comparison mercurial/ui.py @ 41063:6603de284b0a

progress: avoid ui.configbool() lookup when progress bar is active

Profiling revealed that the ui.configbool('progress', 'debug') during
progress bar updates was consuming a significant amount of overhead.

This commit adds an attribute on progress bar instances that caches
this config option.

The impact on `hg perfprogress` with default options is significant:

before: ! wall 4.641942 comb 4.580000 user 4.210000 sys 0.370000 (best of 3)
after:  ! wall 1.948626 comb 1.950000 user 1.950000 sys 0.000000 (best of 5)

After this change, profiling reveals that progress.progbar.progress()
is now consuming ~73% of time.

This change does not improve the execution time if the progress bar
is disabled. We may want a more comprehensive solution for that case,
as the progress bar won't be enabled in a number of scenarios (e.g.
servers and processes not attached to an interactive TTY).

I also think that overhead of ~2.0s for 1M updates is a bit high.
I suspect further refactoring of the progress bar can significantly
reduce overhead. I don't have plans to do this, however.

Differential Revision: https://phab.mercurial-scm.org/D5408

41062:0a7f582f6f1f

            self._fmsgerr.write(None, type=b'progress', topic=topic, pos=pos,
                                item=item, unit=unit, total=total)
        elif self._progbar is not None:
            self._progbar.progress(topic, pos, item=item, unit=unit,
                                   total=total)
        if pos is None or not self.configbool('progress', 'debug'):
            return

        if unit:
            unit = ' ' + unit

41063:6603de284b0a

            self._fmsgerr.write(None, type=b'progress', topic=topic, pos=pos,
                                item=item, unit=unit, total=total)
        elif self._progbar is not None:
            self._progbar.progress(topic, pos, item=item, unit=unit,
                                   total=total)

            # Looking up progress.debug in tight loops is expensive. The value
            # is cached on the progbar object and we can avoid the lookup in
            # the common case where a progbar is active.
            if pos is None or not self._progbar.debug:
                return

        # Keep this logic in sync with above.
        if pos is None or not self.configbool('progress', 'debug'):
            return

        if unit:
            unit = ' ' + unit