verifyBlockFor method

void verifyBlockFor(int docOffset)

Whether the block containing docOffset has passed its CRC check.

The first access to a block computes its CRC; every later access is one bitmap lookup. Compaction goes through the same path, so a corrupt block is reported instead of being rewritten with a fresh checksum.

Implementation

void verifyBlockFor(int docOffset) {
  final verified = _verifiedBlocks;
  if (verified == null) return;
  final index = _blockIndexFor(docOffset);
  if (index < 0) {
    throw VxsFormatException(
      'document offset $docOffset is outside every block',
      offset: docOffset,
    );
  }
  if (verified[index >> 3] & (1 << (index & 7)) != 0) return;
  final blockStart = start + VxsLe.u32(buffer, tableOffset + index * 4);
  final blockEnd = index + 1 < blockCount
      ? start + VxsLe.u32(buffer, tableOffset + (index + 1) * 4)
      : tableOffset;
  // Throws VxsFormatException when the block CRC does not match.
  BlockReader(buffer, offset: blockStart, length: blockEnd - blockStart);
  verified[index >> 3] |= 1 << (index & 7);
}