hgext/logtoprocess.py

revset: inline parents computation to reuse the input argument

Before this change, using `heads(xxx)` would compute `xxx` multiple time. Once
to select the possible candidates, and once to compute the parent set.

The code used to compute parents is a direct copy past from the `parents`
revset. We expect to replace it quickly in a later changeset. So we did not
bother with extracting a function.

In case where the input set is expensive to compute this provides a
significant performance boost.

(output are from contrib/revsetbenchmarks.py)

revset: heads(matching(tip, "author"))
   plain         min           max           first         last          reverse       rev..rst      rev..ast      sort          sor..rst      sor..ast
0) 15.06746      14.92766      7.335694      15.03092      7.635580      15.04133      7.454806      15.27565      14.97796      14.87607      7.480900
1) 7.529300  49% 7.592152  50% 7.480548      7.544528  50% 7.421248      7.522279  50% 7.484876      7.613154  49% 7.599553  50% 7.561410  50% 7.508990

In other cases, with a faster input set, we still see a (smaller) performance
boost.

revset: heads(all())
   plain         min           max           first         last          reverse       rev..rst      rev..ast      sort          sor..rst      sor..ast
0) 0.038994      0.035981      0.033345      0.035751      0.033569      0.039833      0.033653      0.035428      0.039483      0.035750      0.033657
1) 0.036359  93% 0.032613  90% 0.031479  94% 0.032790  91% 0.030681  91% 0.036456  91% 0.031128  92% 0.032461  91% 0.036276  91% 0.032721  91% 0.031024  92%

revset: heads(-10000:-1)
   plain         min           max           first         last          reverse       rev..rst      rev..ast      sort          sor..rst      sor..ast
0) 0.004184      0.003576      0.003593      0.003628      0.003569      0.004277      0.003590      0.003719      0.004194      0.003659      0.003690
1) 0.003850  92% 0.003267  91% 0.003256  90% 0.003261  89% 0.003204  89% 0.003855  90% 0.003294  91% 0.003164  85% 0.003848  91% 0.003302  90% 0.003296  89%

revset: (-5000:-1000) and heads(-10000:-1)
   plain         min           max           first         last          reverse       rev..rst      rev..ast      sort          sor..rst      sor..ast
0) 0.004730      0.003429      0.003359      0.003391      0.003369      0.004787      0.003418      0.003469      0.004772      0.003445      0.003454
1) 0.004277  90% 0.003430      0.003423      0.003353      0.003340      0.004250  88% 0.003387      0.003385      0.004325  90% 0.003413      0.003373

revset: heads(matching(tip, "author")) and -10000:-1
   plain         min           max           first         last          reverse       rev..rst      rev..ast      sort          sor..rst      sor..ast
0) 8.250275      8.231453      7.508579      8.230028      7.529777      8.358590      7.531636      8.301830      8.137196      8.421402      7.540355
1) 7.474707  90% 7.587345  92% 7.486192      7.548340  91% 7.485288      7.659108  91% 7.485307      7.628890  91% 7.523479  92% 7.558384  89% 7.467524

revset: (-10000:-1) and heads(matching(tip, "author"))
   plain         min           max           first         last          reverse       rev..rst      rev..ast      sort          sor..rst      sor..ast
0) 8.341504      8.315248      7.489414      8.320746      7.548816      8.244137      7.514663      8.281701      8.218862      8.412644      7.456793
1) 7.553704  90% 7.570679  91% 7.391438      7.724237  92% 7.527400      7.570637  91% 7.580622      7.450912  89% 7.556154  91% 7.514726  89% 7.494328

# logtoprocess.py - send ui.log() data to a subprocess
#
# Copyright 2016 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""send ui.log() data to a subprocess (EXPERIMENTAL)

This extension lets you specify a shell command per ui.log() event,
sending all remaining arguments to as environment variables to that command.

Positional arguments construct a log message, which is passed in the `MSG1`
environment variables. Each keyword argument is set as a `OPT_UPPERCASE_KEY`
variable (so the key is uppercased, and prefixed with `OPT_`). The original
event name is passed in the `EVENT` environment variable, and the process ID
of mercurial is given in `HGPID`.

So given a call `ui.log('foo', 'bar %s\n', 'baz', spam='eggs'), a script
configured for the `foo` event can expect an environment with `MSG1=bar baz`,
and `OPT_SPAM=eggs`.

Scripts are configured in the `[logtoprocess]` section, each key an event name.
For example::

  [logtoprocess]
  commandexception = echo "$MSG1" > /var/log/mercurial_exceptions.log

would log the warning message and traceback of any failed command dispatch.

Scripts are run asynchronously as detached daemon processes; mercurial will
not ensure that they exit cleanly.

"""

from __future__ import absolute_import

import os

from mercurial.utils import (
    procutil,
)

# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'ships-with-hg-core'

class processlogger(object):
    """Map log events to external commands

    Arguments are passed on as environment variables.
    """

    def __init__(self, ui):
        self._scripts = dict(ui.configitems(b'logtoprocess'))

    def tracked(self, event):
        return bool(self._scripts.get(event))

    def log(self, ui, event, msg, opts):
        script = self._scripts[event]
        env = {
            b'EVENT': event,
            b'HGPID': os.getpid(),
            b'MSG1': msg,
        }
        # keyword arguments get prefixed with OPT_ and uppercased
        env.update((b'OPT_%s' % key.upper(), value)
                   for key, value in opts.items())
        fullenv = procutil.shellenviron(env)
        procutil.runbgcommand(script, fullenv, shell=True)

def uipopulate(ui):
    ui.setlogger(b'logtoprocess', processlogger(ui))