THRIFT-5777: python fix mismatched timeout exceptions.

[bwangelme]

What error occurred?

When the Python client times out while reading content from the server, the exception thrown is not "read timeout," but rather "unexpected exception."

Why did this error occur?

the socket.timeout error doesn't includes the errno parameter in its args attribute.

I try to make a timeout error on my pc, it only contains the error string.

Python 3.11.1 (main, Jan  5 2023, 14:25:08) [GCC 11.3.0]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.13.2 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import socket
   ...: from urllib.request import urlopen
   ...:
   ...: url = 'http://httpbin.org/get'
   ...:
   ...: socket.setdefaulttimeout(0.01)
   ...: try:
   ...:     urlopen(url)
   ...: except Exception as e:
   ...:     err1 = e.reason
   ...:
   ...:

In [2]: type(err1)
Out[2]: TimeoutError

In [3]: err1.args
Out[3]: ('timed out',)

And my system is ubuntu 22.04

ø> uname -a
Linux Macmini 6.2.0-36-generic #37~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Mon Oct  9 15:34:04 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

TSocket.read handle exception error

Because socket.error.args == ('timed out',), the condition elif e.args[0] == errno.ETIMEDOUT cannot be True, resulting in the throwing of the wrong exception TTransportException(message="unexpected exception", inner=e).

How to fix it

I determine whether a timeout has occurred by checking if the exception is a socket.timeout, no longer relying on e.args.

• Did you create an Apache Jira ticket? (Request account here, not required for trivial changes)
  • https://issues.apache.org/jira/browse/THRIFT-5777
• If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• Did you squash your changes to a single commit? (not required, but preferred)
• Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"?
• If your change does not involve any code, include [skip ci] anywhere in the commit message to free up build resources.

[fishy]

starting from python 3.10, this is a deprecated alias to TimeoutError: https://docs.python.org/3.12/library/socket.html#socket.timeout

while TimeoutError also exists in 3.8 (the earliest version of python still supported): https://docs.python.org/3.8/library/exceptions.html#TimeoutError

so I wonder if we should be more future proof and handle both socket.timeout and TimeoutError here, and then we can drop socket.timeout when 3.10 becomes the earliest version of python supported.

[bwangelme]

modified in #2991