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  1. Thrift
  2. THRIFT-4651

Thrift Python encodes and decodes a Thrift list<...> into a Python set

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Invalid
    • Affects Version/s: 1.0
    • Fix Version/s: None
    • Component/s: Python - Compiler
    • Labels:
      None

      Description

      have a Thrift structure which contains a field "headers" which is a list<...> :

      /** A TIDE with sorted TIE headers, if headers unsorted, behavior is undefined */
      {{ struct TIDEPacket {}}
      {{ /** all 00s marks starts */}}
      {{ 1: required TIEID start_range;}}
      {{ /** all FFs mark end */}}
      {{ 2: required TIEID end_range;}}
      {{ /** sorted list of headers */}}
      {{ 3: required list<TIEHeader> headers; /* <<<<<< */}}
      {{ }}}

      This struct is actually deeply nested inside another structure, but that doesn't matter for the bug.

      When I encode the message, I pass a Python LIST into the Thrift-compiler generated encoding functions:

      ... TIREPacket(headers=[TIEHeader(seq_nr=0, origination_lifetime=None, tieid=TIEID(direction=2, tietype=2, originator=2, tie_nr=2), origination_time=None, remaining_lifetime=0)]) ...

      Note the square bracket [ after headers=

      When I decode that encoded message using the Thrift-compiler generated Python decoding functions, it decodes it as a Python SET instead of a Pythin list:

      ... TIREPacket(headers={TIEHeader(seq_nr=0, origination_lifetime=None, tieid=TIEID(direction=2, tietype=2, originator=2, tie_nr=2), origination_time=None, remaining_lifetime=0)}) ...

      Note the curly bracket { after headers=

      Indeed, when I look at the source code of the Python encoding/decoding functions generated by the Thrift compiler, I can see that the list<...> is treated as a SET:

      class TIREPacket(object):
      {{ """}}
      {{ A TIRE packet}}Attributes:
      {{ - headers}}
      {{ """}}thrift_spec = (
      {{ None, # 0}}
      {{ (1, TType.SET, 'headers', (TType.STRUCT, (TIEHeader, TIEHeader.thrift_spec), False), None, ), # 1}}
      {{ )}}

      You might wonder why the code did not crash when I passed a Python list to the encoding function instead of a set.

      It is probably because iterating over a list looks exactly the same as iterating over a set.

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            • Assignee:
              Unassigned
              Reporter:
              brunorijsman Bruno Rijsman
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              • Created:
                Updated:
                Resolved: