Reduce access log overhead when logging is disabled with a logging filter

[bdraco]

alternative to #7240

What do these changes do?

If the logger was disabled the log message would be formatted and thrown away. Avoid formatting the log message when logging is not enabled at info level.

Are there changes in behavior for the user?

If you are using multiple aiohttp.web.AppRunner in the same python process you must also now pass a unique logger to each because AccessLogger will now attach a filter which affects the state of any logger object passed in and is not re-entrant.

Consumers of AccessLogger MUST use a new unique logger as the AccessLogger will now add logging filter to any existing logger that is passed in which will affect logging for all handlers attached to that logger. Be sure to generate a unique logger object for each instance of AccessLogger. It is important the logger is unique because if other code is using the same logger, the logging filter will likely raise an exception or mutate the log messages in an unexpected way.

        log = logging.getLogger("my_unique_logger_per_instance_of_aiohttp")
        log_format = "%a %{User-Agent}i"
        access_logger = AccessLogger(log, log_format)
        access_logger.log(request, response, time)

If multiple aiohttp instances use the same logger object then the log filter will be attached multiple times which will lead to undefined behavior.

Related issue number

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt
  • The format is <Name> <Surname>.
  • Please keep alphabetical order, the file is sorted by names.
• Add a new news fragment into the CHANGES folder
  • name it <issue_id>.<type> for example (588.bugfix)
  • if you don't have an issue_id change it to the pr id after creating the pr
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    • .feature: Signifying a new feature.
    • .bugfix: Signifying a bug fix.
    • .doc: Signifying a documentation improvement.
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    • .misc: A ticket has been closed, but it is not of interest to users.
  • Make sure to use full sentences with correct case and punctuation, for example: "Fix issue with non-ascii contents in doctest text files."

[bdraco]

After writing out Are there changes in behavior for the user? it seems like the side effects of this change are not going to be received well so I think this path doesn't have a way forward.