Method Iterate

src/leveldb/db/write_batch.cc:42–80

size_t WriteBatch::ApproximateSize() const { return rep_.size(); }

Status WriteBatch::Iterate(Handler* handler) const {
  Slice input(rep_);
  if (input.size() < kHeader) {
    return Status::Corruption("malformed WriteBatch (too small)");
  }

  input.remove_prefix(kHeader);
  Slice key, value;
  int found = 0;
  while (!input.empty()) {
    found++;
    char tag = input[0];
    input.remove_prefix(1);
    switch (tag) {
      case kTypeValue:
        if (GetLengthPrefixedSlice(&input, &key) &&
            GetLengthPrefixedSlice(&input, &value)) {
          handler->Put(key, value);
        } else {
          return Status::Corruption("bad WriteBatch Put");
        }
        break;
      case kTypeDeletion:
        if (GetLengthPrefixedSlice(&input, &key)) {
          handler->Delete(key);
        } else {
          return Status::Corruption("bad WriteBatch Delete");
        }
        break;
      default:
        return Status::Corruption("unknown WriteBatch tag");
    }
  }
  if (found != WriteBatchInternal::Count(this)) {
    return Status::Corruption("WriteBatch has wrong count");
  } else {
    return Status::OK();
  }
}

int WriteBatchInternal::Count(const WriteBatch* b) {
  return DecodeFixed32(b->rep_.data() + 8);