mirror of
https://github.com/matrix-construct/construct
synced 2024-08-26 19:35:17 +02:00
166 lines
5.5 KiB
C++
166 lines
5.5 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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#pragma once
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#define HAVE_IRCD_CTX_THIS_CTX_H
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/// Interface to the currently running context
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namespace ircd::ctx {
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inline namespace this_ctx
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{
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struct ctx &cur() noexcept; ///< Assumptional reference to *current
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const uint64_t &id() noexcept; // Unique ID for cur ctx
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string_view name() noexcept; // Optional label for cur ctx
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ulong cycles() noexcept; // misc profiling related
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bool interruption_requested() noexcept; // interruption(cur())
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void interruption_point(); // throws if interruption_requested()
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void wait(); // Returns when context is woken up.
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void yield(); // Allow other contexts to run before returning.
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// Return remaining time if notified; or <= 0 if not, and timeout thrown on throw overloads
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microseconds wait(const microseconds &, const std::nothrow_t &);
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template<class E, class duration> nothrow_overload<E, duration> wait(const duration &);
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template<class E = timeout, class duration> throw_overload<E, duration> wait(const duration &);
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// Returns false if notified; true if time point reached, timeout thrown on throw_overloads
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bool wait_until(const steady_point &tp, const std::nothrow_t &);
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template<class E> nothrow_overload<E, bool> wait_until(const steady_point &tp);
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template<class E = timeout> throw_overload<E> wait_until(const steady_point &tp);
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// Ignores notes. Throws if interrupted.
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void sleep_until(const steady_point &tp);
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template<class duration> void sleep(const duration &);
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void sleep(const int &secs);
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}}
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namespace ircd::ctx
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{
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/// Points to the currently running context or null for main stack (do not modify)
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extern __thread ctx *current;
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}
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namespace ircd
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{
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namespace this_ctx = ctx::this_ctx;
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}
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/// This overload matches ::sleep() and acts as a drop-in for ircd contexts.
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/// interruption point.
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inline void
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ircd::ctx::this_ctx::sleep(const int &secs)
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{
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sleep(seconds(secs));
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}
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/// Yield the context for a period of time and ignore notifications. sleep()
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/// is like wait() but it only returns after the timeout and not because of a
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/// note.
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/// interruption point.
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template<class duration>
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void
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ircd::ctx::this_ctx::sleep(const duration &d)
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{
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sleep_until(steady_clock::now() + d);
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}
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/// Wait for a notification until a point in time. If there is a notification
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/// then context continues normally. If there's never a notification then an
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/// exception (= timeout) is thrown.
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/// interruption point.
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template<class E>
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ircd::throw_overload<E>
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ircd::ctx::this_ctx::wait_until(const steady_point &tp)
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{
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if(wait_until<std::nothrow_t>(tp))
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throw E{};
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}
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/// Wait for a notification until a point in time. If there is a notification
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/// then returns true. If there's never a notification then returns false.
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/// interruption point. this is not noexcept.
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template<class E>
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ircd::nothrow_overload<E, bool>
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ircd::ctx::this_ctx::wait_until(const steady_point &tp)
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{
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return wait_until(tp, std::nothrow);
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}
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/// Wait for a notification for at most some amount of time. If the duration is
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/// reached without a notification then E (= timeout) is thrown. Otherwise,
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/// returns the time remaining on the duration.
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/// interruption point
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template<class E,
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class duration>
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ircd::throw_overload<E, duration>
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ircd::ctx::this_ctx::wait(const duration &d)
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{
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const auto ret
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{
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wait<std::nothrow_t>(d)
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};
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return ret <= duration(0)?
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throw E{}:
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ret;
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}
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/// Wait for a notification for some amount of time. This function returns
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/// when a context is notified. It always returns the duration remaining which
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/// will be <= 0 to indicate a timeout without notification.
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/// interruption point. this is not noexcept.
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template<class E,
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class duration>
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ircd::nothrow_overload<E, duration>
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ircd::ctx::this_ctx::wait(const duration &d)
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{
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const auto ret
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{
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wait(duration_cast<microseconds>(d), std::nothrow)
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};
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return duration_cast<duration>(ret);
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}
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/// View the name of the currently running context, or "*" if no context is
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/// currently running.
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inline ircd::string_view
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ircd::ctx::this_ctx::name()
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noexcept
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{
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return current? name(cur()) : "*"_sv;
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}
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/// Calculate the current TSC (reference cycle count) accumulated for this
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/// context only. This is done by first calculating a cycle count for the
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/// current slice/epoch (see: ctx/prof.h) which is where the RDTSC sample
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/// occurs. This count is added to an accumulator value saved in the ctx
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/// structure. The accumulator value is updated at the end of each execution
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/// slice, thus giving us the cycle count for this ctx only, up to this point.
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extern inline ulong
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__attribute__((flatten, always_inline, gnu_inline, artificial))
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ircd::ctx::this_ctx::cycles()
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noexcept
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{
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const auto slice(prof::cur_slice_cycles());
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const auto accumulated(cycles(cur()));
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return accumulated + slice;
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}
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/// Reference to the currently running context. Call if you expect to be in a
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/// context. Otherwise use the ctx::current pointer.
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inline ircd::ctx::ctx &
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__attribute__((always_inline))
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ircd::ctx::this_ctx::cur()
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noexcept
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{
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assert(current);
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return *current;
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}
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