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construct/ircd/ctx.h
2018-08-21 08:10:37 -07:00

90 lines
3.5 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
namespace ircd::ctx
{
struct stack;
struct profile;
void spawn(ctx *const c, context::function func);
}
/// Internal structure aggregating any stack related state for the ctx
struct ircd::ctx::stack
{
uintptr_t base {0}; // assigned when spawned
size_t max {0}; // User given stack size
size_t at {0}; // Updated for profiling at sleep
stack(const size_t &max = 0)
:max{max}
{}
};
/// Internal structure aggregating any profiling related state for the ctx
struct ircd::ctx::profile
{
ulong cycles {0}; // monotonic counter (rdtsc)
uint64_t yields {0}; // monotonic counter
};
/// Internal context implementation
///
struct ircd::ctx::ctx
:instance_list<ctx>
{
using error_code = boost::system::error_code;
static uint64_t id_ctr; // monotonic
uint64_t id {++id_ctr}; // Unique runtime ID
const char *name {nullptr}; // User given name (optional)
context::flags flags {(context::flags)0}; // User given flags
boost::asio::io_service::strand strand; // mutex/serializer
boost::asio::steady_timer alarm; // acting semaphore (64B)
boost::asio::yield_context *yc {nullptr}; // boost interface
continuation *cont {nullptr}; // valid when asleep; invalid when awake
int64_t notes {0}; // norm: 0 = asleep; 1 = awake; inc by others; dec by self
ircd::ctx::stack stack; // stack related structure
ircd::ctx::profile profile; // prof related structure
list::node node; // node for ctx::list
dock adjoindre; // contexts waiting for this to join()
bool started() const; // context was ever entered
bool finished() const; // context will not be further entered.
bool interruption_point(std::nothrow_t); // Check for interrupt (and clear flag)
bool termination_point(std::nothrow_t); // Check for terminate
void interruption_point(); // throws interrupted or terminated
bool wait(); // yield context to ios queue (returns on this resume)
void jump(); // jump to context directly (returns on your resume)
void wake(); // jump to context by queueing with ios (use note())
bool note(); // properly request wake()
void operator()(boost::asio::yield_context, const std::function<void ()>) noexcept;
ctx(const char *const &name = "<noname>",
const size_t &stack_max = DEFAULT_STACK_SIZE,
const context::flags &flags = (context::flags)0,
boost::asio::io_service *const &ios = ircd::ios)
:name{name}
,flags{flags}
,strand{*ios}
,alarm{*ios}
,stack{stack_max}
{}
ctx(ctx &&) = delete;
ctx(const ctx &) = delete;
ctx &operator=(ctx &&) = delete;
ctx &operator=(const ctx &) = delete;
~ctx() noexcept;
};