C++ SerializeOutput::WriteInt方法代码示例

bool SeqScanPlan::SerializeTo(SerializeOutput &output) {
  // A placeholder for the total size written at the end
  int start = output.Position();
  output.WriteInt(-1);

  // Write the SeqScanPlan type
  PlanNodeType plan_type = GetPlanNodeType();
  output.WriteByte(static_cast<int8_t>(plan_type));

  // Write database id and table id
  if (!GetTable()) {
    // The plan is not completed
    return false;
  }
  oid_t database_id = GetTable()->GetDatabaseOid();
  oid_t table_id = GetTable()->GetOid();

  output.WriteInt(static_cast<int>(database_id));
  output.WriteInt(static_cast<int>(table_id));

  // If column has 0 item, just write the columnid_count with 0
  int columnid_count = GetColumnIds().size();
  output.WriteInt(columnid_count);

  // If column has 0 item, nothing happens here
  for (int it = 0; it < columnid_count; it++) {
    oid_t col_id = GetColumnIds()[it];
    output.WriteInt(static_cast<int>(col_id));
  }

  // Write predicate
  if (GetPredicate() == nullptr) {
    // Write the type
    output.WriteByte(static_cast<int8_t>(EXPRESSION_TYPE_INVALID));
  } else {
    // Write the expression type
    ExpressionType expr_type = GetPredicate()->GetExpressionType();
    output.WriteByte(static_cast<int8_t>(expr_type));
  }

  // Write parent, but parent seems never be set or used right now
  if (GetParent() == nullptr) {
    // Write the type
    output.WriteByte(static_cast<int8_t>(PLAN_NODE_TYPE_INVALID));
  } else {
    // Write the parent type
    PlanNodeType parent_type = GetParent()->GetPlanNodeType();
    output.WriteByte(static_cast<int8_t>(parent_type));

    // Write parent
    GetParent()->SerializeTo(output);
  }

  // Write the total length
  int32_t sz = static_cast<int32_t>(output.Position() - start - sizeof(int));
  PL_ASSERT(sz > 0);
  output.WriteIntAt(start, sz);

  return true;
}

bool Tile::SerializeHeaderTo(SerializeOutput &output) {
  std::size_t start;

  // Use the cache if possible
  if (column_header != NULL) {
    PL_ASSERT(column_header_size != INVALID_OID);
    output.WriteBytes(column_header, column_header_size);
    return true;
  }

  PL_ASSERT(column_header_size == INVALID_OID);

  // Skip header position
  start = output.Position();
  output.WriteInt(-1);

  // Status code
  output.WriteByte(-128);

  // Column counts as a short
  output.WriteShort(static_cast<int16_t>(column_count));

  // Write an array of column types as bytes
  for (oid_t column_itr = 0; column_itr < column_count; ++column_itr) {
    type::Type::TypeId type = schema.GetType(column_itr);
    output.WriteByte(static_cast<int8_t>(type));
  }

  // Write the array of column names as strings
  // NOTE: strings are ASCII only in metadata (UTF-8 in table storage)
  for (oid_t column_itr = 0; column_itr < column_count; ++column_itr) {
    // Column name: Write (offset, length) for column definition, and string to
    // string table
    const std::string &name = GetColumnName(column_itr);

    // Column names can't be null, so length must be >= 0
    int32_t length = static_cast<int32_t>(name.size());
    PL_ASSERT(length >= 0);

    // this is standard string serialization for voltdb
    output.WriteInt(length);
    output.WriteBytes(name.data(), length);
  }

  // Write the header size which is a non-inclusive int
  size_t Position = output.Position();
  column_header_size = static_cast<int32_t>(Position - start);

  int32_t non_inclusive_header_size =
      static_cast<int32_t>(column_header_size - sizeof(int32_t));
  output.WriteIntAt(start, non_inclusive_header_size);

  // Cache the column header
  column_header = new char[column_header_size];
  PL_MEMCPY(column_header, static_cast<const char *>(output.Data()) + start,
            column_header_size);

  return true;
}

void VarlenType::SerializeTo(const Value &val, SerializeOutput &out) const {
  uint32_t len = GetLength(val);
  out.WriteInt(len);
  if (len > 0 && len < PELOTON_VALUE_NULL) {
    out.WriteBytes(val.GetData(), len);
  }
}

//  Serialized only the tuples specified, along with header.
bool Tile::SerializeTuplesTo(SerializeOutput &output, Tuple *tuples,
                             int num_tuples) {
  std::size_t pos = output.Position();
  output.WriteInt(-1);

  PL_ASSERT(!tuples[0].IsNull());

  // Serialize the header
  if (!SerializeHeaderTo(output)) return false;

  output.WriteInt(static_cast<int32_t>(num_tuples));
  for (int tuple_itr = 0; tuple_itr < num_tuples; tuple_itr++) {
    tuples[tuple_itr].SerializeTo(output);
  }

  // Length prefix is non-inclusive
  output.WriteIntAt(
      pos, static_cast<int32_t>(output.Position() - pos - sizeof(int32_t)));

  return true;
}

bool Tile::SerializeTo(SerializeOutput &output, oid_t num_tuples) {
  /**
   * The table is serialized as:
   *
   * [(int) total size]
   * [(int) header size] [num columns] [column types] [column names]
   * [(int) num tuples] [tuple data]
   *
   */

  // A placeholder for the total table size written at the end
  std::size_t pos = output.Position();
  output.WriteInt(-1);

  // Serialize the header
  if (!SerializeHeaderTo(output)) return false;

  // Active tuple count
  output.WriteInt(static_cast<int>(num_tuples));

  oid_t written_count = 0;
  TupleIterator tile_itr(this);
  Tuple tuple(&schema);

  while (tile_itr.Next(tuple) && written_count < num_tuples) {
    tuple.SerializeTo(output);
    ++written_count;
  }

  tuple.SetNull();

  PL_ASSERT(written_count == num_tuples);

  // Length prefix is non-inclusive
  int32_t sz = static_cast<int32_t>(output.Position() - pos - sizeof(int32_t));
  PL_ASSERT(sz > 0);
  output.WriteIntAt(pos, sz);

  return true;
}

void IntegerValue::SerializeTo(SerializeOutput &out) const {
  switch(GetTypeId()) {
    case Type::TINYINT:
      out.WriteByte(value_.tinyint);
      return;
    case Type::SMALLINT:
      out.WriteShort(value_.smallint);
      return;
    case Type::INTEGER:
    case Type::PARAMETER_OFFSET:
      out.WriteInt(value_.integer);
      return;
    case Type::BIGINT:
      out.WriteLong(value_.bigint);
      return;
    default:
      return;
  }
  throw Exception("type error");
}

void Tuple::SerializeWithHeaderTo(SerializeOutput &output) {
  PL_ASSERT(tuple_schema_);
  PL_ASSERT(tuple_data_);

  size_t start = output.Position();
  output.WriteInt(0);  // reserve first 4 bytes for the total tuple size

  const int column_count = tuple_schema_->GetColumnCount();

  for (int column_itr = 0; column_itr < column_count; column_itr++) {
    type::Value value = GetValue(column_itr);
    value.SerializeTo(output);
  }

  int32_t serialized_size =
      static_cast<int32_t>(output.Position() - start - sizeof(int32_t));

  // write out the length of the tuple at start
  output.WriteIntAt(start, serialized_size);
}