mutex lock to prevent rc

README.md

@@ -39,5 +39,9 @@ fmt.println(node) // this will print out one of the nodes
 Benchmark  
 `go test -bench=.`   
 
+Race Condition 
+`go test --race`  
+Thanks to **Mohammad Rajabloo** for reporting the race issue 
+
 Tests  
 `go test`    

consistenthash.go

@@ -5,13 +5,15 @@ import (
 	"hash/crc32"
 	"sort"
 	"strconv"
+	"sync"
 )
 
 // HashFunc hash function to generate random hash
 type HashFunc func(data []byte) uint32
 
 // ConsistentHash everything we need for CH
 type ConsistentHash struct {
+	sync.RWMutex
 	hash            HashFunc
 	defaultReplicas int               // default number of replicas in hash ring (higher number means more posibility for balance equality)
 	hKeys           []uint32          // Sorted
@@ -59,6 +61,8 @@ func (ch *ConsistentHash) Get(key string) string {
 	if ch.IsEmpty() {
 		return ""
 	}
+	ch.RLock()
+	defer ch.RUnlock()
 	hash := ch.hash([]byte(key))
 
 	// Binary search for appropriate replica
@@ -77,6 +81,8 @@ func (ch *ConsistentHash) Remove(key string) bool {
 		return true
 	}
 	replicas := ch.rTable[key]
+	ch.Lock()
+	defer ch.Unlock()
 	for i := 0; i < replicas; i++ {
 		hash := ch.hash([]byte(strconv.Itoa(i) + key))
 		delete(ch.hTable, hash) // delete replica
@@ -98,6 +104,8 @@ func (ch *ConsistentHash) removeHashKey(hash uint32) {
 
 // add inserts new hash in hash table
 func (ch *ConsistentHash) add(key string, replicas int) {
+	ch.Lock()
+	defer ch.Unlock()
 	for i := 0; i < replicas; i++ {
 		hash := ch.hash([]byte(strconv.Itoa(i) + key))
 		ch.hKeys = append(ch.hKeys, hash)

consistenthash_test.go

@@ -107,6 +107,16 @@ func TestReplication(t *testing.T) {
 	}
 }
 
+func TestConcurrency(t *testing.T) {
+	hash := NewConsistentHash(1, nil)
+	items := []string{"Bill", "Bob", "Bonny", "Bob", "Bill", "Bony", "Bob"}
+	for _, item := range items {
+		go func(it string) {
+			hash.Add(it)
+		}(item)
+	}
+}
+
 func TestConsistency(t *testing.T) {
 	hash1 := NewConsistentHash(1, nil)
 	hash2 := NewConsistentHash(1, nil)