mirror of
https://github.com/matrix-construct/construct
synced 2024-10-30 10:28:55 +01:00
159 lines
5.6 KiB
C++
159 lines
5.6 KiB
C++
/*
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* charybdis: oh just a little chat server
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* ctx.h: userland context switching (stackful coroutines)
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*
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* Copyright (C) 2016 Charybdis Development Team
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* Copyright (C) 2016 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.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#define HAVE_IRCD_CTX_H
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#ifdef __cplusplus
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namespace ircd {
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namespace ctx {
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using std::chrono::microseconds;
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using std::chrono::steady_clock;
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using time_point = steady_clock::time_point;
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IRCD_EXCEPTION(ircd::error, error)
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IRCD_EXCEPTION(error, interrupted)
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IRCD_EXCEPTION(error, timeout)
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enum flags
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{
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DEFER_POST = 0x0001, // Defers spawn with an ios.post()
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DEFER_DISPATCH = 0x0002, // (Defers) spawn with an ios.dispatch()
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DEFER_STRAND = 0x0004, // Defers spawn by posting to strand
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SPAWN_STRAND = 0x0008, // Spawn onto a strand, otherwise ios itself
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SELF_DESTRUCT = 0x0010, // Context deletes itself; see struct context constructor notes
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INTERRUPTED = 0x0020, // Marked
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};
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const auto DEFAULT_STACK_SIZE = 64_KiB;
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// Context implementation
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struct ctx; // Internal implementation to hide boost headers
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const int64_t ¬es(const ctx &); // Peeks at internal semaphore count (you don't need this)
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const flags &flags(const ctx &); // Get the internal flags value.
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bool finished(const ctx &); // Context function returned (or exception).
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bool started(const ctx &); // Context was ever entered.
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void interrupt(ctx &); // Interrupt the context for termination.
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bool notify(ctx &); // Increment the semaphore (only library ppl need this)
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// this_context
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extern __thread struct ctx *current; // Always set to the currently running context or null
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ctx &cur(); // Convenience for *current (try to use this instead)
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void wait(); // Returns when context notified.
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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 time_point &tp, const std::nothrow_t &);
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template<class E> nothrow_overload<E, bool> wait_until(const time_point &tp);
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template<class E = timeout> throw_overload<E> wait_until(const time_point &tp);
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class context
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{
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std::unique_ptr<ctx> c;
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public:
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bool operator!() const { return !c; }
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operator bool() const { return bool(c); }
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operator const ctx &() const { return *c; }
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operator ctx &() { return *c; }
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bool joined() const { return !c || ircd::ctx::finished(*c); }
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void interrupt() { ircd::ctx::interrupt(*c); }
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void join(); // Blocks the current context until this one finishes
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ctx *detach(); // other calls undefined after this call
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// Note: Constructing with SELF_DESTRUCT flag makes any further use of this object undefined.
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context(const size_t &stack_size, std::function<void ()>, const enum flags &flags = (enum flags)0);
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context(std::function<void ()>, const enum flags &flags = (enum flags)0);
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context(context &&) noexcept = default;
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context(const context &) = delete;
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~context() noexcept;
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friend void swap(context &a, context &b) noexcept;
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};
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inline void
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swap(context &a, context &b)
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noexcept
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{
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std::swap(a.c, b.c);
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}
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template<class E>
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throw_overload<E>
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wait_until(const time_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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template<class E>
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nothrow_overload<E, bool>
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wait_until(const time_point &tp)
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{
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return wait_until(tp, std::nothrow);
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}
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template<class E,
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class duration>
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throw_overload<E, duration>
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wait(const duration &d)
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{
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const auto ret(wait<std::nothrow_t>(d));
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return ret <= duration(0)? throw E() : ret;
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}
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template<class E,
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class duration>
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nothrow_overload<E, duration>
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wait(const duration &d)
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{
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using std::chrono::duration_cast;
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const auto ret(wait(duration_cast<microseconds>(d), std::nothrow));
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return duration_cast<duration>(ret);
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}
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inline ctx &
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cur()
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{
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assert(current);
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return *current;
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}
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} // namespace ctx
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using ctx::context;
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using ctx::timeout;
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} // namespace ircd
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#endif // __cplusplus
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