Merge pull request #1318 from lowzj/dfget-util

refactor: move package dfget/util to pkg/algorithm

Author: starnop

cmd/dfdaemon/app/init.go

@@ -29,7 +29,7 @@ import (
 	"github.com/dragonflyoss/Dragonfly/dfdaemon/config"
 	"github.com/dragonflyoss/Dragonfly/dfdaemon/constant"
 	dfgetcfg "github.com/dragonflyoss/Dragonfly/dfget/config"
-	"github.com/dragonflyoss/Dragonfly/dfget/util"
+	"github.com/dragonflyoss/Dragonfly/pkg/algorithm"
 	"github.com/dragonflyoss/Dragonfly/pkg/dflog"
 	"github.com/dragonflyoss/Dragonfly/pkg/errortypes"
 	"github.com/dragonflyoss/Dragonfly/pkg/fileutils"
@@ -50,7 +50,7 @@ func adjustSupernodeList(nodes []string) []string {
 	case 1:
 		return append(nodes, nodes[0])
 	default:
-		util.Shuffle(nodesLen, func(i, j int) {
+		algorithm.Shuffle(nodesLen, func(i, j int) {
 			nodes[i], nodes[j] = nodes[j], nodes[i]
 		})
 		return append(nodes, nodes...)

dfget/core/core.go

@@ -34,7 +34,7 @@ import (
 	p2pDown "github.com/dragonflyoss/Dragonfly/dfget/core/downloader/p2p_downloader"
 	"github.com/dragonflyoss/Dragonfly/dfget/core/regist"
 	"github.com/dragonflyoss/Dragonfly/dfget/core/uploader"
-	"github.com/dragonflyoss/Dragonfly/dfget/util"
+	"github.com/dragonflyoss/Dragonfly/pkg/algorithm"
 	"github.com/dragonflyoss/Dragonfly/pkg/constants"
 	"github.com/dragonflyoss/Dragonfly/pkg/errortypes"
 	"github.com/dragonflyoss/Dragonfly/pkg/fileutils"
@@ -282,7 +282,7 @@ func adjustSupernodeList(nodes []string) []string {
 	case 1:
 		return append(nodes, nodes[0])
 	default:
-		util.Shuffle(nodesLen, func(i, j int) {
+		algorithm.Shuffle(nodesLen, func(i, j int) {
 			nodes[i], nodes[j] = nodes[j], nodes[i]
 		})
 		return append(nodes, nodes...)

dfget/core/core_test.go

@@ -33,7 +33,7 @@ import (
 	. "github.com/dragonflyoss/Dragonfly/dfget/core/helper"
 	"github.com/dragonflyoss/Dragonfly/dfget/core/regist"
 	"github.com/dragonflyoss/Dragonfly/dfget/core/uploader"
-	"github.com/dragonflyoss/Dragonfly/dfget/util"
+	"github.com/dragonflyoss/Dragonfly/pkg/algorithm"
 
 	"github.com/go-check/check"
 	"github.com/valyala/fasthttp"
@@ -114,8 +114,8 @@ func (s *CoreTestSuite) TestAdjustSupernodeList(c *check.C) {
 	for _, v := range cases {
 		nodes := adjustSupernodeList(v)
 		for _, n := range v {
-			c.Assert(util.ContainsString(nodes[:len(v)], n), check.Equals, true)
-			c.Assert(util.ContainsString(nodes[len(v):], n), check.Equals, true)
+			c.Assert(algorithm.ContainsString(nodes[:len(v)], n), check.Equals, true)
+			c.Assert(algorithm.ContainsString(nodes[len(v):], n), check.Equals, true)
 		}
 	}
 }

dfget/util/algorithm.go

@@ -16,6 +16,59 @@
 
 package algorithm
 
+import (
+	"math/rand"
+	"time"
+)
+
+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
+// ContainsString returns whether the value is in arr.
+func ContainsString(arr []string, value string) bool {
+	for _, v := range arr {
+		if v == value {
+			return true
+		}
+	}
+	return false
+}
+
+// Shuffle pseudo-randomizes the order of elements.
+// n is the number of elements.
+// swap swaps the elements with indexes i and j.
+// copy from rand.Shuffle of go1.10.
+func Shuffle(n int, swap func(int, int)) {
+	if n < 2 {
+		return
+	}
+	i := n - 1
+	for ; i > 1<<31-1-1; i-- {
+		j := int(rand.Int63n(int64(i + 1)))
+		swap(i, j)
+	}
+	for ; i > 0; i-- {
+		j := int(int31n(int32(i + 1)))
+		swap(i, j)
+	}
+}
+
+func int31n(n int32) int32 {
+	v := rand.Uint32()
+	prod := uint64(v) * uint64(n)
+	low := uint32(prod)
+	if low < uint32(n) {
+		thresh := uint32(-n) % uint32(n)
+		for low < thresh {
+			v = rand.Uint32()
+			prod = uint64(v) * uint64(n)
+			low = uint32(prod)
+		}
+	}
+	return int32(prod >> 32)
+}
+
 // GCDSlice returns the greatest common divisor of a slice.
 // It returns 1 when s is empty because that any number divided by 1 is still
 // itself.

dfget/util/algorithm_test.go

@@ -17,6 +17,7 @@
 package algorithm
 
 import (
+	"math/rand"
 	"testing"
 
 	"github.com/stretchr/testify/suite"
@@ -66,3 +67,26 @@ func (suit *AlgorithmSuite) TestGCDSlice() {
 		suit.Equal(v.result, result)
 	}
 }
+
+func (suit *AlgorithmSuite) TestContainsString() {
+	suit.Equal(ContainsString(nil, "x"), false)
+	suit.Equal(ContainsString([]string{"x", "y"}, "x"), true)
+	suit.Equal(ContainsString([]string{"x", "y"}, "xx"), false)
+}
+
+func (suit *AlgorithmSuite) TestShuffle() {
+	// Check that Shuffle allows n=0 and n=1, but that swap is never called for them.
+	rand.Seed(1)
+	for n := 0; n <= 1; n++ {
+		Shuffle(n, func(i, j int) {
+			suit.Failf("swap called", "n=%d i=%d j=%d", n, i, j)
+		})
+	}
+
+	// Check that Shuffle calls swap n-1 times when n >= 2.
+	for n := 2; n <= 100; n++ {
+		isRun := 0
+		Shuffle(n, func(i, j int) { isRun++ })
+		suit.Equal(isRun, n-1)
+	}
+}