CASSGO-26 consistency serial was added

The user should be able to set consistency to SERIAL or LOCAL_SERIAL
for Paxos reads, but the previous implementation doesn't support such a feature.

patch by Mykyta Oleksiienko; reviewed by João Reis for [CASSGO-26](https://issues.apache.org/jira/browse/CASSGO-26)

Author: OleksiienkoMykyta

CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Allow SERIAL and LOCAL_SERIAL on SELECT statements [CASSGO-26](https://issues.apache.org/jira/browse/CASSGO-26)
+
 ### Changed
 
 - Don't restrict server authenticator unless PasswordAuthentictor.AllowedAuthenticators is provided (CASSGO-19)

cluster.go

@@ -150,7 +150,7 @@ type ClusterConfig struct {
 
 	// Consistency for the serial part of queries, values can be either SERIAL or LOCAL_SERIAL.
 	// Default: unset
-	SerialConsistency SerialConsistency
+	SerialConsistency Consistency
 
 	// SslOpts configures TLS use when HostDialer is not set.
 	// SslOpts is ignored if HostDialer is set.

frame.go

@@ -192,6 +192,9 @@ const (
 
 type Consistency uint16
 
+// SerialConsistency is deprecated. Use Consistency instead.
+type SerialConsistency = Consistency
+
 const (
 	Any         Consistency = 0x00
 	One         Consistency = 0x01
@@ -202,6 +205,8 @@ const (
 	LocalQuorum Consistency = 0x06
 	EachQuorum  Consistency = 0x07
 	LocalOne    Consistency = 0x0A
+	Serial      Consistency = 0x08
+	LocalSerial Consistency = 0x09
 )
 
 func (c Consistency) String() string {
@@ -224,6 +229,10 @@ func (c Consistency) String() string {
 		return "EACH_QUORUM"
 	case LocalOne:
 		return "LOCAL_ONE"
+	case Serial:
+		return "SERIAL"
+	case LocalSerial:
+		return "LOCAL_SERIAL"
 	default:
 		return fmt.Sprintf("UNKNOWN_CONS_0x%x", uint16(c))
 	}
@@ -253,13 +262,21 @@ func (c *Consistency) UnmarshalText(text []byte) error {
 		*c = EachQuorum
 	case "LOCAL_ONE":
 		*c = LocalOne
+	case "SERIAL":
+		*c = Serial
+	case "LOCAL_SERIAL":
+		*c = LocalSerial
 	default:
 		return fmt.Errorf("invalid consistency %q", string(text))
 	}
 
 	return nil
 }
 
+func (c Consistency) IsSerial() bool {
+	return c == Serial || c == LocalSerial
+
+}
 func ParseConsistency(s string) Consistency {
 	var c Consistency
 	if err := c.UnmarshalText([]byte(strings.ToUpper(s))); err != nil {
@@ -286,41 +303,6 @@ func MustParseConsistency(s string) (Consistency, error) {
 	return c, nil
 }
 
-type SerialConsistency uint16
-
-const (
-	Serial      SerialConsistency = 0x08
-	LocalSerial SerialConsistency = 0x09
-)
-
-func (s SerialConsistency) String() string {
-	switch s {
-	case Serial:
-		return "SERIAL"
-	case LocalSerial:
-		return "LOCAL_SERIAL"
-	default:
-		return fmt.Sprintf("UNKNOWN_SERIAL_CONS_0x%x", uint16(s))
-	}
-}
-
-func (s SerialConsistency) MarshalText() (text []byte, err error) {
-	return []byte(s.String()), nil
-}
-
-func (s *SerialConsistency) UnmarshalText(text []byte) error {
-	switch string(text) {
-	case "SERIAL":
-		*s = Serial
-	case "LOCAL_SERIAL":
-		*s = LocalSerial
-	default:
-		return fmt.Errorf("invalid consistency %q", string(text))
-	}
-
-	return nil
-}
-
 const (
 	apacheCassandraTypePrefix = "org.apache.cassandra.db.marshal."
 )
@@ -1452,7 +1434,7 @@ type queryParams struct {
 	values            []queryValues
 	pageSize          int
 	pagingState       []byte
-	serialConsistency SerialConsistency
+	serialConsistency Consistency
 	// v3+
 	defaultTimestamp      bool
 	defaultTimestampValue int64
@@ -1541,7 +1523,7 @@ func (f *framer) writeQueryParams(opts *queryParams) {
 	}
 
 	if opts.serialConsistency > 0 {
-		f.writeConsistency(Consistency(opts.serialConsistency))
+		f.writeConsistency(opts.serialConsistency)
 	}
 
 	if f.proto > protoVersion2 && opts.defaultTimestamp {
@@ -1653,7 +1635,7 @@ type writeBatchFrame struct {
 	consistency Consistency
 
 	// v3+
-	serialConsistency     SerialConsistency
+	serialConsistency     Consistency
 	defaultTimestamp      bool
 	defaultTimestampValue int64
 

session.go

@@ -144,6 +144,10 @@ func NewSession(cfg ClusterConfig) (*Session, error) {
 		return nil, errors.New("Can't use both Authenticator and AuthProvider in cluster config.")
 	}
 
+	if cfg.SerialConsistency > 0 && !cfg.SerialConsistency.IsSerial() {
+		return nil, fmt.Errorf("the default SerialConsistency level is not allowed to be anything else but SERIAL or LOCAL_SERIAL. Recived value: %v", cfg.SerialConsistency)
+	}
+
 	// TODO: we should take a context in here at some point
 	ctx, cancel := context.WithCancel(context.TODO())
 
@@ -915,7 +919,7 @@ type Query struct {
 	rt                    RetryPolicy
 	spec                  SpeculativeExecutionPolicy
 	binding               func(q *QueryInfo) ([]interface{}, error)
-	serialCons            SerialConsistency
+	serialCons            Consistency
 	defaultTimestamp      bool
 	defaultTimestampValue int64
 	disableSkipMetadata   bool
@@ -1264,7 +1268,10 @@ func (q *Query) Bind(v ...interface{}) *Query {
 // either SERIAL or LOCAL_SERIAL and if not present, it defaults to
 // SERIAL. This option will be ignored for anything else that a
 // conditional update/insert.
-func (q *Query) SerialConsistency(cons SerialConsistency) *Query {
+func (q *Query) SerialConsistency(cons Consistency) *Query {
+	if !cons.IsSerial() {
+		panic("Serial consistency can only be SERIAL or LOCAL_SERIAL got " + cons.String())
+	}
 	q.serialCons = cons
 	return q
 }
@@ -1735,7 +1742,7 @@ type Batch struct {
 	trace                 Tracer
 	observer              BatchObserver
 	session               *Session
-	serialCons            SerialConsistency
+	serialCons            Consistency
 	defaultTimestamp      bool
 	defaultTimestampValue int64
 	context               context.Context
@@ -1914,7 +1921,10 @@ func (b *Batch) Size() int {
 // conditional update/insert.
 //
 // Only available for protocol 3 and above
-func (b *Batch) SerialConsistency(cons SerialConsistency) *Batch {
+func (b *Batch) SerialConsistency(cons Consistency) *Batch {
+	if !cons.IsSerial() {
+		panic("Serial consistency can only be SERIAL or LOCAL_SERIAL got " + cons.String())
+	}
 	b.serialCons = cons
 	return b
 }