mount: add on disk caching

weed/util/chunk_cache/chunk_cache_on_disk.go

@@ -0,0 +1,145 @@
+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(0).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), uint32(len(data))); err != nil {
+		glog.V(4).Infof("failed to save in needle map %d: %v", key, err)
+	}
+
+	return nil
+}