Pass optional readers to override and cache metadata objects

file.go

@@ -54,6 +54,9 @@ func OpenFile(r io.ReaderAt, size int64, options ...FileOption) (*File, error) {
 		return nil, fmt.Errorf("invalid magic header of parquet file: %q", b[:4])
 	}
 
+	if cast, ok := f.reader.(interface{ SetMagicFooterSection(offset, length int64) }); ok {
+		cast.SetMagicFooterSection(size-8, 8)
+	}
 	if _, err := r.ReadAt(b[:8], size-8); err != nil {
 		return nil, fmt.Errorf("reading magic footer of parquet file: %w", err)
 	}
@@ -64,6 +67,9 @@ func OpenFile(r io.ReaderAt, size int64, options ...FileOption) (*File, error) {
 	footerSize := int64(binary.LittleEndian.Uint32(b[:4]))
 	footerData := make([]byte, footerSize)
 
+	if cast, ok := f.reader.(interface{ SetFooterSection(offset, length int64) }); ok {
+		cast.SetFooterSection(size-(footerSize+8), footerSize)
+	}
 	if _, err := f.reader.ReadAt(footerData, size-(footerSize+8)); err != nil {
 		return nil, fmt.Errorf("reading footer of parquet file: %w", err)
 	}
@@ -117,6 +123,12 @@ func OpenFile(r io.ReaderAt, size int64, options ...FileOption) (*File, error) {
 						return nil, err
 					}
 					offset, _ = s.Seek(0, io.SeekCurrent)
+					if cast, ok := r.(interface{ SetBloomFilterSection(offset, length int64) }); ok {
+						bloomFilterOffset := c.chunk.MetaData.BloomFilterOffset
+						bloomFilterLength := (offset - bloomFilterOffset) + int64(h.NumBytes)
+						cast.SetBloomFilterSection(bloomFilterOffset, bloomFilterLength)
+					}
+
 					c.bloomFilter = newBloomFilter(r, offset, &h)
 				}
 			}
@@ -192,6 +204,9 @@ func (f *File) ReadPageIndex() ([]format.ColumnIndex, []format.OffsetIndex, erro
 	if columnIndexOffset > 0 {
 		columnIndexData := indexBuffer[:columnIndexLength]
 
+		if cast, ok := f.reader.(interface{ SetColumnIndexSection(offset, length int64) }); ok {
+			cast.SetColumnIndexSection(columnIndexOffset, columnIndexLength)
+		}
 		if _, err := f.reader.ReadAt(columnIndexData, columnIndexOffset); err != nil {
 			return nil, nil, fmt.Errorf("reading %d bytes column index at offset %d: %w", columnIndexLength, columnIndexOffset, err)
 		}
@@ -213,6 +228,9 @@ func (f *File) ReadPageIndex() ([]format.ColumnIndex, []format.OffsetIndex, erro
 	if offsetIndexOffset > 0 {
 		offsetIndexData := indexBuffer[:offsetIndexLength]
 
+		if cast, ok := f.reader.(interface{ SetOffsetIndexSection(offset, length int64) }); ok {
+			cast.SetOffsetIndexSection(offsetIndexOffset, offsetIndexLength)
+		}
 		if _, err := f.reader.ReadAt(offsetIndexData, offsetIndexOffset); err != nil {
 			return nil, nil, fmt.Errorf("reading %d bytes offset index at offset %d: %w", offsetIndexLength, offsetIndexOffset, err)
 		}