From ad3efbb19796b796b3eafe5af66efa5749059d02 Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Sat, 14 Sep 2019 01:21:51 -0700
Subject: [PATCH] tweaking data types

---
 weed/wdclient/vid_map.go      | 19 +++++++++++--------
 weed/wdclient/vid_map_test.go | 17 ++++++++---------
 2 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/weed/wdclient/vid_map.go b/weed/wdclient/vid_map.go
index 7a3f50aad..97df49cb6 100644
--- a/weed/wdclient/vid_map.go
+++ b/weed/wdclient/vid_map.go
@@ -3,7 +3,6 @@ package wdclient
 import (
 	"errors"
 	"fmt"
-	"math"
 	"strconv"
 	"strings"
 	"sync"
@@ -12,6 +11,10 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/glog"
 )
 
+const (
+	maxCursorIndex = 4096
+)
+
 type Location struct {
 	Url       string `json:"url,omitempty"`
 	PublicUrl string `json:"publicUrl,omitempty"`
@@ -21,7 +24,7 @@ type vidMap struct {
 	sync.RWMutex
 	vid2Locations map[uint32][]Location
 
-	cursor int64
+	cursor int32
 }
 
 func newVidMap() vidMap {
@@ -31,14 +34,14 @@ func newVidMap() vidMap {
 	}
 }
 
-func (vc *vidMap) getLocationIndex(length int64) (int64, error) {
+func (vc *vidMap) getLocationIndex(length int) (int, error) {
 	if length <= 0 {
 		return 0, fmt.Errorf("invalid length: %d", length)
 	}
-	if atomic.LoadInt64(&vc.cursor) == math.MaxInt64 {
-		atomic.CompareAndSwapInt64(&vc.cursor, math.MaxInt64, -1)
+	if atomic.LoadInt32(&vc.cursor) == maxCursorIndex {
+		atomic.CompareAndSwapInt32(&vc.cursor, maxCursorIndex, -1)
 	}
-	return atomic.AddInt64(&vc.cursor, 1) % length, nil
+	return int(atomic.AddInt32(&vc.cursor, 1)) % length, nil
 }
 
 func (vc *vidMap) LookupVolumeServerUrl(vid string) (serverUrl string, err error) {
@@ -105,9 +108,9 @@ func (vc *vidMap) GetRandomLocation(vid uint32) (serverUrl string, err error) {
 		return "", fmt.Errorf("volume %d not found", vid)
 	}
 
-	index, err := vc.getLocationIndex(int64(len(locations)))
+	index, err := vc.getLocationIndex(len(locations))
 	if err != nil {
-		return "", fmt.Errorf("volume %d. %v", vid, err)
+		return "", fmt.Errorf("volume %d: %v", vid, err)
 	}
 
 	return locations[index].Url, nil
diff --git a/weed/wdclient/vid_map_test.go b/weed/wdclient/vid_map_test.go
index ae4680e7a..87be2fc25 100644
--- a/weed/wdclient/vid_map_test.go
+++ b/weed/wdclient/vid_map_test.go
@@ -2,14 +2,13 @@ package wdclient
 
 import (
 	"fmt"
-	"math"
 	"testing"
 )
 
 func TestLocationIndex(t *testing.T) {
 	vm := vidMap{}
 	// test must be failed
-	mustFailed := func(length int64) {
+	mustFailed := func(length int) {
 		_, err := vm.getLocationIndex(length)
 		if err == nil {
 			t.Errorf("length %d must be failed", length)
@@ -22,11 +21,11 @@ func TestLocationIndex(t *testing.T) {
 	mustFailed(-1)
 	mustFailed(0)
 
-	mustOk := func(length, cursor, expect int64) {
+	mustOk := func(length, cursor, expect int) {
 		if length <= 0 {
 			t.Fatal("please don't do this")
 		}
-		vm.cursor = cursor
+		vm.cursor = int32(cursor)
 		got, err := vm.getLocationIndex(length)
 		if err != nil {
 			t.Errorf("length: %d, why? %v\n", length, err)
@@ -38,17 +37,17 @@ func TestLocationIndex(t *testing.T) {
 		}
 	}
 
-	for i := int64(-1); i < 100; i++ {
+	for i := -1; i < 100; i++ {
 		mustOk(7, i, (i+1)%7)
 	}
 
 	// when cursor reaches MaxInt64
-	mustOk(7, math.MaxInt64, 0)
+	mustOk(7, maxCursorIndex, 0)
 
 	// test with constructor
 	vm = newVidMap()
-	length := int64(7)
-	for i := int64(0); i < 100; i++ {
+	length := 7
+	for i := 0; i < 100; i++ {
 		got, err := vm.getLocationIndex(length)
 		if err != nil {
 			t.Errorf("length: %d, why? %v\n", length, err)
@@ -63,7 +62,7 @@ func TestLocationIndex(t *testing.T) {
 func BenchmarkLocationIndex(b *testing.B) {
 	b.SetParallelism(8)
 	vm := vidMap{
-		cursor: math.MaxInt64 - 10000,
+		cursor: maxCursorIndex - 4000,
 	}
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {