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memdb: merge nodeData and kvData to speedup access #416

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memdb: merge nodeData and kvData to speedup access #416

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89 changes: 57 additions & 32 deletions leveldb/memdb/memdb.go
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,9 @@ package memdb

import (
"math/rand"
"reflect"
"sync"
"unsafe"

"github.com/syndtr/goleveldb/leveldb/comparer"
"github.com/syndtr/goleveldb/leveldb/errors"
Expand All @@ -24,6 +26,7 @@ var (
)

const tMaxHeight = 12
const intSize = int(unsafe.Sizeof(int(0)))

type dbIter struct {
util.BasicReleaser
Expand All @@ -37,9 +40,8 @@ type dbIter struct {

func (i *dbIter) fill(checkStart, checkLimit bool) bool {
if i.node != 0 {
n := i.p.nodeData[i.node]
m := n + i.p.nodeData[i.node+nKey]
i.key = i.p.kvData[n:m]
kv := i.p.kvSlice(i.p.nodeData[i.node])
i.key = kv[:i.p.nodeData[i.node+nKey]]
if i.slice != nil {
switch {
case checkLimit && i.slice.Limit != nil && i.p.cmp.Compare(i.key, i.slice.Limit) >= 0:
Expand All @@ -49,7 +51,7 @@ func (i *dbIter) fill(checkStart, checkLimit bool) bool {
goto bail
}
}
i.value = i.p.kvData[m : m+i.p.nodeData[i.node+nVal]]
i.value = kv[i.p.nodeData[i.node+nKey]:][:i.p.nodeData[i.node+nVal]]
return true
}
bail:
Expand Down Expand Up @@ -181,21 +183,22 @@ const (
// DB is an in-memory key/value database.
type DB struct {
cmp comparer.BasicComparer
cap int
rnd *rand.Rand

mu sync.RWMutex
kvData []byte
mu sync.RWMutex
// Node data:
// [0] : KV offset
// [1] : Key length
// [2] : Value length
// [3] : Height
// [3..height] : Next nodes
nodeData []int
prevNode [tMaxHeight]int
maxHeight int
n int
kvSize int
nodeData []int
prevNode [tMaxHeight]int
maxHeight int
n int
kvSize int
kvDataSize int
}

func (p *DB) randHeight() (h int) {
Expand All @@ -207,6 +210,15 @@ func (p *DB) randHeight() (h int) {
return
}

// kvSlice converts &nodeData[offset] to byte slice for kv.
func (p *DB) kvSlice(offset int) (s []byte) {
sh := (*reflect.SliceHeader)(unsafe.Pointer(&s))
sh.Data = uintptr(unsafe.Pointer(&p.nodeData[offset]))
sh.Len = (len(p.nodeData) - offset) * intSize
sh.Cap = (cap(p.nodeData) - offset) * intSize
return
}

// Must hold RW-lock if prev == true, as it use shared prevNode slice.
func (p *DB) findGE(key []byte, prev bool) (int, bool) {
node := 0
Expand All @@ -216,7 +228,7 @@ func (p *DB) findGE(key []byte, prev bool) (int, bool) {
cmp := 1
if next != 0 {
o := p.nodeData[next]
cmp = p.cmp.Compare(p.kvData[o:o+p.nodeData[next+nKey]], key)
cmp = p.cmp.Compare(p.kvSlice(o)[:p.nodeData[next+nKey]], key)
}
if cmp < 0 {
// Keep searching in this list
Expand All @@ -241,7 +253,7 @@ func (p *DB) findLT(key []byte) int {
for {
next := p.nodeData[node+nNext+h]
o := p.nodeData[next]
if next == 0 || p.cmp.Compare(p.kvData[o:o+p.nodeData[next+nKey]], key) >= 0 {
if next == 0 || p.cmp.Compare(p.kvSlice(o)[:p.nodeData[next+nKey]], key) >= 0 {
if h == 0 {
break
}
Expand Down Expand Up @@ -278,14 +290,19 @@ func (p *DB) Put(key []byte, value []byte) error {
p.mu.Lock()
defer p.mu.Unlock()

expansion := (len(key) + len(value) + intSize - 1) / intSize
if node, exact := p.findGE(key, true); exact {
kvOffset := len(p.kvData)
p.kvData = append(p.kvData, key...)
p.kvData = append(p.kvData, value...)
kvOffset := len(p.nodeData)
p.nodeData = append(p.nodeData, make([]int, expansion)...)
kv := p.kvSlice(kvOffset)
copy(kv, key)
copy(kv[len(key):], value)

p.nodeData[node] = kvOffset
m := p.nodeData[node+nVal]
p.nodeData[node+nVal] = len(value)
p.kvSize += len(value) - m
p.kvDataSize += len(key) + len(value)
return nil
}

