mirror of
https://github.com/matrix-construct/construct
synced 2024-12-25 06:53:58 +01:00
163 lines
5 KiB
C++
163 lines
5 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#define HAVE_IRCD_RUN_H
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// Forward declarations for because ctx.h is included after runlevel.h.
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namespace ircd::ctx
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{
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struct dock;
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}
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/// Library control details and patch-panel. This namespace contains the
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/// current runlevel state for the library and provides callback interfaces
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/// which can be notified for, or augment the behavior of runlevel transitions
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/// (i.e when the lib is being initialized for service or shutting down, etc).
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namespace ircd::run
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{
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enum class level :int;
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template<class> struct barrier;
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struct changed;
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string_view reflect(const enum level &);
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// Access to the current runlevel indicator.
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extern const enum level &level;
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// Access to the desired runlevel. When this differs from the current
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// level, a command to change the runlevel has been given but not all
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// tasks have completed at the current runlevel.
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extern const enum level &chadburn;
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}
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/// The run::level allows all observers to know the coarse state of IRCd and to
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/// react accordingly. This can be used by the embedder of libircd to know
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/// when it's safe to use or delete libircd resources. It is also used
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/// similarly by the library and its modules. Only one runlevel is active at
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/// any time.
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///
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/// * HALT is the off mode. Nothing is/will be running in libircd until
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/// an invocation of ircd::init();
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///
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/// * READY is the state after calling ircd::init(). Leaving READY is done with
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/// the user either calling their ios.run() to start executing tasks or calling
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/// ircd::quit() to HALT again.
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///
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/// * START indicates the daemon is executing its startup procedures. Leaving
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/// the START state occurs internally when there is success or a fatal error.
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///
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/// * RUN is the service mode. Full client and application functionality exists
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/// in this mode. Leaving the RUN mode is done with ircd::quit();
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///
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/// * QUIT indicates the daemon is executing the shutdown procedures. This
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/// will eventually return back to the HALT state.
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///
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/// * FAULT is a special mode indicating something really bad. The exact
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/// details of this mode are ambiguous. Users do not have to handle this.
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///
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enum class ircd::run::level
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:int
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{
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FAULT = -1, ///< Unrecoverable fault.
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HALT = 0, ///< X <-- IRCd Powered off.
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READY = 1, ///< | | Ready for user to run ios event loop.
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START = 2, ///< | | Starting internal subsystems.
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RUN = 3, ///< O | IRCd in service.
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QUIT = 4, ///< >---^ Clean shutdown starting.
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};
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/// An instance of this class registers itself to be called back when
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/// the ircd::run::level has changed. The context for this callback differs
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/// based on the level argument; not all invocations are on an ircd::ctx, etc.
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///
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/// Note: Its destructor will access a list in libircd; after a callback
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/// for a HALT do not unload libircd.so until destructing this object.
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///
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struct ircd::run::changed
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:instance_list<ircd::run::changed>
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{
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using handler_proto = void (const enum level &);
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static const enum level single_sentinel
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{
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std::numeric_limits<std::underlying_type<enum level>::type>::max()
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};
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static ctx::dock dock;
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enum level single
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{
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single_sentinel
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};
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std::function<void ()> handler_one;
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std::function<handler_proto> handler
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{
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[this](const auto &level)
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{
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if(single == single_sentinel || single != level)
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return;
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if(likely(handler_one))
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handler_one();
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}
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};
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/// The handler function will be called back for any run::level change while
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/// this instance remains in scope.
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changed(decltype(handler) function) noexcept
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:handler{std::move(function)}
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{}
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/// The handler function will be called back for the specific run::level
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/// change while this instance remains in scope.
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changed(const enum level &single, decltype(handler_one) function) noexcept
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:single{single}
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,handler_one{std::move(function)}
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{}
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/// Default construction for no-op
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changed() noexcept;
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~changed() noexcept;
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// convenience to wait on the dock for the levels
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static void wait(const std::initializer_list<enum level> &);
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};
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namespace ircd
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{
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template<>
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decltype(run::changed::allocator)
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instance_list<run::changed>::allocator;
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template<>
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decltype(run::changed::list)
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instance_list<run::changed>::list;
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}
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/// Tool to yield a context until the run::level is RUN or QUIT. Once either is
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/// satisfied (or if already satisfied) the run::level is checked to be RUN
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/// otherwise an exception is thrown.
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///
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template<class E>
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struct [[gnu::visibility("internal")]]
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ircd::run::barrier
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{
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template<class... args>
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barrier(args&&... a)
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{
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changed::wait({level::RUN, level::QUIT});
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if(unlikely(level != level::RUN))
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throw E
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{
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std::forward<args>(a)...
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};
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}
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};
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