api: write a connection schema getter

Write a helper function to load the actual schema for the user.

Previously we stored actual schema in a private `schemaResolver`
field and `Schema` field was used only to get a current schema.
But now because of the new method, we don't need to store the
`Schema` as a different field. So `Schema` was also removed.

Closes #7

Author: DerekBum

Diff for: CHANGELOG.md

@@ -26,6 +26,7 @@ Versioning](http://semver.org/spec/v2.0.0.html) except to the first release.
 - Support `IPROTO_FEATURE_SPACE_AND_INDEX_NAMES` for Tarantool
   version >= 3.0.0-alpha1 (#338). It allows to use space and index names 
   in requests instead of their IDs.
+- `GetSchema` method to the `Connection` struct (#7)
 
 ### Changed
 
@@ -70,6 +71,7 @@ Versioning](http://semver.org/spec/v2.0.0.html) except to the first release.
 - UUID_extId (#158)
 - IPROTO constants (#158)
 - Code() method from the Request interface (#158)
+- `Schema` field from the `Connection` struct (#7)
 
 ### Fixed
 

Diff for: README.md

@@ -248,6 +248,11 @@ now does not attempt to reconnect and tries to establish a connection only once.
 Function might be canceled via context. Context accepted as first argument, 
 and user may cancel it in process.
 
+#### Connection Schema
+
+Removed `Schema` field from the `Connection` struct. Instead, new `GetSchema()` 
+metod was added to get the current connection schema on demand.
+
 #### Protocol changes
 
 * `iproto.Feature` type used instead of `ProtocolFeature`.
@@ -260,6 +265,7 @@ and user may cancel it in process.
 interface to get information if the usage of space and index names in requests 
 is supported.
 * `Schema` structure no longer implements `SchemaResolver` interface.
+* `GetSchema` method added to the `SchemaResolver` interface.
 
 ## Contributing
 

Diff for: connection.go

@@ -160,8 +160,6 @@ type Connection struct {
 	c     Conn
 	mutex sync.Mutex
 	cond  *sync.Cond
-	// Schema contains schema loaded on connection.
-	Schema *Schema
 	// schemaResolver contains a SchemaResolver implementation.
 	schemaResolver SchemaResolver
 	// requestId contains the last request ID for requests with nil context.
@@ -1302,15 +1300,27 @@ func (conn *Connection) ConfiguredTimeout() time.Duration {
 	return conn.opts.Timeout
 }
 
+// GetSchema returns the current connection Schema.
+func (conn *Connection) GetSchema() *Schema {
+	return conn.schemaResolver.GetSchema()
+}
+
 // OverrideSchema sets Schema for the connection.
 func (conn *Connection) OverrideSchema(s *Schema) {
 	if s != nil {
+		spaceAndIndexNamesSupported :=
+			isFeatureInSlice(iproto.IPROTO_FEATURE_SPACE_AND_INDEX_NAMES,
+				conn.serverProtocolInfo.Features)
+
 		conn.mutex.Lock()
 		defer conn.mutex.Unlock()
 		conn.lockShards()
 		defer conn.unlockShards()
 
-		conn.Schema = s
+		conn.schemaResolver = &loadedSchemaResolver{
+			Schema:                      s,
+			SpaceAndIndexNamesSupported: spaceAndIndexNamesSupported,
+		}
 	}
 }
 

Diff for: example_test.go

@@ -1063,7 +1063,7 @@ func ExampleSchema() {
 	conn := exampleConnect(opts)
 	defer conn.Close()
 
-	schema := conn.Schema
+	schema := conn.GetSchema()
 	if schema.SpacesById == nil {
 		fmt.Println("schema.SpacesById is nil")
 	}
@@ -1086,7 +1086,7 @@ func ExampleSpace() {
 	defer conn.Close()
 
 	// Save Schema to a local variable to avoid races
-	schema := conn.Schema
+	schema := conn.GetSchema()
 	if schema.SpacesById == nil {
 		fmt.Println("schema.SpacesById is nil")
 	}

Diff for: request_test.go

@@ -78,6 +78,10 @@ func (r *ValidSchemeResolver) NamesUseSupported() bool {
 	return r.nameUseSupported
 }
 
