directory structure change to work with glide

glide has its own requirements. My previous workaround caused me some
code checkin errors. Need to fix this.

weed/storage/volume_vacuum.go

@@ -0,0 +1,93 @@
+package storage
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+)
+
+func (v *Volume) garbageLevel() float64 {
+	return float64(v.nm.DeletedSize()) / float64(v.ContentSize())
+}
+
+func (v *Volume) Compact() error {
+	glog.V(3).Infof("Compacting ...")
+	//no need to lock for copy on write
+	//v.accessLock.Lock()
+	//defer v.accessLock.Unlock()
+	//glog.V(3).Infof("Got Compaction lock...")
+
+	filePath := v.FileName()
+	glog.V(3).Infof("creating copies for volume %d ...", v.Id)
+	return v.copyDataAndGenerateIndexFile(filePath+".cpd", filePath+".cpx")
+}
+func (v *Volume) commitCompact() error {
+	glog.V(3).Infof("Committing vacuuming...")
+	v.dataFileAccessLock.Lock()
+	defer v.dataFileAccessLock.Unlock()
+	glog.V(3).Infof("Got Committing lock...")
+	v.nm.Close()
+	_ = v.dataFile.Close()
+	var e error
+	if e = os.Rename(v.FileName()+".cpd", v.FileName()+".dat"); e != nil {
+		return e
+	}
+	if e = os.Rename(v.FileName()+".cpx", v.FileName()+".idx"); e != nil {
+		return e
+	}
+	//glog.V(3).Infof("Pretending to be vacuuming...")
+	//time.Sleep(20 * time.Second)
+	glog.V(3).Infof("Loading Commit file...")
+	if e = v.load(true, false, v.needleMapKind); e != nil {
+		return e
+	}
+	return nil
+}
+
+func (v *Volume) copyDataAndGenerateIndexFile(dstName, idxName string) (err error) {
+	var (
+		dst, idx *os.File
+	)
+	if dst, err = os.OpenFile(dstName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644); err != nil {
+		return
+	}
+	defer dst.Close()
+
+	if idx, err = os.OpenFile(idxName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644); err != nil {
+		return
+	}
+	defer idx.Close()
+
+	nm := NewNeedleMap(idx)
+	new_offset := int64(SuperBlockSize)
+
+	now := uint64(time.Now().Unix())
+
+	err = ScanVolumeFile(v.dir, v.Collection, v.Id, v.needleMapKind,
+		func(superBlock SuperBlock) error {
+			superBlock.CompactRevision++
+			_, err = dst.Write(superBlock.Bytes())
+			return err
+		}, true, func(n *Needle, offset int64) error {
+			if n.HasTtl() && now >= n.LastModified+uint64(v.Ttl.Minutes()*60) {
+				return nil
+			}
+			nv, ok := v.nm.Get(n.Id)
+			glog.V(4).Infoln("needle expected offset ", offset, "ok", ok, "nv", nv)
+			if ok && int64(nv.Offset)*NeedlePaddingSize == offset && nv.Size > 0 {
+				if err = nm.Put(n.Id, uint32(new_offset/NeedlePaddingSize), n.Size); err != nil {
+					return fmt.Errorf("cannot put needle: %s", err)
+				}
+				if _, err = n.Append(dst, v.Version()); err != nil {
+					return fmt.Errorf("cannot append needle: %s", err)
+				}
+				new_offset += n.DiskSize()
+				glog.V(3).Infoln("saving key", n.Id, "volume offset", offset, "=>", new_offset, "data_size", n.Size)
+			}
+			return nil
+		})
+
+	return
+}