`str(v)` in `core_enforcer.enforce_ex()` is done even when not needed resulting in unnecessary code execution and DB calls

[manisar2]

Ask

Use str on rvals only if needed (for logging).

Detail

In core_enforcer.py, we have this here - note the [str(v) for v in rvals] in the second line:

        req_str = "Request: "
        req_str = req_str + ", ".join([str(v) for v in rvals])

        req_str = req_str + " ---> %s" % result
        if result:
            self.logger.info(req_str)
        else:
            # leaving this in warning for now, if it's very noise this can be changed to info or debug,
            # or change the log level
            self.logger.warning(req_str)

Our code passes Django model instances as rvals which have custom __str__s.
str(v) above causes the custom __str__s to be called which in turn result in DB calls we are trying to avoid.

We don't need INFO or WARNING level logging, so we have set the log level as error.
Thus we avoid the full logging block above, but in spite of that, the str(v) calls result in unnecessary DB calls - even though the req_str created is not used anywhere.

Suggestion

This altered code (or something similar) can make this block of code more efficient - as str on rvals will only be called if needed for logging.

        req_str = "Request: "

        if result and self.logger.level <=  logging.INFO:
            req_str = req_str + ", ".join([str(v) for v in rvals])
            req_str = req_str + " ---> %s" % result
            self.logger.info(req_str)

        elif self.logger.level <=  logging.WARNING:
            req_str = req_str + ", ".join([str(v) for v in rvals])
            req_str = req_str + " ---> %s" % result
            # leaving this in warning for now, if it's very noise this can be changed to info or debug,
            # or change the log level
            self.logger.warning(req_str)

[manisar2]

This was amazingly quick, thank you @hsluoyz !