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LibJS: Don't punish large arrays with generic indexed property storage

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This patch rethinks the way indexed property storage works:

Instead of having a cut-off point at 200 elements where we always move
to generic property storage, we now allow arrays to stay in simple mode
as long as we don't create a gap/hole larger than 200 elements.

We also simplify generic storage to only have a hash map (for now)
instead of juggling both a vector and a hash map. This is mostly fine
since the vast majority of arrays get to stay simple now.

This is a huge speedup on anything that uses basic JS arrays with more
than 200 elements in them. :^)
This commit is contained in:
Andreas Kling 2021-03-21 11:33:45 +01:00
parent dee0c46c9b
commit d0664ce6c9
3 changed files with 52 additions and 93 deletions
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129
Userland/Libraries/LibJS/Runtime/IndexedProperties.cpp
View file

@ -30,6 +30,8 @@
namespace JS {
const u32 SPARSE_ARRAY_HOLE_THRESHOLD = 200;
SimpleIndexedPropertyStorage::SimpleIndexedPropertyStorage(Vector<Value>&& initial_values)
: m_array_size(initial_values.size())
, m_packed_elements(move(initial_values))
@ -48,15 +50,21 @@ Optional<ValueAndAttributes> SimpleIndexedPropertyStorage::get(u32 index) const
return ValueAndAttributes { m_packed_elements[index], default_attributes };
}
void SimpleIndexedPropertyStorage::grow_storage_if_needed()
{
if (m_array_size <= m_packed_elements.size())
return;
// Grow storage by 25% at a time.
m_packed_elements.resize(m_array_size + (m_array_size / 4));
}
void SimpleIndexedPropertyStorage::put(u32 index, Value value, PropertyAttributes attributes)
{
VERIFY(attributes == default_attributes);
VERIFY(index < SPARSE_ARRAY_THRESHOLD);
if (index >= m_array_size) {
m_array_size = index + 1;
if (index >= m_packed_elements.size())
m_packed_elements.resize(index + MIN_PACKED_RESIZE_AMOUNT >= SPARSE_ARRAY_THRESHOLD ? SPARSE_ARRAY_THRESHOLD : index + MIN_PACKED_RESIZE_AMOUNT);
grow_storage_if_needed();
}
m_packed_elements[index] = value;
}
@ -70,9 +78,7 @@ void SimpleIndexedPropertyStorage::remove(u32 index)
void SimpleIndexedPropertyStorage::insert(u32 index, Value value, PropertyAttributes attributes)
{
VERIFY(attributes == default_attributes);
VERIFY(index < SPARSE_ARRAY_THRESHOLD);
m_array_size++;
VERIFY(m_array_size <= SPARSE_ARRAY_THRESHOLD);
m_packed_elements.insert(index, value);
}
@ -92,7 +98,6 @@ ValueAndAttributes SimpleIndexedPropertyStorage::take_last()
void SimpleIndexedPropertyStorage::set_array_like_size(size_t new_size)
{
VERIFY(new_size <= SPARSE_ARRAY_THRESHOLD);
m_array_size = new_size;
m_packed_elements.resize(new_size);
}
@ -100,14 +105,13 @@ void SimpleIndexedPropertyStorage::set_array_like_size(size_t new_size)
GenericIndexedPropertyStorage::GenericIndexedPropertyStorage(SimpleIndexedPropertyStorage&& storage)
{
m_array_size = storage.array_like_size();
for (auto& element : move(storage.m_packed_elements))
m_packed_elements.append({ element, default_attributes });
for (size_t i = 0; i < storage.m_packed_elements.size(); ++i) {
m_sparse_elements.set(i, { storage.m_packed_elements[i], default_attributes });
}
}
bool GenericIndexedPropertyStorage::has_index(u32 index) const
{
if (index < SPARSE_ARRAY_THRESHOLD)
