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[Core] Optimize HashMap #90082

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[Core] Optimize HashMap #90082

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11 changes: 9 additions & 2 deletions core/string/node_path.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -30,23 +30,30 @@

#include "node_path.h"

#include "core/templates/hashfuncs.h"
#include "core/variant/variant.h"

void NodePath::_update_hash_cache() const {
uint32_t h = data->absolute ? 1 : 0;
int pc = data->path.size();
const StringName *sn = data->path.ptr();
uint32_t hash_mixed = h;
for (int i = 0; i < pc; i++) {
h = h ^ sn[i].hash();
uint32_t string_hash = sn[i].hash();
h = h ^ string_hash;
hash_mixed = hash_djb2_one_32(string_hash, hash_mixed); // Don't change to murmur3 because StringName uses djb2!
}
int spc = data->subpath.size();
const StringName *ssn = data->subpath.ptr();
for (int i = 0; i < spc; i++) {
h = h ^ ssn[i].hash();
uint32_t string_hash = ssn[i].hash();
h = h ^ string_hash;
hash_mixed = hash_djb2_one_32(string_hash, hash_mixed);
}

data->hash_cache_valid = true;
data->hash_cache = h;
data->hash_mixed_cache = hash_fmix32(hash_mixed);
}

void NodePath::prepend_period() {
Expand Down
11 changes: 11 additions & 0 deletions core/string/node_path.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@ class NodePath {
bool absolute;
mutable bool hash_cache_valid;
mutable uint32_t hash_cache;
mutable uint32_t hash_mixed_cache;
};

mutable Data *data = nullptr;
Expand Down Expand Up @@ -78,6 +79,16 @@ class NodePath {
return data->hash_cache;
}

_FORCE_INLINE_ uint32_t hash_mixed() const {
if (!data) {
return 0;
}
if (!data->hash_cache_valid) {
_update_hash_cache();
}
return data->hash_mixed_cache;
}

operator String() const;
bool is_empty() const;

Expand Down
30 changes: 21 additions & 9 deletions core/string/string_name.cpp
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Expand Up @@ -270,14 +270,16 @@ StringName::StringName(const char *p_name, bool p_static) {
}

const uint32_t hash = String::hash(p_name);
const uint32_t idx = hash & STRING_TABLE_MASK;
const uint32_t hash_mixed = hash_fmix32(hash);

const uint32_t idx = hash_mixed & STRING_TABLE_MASK;

MutexLock lock(mutex);
_data = _table[idx];

while (_data) {
// compare hash first
if (_data->hash == hash && _data->operator==(p_name)) {
if (_data->hash_mixed == hash_mixed && _data->operator==(p_name)) {
break;
}
_data = _data->next;
Expand Down Expand Up @@ -305,6 +307,7 @@ StringName::StringName(const char *p_name, bool p_static) {
_data->cname = nullptr;
_data->next = _table[idx];
_data->prev = nullptr;
_data->hash_mixed = hash_mixed;

#ifdef DEBUG_ENABLED
if (unlikely(debug_stringname)) {
Expand All @@ -327,14 +330,16 @@ StringName::StringName(const StaticCString &p_static_string, bool p_static) {
ERR_FAIL_COND(!p_static_string.ptr || !p_static_string.ptr[0]);

const uint32_t hash = String::hash(p_static_string.ptr);
const uint32_t idx = hash & STRING_TABLE_MASK;
const uint32_t hash_mixed = hash_fmix32(hash);

const uint32_t idx = hash_mixed & STRING_TABLE_MASK;

MutexLock lock(mutex);
_data = _table[idx];

while (_data) {
// compare hash first
if (_data->hash == hash && _data->operator==(p_static_string.ptr)) {
if (_data->hash_mixed == hash_mixed && _data->operator==(p_static_string.ptr)) {
break;
}
_data = _data->next;
Expand Down Expand Up @@ -362,6 +367,8 @@ StringName::StringName(const StaticCString &p_static_string, bool p_static) {
_data->cname = p_static_string.ptr;
_data->next = _table[idx];
_data->prev = nullptr;

