mirror of
https://github.com/matrix-construct/construct
synced 2024-11-29 18:22:50 +01:00
96 lines
3.7 KiB
C++
96 lines
3.7 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
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{
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struct stack;
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struct profile;
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void spawn(ctx *const c, context::function func);
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}
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namespace ircd::ctx::prof
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{
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void mark(const event &);
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}
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/// Internal structure aggregating any stack related state for the ctx
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struct ircd::ctx::stack
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{
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uintptr_t base {0}; // assigned when spawned
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size_t max {0}; // User given stack size
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size_t at {0}; // Updated for profiling at sleep
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stack(const size_t &max = 0)
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:max{max}
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{}
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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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static uint64_t id_ctr; // monotonic
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uint64_t id {++id_ctr}; // Unique runtime ID
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string_view name; // User given name (optional)
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context::flags flags; // User given flags
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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::io_service::strand strand; // mutex/serializer
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boost::asio::steady_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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dock adjoindre; // contexts waiting for this to join()
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bool started() const; // context was ever entered
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bool finished() const; // context will not be further entered.
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bool interruption_point(std::nothrow_t); // Check for interrupt (and clear flag)
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bool termination_point(std::nothrow_t); // Check for terminate
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void interruption_point(); // throws interrupted or terminated
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bool wake(); // jump to context by queueing with ios (use note())
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bool note(); // 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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ctx(const string_view &name = "<noname>"_sv,
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const size_t &stack_max = DEFAULT_STACK_SIZE,
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const context::flags &flags = (context::flags)0U,
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boost::asio::io_service &ios = ircd::ios::get())
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:name{name}
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,flags{flags}
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,strand{ios}
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,alarm{ios}
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,stack{stack_max}
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{}
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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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