fix: Stop creating meta files for each new resource #1217

src/storage/accessors/FilterMetadataDataAccessor.ts

@@ -0,0 +1,55 @@
+import type { Readable } from 'stream';
+import type { RepresentationMetadata } from '../../http/representation/RepresentationMetadata';
+import type { ResourceIdentifier } from '../../http/representation/ResourceIdentifier';
+import type { Guarded } from '../../util/GuardedStream';
+import type { FilterPattern } from '../../util/QuadUtil';
+import type { DataAccessor } from './DataAccessor';
+import { PassthroughDataAccessor } from './PassthroughDataAccessor';
+
+/**
+ * A FilterMetadataDataAccessor wraps a DataAccessor such that specific metadata properties
+ * can be filtered before passing on the call to the wrapped DataAccessor.
+ */
+export class FilterMetadataDataAccessor extends PassthroughDataAccessor {
+  private readonly filters: FilterPattern[];
+
+  /**
+   * Construct an instance of FilterMetadataDataAccessor.
+   *
+   * @param accessor - The DataAccessor to wrap.
+   * @param filters - Filter patterns to be used for metadata removal.
+   */
+  public constructor(accessor: DataAccessor, filters: FilterPattern[]) {
+    super(accessor);
+    this.filters = filters;
+  }
+
+  public async writeDocument(
+    identifier: ResourceIdentifier,
+    data: Guarded<Readable>,
+    metadata: RepresentationMetadata,
+  ): Promise<void> {
+    this.applyFilters(metadata);
+    return this.accessor.writeDocument(identifier, data, metadata);
+  }
+
+  public async writeContainer(identifier: ResourceIdentifier, metadata: RepresentationMetadata): Promise<void> {
+    this.applyFilters(metadata);
+    return this.accessor.writeContainer(identifier, metadata);
+  }
+
+  /**
+   * Utility function that removes metadata entries,
+   * based on the configured filter patterns.
+   *
+   * @param metadata - Metadata for the request.
+   */
+  private applyFilters(metadata: RepresentationMetadata): void {
+    for (const filter of this.filters) {
+      // Find the matching quads.
+      const matchingQuads = metadata.quads(filter.subject, filter.predicate, filter.object);
+      // Remove the resulset.
+      metadata.removeQuads(matchingQuads);
+    }
+  }
+}