82 lines
3.4 KiB
C++
82 lines
3.4 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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/// We make a special use of the stack-protector canary in certain places as
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/// another tool to detect corruption of a context's stack, specifically
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/// during yield and resume. This use is not really to provide security; just
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/// a kind of extra assertion, so we eliminate its emission during release.
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#if !defined(NDEBUG) && !defined(__clang__)
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#define IRCD_CTX_STACK_PROTECT __attribute__((stack_protect))
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#else
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#define IRCD_CTX_STACK_PROTECT
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#endif
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namespace ircd::ctx::prof
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{
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static void mark(const event &);
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}
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/// Internal context implementation
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///
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struct ircd::ctx::ctx
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:instance_list<ctx>
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{
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using flags_type = std::underlying_type<context::flags>::type;
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static uint64_t id_ctr; // monotonic
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static ios::descriptor ios_desc;
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static ios::handler ios_handler;
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static ctx *spawning;
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static dock adjoindre; // contexts waiting for join
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uint64_t id {++id_ctr}; // Unique runtime ID
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char name[16] {0}; // User given name
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flags_type flags; // User given flags
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int8_t nice {0}; // Scheduling priority nice-value
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int8_t ionice {0}; // IO priority nice-value (defaults for fs::opts)
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int32_t notes {0}; // norm: 0 = asleep; 1 = awake; inc by others; dec by self
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boost::asio::deadline_timer alarm; // acting semaphore (64B)
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boost::asio::yield_context *yc {nullptr}; // boost interface
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continuation *cont {nullptr}; // valid when asleep; invalid when awake
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list::node node; // node for ctx::list
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ircd::ctx::stack stack; // stack related structure
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prof::ticker profile; // prof related structure
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bool started() const noexcept; // context was ever entered
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bool finished() const noexcept; // context will not be further entered.
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bool interruption() const noexcept;
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bool interruption_point(std::nothrow_t) noexcept;
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bool termination_point(std::nothrow_t) noexcept;
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void interruption_point();
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bool wake() noexcept; // jump to context by queueing with ios (use note())
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bool note() noexcept; // properly request wake()
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bool wait(); // yield context to ios queue (returns on this resume)
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void jump(); // jump to context directly (returns on your resume)
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void operator()(boost::asio::yield_context, const std::function<void ()>) noexcept;
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void spawn(context::function func);
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ctx(const string_view &name = "<noname>"_sv,
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const ircd::ctx::stack & = mutable_buffer{nullptr, DEFAULT_STACK_SIZE},
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const context::flags & = (context::flags)0U);
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ctx(ctx &&) = delete;
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ctx(const ctx &) = delete;
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ctx &operator=(ctx &&) = delete;
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ctx &operator=(const ctx &) = delete;
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~ctx() noexcept;
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};
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template<>
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decltype(ircd::ctx::ctx::list)
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ircd::util::instance_list<ircd::ctx::ctx>::list;
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