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construct/include/ircd/ctx/this_ctx.h

71 lines
2.5 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.
#pragma once
#define HAVE_IRCD_CTX_THIS_CTX_H
/// Interface to the currently running context
namespace ircd::ctx { inline namespace this_ctx
{
struct ctx &cur() noexcept; ///< Assumptional reference to *current
const uint64_t &id() noexcept; // Unique ID for cur ctx
string_view name() noexcept; // Optional label for cur ctx
ulong cycles() noexcept; // misc profiling related
bool interruption_requested() noexcept; // interruption(cur())
void interruption_point(); // throws if interruption_requested()
void yield(); // Allow other contexts to run before returning.
}}
namespace ircd::ctx
{
/// Points to the currently running context or null for main stack (do not modify)
extern thread_local ctx *current;
}
namespace ircd
{
namespace this_ctx = ctx::this_ctx;
}
/// View the name of the currently running context, or "*" if no context is
/// currently running.
inline ircd::string_view
ircd::ctx::this_ctx::name()
noexcept
{
return current? name(cur()) : "*"_sv;
}
/// Calculate the current TSC (reference cycle count) accumulated for this
/// context only. This is done by first calculating a cycle count for the
/// current slice/epoch (see: ctx/prof.h) which is where the RDTSC sample
/// occurs. This count is added to an accumulator value saved in the ctx
/// structure. The accumulator value is updated at the end of each execution
/// slice, thus giving us the cycle count for this ctx only, up to this point.
extern inline ulong
__attribute__((flatten, always_inline, gnu_inline, artificial))
ircd::ctx::this_ctx::cycles()
noexcept
{
const auto slice(prof::cur_slice_cycles());
const auto accumulated(cycles(cur()));
return accumulated + slice;
}
/// Reference to the currently running context. Call if you expect to be in a
/// context. Otherwise use the ctx::current pointer.
inline ircd::ctx::ctx &
__attribute__((always_inline))
ircd::ctx::this_ctx::cur()
noexcept
{
assert(current);
return *current;
}