return index < m_packed_elements.size() && !m_packed_elements[index].value.is_empty();
return m_sparse_elements.contains(index);
}
@ -115,11 +119,6 @@ Optional<ValueAndAttributes> GenericIndexedPropertyStorage::get(u32 index) const
{
if (index >= m_array_size)
return {};
if (index < SPARSE_ARRAY_THRESHOLD) {
if (index >= m_packed_elements.size())
return {};
return m_packed_elements[index];
}
return m_sparse_elements.get(index);
}
@ -127,13 +126,7 @@ void GenericIndexedPropertyStorage::put(u32 index, Value value, PropertyAttribut
{
if (index >= m_array_size)
m_array_size = index + 1;
if (index < SPARSE_ARRAY_THRESHOLD) {
if (index >= m_packed_elements.size())
m_packed_elements.resize(index + MIN_PACKED_RESIZE_AMOUNT >= SPARSE_ARRAY_THRESHOLD ? SPARSE_ARRAY_THRESHOLD : index + MIN_PACKED_RESIZE_AMOUNT);
m_packed_elements[index] = { value, attributes };
} else {
m_sparse_elements.set(index, { value, attributes });
}
m_sparse_elements.set(index, { value, attributes });
}
void GenericIndexedPropertyStorage::remove(u32 index)
@ -144,12 +137,7 @@ void GenericIndexedPropertyStorage::remove(u32 index)
take_last();
return;
}
if (index < SPARSE_ARRAY_THRESHOLD) {
if (index < m_packed_elements.size())
m_packed_elements[index] = {};
} else {
m_sparse_elements.remove(index);
}
m_sparse_elements.remove(index);
}
void GenericIndexedPropertyStorage::insert(u32 index, Value value, PropertyAttributes attributes)
@ -168,11 +156,7 @@ void GenericIndexedPropertyStorage::insert(u32 index, Value value, PropertyAttri
m_sparse_elements = move(new_sparse_elements);
}
if (index < SPARSE_ARRAY_THRESHOLD) {
m_packed_elements.insert(index, { value, attributes });
} else {
m_sparse_elements.set(index, { value, attributes });
}
m_sparse_elements.set(index, { value, attributes });
}
ValueAndAttributes GenericIndexedPropertyStorage::take_first()
@ -180,18 +164,12 @@ ValueAndAttributes GenericIndexedPropertyStorage::take_first()
VERIFY(m_array_size > 0);
m_array_size--;
auto first_element = m_packed_elements.take_first();
if (!m_sparse_elements.is_empty()) {
m_packed_elements.append(m_sparse_elements.get(SPARSE_ARRAY_THRESHOLD).value_or({}));
HashMap<u32, ValueAndAttributes> new_sparse_elements;
for (auto& entry : m_sparse_elements) {
if (entry.key - 1 >= SPARSE_ARRAY_THRESHOLD)
new_sparse_elements.set(entry.key - 1, entry.value);
}
m_sparse_elements = move(new_sparse_elements);
}
auto indices = m_sparse_elements.keys();
quick_sort(indices);
auto it = m_sparse_elements.find(indices.first());
auto first_element = it->value;
m_sparse_elements.remove(it);
return first_element;
}
@ -200,34 +178,22 @@ ValueAndAttributes GenericIndexedPropertyStorage::take_last()
VERIFY(m_array_size > 0);
m_array_size--;
if (m_array_size <= SPARSE_ARRAY_THRESHOLD) {
auto last_element = m_packed_elements[m_array_size];
m_packed_elements[m_array_size] = {};
return last_element;
} else {
auto result = m_sparse_elements.get(m_array_size);
m_sparse_elements.remove(m_array_size);
VERIFY(result.has_value());
return result.value();
}
auto result = m_sparse_elements.get(m_array_size);
m_sparse_elements.remove(m_array_size);
VERIFY(result.has_value());
return result.value();
}
void GenericIndexedPropertyStorage::set_array_like_size(size_t new_size)
{
m_array_size = new_size;
if (new_size < SPARSE_ARRAY_THRESHOLD) {
m_packed_elements.resize(new_size);
