[GitHub] [beam] eantyshev commented on a diff in pull request #24056: [Playground] update snippet by persistence_key

[GitBox <gi...@apache.org>]

eantyshev commented on code in PR #24056:
URL: https://github.com/apache/beam/pull/24056#discussion_r1017884036


##########
playground/backend/internal/db/datastore/datastore_db.go:
##########
@@ -52,76 +52,88 @@ func New(ctx context.Context, responseMapper mapper.ResponseMapper, projectId st
 	return &Datastore{Client: client, ResponseMapper: responseMapper}, nil
 }
 
+// Delete unused snippets by given persistenceKey
+func (d *Datastore) deleteObsoleteSnippets(ctx context.Context, snipKey *datastore.Key, persistenceKey string) error {
+	if persistenceKey == "" || snipKey == nil {
+		logger.Debugf("no persistence key or no current snippet key")
+		return nil
+	}
+	// If persistenceKey is given, find the previous snippet version
+	snippetQuery := datastore.NewQuery(constants.SnippetKind).
+		Namespace(utils.GetNamespace(ctx)).
+		FilterField("persistenceKey", "=", persistenceKey)
+
+		// At the moment, datastore emulator doesn't allow != filters,
+		// hence this crutches
+		// https://cloud.google.com/datastore/docs/tools/datastore-emulator#known_issues
+		// When it's fixed, post-query filter could be replaced with
+		//
+		// FilterField("__key__", "!=", snipKey)
+
+	return d.deleteSnippets(ctx, snippetQuery, func(key *datastore.Key) bool {
+		// keep the current key
+		return *key == *snipKey
+	})
+}
+
 // PutSnippet puts the snippet entity to datastore
 func (d *Datastore) PutSnippet(ctx context.Context, snipId string, snip *entity.Snippet) error {
+	logger.Debugf("putting snippet %q, persistent key %q...", snipId, snip.Snippet.PersistenceKey)
 	if snip == nil {
 		logger.Errorf("Datastore: PutSnippet(): snippet is nil")
 		return nil
 	}
 	snipKey := utils.GetSnippetKey(ctx, snipId)
-	tx, err := d.Client.NewTransaction(ctx)
-	if err != nil {
-		logger.Errorf("Datastore: PutSnippet(): error during the transaction creating, err: %s\n", err.Error())
-		return err
-	}
-	if _, err = tx.Put(snipKey, snip.Snippet); err != nil {
-		if rollBackErr := tx.Rollback(); rollBackErr != nil {
-			err = rollBackErr
-		}
-		logger.Errorf("Datastore: PutSnippet(): error during the snippet entity saving, err: %s\n", err.Error())
-		return err
-	}
 
-	var fileKeys []*datastore.Key
-	for index := range snip.Files {
-		fileKeys = append(fileKeys, utils.GetFileKey(ctx, snipId, index))
-	}
+	// Create the new snippet
+	_, err := d.Client.RunInTransaction(ctx, func(tx *datastore.Transaction) error {
+		if _, err := tx.Put(snipKey, snip.Snippet); err != nil {
+			logger.Errorf("Datastore: PutSnippet(): error during the snippet entity saving, err: %s\n", err.Error())
+			return err
+		}
 
-	if _, err = tx.PutMulti(fileKeys, snip.Files); err != nil {
-		if rollBackErr := tx.Rollback(); rollBackErr != nil {
-			err = rollBackErr
+		var fileKeys []*datastore.Key
+		for index := range snip.Files {
+			fileKeys = append(fileKeys, utils.GetFileKey(ctx, snipId, index))
 		}
-		logger.Errorf("Datastore: PutSnippet(): error during the file entity saving, err: %s\n", err.Error())
-		return err
-	}
 
-	if _, err = tx.Commit(); err != nil {
-		logger.Errorf(errorMsgTemplateTxCommit, err.Error())
+		if _, err := tx.PutMulti(fileKeys, snip.Files); err != nil {
+			logger.Errorf("Datastore: PutSnippet(): error during the file entity saving, err: %s\n", err.Error())
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		logger.Errorf("Datastore: PutSnippet(): error during commit, err: %s\n", err.Error())
 		return err
 	}
 
-	return nil
+	return d.deleteObsoleteSnippets(ctx, snipKey, snip.Snippet.PersistenceKey)
 }
 
 // GetSnippet returns the snippet entity by identifier
 func (d *Datastore) GetSnippet(ctx context.Context, id string) (*entity.SnippetEntity, error) {
 	key := utils.GetSnippetKey(ctx, id)
 	snip := new(entity.SnippetEntity)
-	tx, err := d.Client.NewTransaction(ctx)

Review Comment:
   here and below we just optimize the code



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