joao-r-reis commented on code in PR #1926:
URL:
https://github.com/apache/cassandra-gocql-driver/pull/1926#discussion_r2842639316
##########
metadata.go:
##########
@@ -243,95 +246,257 @@ const (
// queries the cluster for schema information for a specific keyspace
type schemaDescriber struct {
- session *Session
- mu sync.Mutex
+ session *Session
+ schemaRefresher *refreshDebouncer
+ schemaMeta atomic.Value // *schemaMeta
+}
+
+// Schema change type constants as defined in the Cassandra Native Protocol
specification.
+// These values indicate the nature of schema modifications that occurred.
+//
+// See:
https://cassandra.apache.org/doc/latest/cassandra/reference/native-protocol.html
+//
+// Schema change events are server-initiated messages sent to clients that
have registered
+// for schema change notifications. These events indicate modifications to
keyspaces, tables,
+// user-defined types, functions, or aggregates.
+const (
+ SchemaChangeTypeCreated = "CREATED" // Schema object was created
+ SchemaChangeTypeUpdated = "UPDATED" // Schema object was modified
+ SchemaChangeTypeDropped = "DROPPED" // Schema object was removed
+)
- cache map[string]*KeyspaceMetadata
+type schemaMeta struct {
+ keyspaceMeta map[string]*KeyspaceMetadata
}
// creates a session bound schema describer which will query and cache
// keyspace metadata
-func newSchemaDescriber(session *Session) *schemaDescriber {
- return &schemaDescriber{
+func newSchemaDescriber(session *Session, schemaRefresher *refreshDebouncer)
*schemaDescriber {
+ meta := new(schemaMeta)
+ describer := &schemaDescriber{
session: session,
- cache: map[string]*KeyspaceMetadata{},
}
+ describer.schemaMeta.Store(meta)
+ describer.schemaRefresher = schemaRefresher
+ return describer
+}
+
+func (s *schemaDescriber) getSchemaMetaForRead() *schemaMeta {
+ meta, _ := s.schemaMeta.Load().(*schemaMeta)
+ return meta
+}
+
+func (s *schemaDescriber) getSchemaMetaForUpdate() *schemaMeta {
+ meta := s.getSchemaMetaForRead()
+ metaNew := new(schemaMeta)
+ if meta != nil {
+ *metaNew = *meta
+ }
+ return metaNew
}
// returns the cached KeyspaceMetadata held by the describer for the named
// keyspace.
func (s *schemaDescriber) getSchema(keyspaceName string) (*KeyspaceMetadata,
error) {
- s.mu.Lock()
- defer s.mu.Unlock()
+ if s.session.cfg.MetadataCacheMode == Disabled {
+ return s.fetchSchema(keyspaceName)
+ }
+ metadata, found := s.getSchemaMetaForRead().keyspaceMeta[keyspaceName]
- metadata, found := s.cache[keyspaceName]
if !found {
- // refresh the cache for this keyspace
- err := s.refreshSchema(keyspaceName)
- if err != nil {
- return nil, err
- }
-
- metadata = s.cache[keyspaceName]
+ return nil, ErrKeyspaceDoesNotExist
}
return metadata, nil
}
-// clears the already cached keyspace metadata
-func (s *schemaDescriber) clearSchema(keyspaceName string) {
- s.mu.Lock()
- defer s.mu.Unlock()
-
- delete(s.cache, keyspaceName)
-}
-
-// forcibly updates the current KeyspaceMetadata held by the schema describer
-// for a given named keyspace.
-func (s *schemaDescriber) refreshSchema(keyspaceName string) error {
+func (s *schemaDescriber) fetchSchema(keyspaceName string) (*KeyspaceMetadata,
error) {
var err error
// query the system keyspace for schema data
// TODO retrieve concurrently
keyspace, err := getKeyspaceMetadata(s.session, keyspaceName)
if err != nil {
- return err
+ return nil, err
}
tables, err := getTableMetadata(s.session, keyspaceName)
if err != nil {
- return err
+ return nil, err
}
columns, err := getColumnMetadata(s.session, keyspaceName)
if err != nil {
- return err
+ return nil, err
}
functions, err := getFunctionsMetadata(s.session, keyspaceName)
if err != nil {
- return err
+ return nil, err
}
aggregates, err := getAggregatesMetadata(s.session, keyspaceName)
if err != nil {
- return err
+ return nil, err
}
userTypes, err := getUserTypeMetadata(s.session, keyspaceName)
if err != nil {
- return err
+ return nil, err
}
materializedViews, err := getMaterializedViewsMetadata(s.session,
keyspaceName)
if err != nil {
- return err
+ return nil, err
}
// organize the schema data
compileMetadata(s.session, keyspace, tables, columns, functions,
aggregates, userTypes,
materializedViews)
- // update the cache
- s.cache[keyspaceName] = keyspace
+ return keyspace, nil
+}
+// forcibly updates the current KeyspaceMetadata held by the schema describer
+// for all the keyspaces.
+// This function is called via schemaRefresher refreshDebouncer to batch and
+// debounce schema refresh requests.
+func refreshSchemas(session *Session) error {
+ start := time.Now()
+ defer func() {
+ elapsed := time.Since(start)
+ session.logger.Debug("Schema refresh completed",
Review Comment:
I just noticed while troubleshooting that this log message will be
misleading when the refresh fails because it's always printed the same way
regardless of whether this functions fails or not
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