mirror of
https://github.com/matrix-construct/construct
synced 2024-10-31 02:48:58 +01:00
165 lines
4 KiB
C++
165 lines
4 KiB
C++
/*
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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_CTX_H
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#include <boost/asio/io_service.hpp>
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#include <boost/asio/steady_timer.hpp>
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#include <boost/asio/spawn.hpp>
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namespace ircd {
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namespace ctx {
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struct ctx
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{
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boost::asio::steady_timer alarm; // 64B
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boost::asio::yield_context *yc;
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uintptr_t stack_base;
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size_t stack_max;
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int64_t notes; // norm: 0 = asleep; 1 = awake; inc by others; dec by self
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ctx *adjoindre;
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enum flags flags;
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bool finished() const { return yc == nullptr; }
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bool started() const { return bool(yc); }
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bool wait();
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void wake();
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bool note();
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void operator()(boost::asio::yield_context, const std::function<void ()>) noexcept;
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ctx(const size_t &stack_max = DEFAULT_STACK_SIZE,
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const enum flags &flags = (enum flags)0,
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boost::asio::io_service *const &ios = ircd::ios);
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ctx(ctx &&) noexcept = delete;
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ctx(const ctx &) = delete;
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};
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size_t stack_usage_here(const ctx &) __attribute__((noinline));
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bool stack_warning(const ctx &, const double &pct = 0.80);
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void stack_assertion(const ctx &, const double &pct = 0.80);
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struct continuation
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{
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ctx *self;
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operator const boost::asio::yield_context &() const;
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operator boost::asio::yield_context &();
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continuation(ctx *const &self = ircd::ctx::current);
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~continuation() noexcept;
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};
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inline
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continuation::continuation(ctx *const &self)
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:self{self}
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{
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assert(self != nullptr);
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assert(self->notes <= 1);
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stack_assertion(*self);
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ircd::ctx::current = nullptr;
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}
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inline
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continuation::~continuation()
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noexcept
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{
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ircd::ctx::current = self;
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self->notes = 1;
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}
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inline
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continuation::operator boost::asio::yield_context &()
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{
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return *self->yc;
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}
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inline
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continuation::operator const boost::asio::yield_context &()
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const
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{
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return *self->yc;
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}
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inline void
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stack_assertion(const ctx &ctx,
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const double &pct)
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{
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assert(!stack_warning(ctx, pct));
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}
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inline bool
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stack_warning(const ctx &ctx,
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const double &pct)
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{
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return stack_usage_here(ctx) > double(ctx.stack_max) * pct;
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}
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inline bool
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ctx::note()
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{
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if(notes++ > 0)
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return false;
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wake();
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return true;
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}
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inline void
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ctx::wake()
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try
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{
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alarm.cancel();
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}
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catch(const boost::system::system_error &e)
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{
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ircd::log::error("ctx::wake(%p): %s", this, e.what());
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}
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inline bool
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ctx::wait()
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{
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if(--notes > 0)
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return false;
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boost::system::error_code ec;
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alarm.async_wait(boost::asio::yield_context(continuation(this))[ec]);
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assert(ec == boost::system::errc::operation_canceled ||
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ec == boost::system::errc::success);
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// Interruption shouldn't be used for normal operation,
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// so please eat this branch misprediction.
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if(unlikely(flags & INTERRUPTED))
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throw interrupted("ctx(%p)::wait()", (const void *)this);
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// notes = 1; set by continuation dtor on wakeup
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return true;
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}
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} // namespace ctx
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using ctx::continuation;
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using yield = boost::asio::yield_context;
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} // namespace ircd
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