handle for the timer
    handle = mSetTimerKeys.lastUsedID;

    timerItem.countdown = timeouts;
    timerItem.callback = callback;
    timerItem.userData = userData;

    timerItem.handle = handle;

    //we add here the time difference between startTime and currenttime, because this time will be substracted later on in timecorrection
    timespec currentTime;
    clock_gettime(CLOCK_MONOTONIC, &currentTime);
    if (!mDispatchDone)//the mainloop is started
    timerItem.countdown = timespecAdd(timeouts, timespecSub(currentTime, mStartTime));
    mListTimer.push_back(timerItem);
    mListActiveTimer.push_back(timerItem);
    mListActiveTimer.sort(compareCountdown);
    return (E_OK);

#else   
    timerItem.countdown.it_value = timeouts;
    if (repeats)
        timerItem.countdown.it_interval = timeouts;
    else
    {
        timespec zero;
        zero.tv_sec = 0;
        zero.tv_nsec = 0;
        timerItem.countdown.it_interval = zero;
    }

    timerItem.fd = -1;
    timerItem.userData = userData;
    am_Error_e err = createTimeFD(timerItem.countdown, timerItem.fd);
    if (err != E_OK)
    {
        mListTimer.pop_back();
        return err;
    }

    static auto actionPoll = [](const pollfd pollfd, const sh_pollHandle_t handle, void* userData)
    {
        uint64_t mExpirations;
        if (read(pollfd.fd, &mExpirations, sizeof(uint64_t)) == -1)
        {
            //error received...try again
            read(pollfd.fd, &mExpirations, sizeof(uint64_t));
        }
    };

    err = addFDPoll(timerItem.fd, POLLIN, NULL, actionPoll, [callback](const sh_pollHandle_t handle, void* userData)->bool
    {
        callback(handle, userData);
        return false;
    },
    NULL, userData, handle);
    if (E_OK == err)
    {
        timerItem.handle = handle;
    }
    else
    {
        mListTimer.pop_back();
    }
    return err;
#endif    

}

am_Error_e CAmSocketHandler::removeTimer(const sh_timerHandle_t handle)
{
    assert(handle != 0);

    //stop the current timer
#ifdef WITH_TIMERFD 
    std::list<sh_timer_s>::iterator it = mListTimer.begin();
    for (; it != mListTimer.end(); ++it)
    {
        if (it->handle == handle)
            break;
    }
    if (it == mListTimer.end())
        return (E_NON_EXISTENT);

    close(it->fd);
    mListTimer.erase(it);
    return removeFDPoll(handle);
#else
    stopTimer(handle);
    std::list<sh_timer_s>::iterator it(mListTimer.begin());
    for (; it != mListTimer.end(); ++it)
    {
        if (it->handle == handle)
        {
            it = mListTimer.erase(it);
            mSetTimerKeys.pollHandles.erase(handle);
            return (E_OK);
        }
    }
    return (E_UNKNOWN);
#endif
}

am_Error_e CAmSocketHandler::updateTimer(const sh_timerHandle_t handle, const timespec & timeouts)
{
#ifdef WITH_TIMERFD
    std::list<sh_timer_s>::iterator it = mListTimer.begin();
    for (; it != mListTimer.end(); ++it)
    {
        if (it->handle == handle)
            break;
    }
    if (it == mListTimer.end())
        return (E_NON_EXISTENT);

    if (it->countdown.it_interval.tv_nsec != 0 || it->countdown.it_interval.tv_sec != 0)
        it->countdown.it_interval = timeouts;
    it->countdown.it_value = timeouts;

    if (!fdIsValid(it->fd))
    {
        am_Error_e err = createTimeFD(it->countdown, it->fd);
        if (err != E_OK)
            return err;
    }
    else
    {
        if (timerfd_settime(it->fd, 0, &it->countdown, NULL))
        {
            logError("Failed to set timer duration");
            return E_NOT_POSSIBLE;
        }
    }
#else

    //update the mList ....
    sh_timer_s timerItem;
    std::list<sh_timer_s>::iterator it(mListTimer.begin()), activeIt(mListActiveTimer.begin());
    bool found(false);
    for (; it != mListTimer.end(); ++it)
    {
        if (it->handle == handle)
        {
            it->countdown = timeouts;
            timerItem = *it;
            found = true;
            break;
        }
    }
    if (!found)
    return (E_NON_EXISTENT);

    found = false;

    //we add here the time difference between startTime and currenttime, because this time will be substracted later on in timecorrection
    timespec currentTime, timeoutsCorrected;
    currentTime.tv_nsec=timeoutsCorrected.tv_nsec=0;
    currentTime.tv_sec=timeoutsCorrected.tv_sec=0;
    clock_gettime(CLOCK_MONOTONIC, &currentTime);
    if (!mDispatchDone)//the mainloop is started
    timeoutsCorrected = timespecAdd(timeouts, timespecSub(currentTime, mStartTime));

    for (; activeIt != mListActiveTimer.end(); ++activeIt)
    {
        if (activeIt->handle == handle)
        {
            activeIt->countdown = timeoutsCorrected;
            found = true;
            break;
        }
    }

    if (!found)
    timerItem.countdown = timeoutsCorrected;
    mListActiveTimer.push_back(timerItem);

    mListActiveTimer.sort(compareCountdown);

