premiere-libtorrent/include/libtorrent/alert.hpp

/*

Copyright (c) 2003-2016, Arvid Norberg, Daniel Wallin
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#ifndef TORRENT_ALERT_HPP_INCLUDED
#define TORRENT_ALERT_HPP_INCLUDED

#include <string>

// OVERVIEW
//
// The pop_alerts() function on session is the main interface for retrieving
// alerts (warnings, messages and errors from libtorrent). If no alerts have
// been posted by libtorrent pop_alerts() will return an empty list.
// 
// By default, only errors are reported. settings_pack::alert_mask can be
// used to specify which kinds of events should be reported. The alert mask is
// comprised by bits from the category_t enum.
// 
// Every alert belongs to one or more category. There is a cost associated with
// posting alerts. Only alerts that belong to an enabled category are
// posted. Setting the alert bitmask to 0 will disable all alerts (except those
// that are non-discardable). Alerts that are responses to API calls such as
// save_resume_data() and post_session_stats() are non-discardable and will be
// posted even if their category is disabled.
// 
// There are other alert base classes that some alerts derive from, all the
// alerts that are generated for a specific torrent are derived from
// torrent_alert, and tracker events derive from tracker_alert.
//
// Alerts returned by pop_alerts() are only valid until the next call to
// pop_alerts(). You may not copy an alert object to access it after the next
// call to pop_alerts(). Internal members of alerts also become invalid once
// pop_alerts() is called again.

#include "libtorrent/time.hpp"
#include "libtorrent/config.hpp"

namespace libtorrent {

	// The ``alert`` class is the base class that specific messages are derived from.
	// alert types are not copyable, and cannot be constructed by the client. The
	// pointers returned by libtorrent are short lived (the details are described
	// under session_handle::pop_alerts())
	class TORRENT_EXPORT alert
	{
	public:

		alert(alert const& rhs) = delete;
		alert& operator=(alert const&) = delete;
		alert(alert&& rhs) = default;

#ifndef TORRENT_NO_DEPRECATE
		// only here for backwards compatibility
		enum severity_t { debug, info, warning, critical, fatal, none };
#endif

		// these are bits for the alert_mask used by the session. See
		// settings_pack::alert_mask.
		enum category_t
		{
			// Enables alerts that report an error. This includes:
			// 
			// * tracker errors
			// * tracker warnings
			// * file errors
			// * resume data failures
			// * web seed errors
			// * .torrent files errors
			// * listen socket errors
			// * port mapping errors
			error_notification            = 0x1,

			// Enables alerts when peers send invalid requests, get banned or
			// snubbed.
			peer_notification             = 0x2,

			// Enables alerts for port mapping events. For NAT-PMP and UPnP.
			port_mapping_notification     = 0x4,

			// Enables alerts for events related to the storage. File errors and
			// synchronization events for moving the storage, renaming files etc.
			storage_notification          = 0x8,

			// Enables all tracker events. Includes announcing to trackers,
			// receiving responses, warnings and errors.
			tracker_notification          = 0x10,

			// Low level alerts for when peers are connected and disconnected.
			debug_notification            = 0x20,

			// Enables alerts for when a torrent or the session changes state.
			status_notification           = 0x40,

			// Alerts for when blocks are requested and completed. Also when
			// pieces are completed.
			progress_notification         = 0x80,

			// Alerts when a peer is blocked by the ip blocker or port blocker.
			ip_block_notification         = 0x100,

			// Alerts when some limit is reached that might limit the download
			// or upload rate.
			performance_warning           = 0x200,

			// Alerts on events in the DHT node. For incoming searches or
			// bootstrapping being done etc.
			dht_notification              = 0x400,

			// If you enable these alerts, you will receive a stats_alert
			// approximately once every second, for every active torrent.
			// These alerts contain all statistics counters for the interval since
			// the lasts stats alert.
			stats_notification            = 0x800,

#ifndef TORRENT_NO_DEPRECATE
			// Alerts on RSS related events, like feeds being updated, feed error
			// conditions and successful RSS feed updates. Enabling this categoty
			// will make you receive rss_alert alerts.
			rss_notification              = 0x1000,
#endif

			// Enables debug logging alerts. These are available unless libtorrent
			// was built with logging disabled (``TORRENT_DISABLE_LOGGING``). The
			// alerts being posted are log_alert and are session wide.
			session_log_notification      = 0x2000,

