/*

Copyright (c) 2003-2013, Daniel Wallin

Copyright (c) 2013-2020, Arvid Norberg

Copyright (c) 2015, Steven Siloti

Copyright (c) 2016, 2020, Alden Torres

All rights reserved.

Redistribution and use in source and binary forms, with or without

modification, are permitted provided that the following conditions

are met:

    * Redistributions of source code must retain the above copyright

      notice, this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright

      notice, this list of conditions and the following disclaimer in

      the documentation and/or other materials provided with the distribution.

    * Neither the name of the author nor the names of its

      contributors may be used to endorse or promote products derived

      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

POSSIBILITY OF SUCH DAMAGE.

*/

#include "libtorrent/config.hpp"

#include "libtorrent/aux_/alert_manager.hpp"

#include "libtorrent/alert_types.hpp"

#ifndef TORRENT_DISABLE_EXTENSIONS

#include "libtorrent/extensions.hpp"

#include <memory> // for shared_ptr

#endif

namespace libtorrent {

namespace aux {

  alert_manager::alert_manager(int const queue_limit, alert_category_t const alert_mask)

    : m_alert_mask(alert_mask)

    , m_queue_size_limit(queue_limit)

  {}

  alert_manager::~alert_manager() = default;

  alert* alert_manager::wait_for_alert(time_duration max_wait)

  {

    std::unique_lock<std::recursive_mutex> lock(m_mutex);

    if (!m_alerts[m_generation & 1].empty())

      return m_alerts[m_generation & 1].front();

    // this call can be interrupted prematurely by other signals

    m_condition.wait_for(lock, max_wait);

    if (!m_alerts[m_generation & 1].empty())

      return m_alerts[m_generation & 1].front();

    return nullptr;

  }

  void alert_manager::maybe_notify(alert* a)

  {

    if (m_alerts[m_generation & 1].size() == 1)

    {

      // we just posted to an empty queue. If anyone is waiting for

      // alerts, we need to notify them. Also (potentially) call the

      // user supplied m_notify callback to let the client wake up its

      // message loop to poll for alerts.

      if (m_notify) m_notify();

      // TODO: 2 keep a count of the number of threads waiting. Only if it's

      // > 0 notify them

      m_condition.notify_all();

    }

#ifndef TORRENT_DISABLE_EXTENSIONS

    for (auto& e : m_ses_extensions)

      e->on_alert(a);

#else

    TORRENT_UNUSED(a);

#endif

  }

  void alert_manager::set_notify_function(std::function<void()> const& fun)

  {

    std::unique_lock<std::recursive_mutex> lock(m_mutex);

    m_notify = fun;

    if (!m_alerts[m_generation & 1].empty())

    {

      if (m_notify) m_notify();

    }

  }

#ifndef TORRENT_DISABLE_EXTENSIONS

  void alert_manager::add_extension(std::shared_ptr<plugin> ext)

  {

    m_ses_extensions.push_back(std::move(ext));

  }

#endif

  void alert_manager::get_all(std::vector<alert*>& alerts)

  {

    std::lock_guard<std::recursive_mutex> lock(m_mutex);

    if (m_alerts[m_generation & 1].empty())

    {

      alerts.clear();

      return;

    }

    if (m_dropped.any()) {

      emplace_alert<alerts_dropped_alert>(m_dropped);

      m_dropped.reset();

    }

    m_alerts[m_generation & 1].get_pointers(alerts);

    // swap buffers

    m_generation += 1;

    // clear the one we will start writing to now

    m_alerts[m_generation & 1].clear();

    m_allocations[m_generation & 1].reset(m_generation);

  }

  bool alert_manager::pending() const

  {

    std::lock_guard<std::recursive_mutex> lock(m_mutex);

    return !m_alerts[m_generation & 1].empty();

  }

  int alert_manager::set_alert_queue_size_limit(int queue_size_limit_)

  {

    std::lock_guard<std::recursive_mutex> lock(m_mutex);

    std::swap(m_queue_size_limit, queue_size_limit_);

    return queue_size_limit_;

  }

}

}