#endif
    return (E_OK);
}

am_Error_e CAmSocketHandler::restartTimer(const sh_timerHandle_t handle)
{
#ifdef WITH_TIMERFD
    std::list<sh_timer_s>::iterator it = mListTimer.begin();
    for (; it != mListTimer.end(); ++it)
    {
        if (it->handle == handle)
            break;
    }
    if (it == mListTimer.end())
        return (E_NON_EXISTENT);

    if (!fdIsValid(it->fd))
    {
        am_Error_e err = createTimeFD(it->countdown, it->fd);
        if (err != E_OK)
            return err;
    }
    else
    {
        if (timerfd_settime(it->fd, 0, &it->countdown, NULL))
        {
            logError("Failed to set timer duration");
            return E_NOT_POSSIBLE;
        }
    }
#else

    sh_timer_s timerItem; 
    //find the original value
    std::list<sh_timer_s>::iterator it(mListTimer.begin()), activeIt(mListActiveTimer.begin());
    bool found(false);
    for (; it != mListTimer.end(); ++it)
    {
        if (it->handle == handle)
        {
            timerItem = *it;
            found = true;
            break;
        }
    }
    if (!found)
    return (E_NON_EXISTENT);

    found = false;

    //we add here the time difference between startTime and currenttime, because this time will be substracted later on in timecorrection
    timespec currentTime, timeoutsCorrected;
    clock_gettime(CLOCK_MONOTONIC, &currentTime);
    if (!mDispatchDone)//the mainloop is started
    {
        timeoutsCorrected = timespecAdd(timerItem.countdown, timespecSub(currentTime, mStartTime));
        timerItem.countdown = timeoutsCorrected;
    }

    for (; activeIt != mListActiveTimer.end(); ++activeIt)
    {
        if (activeIt->handle == handle)
        {
            activeIt->countdown = timerItem.countdown;
            found = true;
            break;
        }
    }

    if (!found)
    mListActiveTimer.push_back(timerItem);

    mListActiveTimer.sort(compareCountdown);
#endif
    return (E_OK);
}

am_Error_e CAmSocketHandler::stopTimer(const sh_timerHandle_t handle)
{
#ifdef WITH_TIMERFD
    std::list<sh_timer_s>::iterator it = mListTimer.begin();
    for (; it != mListTimer.end(); ++it)
    {
        if (it->handle == handle)
            break;
    }
    if (it == mListTimer.end())
        return (E_NON_EXISTENT);

    itimerspec countdown = it->countdown;
    countdown.it_value.tv_nsec = 0;
    countdown.it_value.tv_sec = 0;

    if (timerfd_settime(it->fd, 0, &countdown, NULL))
    {
        logError("Failed to set timer duration");
        return E_NOT_POSSIBLE;
    }
    return (E_OK);
#else   
    //go through the list and remove the timer with the handle
    std::list<sh_timer_s>::iterator it(mListActiveTimer.begin());
    for (; it != mListActiveTimer.end(); ++it)
    {
        if (it->handle == handle)
        {
            it = mListActiveTimer.erase(it);
            return (E_OK);
        }
    }
    return (E_NON_EXISTENT);
#endif
}

am_Error_e CAmSocketHandler::updateEventFlags(const sh_pollHandle_t handle, const short events)
{
    VectorListPoll_t::iterator iterator = mListPoll.begin();

    for (; iterator != mListPoll.end(); ++iterator)
    {
        if (iterator->handle == handle)
        {
            iterator->pollfdValue.events = events;
            mRecreatePollfds = true;
            return (E_OK);
        }
    }
    return (E_UNKNOWN);
}

bool CAmSocketHandler::fdIsValid(const int fd) const
{
    return (fcntl(fd, F_GETFL) != -1 || errno != EBADF);
}

#ifndef WITH_TIMERFD

void CAmSocketHandler::timerUp()
{
    //find out the timedifference to starttime
    static timespec currentTime, diffTime;
    clock_gettime(CLOCK_MONOTONIC, &currentTime);
    diffTime = timespecSub(currentTime, mStartTime);

    static auto countdownUp = [&](const sh_timer_s& row)->bool
    {
        timespec sub = timespecSub(row.countdown, diffTime);
        if (sub.tv_nsec == 0 && sub.tv_sec == 0)
        return (true);
        return (false);
    };

    //now we need to substract the diffTime from all timers and see if they are up
    std::list<sh_timer_s>::reverse_iterator overflowIter = std::find_if(mListActiveTimer.rbegin(), mListActiveTimer.rend(), countdownUp);