			// Enables debug logging alerts for torrents. These are available
			// unless libtorrent was built with logging disabled
			// (``TORRENT_DISABLE_LOGGING``). The alerts being posted are
			// torrent_log_alert and are torrent wide debug events.
			torrent_log_notification      = 0x4000,

			// Enables debug logging alerts for peers. These are available unless
			// libtorrent was built with logging disabled
			// (``TORRENT_DISABLE_LOGGING``). The alerts being posted are
			// peer_log_alert and low-level peer events and messages.
			peer_log_notification         = 0x8000,

			// enables the incoming_request_alert.
			incoming_request_notification = 0x10000,

			// enables dht_log_alert, debug logging for the DHT
			dht_log_notification          = 0x20000,

			// enable events from pure dht operations not related to torrents
			dht_operation_notification    = 0x40000,

			// enables port mapping log events. This log is useful
			// for debugging the UPnP or NAT-PMP implementation
			port_mapping_log_notification = 0x80000,

			// enables verbose logging from the piece picker.
			picker_log_notification       = 0x100000,

			// The full bitmask, representing all available categories.
			//
			// since the enum is signed, make sure this isn't
			// interpreted as -1. For instance, boost.python
			// does that and fails when assigning it to an
			// unsigned parameter.
			all_categories = 0x7fffffff
		};

		// hidden
		alert();
		// hidden
		virtual ~alert();

		// a timestamp is automatically created in the constructor
		time_point timestamp() const;

		// returns an integer that is unique to this alert type. It can be
		// compared against a specific alert by querying a static constant called ``alert_type``
		// in the alert. It can be used to determine the run-time type of an alert* in
		// order to cast to that alert type and access specific members.
		// 
		// e.g:
		//
		// .. code:: c++
		//
		//	std::vector<alert*> alerts;
		//	ses.pop_alerts(&alerts);
		//	for (alert* i : alerts) {
		//		switch (a->type()) {
		// 
		//			case read_piece_alert::alert_type:
		//			{
		//				read_piece_alert* p = (read_piece_alert*)a;
		//				if (p->ec) {
		//					// read_piece failed
		//					break;
		//				}
		//				// use p
		//				break;
		//			}
		//			case file_renamed_alert::alert_type:
		//			{
		//				// etc...
		//			}
		//		}
		//	}
		virtual int type() const = 0;

		// returns a string literal describing the type of the alert. It does
		// not include any information that might be bundled with the alert.
		virtual char const* what() const = 0;

		// generate a string describing the alert and the information bundled
		// with it. This is mainly intended for debug and development use. It is not suitable
		// to use this for applications that may be localized. Instead, handle each alert
		// type individually and extract and render the information from the alert depending
		// on the locale.
		virtual std::string message() const = 0;

		// returns a bitmask specifying which categories this alert belong to.
		virtual int category() const = 0;

#ifndef TORRENT_NO_DEPRECATE

		// determines whether or not an alert is allowed to be discarded
		// when the alert queue is full. There are a few alerts which may not be discared,
		// since they would break the user contract, such as save_resume_data_alert.
		TORRENT_DEPRECATED
		bool discardable() const { return discardable_impl(); }

		TORRENT_DEPRECATED
		severity_t severity() const { return warning; }

	protected:

		virtual bool discardable_impl() const { return true; }

#endif // TORRENT_NO_DEPRECATE

	private:
		time_point m_timestamp;
	};

// When you get an alert, you can use ``alert_cast<>`` to attempt to cast the
// pointer to a specific alert type, in order to query it for more
// information.
// 
// .. note::
//   ``alert_cast<>`` can only cast to an exact alert type, not a base class
template <class T> T* alert_cast(alert* a)
{
	static_assert(std::is_base_of<alert, T>::value
		, "alert_cast<> can only be used with alert types (deriving from libtorrent::alert)");

	if (a == nullptr) return nullptr;
	if (a->type() == T::alert_type) return static_cast<T*>(a);
	return nullptr;
}
template <class T> T const* alert_cast(alert const* a)
{
	static_assert(std::is_base_of<alert, T>::value
		, "alert_cast<> can only be used with alert types (deriving from libtorrent::alert)");
	if (a == nullptr) return nullptr;
	if (a->type() == T::alert_type) return static_cast<T const*>(a);
	return nullptr;
}

} // namespace libtorrent

#endif // TORRENT_ALERT_HPP_INCLUDED