From 50fafa3a2c4bc1b830cac5e7ae0043f2be05dc08 Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Thu, 17 Jan 2013 00:15:13 -0800
Subject: [PATCH] Revert "sort writables to be able to skew write probability
 to lesser ids (older volumes)"

This reverts commit ce7394f3bfe50b6dcb7ff1682bd7e5e1b5574da2.
---
 weed-fs/src/pkg/topology/volume_layout.go | 40 +++--------------------
 1 file changed, 5 insertions(+), 35 deletions(-)

diff --git a/weed-fs/src/pkg/topology/volume_layout.go b/weed-fs/src/pkg/topology/volume_layout.go
index 23802ca81..314aca69f 100644
--- a/weed-fs/src/pkg/topology/volume_layout.go
+++ b/weed-fs/src/pkg/topology/volume_layout.go
@@ -5,15 +5,12 @@ import (
 	"fmt"
 	"math/rand"
 	"pkg/storage"
-	"sort"
 )
 
-type volumeIdList []storage.VolumeId
-
 type VolumeLayout struct {
 	repType         storage.ReplicationType
 	vid2location    map[storage.VolumeId]*VolumeLocationList
-	writables       volumeIdList // transient (sorted!) array of writable volume Ids
+	writables       []storage.VolumeId // transient array of writable volume id
 	pulse           int64
 	volumeSizeLimit uint64
 }
@@ -22,7 +19,7 @@ func NewVolumeLayout(repType storage.ReplicationType, volumeSizeLimit uint64, pu
 	return &VolumeLayout{
 		repType:         repType,
 		vid2location:    make(map[storage.VolumeId]*VolumeLocationList),
-		writables:       make(volumeIdList, 0, 4),
+		writables:       *new([]storage.VolumeId),
 		pulse:           pulse,
 		volumeSizeLimit: volumeSizeLimit,
 	}
@@ -36,16 +33,13 @@ 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 {
@@ -58,13 +52,7 @@ 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!")
 	}
-	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]
-	}
+	vid := vl.writables[rand.Intn(len_writers)]
 	locationList := vl.vid2location[vid]
 	if locationList != nil {
 		return &vid, count, locationList, nil
@@ -94,9 +82,6 @@ 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
 }
 
@@ -129,18 +114,3 @@ 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)
-}