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package chunk_cache
import (
"fmt"
"os"
"time"
"github.com/syndtr/goleveldb/leveldb/opt"
"github.com/chrislusf/seaweedfs/weed/glog"
"github.com/chrislusf/seaweedfs/weed/storage"
"github.com/chrislusf/seaweedfs/weed/storage/backend"
"github.com/chrislusf/seaweedfs/weed/storage/types"
"github.com/chrislusf/seaweedfs/weed/util"
)
// This implements an on disk cache
// The entries are an FIFO with a size limit
type ChunkCacheVolume struct {
DataBackend backend.BackendStorageFile
nm storage.NeedleMapper
fileName string
smallBuffer []byte
sizeLimit int64
lastModTime time.Time
fileSize int64
}
func LoadOrCreateChunkCacheVolume(fileName string, preallocate int64) (*ChunkCacheVolume, error) {
v := &ChunkCacheVolume{
smallBuffer: make([]byte, types.NeedlePaddingSize),
fileName: fileName,
sizeLimit: preallocate,
}
var err error
if exists, canRead, canWrite, modTime, fileSize := util.CheckFile(v.fileName + ".dat"); exists {
if !canRead {
return nil, fmt.Errorf("cannot read cache file %s.dat", v.fileName)
}
if !canWrite {
return nil, fmt.Errorf("cannot write cache file %s.dat", v.fileName)
}
if dataFile, err := os.OpenFile(v.fileName+".dat", os.O_RDWR|os.O_CREATE, 0644); err != nil {
return nil, fmt.Errorf("cannot create cache file %s.dat: %v", v.fileName, err)
} else {
v.DataBackend = backend.NewDiskFile(dataFile)
v.lastModTime = modTime
v.fileSize = fileSize
}
} else {
if v.DataBackend, err = backend.CreateVolumeFile(v.fileName+".dat", preallocate, 0); err != nil {
return nil, fmt.Errorf("cannot create cache file %s.dat: %v", v.fileName, err)
}
v.lastModTime = time.Now()
}
var indexFile *os.File
if indexFile, err = os.OpenFile(v.fileName+".idx", os.O_RDWR|os.O_CREATE, 0644); err != nil {
return nil, fmt.Errorf("cannot write cache index %s.idx: %v", v.fileName, err)
}
glog.V(1).Infoln("loading leveldb", v.fileName+".ldb")
opts := &opt.Options{
BlockCacheCapacity: 2 * 1024 * 1024, // default value is 8MiB
WriteBuffer: 1 * 1024 * 1024, // default value is 4MiB
CompactionTableSizeMultiplier: 10, // default value is 1
}
if v.nm, err = storage.NewLevelDbNeedleMap(v.fileName+".ldb", indexFile, opts); err != nil {
return nil, fmt.Errorf("loading leveldb %s error: %v", v.fileName+".ldb", err)
}
return v, nil
}
func (v *ChunkCacheVolume) Shutdown() {
if v.DataBackend != nil {
v.DataBackend.Close()
v.DataBackend = nil
}
if v.nm != nil {
v.nm.Close()
v.nm = nil
}
}
func (v *ChunkCacheVolume) destroy() {
v.Shutdown()
os.Remove(v.fileName + ".dat")
os.Remove(v.fileName + ".idx")
os.RemoveAll(v.fileName + ".ldb")
}
func (v *ChunkCacheVolume) Reset() (*ChunkCacheVolume, error) {
v.destroy()
return LoadOrCreateChunkCacheVolume(v.fileName, v.sizeLimit)
}
func (v *ChunkCacheVolume) GetNeedle(key types.NeedleId) ([]byte, error) {
nv, ok := v.nm.Get(key)
if !ok {
return nil, storage.ErrorNotFound
}
data := make([]byte, nv.Size)
if readSize, readErr := v.DataBackend.ReadAt(data, nv.Offset.ToAcutalOffset()); readErr != nil {
return nil, fmt.Errorf("read %s.dat [%d,%d): %v",
v.fileName, nv.Offset.ToAcutalOffset(), nv.Offset.ToAcutalOffset()+int64(nv.Size), readErr)
} else {
if readSize != int(nv.Size) {
return nil, fmt.Errorf("read %d, expected %d", readSize, nv.Size)
}
}
return data, nil
}
func (v *ChunkCacheVolume) WriteNeedle(key types.NeedleId, data []byte) error {
offset := v.fileSize
written, err := v.DataBackend.WriteAt(data, offset)
if err != nil {
return err
} else if written != len(data) {
return fmt.Errorf("partial written %d, expected %d", written, len(data))
}
v.fileSize += int64(written)
extraSize := written % types.NeedlePaddingSize
if extraSize != 0 {
v.DataBackend.WriteAt(v.smallBuffer[:types.NeedlePaddingSize-extraSize], offset+int64(written))
v.fileSize += int64(types.NeedlePaddingSize - extraSize)
}
if err := v.nm.Put(key, types.ToOffset(offset), types.Size(len(data))); err != nil {
return err
}
return nil
}
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