sort writables to be able to skew write probability to lesser ids (older volumes)

This commit is contained in:
Tamás Gulácsi 2013-01-04 22:49:40 +01:00
parent 8fb8ebdf14
commit ce7394f3bf

View file

@ -5,12 +5,15 @@ import (
"fmt"
"math/rand"
"pkg/storage"
"sort"
)
type volumeIdList []storage.VolumeId
type VolumeLayout struct {
repType storage.ReplicationType
vid2location map[storage.VolumeId]*VolumeLocationList
writables []storage.VolumeId // transient array of writable volume id
writables volumeIdList // transient (sorted!) array of writable volume Ids
pulse int64
volumeSizeLimit uint64
}
@ -19,7 +22,7 @@ func NewVolumeLayout(repType storage.ReplicationType, volumeSizeLimit uint64, pu
return &VolumeLayout{
repType: repType,
vid2location: make(map[storage.VolumeId]*VolumeLocationList),
writables: *new([]storage.VolumeId),
writables: make(volumeIdList, 0, 4),
pulse: pulse,
volumeSizeLimit: volumeSizeLimit,
}
@ -33,13 +36,16 @@ func (vl *VolumeLayout) RegisterVolume(v *storage.VolumeInfo, dn *DataNode) {
if len(vl.vid2location[v.Id].list) == v.RepType.GetCopyCount() {
if vl.isWritable(v) {
vl.writables = append(vl.writables, v.Id)
if len(vl.writables) > 1 {
vl.writables.Sort()
}
}
}
}
}
func (vl *VolumeLayout) isWritable(v *storage.VolumeInfo) bool{
return uint64(v.Size) < vl.volumeSizeLimit && v.Version == storage.CurrentVersion
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 {
@ -52,7 +58,13 @@ func (vl *VolumeLayout) PickForWrite(count int) (*storage.VolumeId, int, *Volume
fmt.Println("No more writable volumes!")
return nil, 0, nil, errors.New("No more writable volumes!")
}
vid := vl.writables[rand.Intn(len_writers)]
var vid storage.VolumeId
if len_writers == 1 {
vid = vl.writables[0]
} else {
// skew for lesser indices
vid = vl.writables[rand.Intn(len_writers+1)%len_writers]
}
locationList := vl.vid2location[vid]
if locationList != nil {
return &vid, count, locationList, nil
@ -82,6 +94,9 @@ func (vl *VolumeLayout) setVolumeWritable(vid storage.VolumeId) bool {
}
fmt.Println("Volume", vid, "becomes writable")
vl.writables = append(vl.writables, vid)
if len(vl.writables) > 1 {
vl.writables.Sort()
}
return true
}
@ -114,3 +129,18 @@ func (vl *VolumeLayout) ToMap() interface{} {
//m["locations"] = vl.vid2location
return m
}
func (vls volumeIdList) Len() int { return len(vls) }
func (vls volumeIdList) Less(i, j int) bool {
return vls[i] < vls[j]
}
func (vls volumeIdList) Swap(i, j int) {
vls[i], vls[j] = vls[j], vls[i]
}
// convienence sorting
func (vls volumeIdList) Sort() {
sort.Sort(vls)
}