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ircd::ctx: shared_mutex; peek / view / shared_view; fixes.

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This commit is contained in:
Jason Volk 2017-09-29 23:06:23 -07:00
parent eeceba51b8
commit 19451ab914
6 changed files with 379 additions and 57 deletions
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4
include/ircd/ctx.h
View file

@ -107,10 +107,12 @@ namespace ircd::ctx { inline namespace this_ctx
#include "ctx/context.h"
#include "ctx/prof.h"
#include "ctx/dock.h"
#include "ctx/view.h"
#include "ctx/queue.h"
#include "ctx/mutex.h"
#include "ctx/shared_mutex.h"
#include "ctx/peek.h"
#include "ctx/view.h"
#include "ctx/shared_view.h"
#include "ctx/shared_state.h"
#include "ctx/promise.h"
#include "ctx/future.h"

2
include/ircd/ctx/mutex.h
View file

@ -66,6 +66,8 @@ noexcept
inline void
ircd::ctx::mutex::unlock()
{
assert(m);
ctx *next; do
{
if(!q.empty())

161
include/ircd/ctx/peek.h Normal file
View file

@ -0,0 +1,161 @@
/*
* Copyright (C) 2016 Charybdis Development Team
* Copyright (C) 2016 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#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;
}

159
include/ircd/ctx/shared_view.h Normal file
View file

@ -0,0 +1,159 @@
/*
* Copyright (C) 2016 Charybdis Development Team
* Copyright (C) 2016 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#define HAVE_IRCD_CTX_SHARED_VIEW_H
namespace ircd::ctx
{
template<class T> class shared_view;
}
/// Device for a context to share data on its stack with others while yielding
///
/// The shared_view yields a context while other contexts examine the object pointed
/// to in the shared_view. 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.
///
/// The producer is blocked until all consumers are finished with their shared_view.
/// The consumers acquire the shared_lock before passing it to the call to wait().
/// wait() returns with a shared_view of the object under shared_lock. Once the
/// consumer releases the shared_lock the viewed object is not safe for them.
///
template<class T>
class ircd::ctx::shared_view
:public shared_mutex
{
T *t {nullptr};
dock q;
size_t waiting {0};
bool ready() const;
public:
// Consumer interface;
template<class time_point> T &wait_until(std::shared_lock<shared_view> &, time_point&&);
template<class duration> T &wait_for(std::shared_lock<shared_view> &, const duration &);
T &wait(std::shared_lock<shared_view> &);
// Producer interface;
void notify(T &);
shared_view() = default;
~shared_view() noexcept;
};
template<class T>
ircd::ctx::shared_view<T>::~shared_view()
noexcept
{
assert(!waiting);
}
template<class T>
void
ircd::ctx::shared_view<T>::notify(T &t)
{
if(!waiting)
return;
this->t = &t;
q.notify_all();
q.wait([this] { return !waiting; });
const std::lock_guard<shared_view> lock{*this};
this->t = nullptr;
assert(!waiting);
q.notify_all();
}
template<class T>
T &
ircd::ctx::shared_view<T>::wait(std::shared_lock<shared_view> &lock)
{
for(assert(lock.owns_lock_shared()); ready(); lock.lock_shared())
{
lock.unlock_shared();
q.wait();
}
const unwind ul{[this]
{
--waiting;
q.notify_all();
}};
for(++waiting; !ready(); lock.lock_shared())
{
lock.unlock_shared();
q.wait();
}
assert(t != nullptr);
return *t;
}
template<class T>
template<class duration>
T &
ircd::ctx::shared_view<T>::wait_for(std::shared_lock<shared_view> &lock,
const duration &dur)
{
return wait_until(now<steady_point>() + dur);
}
template<class T>
template<class time_point>
T &
ircd::ctx::shared_view<T>::wait_until(std::shared_lock<shared_view> &lock,
time_point&& tp)
{
for(assert(lock.owns_lock_shared()); ready(); lock.lock_shared())
{
lock.unlock_shared();
q.wait_until(tp);
}
const unwind ul{[this]
{
--waiting;
q.notify_all();
}};
for(++waiting; !ready(); lock.lock_shared())
{
lock.unlock_shared();
q.wait_until(tp);
}
assert(t != nullptr);
return *t;
}
template<class T>
bool
ircd::ctx::shared_view<T>::ready()
const
{
return t != nullptr;
}

