feat: new method--Persist (#135)

structure/string.go

@@ -15,6 +15,11 @@ type StringStructure struct {
 	db *engine.DB
 }
 
+var (
+	// ErrWrongNumberOfArguments is returned when the number of arguments is wrong
+	ErrWrongNumberOfArguments = errors.New("wrong number of arguments")
+)
+
 // NewStringStructure returns a new StringStructure
 // It will return a nil StringStructure if the database cannot be opened
 // or the database cannot be created
@@ -296,6 +301,18 @@ func (s *StringStructure) Expire(key []byte, ttl time.Duration) error {
 	return s.Set(key, value, ttl)
 }
 
+// Persist removes the expiration time of a key
+func (s *StringStructure) Persist(key []byte) error {
+	// Get the value
+	value, err := s.Get(key)
+	if err != nil {
+		return err
+	}
+
+	// Set the value
+	return s.Set(key, value, 0)
+}
+
 // encodeStringValue encodes the value
 // format: [type][expire][value]
 // type: 1 byte

structure/string_test.go

@@ -223,3 +223,22 @@ func TestStringStructure_Expire(t *testing.T) {
 	assert.Equal(t, err, ErrKeyExpired)
 	assert.Equal(t, string(v2), "")
 }
+
+func TestStringStructure_Persist(t *testing.T) {
+	str := initdb()
+
+	err = str.Set(randkv.GetTestKey(1), []byte("1"), 0)
+	assert.Nil(t, err)
+
+	err = str.Expire(randkv.GetTestKey(1), 1*time.Second)
+	assert.Nil(t, err)
+	v1, err := str.Get(randkv.GetTestKey(1))
+	assert.Nil(t, err)
+	assert.Equal(t, string(v1), "1")
+
+	err = str.Persist(randkv.GetTestKey(1))
+	assert.Nil(t, err)
+	v2, err := str.Get(randkv.GetTestKey(1))
+	assert.Nil(t, err)
+	assert.Equal(t, string(v2), "1")
+}