private void ReadSchema(Memory <byte> buffer)
{
// Deserialize the footer from the footer flatbuffer
_footer = new ArrowFooter(Flatbuf.Footer.GetRootAsFooter(CreateByteBuffer(buffer)));
Schema = _footer.Schema;
}
protected override async Task <Schema> ReadSchemaAsync()
{
if (HasReadSchema)
{
return(Schema);
}
await ValidateFileAsync();
var bytesRead = 0;
var footerLength = 0;
await Buffers.RentReturnAsync(4, async (buffer) =>
{
BaseStream.Position = BaseStream.Length - ArrowFileConstants.Magic.Length - 4;
bytesRead = await BaseStream.ReadAsync(buffer, 0, 4);
footerLength = BinaryPrimitives.ReadInt32LittleEndian(buffer);
if (bytesRead != 4)
{
throw new InvalidDataException(
$"Failed to read footer length. Read <{bytesRead}>, expected 4.");
}
if (footerLength <= 0)
{
throw new InvalidDataException(
$"Footer length has invalid size <{footerLength}>");
}
});
await Buffers.RentReturnAsync(footerLength, async (buffer) =>
{
_footerStartPostion = (int)BaseStream.Length - footerLength - ArrowFileConstants.Magic.Length - 4;
BaseStream.Position = _footerStartPostion;
bytesRead = await BaseStream.ReadAsync(buffer, 0, footerLength);
if (bytesRead != footerLength)
{
throw new InvalidDataException(
$"Failed to read footer. Read <{bytesRead}> bytes, expected <{footerLength}>.");
}
// Deserialize the footer from the footer flatbuffer
_footer = new ArrowFooter(Flatbuf.Footer.GetRootAsFooter(new ByteBuffer(buffer)));
Schema = _footer.Schema;
});
return(Schema);
}