m_sparse_elements.clear();
} else {
m_packed_elements.resize(SPARSE_ARRAY_THRESHOLD);
HashMap<u32, ValueAndAttributes> new_sparse_elements;
for (auto& entry : m_sparse_elements) {
if (entry.key < new_size)
new_sparse_elements.set(entry.key, entry.value);
}
m_sparse_elements = move(new_sparse_elements);
HashMap<u32, ValueAndAttributes> new_sparse_elements;
for (auto& entry : m_sparse_elements) {
if (entry.key < new_size)
new_sparse_elements.set(entry.key, entry.value);
}
m_sparse_elements = move(new_sparse_elements);
}
IndexedPropertyIterator::IndexedPropertyIterator(const IndexedProperties& indexed_properties, u32 staring_index, bool skip_empty)
@ -296,8 +262,10 @@ Optional<ValueAndAttributes> IndexedProperties::get(Object* this_object, u32 ind
void IndexedProperties::put(Object* this_object, u32 index, Value value, PropertyAttributes attributes, bool evaluate_accessors)
{
if (m_storage->is_simple_storage() && (index >= SPARSE_ARRAY_THRESHOLD || attributes != default_attributes))
if (m_storage->is_simple_storage() && (attributes != default_attributes || index > (array_like_size() + SPARSE_ARRAY_HOLE_THRESHOLD))) {
switch_to_generic_storage();
}
if (m_storage->is_simple_storage() || !evaluate_accessors) {
m_storage->put(index, value, attributes);
return;
@ -325,9 +293,13 @@ bool IndexedProperties::remove(u32 index)
void IndexedProperties::insert(u32 index, Value value, PropertyAttributes attributes)
{
if (m_storage->is_simple_storage() && (index >= SPARSE_ARRAY_THRESHOLD || attributes != default_attributes || array_like_size() == SPARSE_ARRAY_THRESHOLD))
switch_to_generic_storage();
m_storage->insert(index, move(value), attributes);
if (m_storage->is_simple_storage()) {
if (attributes != default_attributes
|| index > (array_like_size() + SPARSE_ARRAY_HOLE_THRESHOLD)) {
switch_to_generic_storage();
}
}
m_storage->insert(index, value, attributes);
}
ValueAndAttributes IndexedProperties::take_first(Object* this_object)
@ -361,34 +333,25 @@ void IndexedProperties::append_all(Object* this_object, const IndexedProperties&
void IndexedProperties::set_array_like_size(size_t new_size)
{
if (m_storage->is_simple_storage() && new_size > SPARSE_ARRAY_THRESHOLD)
switch_to_generic_storage();
m_storage->set_array_like_size(new_size);
}
Vector<u32> IndexedProperties::indices() const
{
Vector<u32> indices;
if (m_storage->is_simple_storage()) {
const auto& storage = static_cast<const SimpleIndexedPropertyStorage&>(*m_storage);
const auto& elements = storage.elements();
Vector<u32> indices;
indices.ensure_capacity(storage.array_like_size());
for (size_t i = 0; i < elements.size(); ++i) {
if (!elements.at(i).is_empty())
indices.unchecked_append(i);
}
} else {
const auto& storage = static_cast<const GenericIndexedPropertyStorage&>(*m_storage);
const auto& packed_elements = storage.packed_elements();
indices.ensure_capacity(storage.array_like_size());
for (size_t i = 0; i < packed_elements.size(); ++i) {
if (!packed_elements.at(i).value.is_empty())
indices.unchecked_append(i);
}
auto sparse_elements_keys = storage.sparse_elements().keys();
quick_sort(sparse_elements_keys);
indices.append(move(sparse_elements_keys));
return indices;
}
const auto& storage = static_cast<const GenericIndexedPropertyStorage&>(*m_storage);
auto indices = storage.sparse_elements().keys();
quick_sort(indices);
return indices;
}