    //copy all fired timers into a list
    std::vector<sh_timer_s> tempList(overflowIter, mListActiveTimer.rend());

    //erase all fired timers
    std::list<sh_timer_s>::iterator it(overflowIter.base());
    mListActiveTimer.erase(mListActiveTimer.begin(), it);

    //call the callbacks for the timers
    std::for_each(tempList.begin(), tempList.end(), CAmSocketHandler::callTimer);
}

void CAmSocketHandler::timerCorrection()
{
    //get the current time and calculate the correction value
    static timespec currentTime, correctionTime;
    clock_gettime(CLOCK_MONOTONIC, &currentTime);
    correctionTime = timespecSub(currentTime, mStartTime);
    mStartTime = currentTime;

    static auto countdownZero = [](const sh_timer_s& row)->bool
    {
        if (row.countdown.tv_nsec == 0 && row.countdown.tv_sec == 0)
        return (true);
        return (false);
    };

    static auto substractTime = [&](sh_timer_s& t)
    {
        t.countdown = timespecSub(t.countdown, correctionTime);
    };

    if (!mListActiveTimer.empty())
    {

        //subtract the correction value from all items in the list
        std::for_each(mListActiveTimer.begin(), mListActiveTimer.end(), substractTime);

        //find the last occurrence of zero -> timer overflowed
        std::list<sh_timer_s>::reverse_iterator overflowIter = std::find_if(mListActiveTimer.rbegin(), mListActiveTimer.rend(), countdownZero);

        //only if a timer overflowed
        if (overflowIter != mListActiveTimer.rend())
        {
            //copy all timers that need to be called to a new list
            std::vector<sh_timer_s> tempList(overflowIter, mListActiveTimer.rend());

            //erase all fired timers
            std::list<sh_timer_s>::iterator it(overflowIter.base());
            mListActiveTimer.erase(mListActiveTimer.begin(), it);

            //call the callbacks for the timers
            std::for_each(tempList.begin(), tempList.end(), CAmSocketHandler::callTimer);
        }
    }
}
#endif

void CAmSocketHandler::prepare(am::CAmSocketHandler::sh_poll_s& row)
{
    if (row.prepareCB)
    {
        try
        {
            row.prepareCB(row.handle, row.userData);
        } catch (std::exception& e)
        {
            logError("Sockethandler: Exception in Preparecallback,caught", e.what());
        }
    }
}

void CAmSocketHandler::fire(sh_poll_s& a)
{
    try
    {
        a.firedCB(a.pollfdValue, a.handle, a.userData);
    } catch (std::exception& e)
    {
        logError("Sockethandler: Exception in Preparecallback,caught", e.what());
    }
}

bool CAmSocketHandler::noDispatching(const sh_poll_s& a)
{
    //remove from list of there is no checkCB
    if (nullptr == a.checkCB)
        return (true);
    return (!a.checkCB(a.handle, a.userData));
}

bool CAmSocketHandler::dispatchingFinished(const sh_poll_s& a)
{
    //remove from list of there is no dispatchCB
    if (nullptr == a.dispatchCB)
        return (true);
    return (!a.dispatchCB(a.handle, a.userData));
}

bool CAmSocketHandler::eventFired(const pollfd& a)
{
    return (a.revents == 0 ? false : true);
}

inline timespec* CAmSocketHandler::insertTime(timespec& buffertime)
{
#ifndef WITH_TIMERFD
    if (!mListActiveTimer.empty())
    {
        buffertime = mListActiveTimer.front().countdown;
        return (&buffertime);
    }
    else
#endif    
    {
        return (NULL);
    }
}

#ifdef WITH_TIMERFD   
am_Error_e CAmSocketHandler::createTimeFD(const itimerspec & timeouts, int & fd)
{
    fd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC);
    if (fd <= 0)
    {
        logError("Failed to create timer");
        return E_NOT_POSSIBLE;
    }

    if (timerfd_settime(fd, 0, &timeouts, NULL))
    {
        logError("Failed to set timer duration");
        return E_NOT_POSSIBLE;
    }
    return E_OK;
}
#endif 

void CAmSocketHandler::callTimer(sh_timer_s& a)
{
    try
    {
        a.callback(a.handle, a.userData);
    } catch (std::exception& e)
    {
        logError("Sockethandler: Exception in Timercallback,caught", e.what());
    }
}

bool CAmSocketHandler::nextHandle(sh_identifier_s & handle)
{
    //create a new handle for the poll
    const sh_pollHandle_t lastHandle(handle.lastUsedID);
    do
    {
        ++handle.lastUsedID;
        if (handle.lastUsedID == handle.limit)
        {
            handle.lastUsedID = 1;
        }
        if (handle.lastUsedID == lastHandle)
        {
            logError("Could not create new polls, too many open!");
            return (false);
        }

    } while (handle.pollHandles.find(handle.lastUsedID) != handle.pollHandles.end());

    handle.pollHandles.insert(handle.lastUsedID);

    return (true);
}

}