adds None check for backoff.expo() iteration

[topleft]

Description

Periodic back off in exporter is broken. Full description in issue #2829.

Fixes #2829

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Tests Suite

  • Run tox tests locally

• Recreate and fix locally

  • pull down https://github.com/topleft/otel-bug-fix-sample (sample code from issue backoff.expo v2.0.0 breaking change #2829)
  • run poetry install && poetry run uvicorn main:app
  • notice error
  • fix bug in local copy of opentelemetry-python
  • update pyproject.toml to reference local opentelemetry-python:
    • opentelemetry-exporter-otlp-proto-grpc = { path = "$HOME/.../opentelemetry-python/exporter/opentelemetry-exporter-otlp-proto-grpc" }
  • run poetry lock && poetry install --sync && poetry run uvicorn main:app
  • notice working code

Does This PR Require a Contrib Repo Change?

Answer the following question based on these examples of changes that would require a Contrib Repo Change:

• The OTel specification has changed which prompted this PR to update the method interfaces of opentelemetry-api/ or opentelemetry-sdk/

• The method interfaces of test/util have changed

• Scripts in scripts/ that were copied over to the Contrib repo have changed

• Configuration files that were copied over to the Contrib repo have changed (when consistency between repositories is applicable) such as in

  • pyproject.toml
  • isort.cfg
  • .flake8

• When a new .github/CODEOWNER is added

• Major changes to project information, such as in:

  • README.md
  • CONTRIBUTING.md

• Yes. - Link to PR:

• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: topleft / name: Pete Jeffryes (bb41c78)

[ocelotl]

Please add changelog entry

Missing changelog entry

[ElementalWarrior]

I think you actually just want to do a check for none, then continue. The next value in expo will be one:

    >>> import backoff
    >>> for v in backoff.expo(max_value=64):
    ...   print(v)
    ...   if v == 64:
    ...     break
    ... 
    1
    2
    4
    8
    16
    32
    64
    >>> 

for v backoff v2

    >>> from backoff import expo
    >>> for v in expo(max_value=64):
    ...   print(v)
    ...   if v == 64:
    ...     break
    ... 
    None
    1
    2
    4
    8
    16
    32
    64
    >>>

[topleft]

@ElementalWarrior Thanks for the suggestion, updated.

[srikanthccv]

Addressed in #2980 so I am going to close this.