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map: faster get and exists

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ka-weihe 2020-05-09 12:42:01 +02:00 committed by GitHub
parent 1c8d2c21b5
commit 85763d0539
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 39 additions and 35 deletions
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74
vlib/builtin/map.v
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@ -61,24 +61,24 @@ much faster rehashing.
const ( const (
// Number of bits from the hash stored for each entry // Number of bits from the hash stored for each entry
hashbits = 24 hashbits = 24
// Number of bits from the hash stored for rehashing // Number of bits from the hash stored for rehashing
max_cached_hashbits = 16 max_cached_hashbits = 16
// Initial log-number of buckets in the hashtable // Initial log-number of buckets in the hashtable
init_log_capicity = 5 init_log_capicity = 5
// Initial number of buckets in the hashtable // Initial number of buckets in the hashtable
init_capicity = 1<<init_log_capicity init_capicity = 1 << init_log_capicity
// Maximum load-factor (size / capacity) // Maximum load-factor (size / capacity)
max_load_factor = 0.8 max_load_factor = 0.8
// Initial highest even index in metas // Initial highest even index in metas
init_cap = init_capicity - 2 init_cap = init_capicity - 2
// Used for incrementing `extra_metas` when max // Used for incrementing `extra_metas` when max
// probe count is too high, to avoid overflow // probe count is too high, to avoid overflow
extra_metas_inc = 4 extra_metas_inc = 4
// Bitmask to select all the hashbits // Bitmask to select all the hashbits
hash_mask = u32(0x00FFFFFF) hash_mask = u32(0x00FFFFFF)
// Used for incrementing the probe-count // Used for incrementing the probe-count
probe_inc = u32(0x01000000) probe_inc = u32(0x01000000)
) )
// This function is intended to be fast when // This function is intended to be fast when
@ -170,26 +170,26 @@ fn (d mut DenseArray) zeros_to_end() {
pub struct map { pub struct map {
// Byte size of value // Byte size of value
value_bytes int value_bytes int
mut: mut:
// highest even index in the hashtable // highest even index in the hashtable
cap u32 cap u32
// Number of cached hashbits left for rehasing // Number of cached hashbits left for rehasing
cached_hashbits byte cached_hashbits byte
// Used for right-shifting out used hashbits // Used for right-shifting out used hashbits
shift byte shift byte
// Array storing key-values (ordered) // Array storing key-values (ordered)
key_values DenseArray key_values DenseArray
// Pointer to meta-data: // Pointer to meta-data:
// Odd indices store kv_index. // Odd indices store kv_index.
// Even indices store probe_count and hashbits. // Even indices store probe_count and hashbits.
metas &u32 metas &u32
// Extra metas that allows for no ranging when incrementing // Extra metas that allows for no ranging when incrementing
// index in the hashmap // index in the hashmap
extra_metas u32 extra_metas u32
pub mut: pub mut:
// Number of key-values currently in the hashmap // Number of key-values currently in the hashmap
size int size int
} }
fn new_map_1(value_bytes int) map { fn new_map_1(value_bytes int) map {
@ -217,7 +217,7 @@ fn new_map_init(n, value_bytes int, keys &string, values voidptr) map {
fn (m &map) key_to_index(key string) (u32,u32) { fn (m &map) key_to_index(key string) (u32,u32) {
hash := wyhash.wyhash_c(key.str, u64(key.len), 0) hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
index := hash & m.cap index := hash & m.cap
meta := ((hash>>m.shift) & hash_mask) | probe_inc meta := ((hash >> m.shift) & hash_mask) | probe_inc
return u32(index),u32(meta) return u32(index),u32(meta)
} }
@ -251,8 +251,8 @@ fn (m mut map) meta_greater(_index u32, _metas u32, kvi u32) {
} }
m.metas[index] = meta m.metas[index] = meta
