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construct/include/ircd/ctx/dock.h

158 lines
3.6 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_DOCK_H
namespace ircd::ctx
{
struct dock;
void terminate(dock &) noexcept;
void interrupt(dock &) noexcept;
void notify(dock &) noexcept;
}
/// dock is a condition variable which has no requirement for locking because
/// the context system does not require mutual exclusion for coherence.
///
struct ircd::ctx::dock
{
enum opts :uint;
struct continuation;
using predicate = std::function<bool ()>;
private:
list q;
public:
bool empty() const noexcept;
size_t size() const noexcept;
bool waiting(const ctx &) const noexcept;
bool wait_until(const system_point, const predicate &, const opts = (opts)0);
bool wait_until(const system_point, const opts = (opts)0);
template<class duration> bool wait_for(const duration, const predicate &, const opts = (opts)0);
template<class duration> bool wait_for(const duration, const opts = (opts)0);
void wait(const predicate &, const opts = (opts)0);
void wait(const opts = (opts)0);
void terminate_all() noexcept;
void interrupt_all() noexcept;
void notify_all() noexcept;
void notify_one() noexcept;
void notify() noexcept;
};
namespace ircd::ctx
{
template<> bool dock::wait_for(const microseconds, const predicate &, const opts);
template<> bool dock::wait_for(const microseconds, const opts);
}
struct [[gnu::visibility("internal")]]
ircd::ctx::dock::continuation
{
dock *const d;
const opts *const o;
continuation(dock *, const opts &opts);
~continuation() noexcept;
};
/// Options. These are bitflags for forward compatibility with unrelated opts
/// even though some flags are exclusive to others.
enum ircd::ctx::dock::opts
:uint
{
/// No options.
NONE = 0x00,
/// Waiting context will add itself to back of queue. This is the default.
FIFO = 0x01,
/// Waiting context will add itself to front of queue. The default is FIFO
/// for fair queuing preventing starvation.
LIFO = 0x02,
/// Waiting context will add itself to front if its ID is lower than the
/// front, otherwise back.
SORT = 0x04,
};
/// Wake up the next context waiting on the dock
inline void
ircd::ctx::dock::notify_one()
noexcept
{
if(q.empty())
return;
ircd::ctx::notify(*q.front());
}
template<class duration>
inline bool
ircd::ctx::dock::wait_for(const duration dur,
const predicate &pred,
const opts opts)
{
static_assert(!std::is_same<duration, microseconds>());
return wait_for(duration_cast<microseconds>(dur), pred, opts);
}
template<class duration>
inline bool
ircd::ctx::dock::wait_for(const duration dur,
const opts opts)
{
static_assert(!std::is_same<duration, microseconds>());
return wait_for(duration_cast<microseconds>(dur), opts);
}
/// The number of contexts waiting in the queue.
inline size_t
ircd::ctx::dock::size()
const noexcept
{
return q.size();
}
/// The number of contexts waiting in the queue.
inline bool
ircd::ctx::dock::empty()
const noexcept
{
return q.empty();
}
inline void
ircd::ctx::notify(dock &dock)
noexcept
{
dock.notify();
}
inline void
ircd::ctx::interrupt(dock &dock)
noexcept
{
dock.interrupt_all();
}
inline void
ircd::ctx::terminate(dock &dock)
noexcept
{
dock.terminate_all();
}