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Performance improvement to if_contains and modify_if. Works with pointers rather than constructing iterators. A test I conducted which heavily uses these functions a ~10% improvement in runtime.

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This commit is contained in:
Brian McKinnon
2021-05-12 19:59:02 -05:00
parent d704abced8
commit 1557461428
1 changed files with 46 additions and 24 deletions
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parallel_hashmap/phmap.h
Vendored
+46 -24
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@@ -1628,20 +1628,22 @@ public:
// called heterogeneous key support.
template <class K = key_type>
iterator find(const key_arg<K>& key, size_t hashval) {
auto seq = probe(hashval);
while (true) {
Group g{ctrl_ + seq.offset()};
for (int i : g.Match((h2_t)H2(hashval))) {
if (PHMAP_PREDICT_TRUE(PolicyTraits::apply(
EqualElement<K>{key, eq_ref()},
PolicyTraits::element(slots_ + seq.offset((size_t)i)))))
return iterator_at(seq.offset((size_t)i));
}
if (PHMAP_PREDICT_TRUE(g.MatchEmpty()))
return end();
seq.next();
}
size_t offset;
if (find_impl(key, hashval, offset))
return iterator_at(offset);
else
return end();
}
template <class K = key_type>
pointer find_ptr(const key_arg<K>& key, size_t hashval) {
size_t offset;
if (find_impl(key, hashval, offset))
return &PolicyTraits::element(slots_ + offset);
else
return nullptr;
}
template <class K = key_type>
iterator find(const key_arg<K>& key) {
return find(key, this->hash(key));
@@ -1722,6 +1724,24 @@ private:
template <class Container, typename Enabler>
friend struct phmap::priv::hashtable_debug_internal::HashtableDebugAccess;
template <class K = key_type>
bool find_impl(const key_arg<K>& key, size_t hashval, size_t& offset) {
auto seq = probe(hashval);
while (true) {
Group g{ ctrl_ + seq.offset() };
for (int i : g.Match((h2_t)H2(hashval))) {
offset = seq.offset((size_t)i);
if (PHMAP_PREDICT_TRUE(PolicyTraits::apply(
EqualElement<K>{key, eq_ref()},
PolicyTraits::element(slots_ + offset))))
return true;
}
if (PHMAP_PREDICT_TRUE(g.MatchEmpty()))
return false;
seq.next();
}
}
struct FindElement
{
template <class K, class... Args>
@@ -3376,18 +3396,20 @@ private:
protected:
template <class K = key_type, class L = typename Lockable::SharedLock>
std::pair<Inner*, EmbeddedIterator> find_as_pair(const key_arg<K>& key, size_t hashval, L& mutexlock)
pointer find_ptr(const key_arg<K>& key, size_t hashval, L& mutexlock)
{
Inner& inner = sets_[subidx(hashval)];
auto& set = inner.set_;
mutexlock = std::move(L(inner));
return std::make_pair(&inner, set.find(key, hashval));
return set.find_ptr(key, hashval);
}
template <class K = key_type, class L = typename Lockable::SharedLock>
iterator find(const key_arg<K>& key, size_t hashval, L& mutexlock) {
auto res = find_as_pair(key, hashval, mutexlock);
return make_iterator(res.first, res.second);
Inner& inner = sets_[subidx(hashval)];
auto& set = inner.set_;
mutexlock = std::move(L(inner));
return make_iterator(&inner, set.find(key, hashval));
}
template <class K>
@@ -3690,10 +3712,10 @@ private:
static_assert(std::is_invocable<F, mapped_type&>::value);
#endif
L m;
auto res = this->template find_as_pair<K, L>(key, this->hash(key), m);
if (res.second == res.first->set_.end())
auto ptr = this->template find_ptr<K, L>(key, this->hash(key), m);
if (ptr == nullptr)
return false;
std::forward<F>(f)(Policy::value(&*res.second));
std::forward<F>(f)(Policy::value(ptr));
return true;
}
@@ -3703,11 +3725,11 @@ private:
static_assert(std::is_invocable<F, mapped_type&>::value);
#endif
L m;
auto res = this->template find_as_pair<K, L>(key, this->hash(key), m);
if (res.second != res.first->set_.end() &&
std::forward<F>(f)(Policy::value(&*res.second)))
auto it = this->template find<K, L>(key, this->hash(key), m);
if (it == this->end()) return false;
if (std::forward<F>(f)(Policy::value(&*it)))
{
res.first->set_.erase(res.second);
this->erase(it);
return true;
}
return false;