_data->hash_mixed = hash_mixed;
#ifdef DEBUG_ENABLED
if (unlikely(debug_stringname)) {
// Keep in memory, force static.
Expand All @@ -385,13 +392,14 @@ StringName::StringName(const String &p_name, bool p_static) {
}

const uint32_t hash = p_name.hash();
const uint32_t idx = hash & STRING_TABLE_MASK;
const uint32_t hash_mixed = hash_fmix32(hash);
const uint32_t idx = hash_mixed & STRING_TABLE_MASK;

MutexLock lock(mutex);
_data = _table[idx];

while (_data) {
if (_data->hash == hash && _data->operator==(p_name)) {
if (_data->hash_mixed == hash_mixed && _data->operator==(p_name)) {
break;
}
_data = _data->next;
Expand Down Expand Up @@ -419,6 +427,7 @@ StringName::StringName(const String &p_name, bool p_static) {
_data->cname = nullptr;
_data->next = _table[idx];
_data->prev = nullptr;
_data->hash_mixed = hash_mixed;
#ifdef DEBUG_ENABLED
if (unlikely(debug_stringname)) {
// Keep in memory, force static.
Expand All @@ -441,10 +450,11 @@ StringName StringName::search(const char *p_name) {
return StringName();
}

const uint32_t hash = String::hash(p_name);
const uint32_t hash = hash_fmix32(String::hash(p_name));
const uint32_t idx = hash & STRING_TABLE_MASK;

MutexLock lock(mutex);

_Data *_data = _table[idx];

while (_data) {
Expand Down Expand Up @@ -476,10 +486,11 @@ StringName StringName::search(const char32_t *p_name) {
return StringName();
}

const uint32_t hash = String::hash(p_name);
const uint32_t hash = hash_fmix32(String::hash(p_name));
const uint32_t idx = hash & STRING_TABLE_MASK;

MutexLock lock(mutex);

_Data *_data = _table[idx];

while (_data) {
Expand All @@ -500,10 +511,11 @@ StringName StringName::search(const char32_t *p_name) {
StringName StringName::search(const String &p_name) {
ERR_FAIL_COND_V(p_name.is_empty(), StringName());

const uint32_t hash = p_name.hash();
const uint32_t hash = hash_fmix32(p_name.hash());
const uint32_t idx = hash & STRING_TABLE_MASK;

MutexLock lock(mutex);

_Data *_data = _table[idx];

while (_data) {
Expand Down
11 changes: 11 additions & 0 deletions core/string/string_name.h
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Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,7 @@ class StringName {
bool operator!=(const char *p_name) const;

int idx = 0;
uint32_t hash_mixed = 0;
uint32_t hash = 0;
_Data *prev = nullptr;
_Data *next = nullptr;
Expand Down Expand Up @@ -145,6 +146,16 @@ class StringName {
return get_empty_hash();
}
}

// Used by HashMapHasherDefault. Don`t use it as seed to create other hash.
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@Ivorforce Ivorforce Mar 28, 2025

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Suggested change
// Used by HashMapHasherDefault. Don`t use it as seed to create other hash.
// Returns the hash finalized by mixing. To combine this StringName into a hash, use `hash()` instead.

_FORCE_INLINE_ uint32_t hash_mixed() const {
if (unlikely(_data == nullptr)) {
return get_empty_hash();
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@Ivorforce Ivorforce Mar 28, 2025

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Does this not have to be mixed? It should return a plain djb2 hash, no?

}

return _data->hash_mixed;
}

_FORCE_INLINE_ const void *data_unique_pointer() const {
return (void *)_data;
}
Expand Down
9 changes: 9 additions & 0 deletions core/templates/hash_map.cpp
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Expand Up @@ -41,3 +41,12 @@ bool _hashmap_variant_less_than(const Variant &p_left, const Variant &p_right) {
}
return res;
}

// Explicit instantiation.
template class HashMap<int, int>;
template class HashMap<String, int>;
template class HashMap<StringName, bool>;
template class HashMap<StringName, StringName>;
template class HashMap<StringName, String>;
template class HashMap<StringName, Variant>;
template class HashMap<StringName, int>;
Comment on lines +45 to +52
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@Ivorforce Ivorforce Mar 28, 2025

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I believe explicit HashMap instantiation is out of scope for this PR.
(even though it may be a good idea)

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