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Code Issues Releases Wiki Activity

ircd::ctx: Allow lambda transformation of the iterable for when_any()/when_all().

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This commit is contained in:
Jason Volk 2019-04-18 16:01:48 -07:00
parent 0edd47d383
commit 12df824cf4
1 changed files with 63 additions and 19 deletions
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82
include/ircd/ctx/when.h
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@ -13,7 +13,10 @@
namespace ircd::ctx
{
template<class it, class F> future<void> when_all(it first, const it &last, F&& closure);
template<class it> future<void> when_all(it first, const it &last);
template<class it, class F> future<it> when_any(it first, const it &last, F&& closure);
template<class it> future<it> when_any(it first, const it &last);
}
@ -22,9 +25,9 @@ namespace ircd::ctx::when
{
template<class T> auto &state(const future<T> &);
void all_then(promise<void> &p);
template<class it> void any_then(promise<it> &p, it &f);
template<class it> void set_all_then(promise<void> &p, it &f);
template<class it> void set_any_then(promise<it> &p, it &f);
template<class it, class F> void any_then(promise<it> &, it &, F&&);
template<class it, class F> void set_all_then(promise<void> &, it &, F&&);
template<class it, class F> void set_any_then(promise<it> &, it &, F&&);
}
/// Returns a future which becomes ready when any of the futures in the
@ -41,20 +44,39 @@ template<class it>
ircd::ctx::future<it>
ircd::ctx::when_any(it first,
const it &last)
{
return when_any(first, last, []
(auto &iterator) -> decltype(*iterator) &
{
return *iterator;
});
}
/// Implementation of when_any(); this requires a closure from the user which
/// knows how to use the iterable being passed. The closure must return a
/// a reference to the future. This allows for complex iterables which may
/// have pointers to pointers, etc. The default non-closure when_any() overload
/// supplies a closure that simply dereferences the argument (i.e `return *it;`)
template<class it,
class F>
ircd::ctx::future<it>
ircd::ctx::when_any(it first,
const it &last,
F&& closure)
{
promise<it> p;
future<it> ret(p);
for(auto f(first); f != last; ++f)
if(is(state(*f), future_state::READY))
if(is(state(closure(f)), future_state::READY))
{
set(when::state(*f), future_state::OBSERVED);
set(when::state(closure(f)), future_state::OBSERVED);
p.set_value(f);
return ret;
}
for(; first != last; ++first)
if(is(state(*first), future_state::PENDING))
when::set_any_then(p, first);
if(is(state(closure(first)), future_state::PENDING))
when::set_any_then(p, first, closure);
if(refcount(p.state()) <= 1)
p.set_value(first);
@ -69,12 +91,28 @@ template<class it>
ircd::ctx::future<void>
ircd::ctx::when_all(it first,
const it &last)
{
return when_all(first, last, []
(auto &iterator) -> decltype(*iterator) &
{
return *iterator;
});
}
/// Implementation of when_all(); this requires a closure from the user which
/// knows how to use the iterable being passed. See related when_any() docs.
template<class it,
class F>
ircd::ctx::future<void>
ircd::ctx::when_all(it first,
const it &last,
F&& closure)
{
promise<void> p;
future<void> ret(p);
for(; first != last; ++first)
if(is(state(*first), future_state::PENDING))
when::set_all_then(p, first);
if(is(state(closure(first)), future_state::PENDING))
when::set_all_then(p, first, closure);
if(refcount(p.state()) <= 1)
p.set_value();
@ -82,25 +120,29 @@ ircd::ctx::when_all(it first,
return ret;
}
template<class it>
template<class it,
class F>
void
ircd::ctx::when::set_any_then(promise<it> &p,
it &f)
it &f,
F&& closure)
{
when::state(*f).then = [p, f] // TODO: quash this alloc
when::state(closure(f)).then = [p, f, closure] // TODO: quash this alloc
(shared_state_base &sb) mutable
{
if(sb.then)
any_then(p, f);
any_then(p, f, closure);
};
}
template<class it>
template<class it,
class F>
void
ircd::ctx::when::set_all_then(promise<void> &p,
it &f)
it &f,
F&& closure)
{
when::state(*f).then = [p] // TODO: quash this alloc
when::state(closure(f)).then = [p] // TODO: quash this alloc
(shared_state_base &sb) mutable
{
if(sb.then)
@ -108,15 +150,17 @@ ircd::ctx::when::set_all_then(promise<void> &p,
};
}
template<class it>
template<class it,
class F>
void
ircd::ctx::when::any_then(promise<it> &p,
it &f)
it &f,
F&& closure)
{
if(!p.valid())
return;
set(when::state(*f), future_state::OBSERVED);
set(when::state(closure(f)), future_state::OBSERVED);
p.set_value(f);
}