text: /*
  
  Copyright (c) 2003-2016, Arvid Norberg, Daniel Wallin
  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/alert_manager.hpp"
  #include "libtorrent/alert_types.hpp"
  
  #ifndef TORRENT_DISABLE_EXTENSIONS
  #include "libtorrent/extensions.hpp"
  #endif
  
  namespace libtorrent
  {
  
  	alert_manager::alert_manager(int queue_limit, boost::uint32_t alert_mask)
  		: m_alert_mask(alert_mask)
  		, m_queue_size_limit(queue_limit)
  		, m_generation(0)
  	{}
  
  	alert_manager::~alert_manager() {}
  
  	alert* alert_manager::wait_for_alert(time_duration max_wait)
  	{
  		std::unique_lock<std::mutex> lock(m_mutex);
  
  		if (!m_alerts[m_generation].empty())
  			return m_alerts[m_generation].front();
  
  		// this call can be interrupted prematurely by other signals
  		m_condition.wait_for(lock, max_wait);
  		if (!m_alerts[m_generation].empty())
  			return m_alerts[m_generation].front();
  
  		return NULL;
  	}
  
  	void alert_manager::maybe_notify(alert* a, std::unique_lock<std::mutex>& lock)
  	{
  		if (m_alerts[m_generation].size() == 1)
  		{
  			lock.unlock();
  
  			// 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();
  		}
  		else
  		{
  			lock.unlock();
  		}
  
  #ifndef TORRENT_DISABLE_EXTENSIONS
  		for (ses_extension_list_t::iterator i = m_ses_extensions.begin()
  			, end(m_ses_extensions.end()); i != end; ++i)
  		{
  			(*i)->on_alert(a);
  		}
  #else
  		TORRENT_UNUSED(a);
  #endif
  	}
  
  #ifndef TORRENT_NO_DEPRECATE
  
  	bool alert_manager::maybe_dispatch(alert const& a)
  	{
  		if (m_dispatch)
  		{
  			m_dispatch(a.clone());
  			return true;
  		}
  		return false;
  	}
  
  #ifdef __GNUC__
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
  #endif
  
  	void alert_manager::set_dispatch_function(
  		boost::function<void(std::auto_ptr<alert>)> const& fun)
  	{
  		std::unique_lock<std::mutex> lock(m_mutex);
  
  		m_dispatch = fun;
  
  		heterogeneous_queue<alert> storage;
  		m_alerts[m_generation].swap(storage);
  		lock.unlock();
  
  		std::vector<alert*> alerts;
  		storage.get_pointers(alerts);
  
  		for (std::vector<alert*>::iterator i = alerts.begin()
  			, end(alerts.end()); i != end; ++i)
  		{
  			m_dispatch((*i)->clone());
  		}
  	}
  
  #ifdef __GNUC__
  #pragma GCC diagnostic pop
  #endif
  
  #endif
  
  	void alert_manager::set_notify_function(boost::function<void()> const& fun)
  	{
  		std::unique_lock<std::mutex> lock(m_mutex);
  		m_notify = fun;
  		if (!m_alerts[m_generation].empty())
  		{
  			// never call a callback with the lock held!
  			lock.unlock();
  			if (m_notify) m_notify();
  		}
  	}
  
  #ifndef TORRENT_DISABLE_EXTENSIONS
  	void alert_manager::add_extension(boost::shared_ptr<plugin> ext)
  	{
  		m_ses_extensions.push_back(ext);
  	}
  #endif
  
  	void alert_manager::get_all(std::vector<alert*>& alerts)
  	{
  		std::lock_guard<std::mutex> lock(m_mutex);
  
  		alerts.clear();
  		if (m_alerts[m_generation].empty()) return;
  
  		m_alerts[m_generation].get_pointers(alerts);
  
  		// swap buffers
  		m_generation = (m_generation + 1) & 1;
  		// clear the one we will start writing to now
  		m_alerts[m_generation].clear();
  		m_allocations[m_generation].reset();
  	}
  
  	bool alert_manager::pending() const
  	{
  		std::lock_guard<std::mutex> lock(m_mutex);
  		return !m_alerts[m_generation].empty();
  	}
  
  	int alert_manager::set_alert_queue_size_limit(int queue_size_limit_)
  	{
  		std::lock_guard<std::mutex> lock(m_mutex);
  
  		std::swap(m_queue_size_limit, queue_size_limit_);
  		return queue_size_limit_;
  	}
  
  }
  
  