+func (r *ValidSchemeResolver) GetSchema() *Schema {
+	return nil
+}
+
 var resolver ValidSchemeResolver
 
 func assertBodyCall(t testing.TB, requests []Request, errorMsg string) {

Diff for: schema.go

@@ -52,6 +52,8 @@ type SchemaResolver interface {
 	// IDs, is supported. It must return true if
 	// iproto.IPROTO_FEATURE_SPACE_AND_INDEX_NAMES is supported.
 	NamesUseSupported() bool
+	// GetSchema returns inner Schema.
+	GetSchema() *Schema
 }
 
 // Schema contains information about spaces and indexes.
@@ -377,7 +379,6 @@ func (conn *Connection) loadSchema() (err error) {
 			conn.serverProtocolInfo.Features)
 
 	conn.lockShards()
-	conn.Schema = schema
 	conn.schemaResolver = &loadedSchemaResolver{
 		Schema:                      schema,
 		SpaceAndIndexNamesSupported: spaceAndIndexNamesSupported,
@@ -502,6 +503,10 @@ func (r *loadedSchemaResolver) NamesUseSupported() bool {
 	return r.SpaceAndIndexNamesSupported
 }
 
+func (r *loadedSchemaResolver) GetSchema() *Schema {
+	return r.Schema
+}
+
 type noSchemaResolver struct {
 	// SpaceAndIndexNamesSupported shows if a current Tarantool version supports
 	// iproto.IPROTO_FEATURE_SPACE_AND_INDEX_NAMES.
@@ -527,3 +532,7 @@ func (*noSchemaResolver) ResolveIndex(i interface{}, spaceNo uint32) (uint32, er
 func (r *noSchemaResolver) NamesUseSupported() bool {
 	return r.SpaceAndIndexNamesSupported
 }
+
+func (r *noSchemaResolver) GetSchema() *Schema {
+	return nil
+}

Diff for: settings/request_test.go

@@ -28,6 +28,10 @@ func (r *ValidSchemeResolver) NamesUseSupported() bool {
 	return false
 }
 
+func (r *ValidSchemeResolver) GetSchema() *tarantool.Schema {
+	return nil
+}
+
 var resolver ValidSchemeResolver
 
 func TestRequestsAPI(t *testing.T) {

Diff for: tarantool_test.go

@@ -1851,6 +1851,31 @@ func TestConnection_DoWithStrangerConn(t *testing.T) {
 	}
 }
 
+func TestConnection_GetSchema(t *testing.T) {
+	conn := test_helpers.ConnectWithValidation(t, server, opts)
+	defer conn.Close()
+
+	s := conn.GetSchema()
+	if s.Version != 0 || s.Spaces[spaceName].Id != spaceNo {
+		t.Errorf("GetSchema() returns incorrect schema")
+	}
+}
+
+func TestConnection_OverrideSchema(t *testing.T) {
+	conn := test_helpers.ConnectWithValidation(t, server, opts)
+	defer conn.Close()
+
+	newSchema := Schema{
+		Version: 2,
+	}
+	conn.OverrideSchema(&newSchema)
+
+	s := conn.GetSchema()
+	if s.Version != 2 || len(s.Spaces) != 0 || len(s.SpacesById) != 0 {
+		t.Errorf("schema did not get updated")
+	}
+}
+
 func TestNewPreparedFromResponse(t *testing.T) {
 	var (
 		ErrNilResponsePassed = fmt.Errorf("passed nil response")
@@ -1882,7 +1907,7 @@ func TestSchema(t *testing.T) {
 	defer conn.Close()
 
 	// Schema
-	schema := conn.Schema
+	schema := conn.GetSchema()
 	if schema.SpacesById == nil {
 		t.Errorf("schema.SpacesById is nil")
 	}
@@ -2028,7 +2053,7 @@ func TestSchema_IsNullable(t *testing.T) {
 	conn := test_helpers.ConnectWithValidation(t, server, opts)
 	defer conn.Close()
 
-	schema := conn.Schema
+	schema := conn.GetSchema()
 	if schema.Spaces == nil {
 		t.Errorf("schema.Spaces is nil")
 	}