106
include/ircd/ctx/view.h
View file

@ -36,31 +36,26 @@ namespace ircd::ctx
/// This creates a very simple and lightweight single-producer/multi-consumer
/// queue mechanism using only context switching.
///
/// Consumers get one chance to safely view 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 viewed 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 viewed the data and the producer is
/// free to destroy it.
/// The producer is blocked until all consumers are finished with their view.
/// The consumers acquire the unique_lock before passing it to the call to wait().
/// wait() returns with a view of the object under unique_lock. Once the
/// consumer releases the unique_lock the viewed object is not safe for them.
///
template<class T>
class ircd::ctx::view
:public mutex
{
T *t {nullptr};
dock a, b;
dock q;
size_t waiting {0};
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();
template<class time_point> T &wait_until(std::unique_lock<view> &, time_point&&);
template<class duration> T &wait_for(std::unique_lock<view> &, const duration &);
T &wait(std::unique_lock<view> &);
// Producer interface;
void notify(T &);
@ -73,43 +68,46 @@ template<class T>
ircd::ctx::view<T>::~view()
noexcept
{
assert(!waiting());
assert(!waiting);
}
template<class T>
void
ircd::ctx::view<T>::notify(T &t)
{
const unwind afterward{[this]
{
assert(a.empty());
this->t = nullptr;
if(!b.empty())
{
b.notify_all();
yield();
}
}};
if(!waiting)
return;
assert(b.empty());
this->t = &t;
a.notify_all();
yield();
q.notify_all();
q.wait([this] { return !waiting; });
const std::lock_guard<view> lock{*this};
this->t = nullptr;
assert(!waiting);
q.notify_all();
}
template<class T>
T &
ircd::ctx::view<T>::wait()
ircd::ctx::view<T>::wait(std::unique_lock<view> &lock)
{
b.wait([this]
for(assert(lock.owns_lock()); ready(); lock.lock())
{
return !ready();
});
lock.unlock();
q.wait();
}
a.wait([this]
const unwind ul{[this]
{
return ready();
});
--waiting;
q.notify_all();
}};
for(++waiting; !ready(); lock.lock())
{
lock.unlock();
q.wait();
}
assert(t != nullptr);
return *t;
@ -118,7 +116,8 @@ ircd::ctx::view<T>::wait()
template<class T>
template<class duration>
T &
ircd::ctx::view<T>::wait_for(const duration &dur)
ircd::ctx::view<T>::wait_for(std::unique_lock<view> &lock,
const duration &dur)
{
return wait_until(now<steady_point>() + dur);
}
@ -126,32 +125,31 @@ ircd::ctx::view<T>::wait_for(const duration &dur)
template<class T>
template<class time_point>
T &
ircd::ctx::view<T>::wait_until(time_point&& tp)
ircd::ctx::view<T>::wait_until(std::unique_lock<view> &lock,
time_point&& tp)
{
if(!b.wait_until(tp, [this]
for(assert(lock.owns_lock()); ready(); lock.lock())
{
return !ready();
}))
throw timeout();
lock.unlock();
q.wait_until(tp);
}
if(!a.wait_until(tp, [this]
const unwind ul{[this]
{
return ready();
}))
throw timeout();
--waiting;
q.notify_all();
}};
for(++waiting; !ready(); lock.lock())
{
lock.unlock();
q.wait_until(tp);
}
assert(t != nullptr);
return *t;
}
template<class T>
size_t
ircd::ctx::view<T>::waiting()
const
{
return a.size() + b.size();
}
template<class T>
bool
ircd::ctx::view<T>::ready()

4
ircd/ctx.cc
View file

@ -741,7 +741,7 @@ ircd::ctx::prof::check_slice()
if(unlikely(settings.slice_warning > 0us && time_usage >= settings.slice_warning))
{
log::warning("CONTEXT TIMESLICE EXCEEDED (%p) '%s' last: %06ld$us total: %06ld$us",
log::warning("context timeslice exceeded (%p) '%s' last: %06ld$us total: %06ld$us",
(const void *)&c,
c.name,
duration_cast<microseconds>(time_usage).count(),
@ -765,7 +765,7 @@ ircd::ctx::prof::check_stack()
if(unlikely(stack_usage > stack_max * settings.stack_usage_warning))
{
log::warning("CONTEXT STACK USAGE ctx(%p) used %zu of %zu bytes",
log::warning("context stack usage ctx(%p) used %zu of %zu bytes",
(const void *)&c,
stack_usage,
c.stack_max);