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Code Issues Releases Wiki Activity

ircd::ctx: Replace the std::deque with a ctx::list for ctx::dock's queue.

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This commit is contained in:
Jason Volk 2018-01-13 23:14:23 -08:00
parent df0e59a5e0
commit dcd36f8200
1 changed files with 46 additions and 53 deletions
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99
include/ircd/ctx/dock.h
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@ -28,16 +28,13 @@ namespace ircd::ctx
enum class cv_status;
}
//
// a dock is a condition variable which has no requirement for locking because
// the context system does not require mutual exclusion for coherence, however
// we have to create our own queue here rather than piggyback a mutex's.
//
/// dock is a condition variable which has no requirement for locking because
/// the context system does not require mutual exclusion for coherence.
///
class ircd::ctx::dock
{
std::deque<ctx *> q;
list q;
void remove_self();
void notify(ctx &) noexcept;
public:
@ -81,12 +78,11 @@ inline void
ircd::ctx::dock::notify()
noexcept
{
if(q.empty())
ctx *c;
if(!(c = q.pop_front()))
return;
auto c(q.front());
q.pop_front();
q.emplace_back(c);
q.push_back(c);
notify(*c);
}
@ -95,35 +91,35 @@ inline void
ircd::ctx::dock::notify_one()
noexcept
{
if(q.empty())
return;
notify(*q.front());
if(!q.empty())
notify(*q.front());
}
/// Wake up all contexts waiting on the dock.
///
/// We copy the queue and post all notifications without requesting direct context
/// switches. This ensures everyone gets notified in a single transaction without
/// any interleaving during this process.
/// We post all notifications without requesting direct context
/// switches. This ensures everyone gets notified in a single
/// transaction without any interleaving during this process.
inline void
ircd::ctx::dock::notify_all()
noexcept
{
const auto copy(q);
for(const auto &c : copy)
ircd::ctx::notify(*c);
q.for_each([](ctx &c)
{
ircd::ctx::notify(c);
});
}
inline void
ircd::ctx::dock::wait()
{
const unwind remove
assert(current);
const unwind remove{[this]
{
std::bind(&dock::remove_self, this)
};
q.remove(current);
}};
q.emplace_back(&cur());
q.push_back(current);
ircd::ctx::wait();
}
@ -134,12 +130,13 @@ ircd::ctx::dock::wait(predicate&& pred)
if(pred())
return;
const unwind remove
assert(current);
const unwind remove{[this]
{
std::bind(&dock::remove_self, this)
};
q.remove(current);
}};
q.emplace_back(&cur()); do
q.push_back(current); do
{
ircd::ctx::wait();
}
@ -152,12 +149,13 @@ ircd::ctx::dock::wait_for(const duration &dur)
{
static const duration zero(0);
const unwind remove
assert(current);
const unwind remove{[this]
{
std::bind(&dock::remove_self, this)
};
q.remove(current);
}};
q.emplace_back(&cur());
q.push_back(current);
return ircd::ctx::wait<std::nothrow_t>(dur) > zero? cv_status::no_timeout:
cv_status::timeout;
}
@ -173,12 +171,13 @@ ircd::ctx::dock::wait_for(const duration &dur,
if(pred())
return true;
const unwind remove
assert(current);
const unwind remove{[this]
{
std::bind(&dock::remove_self, this)
};
q.remove(current);
}};
q.emplace_back(&cur()); do
q.push_back(current); do
{
const bool expired(ircd::ctx::wait<std::nothrow_t>(dur) <= zero);
@ -195,12 +194,13 @@ template<class time_point>
ircd::ctx::cv_status
ircd::ctx::dock::wait_until(time_point&& tp)
{
const unwind remove
assert(current);
const unwind remove{[this]
{
std::bind(&dock::remove_self, this)
};
q.remove(current);
}};
q.emplace_back(&cur());
q.push_back(current);
return ircd::ctx::wait_until<std::nothrow_t>(tp)? cv_status::timeout:
cv_status::no_timeout;
}
@ -214,12 +214,13 @@ ircd::ctx::dock::wait_until(time_point&& tp,
if(pred())
return true;
const unwind remove
assert(current);
const unwind remove{[this]
{
std::bind(&dock::remove_self, this)
};
q.remove(current);
}};
q.emplace_back(&cur()); do
q.push_back(current); do
{
const bool expired
{
@ -249,14 +250,6 @@ noexcept
ircd::ctx::notify(ctx);
}
inline void
ircd::ctx::dock::remove_self()
{
const auto it(std::find(begin(q), end(q), &cur()));
assert(it != end(q));
q.erase(it);
}
/// The number of contexts waiting in the queue.
inline size_t
ircd::ctx::dock::size()