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construct/include/ircd/ctx/this_ctx.h
2018-12-07 12:03:25 -08:00

136 lines
4.5 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
namespace ircd::ctx {
/// Interface to the currently running context
inline namespace this_ctx
{
struct ctx &cur(); ///< Assumptional reference to *current
const uint64_t &id(); // Unique ID for cur ctx
string_view name(); // Optional label for cur ctx
ulong cycles_here(); // misc profiling related
bool interruption_requested(); // interruption(cur())
void interruption_point(); // throws if interruption_requested()
void wait(); // Returns when context is woken up.
void yield(); // Allow other contexts to run before returning.
// Return remaining time if notified; or <= 0 if not, and timeout thrown on throw overloads
microseconds wait(const microseconds &, const std::nothrow_t &);
template<class E, class duration> nothrow_overload<E, duration> wait(const duration &);
template<class E = timeout, class duration> throw_overload<E, duration> wait(const duration &);
// Returns false if notified; true if time point reached, timeout thrown on throw_overloads
bool wait_until(const steady_point &tp, const std::nothrow_t &);
template<class E> nothrow_overload<E, bool> wait_until(const steady_point &tp);
template<class E = timeout> throw_overload<E> wait_until(const steady_point &tp);
// Ignores notes. Throws if interrupted.
void sleep_until(const steady_point &tp);
template<class duration> void sleep(const duration &);
void sleep(const int &secs);
}}
namespace ircd::ctx
{
/// Points to the currently running context or null for main stack (do not modify)
extern __thread ctx *current;
}
/// This overload matches ::sleep() and acts as a drop-in for ircd contexts.
/// interruption point.
inline void
ircd::ctx::this_ctx::sleep(const int &secs)
{
sleep(seconds(secs));
}
/// Yield the context for a period of time and ignore notifications. sleep()
/// is like wait() but it only returns after the timeout and not because of a
/// note.
/// interruption point.
template<class duration>
void
ircd::ctx::this_ctx::sleep(const duration &d)
{
sleep_until(steady_clock::now() + d);
}
/// Wait for a notification until a point in time. If there is a notification
/// then context continues normally. If there's never a notification then an
/// exception (= timeout) is thrown.
/// interruption point.
template<class E>
ircd::throw_overload<E>
ircd::ctx::this_ctx::wait_until(const steady_point &tp)
{
if(wait_until<std::nothrow_t>(tp))
throw E{};
}
/// Wait for a notification until a point in time. If there is a notification
/// then returns true. If there's never a notification then returns false.
/// interruption point. this is not noexcept.
template<class E>
ircd::nothrow_overload<E, bool>
ircd::ctx::this_ctx::wait_until(const steady_point &tp)
{
return wait_until(tp, std::nothrow);
}
/// Wait for a notification for at most some amount of time. If the duration is
/// reached without a notification then E (= timeout) is thrown. Otherwise,
/// returns the time remaining on the duration.
/// interruption point
template<class E,
class duration>
ircd::throw_overload<E, duration>
ircd::ctx::this_ctx::wait(const duration &d)
{
const auto ret
{
wait<std::nothrow_t>(d)
};
return ret <= duration(0)?
throw E{}:
ret;
}
/// Wait for a notification for some amount of time. This function returns
/// when a context is notified. It always returns the duration remaining which
/// will be <= 0 to indicate a timeout without notification.
/// interruption point. this is not noexcept.
template<class E,
class duration>
ircd::nothrow_overload<E, duration>
ircd::ctx::this_ctx::wait(const duration &d)
{
const auto ret
{
wait(duration_cast<microseconds>(d), std::nothrow)
};
return duration_cast<duration>(ret);
}
/// 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 &
ircd::ctx::this_ctx::cur()
{
assert(current);
return *current;
}