mirror of
https://github.com/matrix-construct/construct
synced 2024-11-29 18:22:50 +01:00
135 lines
2.6 KiB
C++
135 lines
2.6 KiB
C++
/*
|
|
* 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_MUTEX_H
|
|
|
|
namespace ircd {
|
|
namespace ctx {
|
|
|
|
/**
|
|
* The mutex only allows one context to lock it and continue,
|
|
* additional contexts are queued. This can be used with std::
|
|
* locking concepts.
|
|
*/
|
|
class mutex
|
|
{
|
|
bool m;
|
|
std::deque<ctx *> q;
|
|
|
|
public:
|
|
bool try_lock();
|
|
template<class time_point> bool try_lock_until(const time_point &);
|
|
template<class duration> bool try_lock_for(const duration &);
|
|
|
|
void lock();
|
|
void unlock();
|
|
|
|
mutex();
|
|
~mutex() noexcept;
|
|
};
|
|
|
|
inline
|
|
mutex::mutex():
|
|
m(false)
|
|
{
|
|
}
|
|
|
|
inline
|
|
mutex::~mutex()
|
|
noexcept
|
|
{
|
|
assert(!m);
|
|
assert(q.empty());
|
|
}
|
|
|
|
inline void
|
|
mutex::unlock()
|
|
{
|
|
ctx *next; do
|
|
{
|
|
if(!q.empty())
|
|
{
|
|
next = q.front();
|
|
q.pop_front();
|
|
}
|
|
else next = nullptr;
|
|
}
|
|
while(next == &cur());
|
|
|
|
m = false;
|
|
|
|
if(next)
|
|
yield(*next);
|
|
}
|
|
|
|
inline void
|
|
mutex::lock()
|
|
{
|
|
if(likely(try_lock()))
|
|
return;
|
|
|
|
q.emplace_back(&cur());
|
|
while(!try_lock())
|
|
wait();
|
|
}
|
|
|
|
template<class duration>
|
|
bool
|
|
mutex::try_lock_for(const duration &d)
|
|
{
|
|
return try_lock_until(steady_clock::now() + d);
|
|
}
|
|
|
|
template<class time_point>
|
|
bool
|
|
mutex::try_lock_until(const time_point &tp)
|
|
{
|
|
if(likely(try_lock()))
|
|
return true;
|
|
|
|
q.emplace_back(&cur());
|
|
while(!try_lock())
|
|
{
|
|
if(unlikely(wait_until<std::nothrow_t>(tp)))
|
|
{
|
|
const auto it(std::find(begin(q), end(q), &cur()));
|
|
assert(it != end(q));
|
|
q.erase(it);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
inline bool
|
|
mutex::try_lock()
|
|
{
|
|
if(m)
|
|
return false;
|
|
|
|
m = true;
|
|
return true;
|
|
}
|
|
|
|
} // namespace ctx
|
|
} // namespace ircd
|