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blockcache.go
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blockcache.go
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package nvm
import (
"bytes"
"errors"
"sync"
"time"
"unsafe"
"github.com/Yiling-J/theine-go/internal/alloc"
"github.com/Yiling-J/theine-go/internal/clock"
"github.com/Yiling-J/theine-go/internal/nvm/serializers"
"github.com/zeebo/xxh3"
)
const (
alignSize = 512
readBufSize = 64
)
func spread(h uint64) uint64 {
h ^= h >> 17
h *= 0xed5ad4bb
h ^= h >> 11
h *= 0xac4c1b51
h ^= h >> 15
return h
}
func align(n int) int {
l := n % alignSize
if l != 0 {
return n + alignSize - l
}
return n
}
type BlockInfo struct {
address uint32
sizeHint uint32
removed bool
}
type BlockInfoP struct {
KeyHash uint64
Address uint32
SizeHint uint32
}
type BlockEntry struct {
keySize uint64
valueSize uint64
cost int64
expire int64
checksum uint64
}
type BlockCache struct {
Offset uint64
mu *sync.RWMutex
Clock *clock.Clock
CacheSize uint64
entrySize uint64
RegionSize uint32
index map[uint64]*BlockInfo
entrySerializer serializers.Serializer[BlockEntry]
regionManager *RegionManager
}
func NewBlockCache(cacheSize int, regionSize int, cleanRegionSize uint32, offset uint64, allocator *alloc.Allocator, errHandler func(err error)) *BlockCache {
regionSize = align(regionSize)
regionCount := cacheSize / regionSize
b := &BlockCache{
Offset: offset,
mu: &sync.RWMutex{},
entrySerializer: serializers.NewMemorySerializer[BlockEntry](),
CacheSize: uint64(cacheSize),
RegionSize: uint32(regionSize),
entrySize: uint64(unsafe.Sizeof(BlockEntry{})),
index: make(map[uint64]*BlockInfo, cacheSize/regionSize),
Clock: &clock.Clock{Start: time.Now().UTC()},
}
if errHandler == nil {
errHandler = func(err error) {}
}
b.regionManager = NewRegionManager(
offset, uint32(regionSize), uint32(regionCount), cleanRegionSize, b.removeRegion,
allocator, errHandler,
)
return b
}
func (c *BlockCache) realAddress(address uint32) (uint64, uint64) {
base := uint64(address) * uint64(alignSize)
return base / uint64(c.RegionSize), base % uint64(c.RegionSize)
}
func (c *BlockCache) Lookup(key []byte) (item *alloc.AllocItem, cost int64, expire int64, ok bool, err error) {
kh := xxh3.Hash(key)
c.mu.RLock()
index, ok := c.index[kh]
if !ok {
c.mu.RUnlock()
return nil, cost, expire, false, nil
}
c.mu.RUnlock()
rid, offset := c.realAddress(index.address)
item, err = c.regionManager.GetData(
index, rid, offset, uint64(index.sizeHint)*alignSize,
)
if err != nil {
return item, cost, expire, false, err
}
if item == nil {
return item, cost, expire, false, nil
}
var entry BlockEntry
err = c.entrySerializer.Unmarshal(item.Data[:c.entrySize], &entry)
if err != nil {
return item, cost, expire, false, err
}
checksum := xxh3.Hash(item.Data[c.entrySize : c.entrySize+entry.keySize+entry.valueSize])
if checksum != entry.checksum {
return item, cost, expire, false, errors.New("checksum mismatch")
}
if entry.expire > 0 && entry.expire <= c.Clock.NowNano() {
return item, cost, expire, false, err
}
if !bytes.Equal(key, item.Data[c.entrySize:c.entrySize+entry.keySize]) {
return item, cost, expire, false, err
}
offset = c.entrySize + entry.keySize
item.Data = item.Data[offset : offset+entry.valueSize]
return item, entry.cost, entry.expire, true, err
}
func (c *BlockCache) Insert(key []byte, value []byte, cost int64, expire int64) error {
kh := xxh3.Hash(key)
header := BlockEntry{
keySize: uint64(len(key)),
valueSize: uint64(len(value)),
cost: cost,
expire: expire,
}
size := int(c.entrySize) + len(key) + len(value)
res := size % alignSize
if res != 0 {
size += (alignSize - res)
}
rid, offset, buffer, cb, err := c.regionManager.Allocate(size)
if err != nil {
return err
}
// esacpe
_, err = buffer.Write(make([]byte, c.entrySize))
if err != nil {
return err
}
_, err = buffer.Write(key)
if err != nil {
return err
}
_, err = buffer.Write(value)
if err != nil {
return err
}
b := buffer.Bytes()
header.checksum = xxh3.Hash(b[int(c.entrySize):])
hb, err := c.entrySerializer.Marshal(header)
if err != nil {
return err
}
_ = copy(b[:], hb)
cb()
c.mu.Lock()
c.index[kh] = &BlockInfo{
sizeHint: uint32(size / alignSize),
address: uint32((uint64(rid)*uint64(c.RegionSize) + offset) / alignSize),
}
c.mu.Unlock()
return nil
}
func (c *BlockCache) removeRegion(data []byte, endOffset uint64) error {
offset := 0
for offset < int(endOffset) {
var entry BlockEntry
err := c.entrySerializer.Unmarshal(data[offset:offset+int(c.entrySize)], &entry)
if err != nil {
return err
}
offset += int(c.entrySize)
checksum := xxh3.Hash(data[offset : offset+int(entry.keySize+entry.valueSize)])
if checksum != entry.checksum {
return errors.New("checksum mismatch")
}
keyh := xxh3.Hash(data[offset : offset+int(entry.keySize)])
c.mu.Lock()
i, ok := c.index[keyh]
if ok {
i.removed = true
delete(c.index, keyh)
}
c.mu.Unlock()
offset += int(entry.keySize + entry.valueSize)
offset = align(offset)
}
return nil
}
func (c *BlockCache) Delete(key []byte) {
kh := xxh3.Hash(key)
c.mu.Lock()
delete(c.index, kh)
c.mu.Unlock()
}