Expand All @@ -297,9 +314,11 @@ func (p *DB) Put(key []byte, value []byte) error {
p.maxHeight = h
}

kvOffset := len(p.kvData)
p.kvData = append(p.kvData, key...)
p.kvData = append(p.kvData, value...)
kvOffset := len(p.nodeData)
p.nodeData = append(p.nodeData, make([]int, expansion)...)
kv := p.kvSlice(kvOffset)
copy(kv, key)
copy(kv[len(key):], value)
// Node
node := len(p.nodeData)
p.nodeData = append(p.nodeData, kvOffset, len(key), len(value), h)
Expand All @@ -310,6 +329,7 @@ func (p *DB) Put(key []byte, value []byte) error {
}

p.kvSize += len(key) + len(value)
p.kvDataSize += len(key) + len(value)
p.n++
return nil
}
Expand Down Expand Up @@ -356,8 +376,8 @@ func (p *DB) Contains(key []byte) bool {
func (p *DB) Get(key []byte) (value []byte, err error) {
p.mu.RLock()
if node, exact := p.findGE(key, false); exact {
o := p.nodeData[node] + p.nodeData[node+nKey]
value = p.kvData[o : o+p.nodeData[node+nVal]]
kv := p.kvSlice(p.nodeData[node])
value = kv[p.nodeData[node+nKey]:][:p.nodeData[node+nVal]]
} else {
err = ErrNotFound
}
Expand All @@ -374,10 +394,9 @@ func (p *DB) Get(key []byte) (value []byte, err error) {
func (p *DB) Find(key []byte) (rkey, value []byte, err error) {
p.mu.RLock()
if node, _ := p.findGE(key, false); node != 0 {
n := p.nodeData[node]
m := n + p.nodeData[node+nKey]
rkey = p.kvData[n:m]
value = p.kvData[m : m+p.nodeData[node+nVal]]
kv := p.kvSlice(p.nodeData[node])
rkey = kv[:p.nodeData[node+nKey]]
value = kv[p.nodeData[node+nKey]:][:p.nodeData[node+nVal]]
} else {
err = ErrNotFound
}
Expand Down Expand Up @@ -410,9 +429,10 @@ func (p *DB) NewIterator(slice *util.Range) iterator.Iterator {

// Capacity returns keys/values buffer capacity.
func (p *DB) Capacity() int {
p.mu.RLock()
defer p.mu.RUnlock()
return cap(p.kvData)
if p.cap < p.kvDataSize {
return p.kvDataSize
}
return p.cap
}

// Size returns sum of keys and values length. Note that deleted
Expand All @@ -428,7 +448,10 @@ func (p *DB) Size() int {
func (p *DB) Free() int {
p.mu.RLock()
defer p.mu.RUnlock()
return cap(p.kvData) - len(p.kvData)
if f := p.cap - p.kvDataSize; f > 0 {
return f
}
return 0
}

// Len returns the number of entries in the DB.
Expand All @@ -445,7 +468,7 @@ func (p *DB) Reset() {
p.maxHeight = 1
p.n = 0
p.kvSize = 0
p.kvData = p.kvData[:0]
p.kvDataSize = 0
p.nodeData = p.nodeData[:nNext+tMaxHeight]
p.nodeData[nKV] = 0
p.nodeData[nKey] = 0
Expand All @@ -467,12 +490,14 @@ func (p *DB) Reset() {
//
// The returned DB instance is safe for concurrent use.
func New(cmp comparer.BasicComparer, capacity int) *DB {
prealloc := capacity / intSize // for kv data
prealloc += prealloc / 2 // for skip list nodes
p := &DB{
cmp: cmp,
cap: capacity,
rnd: rand.New(rand.NewSource(0xdeadbeef)),
maxHeight: 1,
kvData: make([]byte, 0, capacity),
nodeData: make([]int, 4+tMaxHeight),
nodeData: make([]int, 4+tMaxHeight, 4+tMaxHeight+prealloc),
}
p.nodeData[nHeight] = tMaxHeight
return p
Expand Down
14 changes: 6 additions & 8 deletions leveldb/memdb/memdb_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,10 +19,9 @@ import (
func (p *DB) TestFindLT(key []byte) (rkey, value []byte, err error) {
p.mu.RLock()
if node := p.findLT(key); node != 0 {
n := p.nodeData[node]
m := n + p.nodeData[node+nKey]
rkey = p.kvData[n:m]
value = p.kvData[m : m+p.nodeData[node+nVal]]
kv := p.kvSlice(p.nodeData[node])
rkey = kv[:p.nodeData[node+nKey]]
value = kv[p.nodeData[node+nKey]:][:p.nodeData[node+nVal]]
} else {
err = ErrNotFound
}
Expand All @@ -33,10 +32,9 @@ func (p *DB) TestFindLT(key []byte) (rkey, value []byte, err error) {
func (p *DB) TestFindLast() (rkey, value []byte, err error) {
p.mu.RLock()
if node := p.findLast(); node != 0 {
n := p.nodeData[node]
m := n + p.nodeData[node+nKey]
rkey = p.kvData[n:m]
value = p.kvData[m : m+p.nodeData[node+nVal]]
kv := p.kvSlice(p.nodeData[node])
rkey = kv[:p.nodeData[node+nKey]]
value = kv[p.nodeData[node+nKey]:][:p.nodeData[node+nVal]]
} else {
err = ErrNotFound
}
Expand Down