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package chunk_cache
import (
"errors"
"sync"
"github.com/chrislusf/seaweedfs/weed/glog"
"github.com/chrislusf/seaweedfs/weed/storage/needle"
)
var ErrorOutOfBounds = errors.New("attempt to read out of bounds")
type ChunkCache interface {
ReadChunkAt(data []byte, fileId string, offset uint64) (n int, err error)
SetChunk(fileId string, data []byte)
}
// a global cache for recently accessed file chunks
type TieredChunkCache struct {
memCache *ChunkCacheInMemory
diskCaches []*OnDiskCacheLayer
sync.RWMutex
onDiskCacheSizeLimit0 uint64
onDiskCacheSizeLimit1 uint64
onDiskCacheSizeLimit2 uint64
}
var _ ChunkCache = &TieredChunkCache{}
func NewTieredChunkCache(maxEntries int64, dir string, diskSizeInUnit int64, unitSize int64) *TieredChunkCache {
c := &TieredChunkCache{
memCache: NewChunkCacheInMemory(maxEntries),
}
c.diskCaches = make([]*OnDiskCacheLayer, 3)
c.onDiskCacheSizeLimit0 = uint64(unitSize)
c.onDiskCacheSizeLimit1 = 4 * c.onDiskCacheSizeLimit0
c.onDiskCacheSizeLimit2 = 2 * c.onDiskCacheSizeLimit1
c.diskCaches[0] = NewOnDiskCacheLayer(dir, "c0_2", diskSizeInUnit*unitSize/8, 2)
c.diskCaches[1] = NewOnDiskCacheLayer(dir, "c1_3", diskSizeInUnit*unitSize/4+diskSizeInUnit*unitSize/8, 3)
c.diskCaches[2] = NewOnDiskCacheLayer(dir, "c2_2", diskSizeInUnit*unitSize/2, 2)
return c
}
func (c *TieredChunkCache) ReadChunkAt(data []byte, fileId string, offset uint64) (n int, err error) {
if c == nil {
return 0, nil
}
c.RLock()
defer c.RUnlock()
minSize := offset + uint64(len(data))
if minSize <= c.onDiskCacheSizeLimit0 {
n, err = c.memCache.readChunkAt(data, fileId, offset)
if err != nil {
glog.Errorf("failed to read from memcache: %s", err)
}
if n >= int(minSize) {
return n, nil
}
}
fid, err := needle.ParseFileIdFromString(fileId)
if err != nil {
glog.Errorf("failed to parse file id %s", fileId)
return n, nil
}
if minSize <= c.onDiskCacheSizeLimit0 {
n, err = c.diskCaches[0].readChunkAt(data, fid.Key, offset)
if n >= int(minSize) {
return
}
}
if minSize <= c.onDiskCacheSizeLimit1 {
n, err = c.diskCaches[1].readChunkAt(data, fid.Key, offset)
if n >= int(minSize) {
return
}
}
{
n, err = c.diskCaches[2].readChunkAt(data, fid.Key, offset)
if n >= int(minSize) {
return
}
}
return 0, nil
}
func (c *TieredChunkCache) SetChunk(fileId string, data []byte) {
if c == nil {
return
}
c.Lock()
defer c.Unlock()
glog.V(4).Infof("SetChunk %s size %d\n", fileId, len(data))
c.doSetChunk(fileId, data)
}
func (c *TieredChunkCache) doSetChunk(fileId string, data []byte) {
if len(data) <= int(c.onDiskCacheSizeLimit0) {
c.memCache.SetChunk(fileId, data)
}
fid, err := needle.ParseFileIdFromString(fileId)
if err != nil {
glog.Errorf("failed to parse file id %s", fileId)
return
}
if len(data) <= int(c.onDiskCacheSizeLimit0) {
c.diskCaches[0].setChunk(fid.Key, data)
} else if len(data) <= int(c.onDiskCacheSizeLimit1) {
c.diskCaches[1].setChunk(fid.Key, data)
} else {
c.diskCaches[2].setChunk(fid.Key, data)
}
}
func (c *TieredChunkCache) Shutdown() {
if c == nil {
return
}
c.Lock()
defer c.Unlock()
for _, diskCache := range c.diskCaches {
diskCache.shutdown()
}
}
func min(x, y int) int {
if x < y {
return x
}
return y
}
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