1 files changed, 116 insertions, 0 deletions
diff --git a/src/weed/topology/volume_layout.go b/src/weed/topology/volume_layout.go
new file mode 100644
index 000000000..c144c1861
--- /dev/null
+++ b/src/weed/topology/volume_layout.go
@@ -0,0 +1,116 @@
+package topology
+
+import (
+	"errors"
+	"fmt"
+	"math/rand"
+	"weed/storage"
+)
+
+type VolumeLayout struct {
+	repType         storage.ReplicationType
+	vid2location    map[storage.VolumeId]*VolumeLocationList
+	writables       []storage.VolumeId // transient array of writable volume id
+	pulse           int64
+	volumeSizeLimit uint64
+}
+
+func NewVolumeLayout(repType storage.ReplicationType, volumeSizeLimit uint64, pulse int64) *VolumeLayout {
+	return &VolumeLayout{
+		repType:         repType,
+		vid2location:    make(map[storage.VolumeId]*VolumeLocationList),
+		writables:       *new([]storage.VolumeId),
+		pulse:           pulse,
+		volumeSizeLimit: volumeSizeLimit,
+	}
+}
+
+func (vl *VolumeLayout) RegisterVolume(v *storage.VolumeInfo, dn *DataNode) {
+	if _, ok := vl.vid2location[v.Id]; !ok {
+		vl.vid2location[v.Id] = NewVolumeLocationList()
+	}
+	if vl.vid2location[v.Id].Add(dn) {
+		if len(vl.vid2location[v.Id].list) == v.RepType.GetCopyCount() {
+			if vl.isWritable(v) {
+				vl.writables = append(vl.writables, v.Id)
+			}
+		}
+	}
+}
+
+func (vl *VolumeLayout) isWritable(v *storage.VolumeInfo) bool {
+	return uint64(v.Size) < vl.volumeSizeLimit && v.Version == storage.CurrentVersion
+}
+
+func (vl *VolumeLayout) Lookup(vid storage.VolumeId) []*DataNode {
+	return vl.vid2location[vid].list
+}
+
+func (vl *VolumeLayout) PickForWrite(count int) (*storage.VolumeId, int, *VolumeLocationList, error) {
+	len_writers := len(vl.writables)
+	if len_writers <= 0 {
+		fmt.Println("No more writable volumes!")
+		return nil, 0, nil, errors.New("No more writable volumes!")
+	}
+	vid := vl.writables[rand.Intn(len_writers)]
+	locationList := vl.vid2location[vid]
+	if locationList != nil {
+		return &vid, count, locationList, nil
+	}
+	return nil, 0, nil, errors.New("Strangely vid " + vid.String() + " is on no machine!")
+}
+
+func (vl *VolumeLayout) GetActiveVolumeCount() int {
+	return len(vl.writables)
+}
+
+func (vl *VolumeLayout) removeFromWritable(vid storage.VolumeId) bool {
+	for i, v := range vl.writables {
+		if v == vid {
+			fmt.Println("Volume", vid, "becomes unwritable")
+			vl.writables = append(vl.writables[:i], vl.writables[i+1:]...)
+			return true
+		}
+	}
+	return false
+}
+func (vl *VolumeLayout) setVolumeWritable(vid storage.VolumeId) bool {
+	for _, v := range vl.writables {
+		if v == vid {
+			return false
+		}
+	}
+	fmt.Println("Volume", vid, "becomes writable")
+	vl.writables = append(vl.writables, vid)
+	return true
+}
+
+func (vl *VolumeLayout) SetVolumeUnavailable(dn *DataNode, vid storage.VolumeId) bool {
+	if vl.vid2location[vid].Remove(dn) {
+		if vl.vid2location[vid].Length() < vl.repType.GetCopyCount() {
+			fmt.Println("Volume", vid, "has", vl.vid2location[vid].Length(), "replica, less than required", vl.repType.GetCopyCount())
+			return vl.removeFromWritable(vid)
+		}
+	}
+	return false
+}
+func (vl *VolumeLayout) SetVolumeAvailable(dn *DataNode, vid storage.VolumeId) bool {
+	if vl.vid2location[vid].Add(dn) {
+		if vl.vid2location[vid].Length() >= vl.repType.GetCopyCount() {
+			return vl.setVolumeWritable(vid)
+		}
+	}
+	return false
+}
+
+func (vl *VolumeLayout) SetVolumeCapacityFull(vid storage.VolumeId) bool {
+	return vl.removeFromWritable(vid)
+}
+
+func (vl *VolumeLayout) ToMap() interface{} {
+	m := make(map[string]interface{})
+	m["replication"] = vl.repType.String()
+	m["writables"] = vl.writables
+	//m["locations"] = vl.vid2location
+	return m
+}