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Optimize HashMap/HashSet using fastmod

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This commit is contained in:
Hendrik Brucker
2022-06-23 18:08:52 +02:00
parent d1dac8427a
commit fddafed919
3 changed files with 98 additions and 30 deletions
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33
core/templates/hash_map.h
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@@ -91,9 +91,9 @@ private:
return hash;
}
_FORCE_INLINE_ uint32_t _get_probe_length(uint32_t p_pos, uint32_t p_hash, uint32_t p_capacity) const {
uint32_t original_pos = p_hash % p_capacity;
return (p_pos - original_pos + p_capacity) % p_capacity;
static _FORCE_INLINE_ uint32_t _get_probe_length(const uint32_t p_pos, const uint32_t p_hash, const uint32_t p_capacity, const uint64_t p_capacity_inv) {
const uint32_t original_pos = fastmod(p_hash, p_capacity_inv, p_capacity);
return fastmod(p_pos - original_pos + p_capacity, p_capacity_inv, p_capacity);
}
bool _lookup_pos(const TKey &p_key, uint32_t &r_pos) const {
@@ -101,9 +101,10 @@ private:
return false; // Failed lookups, no elements
}
uint32_t capacity = hash_table_size_primes[capacity_index];
const uint32_t capacity = hash_table_size_primes[capacity_index];
const uint64_t capacity_inv = hash_table_size_primes_inv[capacity_index];
uint32_t hash = _hash(p_key);
uint32_t pos = hash % capacity;
uint32_t pos = fastmod(hash, capacity_inv, capacity);
uint32_t distance = 0;
while (true) {
@@ -111,7 +112,7 @@ private:
return false;
}
if (distance > _get_probe_length(pos, hashes[pos], capacity)) {
if (distance > _get_probe_length(pos, hashes[pos], capacity, capacity_inv)) {
return false;
}
@@ -120,17 +121,18 @@ private:
return true;
}
pos = (pos + 1) % capacity;
pos = fastmod((pos + 1), capacity_inv, capacity);
distance++;
}
}
void _insert_with_hash(uint32_t p_hash, HashMapElement<TKey, TValue> *p_value) {
uint32_t capacity = hash_table_size_primes[capacity_index];
const uint32_t capacity = hash_table_size_primes[capacity_index];
const uint64_t capacity_inv = hash_table_size_primes_inv[capacity_index];
uint32_t hash = p_hash;
HashMapElement<TKey, TValue> *value = p_value;
uint32_t distance = 0;
uint32_t pos = hash % capacity;
uint32_t pos = fastmod(hash, capacity_inv, capacity);
while (true) {
if (hashes[pos] == EMPTY_HASH) {
@@ -143,14 +145,14 @@ private:
}
// Not an empty slot, let's check the probing length of the existing one.
uint32_t existing_probe_len = _get_probe_length(pos, hashes[pos], capacity);
uint32_t existing_probe_len = _get_probe_length(pos, hashes[pos], capacity, capacity_inv);
if (existing_probe_len < distance) {
SWAP(hash, hashes[pos]);
SWAP(value, elements[pos]);
distance = existing_probe_len;
}
pos = (pos + 1) % capacity;
pos = fastmod((pos + 1), capacity_inv, capacity);
distance++;
}
}
@@ -316,13 +318,14 @@ public:
return false;
}
uint32_t capacity = hash_table_size_primes[capacity_index];
uint32_t next_pos = (pos + 1) % capacity;
while (hashes[next_pos] != EMPTY_HASH && _get_probe_length(next_pos, hashes[next_pos], capacity) != 0) {
const uint32_t capacity = hash_table_size_primes[capacity_index];
const uint64_t capacity_inv = hash_table_size_primes_inv[capacity_index];
uint32_t next_pos = fastmod((pos + 1), capacity_inv, capacity);
while (hashes[next_pos] != EMPTY_HASH && _get_probe_length(next_pos, hashes[next_pos], capacity, capacity_inv) != 0) {
SWAP(hashes[next_pos], hashes[pos]);
SWAP(elements[next_pos], elements[pos]);
pos = next_pos;
next_pos = (pos + 1) % capacity;
next_pos = fastmod((pos + 1), capacity_inv, capacity);
}
hashes[pos] = EMPTY_HASH;