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Code Issues Releases Wiki Activity

ircd::ctx: Remove unused peek.

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This commit is contained in:
Jason Volk 2018-10-06 22:16:37 -07:00
parent efd8a8c640
commit f369af944b
2 changed files with 0 additions and 151 deletions
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1
include/ircd/ctx/ctx.h
View file

@ -83,7 +83,6 @@ namespace ircd::ctx
#include "upgrade_lock.h"
#include "unlock_guard.h"
#include "condition_variable.h"
#include "peek.h"
#include "view.h"
#include "shared_state.h"
#include "promise.h"

150
include/ircd/ctx/peek.h
View file

@ -1,150 +0,0 @@
// 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_PEEK_H
namespace ircd::ctx
{
template<class T> class peek;
}
/// Device for a context to share data on its stack with others while yielding
///
/// The peek yields a context while other contexts examine the object pointed
/// to in the peek. This allows a producing context to construct something
/// on its stack and then wait for the consuming contexts to do something with
/// that data before the producer resumes and potentially destroys the data.
/// This creates a very simple and lightweight single-producer/multi-consumer
/// queue mechanism using only context switching.
///
/// Consumers get one chance to safely peek the data when a call to wait()
/// returns. Once the consumer context yields again for any reason the data is
/// potentially invalid. The data can only be peeked once by the consumer
/// because the second call to wait() will yield until the next data is
/// made available by the producer, not the same data.
///
/// Producers will share an object during the call to notify(). Once the call
/// to notify() returns all consumers have peeked the data and the producer is
/// free to destroy it.
///
template<class T>
class ircd::ctx::peek
{
T *t {nullptr};
dock a, b;
bool ready() const;
public:
size_t waiting() const;
// Consumer interface;
template<class time_point> T &wait_until(time_point&&);
template<class duration> T &wait_for(const duration &);
T &wait();
// Producer interface;
void notify(T &);
peek() = default;
~peek() noexcept;
};
template<class T>
ircd::ctx::peek<T>::~peek()
noexcept
{
assert(!waiting());
}
template<class T>
void
ircd::ctx::peek<T>::notify(T &t)
{
const unwind afterward{[this]
{
assert(a.empty());
this->t = nullptr;
if(!b.empty())
{
b.notify_all();
yield();
}
}};
assert(b.empty());
this->t = &t;
a.notify_all();
yield();
}
template<class T>
T &
ircd::ctx::peek<T>::wait()
{
b.wait([this]
{
return !ready();
});
a.wait([this]
{
return ready();
});
assert(t != nullptr);
return *t;
}
template<class T>
template<class duration>
T &
ircd::ctx::peek<T>::wait_for(const duration &dur)
{
return wait_until(now<steady_point>() + dur);
}
template<class T>
template<class time_point>
T &
ircd::ctx::peek<T>::wait_until(time_point&& tp)
{
if(!b.wait_until(tp, [this]
{
return !ready();
}))
throw timeout();
if(!a.wait_until(tp, [this]
{
return ready();
}))
throw timeout();
assert(t != nullptr);
return *t;
}
template<class T>
size_t
ircd::ctx::peek<T>::waiting()
const
{
return a.size() + b.size();
}
template<class T>
bool
ircd::ctx::peek<T>::ready()
const
{
return t != nullptr;
}