Shreyas220 commented on code in PR #866: URL: https://github.com/apache/iceberg-go/pull/866#discussion_r3163994933
########## table/dv/deletion_vector.go: ########## @@ -0,0 +1,133 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +package dv + +import ( + "bytes" + "encoding/binary" + "fmt" + "hash/crc32" + + "github.com/apache/iceberg-go" + iceio "github.com/apache/iceberg-go/io" + "github.com/apache/iceberg-go/puffin" +) + +const ( + // DVMagicNumber is the magic number for deletion vectors. + // Spec bytes: D1 D3 39 64 (big-endian) = 0x6439D3D1 (little-endian uint32) + DVMagicNumber uint32 = 0x6439D3D1 + + dvLengthSize = 4 // length field + dvMagicSize = 4 // magic field + dvCRCSize = 4 // CRC-32 checksum + dvMinSize = dvLengthSize + dvMagicSize + dvCRCSize +) + +// DeserializeDV parses a deletion vector blob and returns a bitmap of deleted positions. +// +// The DV binary format is: +// - Length (4 bytes, big-endian): size of magic + bitmap data +// - Magic (4 bytes, little-endian): must be 0x6439D3D1 +// - Bitmap (variable): roaring bitmap in Iceberg portable format +// - CRC-32 (4 bytes, big-endian): checksum over magic + bitmap +// +// If expectedCardinality >= 0, the bitmap's cardinality is validated against it. +func DeserializeDV(data []byte, expectedCardinality int64) (*RoaringPositionBitmap, error) { + if len(data) < dvMinSize { + return nil, fmt.Errorf("deletion vector payload too short: %d bytes (minimum %d)", len(data), dvMinSize) + } + + // 1. Read and validate length + length := binary.BigEndian.Uint32(data[0:dvLengthSize]) + expectedLength := uint32(len(data) - dvLengthSize - dvCRCSize) + if length != expectedLength { + return nil, fmt.Errorf("deletion vector length mismatch: got %d, expected %d", length, expectedLength) + } + + // 2. Read and validate magic + magic := binary.LittleEndian.Uint32(data[dvLengthSize : dvLengthSize+dvMagicSize]) + if magic != DVMagicNumber { + return nil, fmt.Errorf("invalid deletion vector magic: 0x%08x, expected 0x%08x", magic, DVMagicNumber) + } + + // 3. Verify CRC-32 over magic + bitmap (bytes 4 to len-4) + bitmapDataStart := dvLengthSize + bitmapDataEnd := len(data) - dvCRCSize + computedCRC := crc32.ChecksumIEEE(data[bitmapDataStart:bitmapDataEnd]) + expectedCRC := binary.BigEndian.Uint32(data[bitmapDataEnd:]) + if computedCRC != expectedCRC { + return nil, fmt.Errorf("deletion vector CRC mismatch: computed 0x%08x, expected 0x%08x", computedCRC, expectedCRC) + } + + // 4. Deserialize roaring bitmap from the inner bytes (after length + magic, before CRC) + roaringStart := dvLengthSize + dvMagicSize + bitmap, err := DeserializeRoaringPositionBitmap(bytes.NewReader(data[roaringStart:bitmapDataEnd])) + if err != nil { + return nil, fmt.Errorf("deserialize deletion vector bitmap: %w", err) + } + + // 5. Validate cardinality if requested + if expectedCardinality >= 0 { + actual := bitmap.Cardinality() + if actual != expectedCardinality { + return nil, fmt.Errorf("deletion vector cardinality mismatch: got %d, expected %d", actual, expectedCardinality) + } + } + + return bitmap, nil +} + +// ReadDV reads a deletion vector from a puffin file using the manifest entry metadata. +// ContentOffset and ContentSizeInBytes must be set on the DataFile (required by v3 spec). +func ReadDV(fs iceio.IO, dvFile iceberg.DataFile) (*RoaringPositionBitmap, error) { + if dvFile.FileFormat() != iceberg.PuffinFile { + return nil, fmt.Errorf("expected PUFFIN format for deletion vector, got %s", dvFile.FileFormat()) + } + + if dvFile.ContentOffset() == nil || dvFile.ContentSizeInBytes() == nil { + return nil, fmt.Errorf("DV file %s missing ContentOffset/ContentSizeInBytes", dvFile.FilePath()) + } + + size := *dvFile.ContentSizeInBytes() + if size < 0 || size > int64(puffin.DefaultMaxBlobSize) { + return nil, fmt.Errorf("DV blob size %d out of valid range [0, %d]", size, puffin.DefaultMaxBlobSize) + } + + f, err := fs.Open(dvFile.FilePath()) + if err != nil { + return nil, fmt.Errorf("open DV file %s: %w", dvFile.FilePath(), err) + } + defer f.Close() + + reader, err := puffin.NewReader(f) Review Comment: puffin reader doesn't own the file IO , it gets it from caller so i would like the caller of puffin file be responsible for closing not puffin reader let me know if you think otherwise -- This is an automated message from the Apache Git Service. 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