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LibRegex: Use a bump-allocated linked list for fork save states

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This makes it avoid the excessively high malloc() traffic.
This commit is contained in:
Ali Mohammad Pur 2021-07-31 18:50:51 +04:30 committed by Ali Mohammad Pur
parent b034fa9f1f
commit a7653e6a05
Notes: sideshowbarker 2024-07-18 08:59:31 +09:00 
Author: https://github.com/alimpfard
Commit: https://github.com/SerenityOS/serenity/commit/a7653e6a051
Pull-request: https://github.com/SerenityOS/serenity/pull/9127
1 changed files with 60 additions and 1 deletions
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61
Userland/Libraries/LibRegex/RegexMatcher.cpp
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@ -4,6 +4,7 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/BumpAllocator.h>
#include <AK/Debug.h>
#include <AK/String.h>
#include <AK/StringBuilder.h>
@ -334,12 +335,70 @@ RegexResult Matcher<Parser>::match(Vector<RegexStringView> const views, Optional
};
}
template<typename T>
class BumpAllocatedLinkedList {
public:
BumpAllocatedLinkedList() = default;
ALWAYS_INLINE void append(T value)
{
auto new_node = m_allocator.allocate();
VERIFY(new_node);
auto node_ptr = new (new_node) Node { move(value), nullptr, nullptr };
if (!m_first) {
m_first = new_node;
m_last = new_node;
return;
}
node_ptr->previous = m_last;
m_last->next = node_ptr;
m_last = node_ptr;
}
ALWAYS_INLINE T take_last()
{
VERIFY(m_last);
T value = move(m_last->value);
if (m_last == m_first) {
m_last = nullptr;
m_first = nullptr;
} else {
m_last = m_last->previous;
m_last->next = nullptr;
}
return value;
}
ALWAYS_INLINE T& last()
{
return m_last->value;
}
ALWAYS_INLINE bool is_empty() const
{
return m_first == nullptr;
}
private:
struct Node {
T value;
Node* next { nullptr };
Node* previous { nullptr };
};
UniformBumpAllocator<Node, true> m_allocator;
Node* m_first { nullptr };
Node* m_last { nullptr };
};
template<class Parser>
Optional<bool> Matcher<Parser>::execute(MatchInput const& input, MatchState& state, MatchOutput& output) const
{
state.recursion_level = 0;
Vector<MatchState, 64> states_to_try_next;
BumpAllocatedLinkedList<MatchState> states_to_try_next;
auto& bytecode = m_pattern->parser_result.bytecode;