m.metas[index + 1] = kv_index m.metas[index + 1] = kv_index
probe_count := (meta>>hashbits) - 1 probe_count := (meta >> hashbits) - 1
if (probe_count<<1) == m.extra_metas { if (probe_count << 1) == m.extra_metas {
m.extra_metas += extra_metas_inc m.extra_metas += extra_metas_inc
mem_size := (m.cap + 2 + m.extra_metas) mem_size := (m.cap + 2 + m.extra_metas)
m.metas = &u32(C.realloc(m.metas, sizeof(u32) * mem_size)) m.metas = &u32(C.realloc(m.metas, sizeof(u32) * mem_size))
@ -265,7 +265,7 @@ fn (m mut map) meta_greater(_index u32, _metas u32, kvi u32) {
} }
fn (m mut map) set(key string, value voidptr) { fn (m mut map) set(key string, value voidptr) {
load_factor := f32(m.size<<1) / f32(m.cap) load_factor := f32(m.size << 1) / f32(m.cap)
if load_factor > max_load_factor { if load_factor > max_load_factor {
m.expand() m.expand()
} }
@ -289,7 +289,7 @@ fn (m mut map) set(key string, value voidptr) {
// Doubles the size of the hashmap // Doubles the size of the hashmap
fn (m mut map) expand() { fn (m mut map) expand() {
old_cap := m.cap old_cap := m.cap
m.cap = ((m.cap + 2)<<1) - 2 m.cap = ((m.cap + 2) << 1) - 2
// Check if any hashbits are left // Check if any hashbits are left
if m.cached_hashbits == 0 { if m.cached_hashbits == 0 {
m.shift += max_cached_hashbits m.shift += max_cached_hashbits
@ -325,9 +325,9 @@ fn (m mut map) cached_rehash(old_cap u32) {
continue continue
} }
old_meta := old_metas[i] old_meta := old_metas[i]
old_probe_count := ((old_meta>>hashbits) - 1)<<1 old_probe_count := ((old_meta >> hashbits) - 1) << 1
old_index := (i - old_probe_count) & (m.cap>>1) old_index := (i - old_probe_count) & (m.cap >> 1)
mut index := (old_index | (old_meta<<m.shift)) & m.cap mut index := (old_index | (old_meta << m.shift)) & m.cap
mut meta := (old_meta & hash_mask) | probe_inc mut meta := (old_meta & hash_mask) | probe_inc
index,meta = m.meta_less(index, meta) index,meta = m.meta_less(index, meta)
kv_index := old_metas[i + 1] kv_index := old_metas[i + 1]
@ -340,28 +340,32 @@ fn (m mut map) cached_rehash(old_cap u32) {
fn (m map) get3(key string, zero voidptr) voidptr { fn (m map) get3(key string, zero voidptr) voidptr {
mut index,mut meta := m.key_to_index(key) mut index,mut meta := m.key_to_index(key)
index,meta = m.meta_less(index, meta) for {
for meta == m.metas[index] { if meta == m.metas[index] {
kv_index := m.metas[index + 1] kv_index := m.metas[index + 1]
if fast_string_eq(key, m.key_values.keys[kv_index]) { if fast_string_eq(key, m.key_values.keys[kv_index]) {
return voidptr(m.key_values.values + kv_index * m.value_bytes) return voidptr(m.key_values.values + kv_index * m.value_bytes)
}
} }
index += 2 index += 2
meta += probe_inc meta += probe_inc
if meta > m.metas[index] { break }
} }
return zero return zero
} }
fn (m map) exists(key string) bool { fn (m map) exists(key string) bool {
mut index,mut meta := m.key_to_index(key) mut index,mut meta := m.key_to_index(key)
index,meta = m.meta_less(index, meta) for {
for meta == m.metas[index] { if meta == m.metas[index] {
kv_index := m.metas[index + 1] kv_index := m.metas[index + 1]
if fast_string_eq(key, m.key_values.keys[kv_index]) { if fast_string_eq(key, m.key_values.keys[kv_index]) {
return true return true
}
} }
index += 2 index += 2
meta += probe_inc meta += probe_inc
if meta > m.metas[index] { break }
} }
return false return false
} }
@ -373,7 +377,7 @@ pub fn (m mut map) delete(key string) {
for meta == m.metas[index] { for meta == m.metas[index] {
kv_index := m.metas[index + 1] kv_index := m.metas[index + 1]
if fast_string_eq(key, m.key_values.keys[kv_index]) { if fast_string_eq(key, m.key_values.keys[kv_index]) {
for (m.metas[index + 2]>>hashbits) > 1 { for (m.metas[index + 2] >> hashbits) > 1 {
m.metas[index] = m.metas[index + 2] - probe_inc m.metas[index] = m.metas[index + 2] - probe_inc
m.metas[index + 1] = m.metas[index + 3] m.metas[index + 1] = m.metas[index + 3]
index += 2 index += 2