forked from tidwall/rhh
/
u64.go
185 lines (169 loc) · 4.17 KB
/
u64.go
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// Copyright 2019 Joshua J Baker. All rights reserved.
// Use of this source code is governed by an ISC-style
// license that can be found in the LICENSE file.
package rhh
import (
"reflect"
"unsafe"
"github.com/cespare/xxhash"
)
type entryU64 struct {
hdib uint64 // bitfield { hash:48 dib:16 }
key uint64 // user key
value interface{} // user value
}
func (e *entryU64) dib() int {
return int(e.hdib & maxDIB)
}
func (e *entryU64) hash() int {
return int(e.hdib >> dibBitSize)
}
func (e *entryU64) setDIB(dib int) {
e.hdib = e.hdib>>dibBitSize<<dibBitSize | uint64(dib)&maxDIB
}
func (e *entryU64) setHash(hash int) {
e.hdib = uint64(hash)<<dibBitSize | e.hdib&maxDIB
}
// hash returns a 48-bit hash for 64-bit environments, or 32-bit hash for
// 32-bit environments.
func (m *MapU64) hash(key uint64) int {
return int(xxhash.Sum64(*(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{
Data: uintptr(unsafe.Pointer(&key)), Len: 8, Cap: 8,
}))) >> dibBitSize)
}
// MapU64 is a map. Like map[uint64]interface{}
type MapU64 struct {
cap int
length int
mask int
growAt int
shrinkAt int
buckets []entryU64
}
// NewU64 returns a new map. Like map[uint64]interface{}
func NewU64(cap int) *MapU64 {
m := new(MapU64)
m.cap = cap
sz := 8
for sz < m.cap {
sz *= 2
}
m.buckets = make([]entryU64, sz)
m.mask = len(m.buckets) - 1
m.growAt = int(float64(len(m.buckets)) * loadFactor)
m.shrinkAt = int(float64(len(m.buckets)) * (1 - loadFactor))
return m
}
func (m *MapU64) resize(newCap int) {
nmap := NewU64(newCap)
for i := 0; i < len(m.buckets); i++ {
if m.buckets[i].dib() > 0 {
nmap.set(m.buckets[i].hash(), m.buckets[i].key, m.buckets[i].value)
}
}
cap := m.cap
*m = *nmap
m.cap = cap
}
// Set assigns a value to a key.
// Returns the previous value, or false when no value was assigned.
func (m *MapU64) Set(key uint64, value interface{}) (interface{}, bool) {
if len(m.buckets) == 0 {
*m = *NewU64(0)
}
if m.length >= m.growAt {
m.resize(len(m.buckets) * 2)
}
return m.set(m.hash(key), key, value)
}
func (m *MapU64) set(hash int, key uint64, value interface{}) (interface{}, bool) {
e := entryU64{makeHDIB(hash, 1), key, value}
i := e.hash() & m.mask
for {
if m.buckets[i].dib() == 0 {
m.buckets[i] = e
m.length++
return nil, false
}
if e.hash() == m.buckets[i].hash() && e.key == m.buckets[i].key {
old := m.buckets[i].value
m.buckets[i].value = e.value
return old, true
}
if m.buckets[i].dib() < e.dib() {
e, m.buckets[i] = m.buckets[i], e
}
i = (i + 1) & m.mask
e.setDIB(e.dib() + 1)
}
}
// Get returns a value for a key.
// Returns false when no value has been assign for key.
func (m *MapU64) Get(key uint64) (interface{}, bool) {
if len(m.buckets) == 0 {
return nil, false
}
hash := m.hash(key)
i := hash & m.mask
for {
if m.buckets[i].dib() == 0 {
return nil, false
}
if m.buckets[i].hash() == hash && m.buckets[i].key == key {
return m.buckets[i].value, true
}
i = (i + 1) & m.mask
}
}
// Len returns the number of values in map.
func (m *MapU64) Len() int {
return m.length
}
// Delete deletes a value for a key.
// Returns the deleted value, or false when no value was assigned.
func (m *MapU64) Delete(key uint64) (interface{}, bool) {
if len(m.buckets) == 0 {
return nil, false
}
hash := m.hash(key)
i := hash & m.mask
for {
if m.buckets[i].dib() == 0 {
return nil, false
}
if m.buckets[i].hash() == hash && m.buckets[i].key == key {
old := m.buckets[i].value
m.remove(i)
return old, true
}
i = (i + 1) & m.mask
}
}
func (m *MapU64) remove(i int) {
m.buckets[i].setDIB(0)
for {
pi := i
i = (i + 1) & m.mask
if m.buckets[i].dib() <= 1 {
m.buckets[pi] = entryU64{}
break
}
m.buckets[pi] = m.buckets[i]
m.buckets[pi].setDIB(m.buckets[pi].dib() - 1)
}
m.length--
if len(m.buckets) > m.cap && m.length <= m.shrinkAt {
m.resize(m.length)
}
}
// Range iterates overall all key/values.
// It's not safe to call or Set or Delete while ranging.
func (m *MapU64) Range(iter func(key uint64, value interface{}) bool) {
for i := 0; i < len(m.buckets); i++ {
if m.buckets[i].dib() > 0 {
if !iter(m.buckets[i].key, m.buckets[i].value) {
return
}
}
}
}