fix(redis): handle rowcount when BaseException is raised [backport 2.9]

[github-actions]

Backport 8d3f827 from #9511 to 2.9.

In case of Redis raised a BaseException like asyncio.CancelledError.

ddtrace integration tries to compute the rowcount while "result"
variable does not exists.

  File "ddtrace/contrib/redis_utils.py", line 72, in _run_redis_command_async
    result = await func(*args, **kwargs)
  File "redis/asyncio/client.py", line 605, in execute_command
    conn = self.connection or await pool.get_connection(command_name, **options)
  File "redis/asyncio/connection.py", line 1076, in get_connection
    await self.ensure_connection(connection)
  File "redis/asyncio/connection.py", line 1115, in ensure_connection
    if await connection.can_read_destructive():
  File "redis/asyncio/connection.py", line 504, in can_read_destructive
    return await self._parser.can_read_destructive()
  File "redis/_parsers/hiredis.py", line 179, in can_read_destructive
    return await self.read_from_socket()
  File "redis/_parsers/hiredis.py", line 184, in read_from_socket
    buffer = await self._stream.read(self._read_size)
  File "asyncio/streams.py", line 713, in read
    await self._wait_for_data('read')
  File "asyncio/streams.py", line 545, in _wait_for_data
    await self._waiter
CancelledError: null

  File "xxxxxxx.py", line 287, in list_pulls
    await redis.zrangebyscore(
  File "ddtrace/contrib/redis/asyncio_patch.py", line 20, in traced_async_execute_command
    return await _run_redis_command_async(span=span, func=func, args=args, kwargs=kwargs)
  File "ddtrace/contrib/redis_utils.py", line 79, in _run_redis_command_async
    rowcount = determine_row_count(redis_command=redis_command, result=result)
UnboundLocalError: cannot access local variable 'result' where it is not associated with a value

This change fixes that.

Fixes #9548

Checklist

• Change(s) are motivated and described in the PR description
• Testing strategy is described if automated tests are not included in the PR
• Risks are described (performance impact, potential for breakage, maintainability)
• Change is maintainable (easy to change, telemetry, documentation)
• Library release note guidelines are followed or label changelog/no-changelog is set
• Documentation is included (in-code, generated user docs, public corp docs)
• Backport labels are set (if applicable)
• If this PR changes the public interface, I've notified @DataDog/apm-tees.

Reviewer Checklist

• Title is accurate
• All changes are related to the pull request's stated goal
• Description motivates each change
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Change is maintainable (easy to change, telemetry, documentation)
• Release note makes sense to a user of the library
• Author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[dnguy078]

thank you @erikayasuda

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: backport-9511-to-2.9
Commit report: a9bfd27
Test service: dd-trace-py

✅ 0 Failed, 847 Passed, 46 Skipped, 14m 47.24s Total duration (41.61s time saved)

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-07-22 22:31:47

Comparing candidate commit a9bfd27 in PR branch backport-9511-to-2.9 with baseline commit 94fe5ff in branch 2.9.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 175 metrics, 9 unstable metrics.

[erikayasuda]

Closing and re-opening to re-trigger the system tests

[dnguy078]

Hi @erikayasuda @emmettbutler , would it be possible to cut a new release 2.9.4 that includes this change? Thank you !