timer_mgr.cc

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// Copyright (C) 2016-2018 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include <config.h>
#include <asiolink/asio_wrapper.h>
#include <asiolink/io_service.h>
#include <dhcpsrv/dhcpsrv_log.h>
#include <dhcpsrv/timer_mgr.h>
#include <exceptions/exceptions.h>

#include <boost/bind.hpp>

#include <utility>

using namespace isc;
using namespace isc::asiolink;

namespace {

struct TimerInfo {
    asiolink::IntervalTimer interval_timer_;

    asiolink::IntervalTimer::Callback user_callback_;

    long interval_;

    asiolink::IntervalTimer::Mode scheduling_mode_;

    TimerInfo(asiolink::IOService& io_service,
              const asiolink::IntervalTimer::Callback& user_callback,
              const long interval,
              const asiolink::IntervalTimer::Mode& mode)
        : interval_timer_(io_service),
          user_callback_(user_callback),
          interval_(interval),
          scheduling_mode_(mode) { };
};

}

namespace isc {
namespace dhcp {

typedef boost::shared_ptr<TimerInfo> TimerInfoPtr;

typedef std::map<std::string, TimerInfoPtr> TimerInfoMap;


class TimerMgrImpl {
public:

    TimerMgrImpl();

    void setIOService(const IOServicePtr& io_service);

    void registerTimer(const std::string& timer_name,
                       const asiolink::IntervalTimer::Callback& callback,
                       const long interval,
                       const asiolink::IntervalTimer::Mode& scheduling_mode);


    void unregisterTimer(const std::string& timer_name);

    void unregisterTimers();

    bool isTimerRegistered(const std::string& timer_name);

    size_t timersCount() const;

    void setup(const std::string& timer_name);

    void cancel(const std::string& timer_name);

private:

    void timerCallback(const std::string& timer_name);

    asiolink::IOServicePtr io_service_;

    TimerInfoMap registered_timers_;
};

TimerMgrImpl::TimerMgrImpl() :
    io_service_(new IOService()), registered_timers_() {
}

void
TimerMgrImpl::setIOService(const IOServicePtr& io_service) {
    if (!io_service) {
        isc_throw(BadValue, "IO service object must not be null for TimerMgr");
    }
    io_service_ = io_service;
}

void
TimerMgrImpl::registerTimer(const std::string& timer_name,
                            const IntervalTimer::Callback& callback,
                            const long interval,
                            const IntervalTimer::Mode& scheduling_mode) {

    // Timer name must not be empty.
    if (timer_name.empty()) {
        isc_throw(BadValue, "registered timer name must not be empty");
    }

    // Must not register two timers under the same name.
    if (registered_timers_.find(timer_name) != registered_timers_.end()) {
        isc_throw(BadValue, "trying to register duplicate timer '"
                  << timer_name << "'");
    }

    // Create a structure holding the configuration for the timer. It will
    // create the instance if the IntervalTimer. It will also hold the
    // callback, interval and scheduling mode parameters.
    TimerInfoPtr timer_info(new TimerInfo(*io_service_, callback,
                                          interval, scheduling_mode));

    // Actually register the timer.
    registered_timers_.insert(std::pair<std::string, TimerInfoPtr>(timer_name,
                                                                   timer_info));
}

void
TimerMgrImpl::unregisterTimer(const std::string& timer_name) {

    // Find the timer with specified name.
    TimerInfoMap::iterator timer_info_it = registered_timers_.find(timer_name);

    // Check if the timer has been registered.
    if (timer_info_it == registered_timers_.end()) {
        isc_throw(BadValue, "unable to unregister non existing timer '"
                  << timer_name << "'");
    }

    // Cancel any pending asynchronous operation and stop the timer.
    cancel(timer_name);

    // Remove the timer.
    registered_timers_.erase(timer_info_it);
}

void
TimerMgrImpl::unregisterTimers() {
    // Copy the map holding timers configuration. This is required so as
    // we don't cut the branch which we're sitting on when we will be
    // erasing the timers. We're going to iterate over the register timers
    // and remove them with the call to unregisterTimer function. But this
    // function will remove them from the register_timers_ map. If we
    // didn't work on the copy here, our iterator would invalidate. The
    // TimerInfo structure is copyable and since it is using the shared
    // pointers the copy is not expensive. Also this function is called when
    // the process terminates so it is not critical for performance.
    TimerInfoMap registered_timers_copy(registered_timers_);

