add scan command

datastruct/dict/concurrent.go

@@ -1,6 +1,7 @@
 package dict
 
 import (
+	"github.com/hdt3213/godis/lib/wildcard"
 	"math"
 	"math/rand"
 	"sort"
@@ -435,3 +436,47 @@ func (dict *ConcurrentDict) RWUnLocks(writeKeys []string, readKeys []string) {
 		}
 	}
 }
+
+func stringsToBytes(strSlice []string) [][]byte {
+	byteSlice := make([][]byte, len(strSlice))
+	for i, str := range strSlice {
+		byteSlice[i] = []byte(str)
+	}
+	return byteSlice
+}
+
+func (dict *ConcurrentDict) DictScan(cursor int, count int, pattern string) ([][]byte, int) {
+	size := dict.Len()
+	result := make([][]byte, 0)
+
+	if pattern == "*" && count >= size {
+		return stringsToBytes(dict.Keys()), 0
+	}
+
+	matchKey, err := wildcard.CompilePattern(pattern)
+	if err != nil {
+		return result, -1
+	}
+
+	shardCount := len(dict.table)
+	shardIndex := cursor
+
+	for shardIndex < shardCount {
+		shard := dict.table[shardIndex]
+		shard.mutex.RLock()
+		if len(result)+len(shard.m) > count && shardIndex > cursor {
+			shard.mutex.RUnlock()
+			return result, shardIndex
+		}
+
+		for key := range shard.m {
+			if pattern == "*" || matchKey.IsMatch(key) {
+				result = append(result, []byte(key))
+			}
+		}
+		shard.mutex.RUnlock()
+		shardIndex++
+	}
+
+	return result, 0
+}

datastruct/dict/concurrent_test.go

@@ -465,7 +465,7 @@ func TestConcurrentRemoveWithLock(t *testing.T) {
 	}
 }
 
-//change t.Error remove->forEach
+// change t.Error remove->forEach
 func TestConcurrentForEach(t *testing.T) {
 	d := MakeConcurrent(0)
 	size := 100
@@ -524,3 +524,51 @@ func TestConcurrentDict_Keys(t *testing.T) {
 		t.Errorf("expect %d keys, actual: %d", size, len(d.Keys()))
 	}
 }
+
+func TestDictScan(t *testing.T) {
+	d := MakeConcurrent(0)
+	count := 100
+	for i := 0; i < count; i++ {
+		key := "kkk" + strconv.Itoa(i)
+		d.Put(key, i)
+	}
+	for i := 0; i < count; i++ {
+		key := "key" + strconv.Itoa(i)
+		d.Put(key, i)
+	}
+	cursor := 0
+	matchKey := "*"
+	c := 20
+	result := make([][]byte, 0)
+	var returnKeys [][]byte
+	for {
+		returnKeys, cursor = d.DictScan(cursor, c, matchKey)
+		result = append(result, returnKeys...)
+		if cursor == 0 {
+			break
+		}
+	}
+	result = utils.RemoveDuplicates(result)
+	if len(result) != count*2 {
+		t.Errorf("scan command result number error: %d, should be %d ", len(result), count*2)
+	}
+	matchKey = "key*"
+	cursor = 0
+	mresult := make([][]byte, 0)
+	for {
+		returnKeys, cursor = d.DictScan(cursor, c, matchKey)
+		mresult = append(mresult, returnKeys...)
+		if cursor == 0 {
+			break
+		}
+	}
+	mresult = utils.RemoveDuplicates(mresult)
+	if len(mresult) != count {
+		t.Errorf("scan command result number error: %d, should be %d ", len(mresult), count)
+	}
+	matchKey = "no*"
+	returnKeys, _ = d.DictScan(cursor, c, matchKey)
+	if len(returnKeys) != 0 {
+		t.Errorf("returnKeys should be empty")
+	}
+}

datastruct/dict/dict.go

@@ -16,4 +16,5 @@ type Dict interface {
 	RandomKeys(limit int) []string
 	RandomDistinctKeys(limit int) []string
 	Clear()
+	DictScan(cursor int, count int, pattern string) ([][]byte, int)
 }

datastruct/dict/simple.go

@@ -120,3 +120,7 @@ func (dict *SimpleDict) RandomDistinctKeys(limit int) []string {
 func (dict *SimpleDict) Clear() {
 	*dict = *MakeSimple()
 }
+
+func (dict *SimpleDict) DictScan(cursor int, count int, pattern string) ([][]byte, int) {
+	return stringsToBytes(dict.Keys()), 0
+}