    // Iterate over the existing timers and unregister them.
    for (TimerInfoMap::iterator timer_info_it = registered_timers_copy.begin();
         timer_info_it != registered_timers_copy.end(); ++timer_info_it) {
        unregisterTimer(timer_info_it->first);
    }
}

bool
TimerMgrImpl::isTimerRegistered(const std::string& timer_name) {
    return (registered_timers_.find(timer_name) != registered_timers_.end());
}

size_t
TimerMgrImpl::timersCount() const {
    return (registered_timers_.size());
}

void
TimerMgrImpl::setup(const std::string& timer_name) {

   // Check if the specified timer exists.
   TimerInfoMap::const_iterator timer_info_it = registered_timers_.find(timer_name);
   if (timer_info_it == registered_timers_.end()) {
       isc_throw(BadValue, "unable to setup timer '" << timer_name << "': "
                 "no such timer registered");
   }

   // Schedule the execution of the timer using the parameters supplied
   // during the registration.
   const TimerInfoPtr& timer_info = timer_info_it->second;
   IntervalTimer::Callback cb = boost::bind(&TimerMgrImpl::timerCallback, this,
                                            timer_name);
   timer_info->interval_timer_.setup(cb, timer_info->interval_,
                                     timer_info->scheduling_mode_);
}

void
TimerMgrImpl::cancel(const std::string& timer_name) {

    // Find the timer of our interest.
    TimerInfoMap::const_iterator timer_info_it = registered_timers_.find(timer_name);
    if (timer_info_it == registered_timers_.end()) {
        isc_throw(BadValue, "unable to cancel timer '" << timer_name << "': "
                  "no such timer registered");
    }
    // Cancel the timer.
    timer_info_it->second->interval_timer_.cancel();
}

void
TimerMgrImpl::timerCallback(const std::string& timer_name) {
    // Find the specified timer setup.
    TimerInfoMap::iterator timer_info_it = registered_timers_.find(timer_name);
    if (timer_info_it != registered_timers_.end()) {

        // Running user-defined operation for the timer. Logging it
        // on the slightly lower debug level as there may be many
        // such traces.
        LOG_DEBUG(dhcpsrv_logger, DHCPSRV_DBG_TRACE_DETAIL,
                  DHCPSRV_TIMERMGR_RUN_TIMER_OPERATION)
            .arg(timer_info_it->first);

        std::string error_string;
        try {
            timer_info_it->second->user_callback_();

        } catch (const std::exception& ex){
            error_string = ex.what();

        } catch (...) {
            error_string = "unknown reason";
        }

        // Exception was thrown. Log an error.
        if (!error_string.empty()) {
            LOG_ERROR(dhcpsrv_logger, DHCPSRV_TIMERMGR_CALLBACK_FAILED)
                .arg(timer_info_it->first)
                .arg(error_string);
        }
    }
}

const TimerMgrPtr&
TimerMgr::instance() {
    static TimerMgrPtr timer_mgr(new TimerMgr());
    return (timer_mgr);
}

TimerMgr::TimerMgr()
    : impl_(new TimerMgrImpl()) {
}

TimerMgr::~TimerMgr() {
    impl_->unregisterTimers();
    delete impl_;
}

void
TimerMgr::registerTimer(const std::string& timer_name,
                        const IntervalTimer::Callback& callback,
                        const long interval,
                        const IntervalTimer::Mode& scheduling_mode) {

    LOG_DEBUG(dhcpsrv_logger, DHCPSRV_DBG_TRACE,
              DHCPSRV_TIMERMGR_REGISTER_TIMER)
        .arg(timer_name)
        .arg(interval);

    impl_->registerTimer(timer_name, callback, interval, scheduling_mode);
}

void
TimerMgr::unregisterTimer(const std::string& timer_name) {

    LOG_DEBUG(dhcpsrv_logger, DHCPSRV_DBG_TRACE,
              DHCPSRV_TIMERMGR_UNREGISTER_TIMER)
        .arg(timer_name);

    impl_->unregisterTimer(timer_name);
}

void
TimerMgr::unregisterTimers() {

    LOG_DEBUG(dhcpsrv_logger, DHCPSRV_DBG_TRACE,
              DHCPSRV_TIMERMGR_UNREGISTER_ALL_TIMERS);

    impl_->unregisterTimers();
}

bool
TimerMgr::isTimerRegistered(const std::string& timer_name) {
    return (impl_->isTimerRegistered(timer_name));
}

size_t
TimerMgr::timersCount() const {
    return (impl_->timersCount());
}

void
TimerMgr::setup(const std::string& timer_name) {

    LOG_DEBUG(dhcpsrv_logger, DHCPSRV_DBG_TRACE,
              DHCPSRV_TIMERMGR_START_TIMER)
        .arg(timer_name);

    impl_->setup(timer_name);
}

void
TimerMgr::cancel(const std::string& timer_name) {

    LOG_DEBUG(dhcpsrv_logger, DHCPSRV_DBG_TRACE,
              DHCPSRV_TIMERMGR_STOP_TIMER)
        .arg(timer_name);

    impl_->cancel(timer_name);
}

void
TimerMgr::setIOService(const IOServicePtr& io_service) {
    impl_->setIOService(io_service);
}


} // end of namespace isc::dhcp
} // end of namespace isc