view hgext/logtoprocess.py @ 45773:210f9b8d7bbd stable

diff: do not concatenate immutable bytes while building a/b bodies (issue6445)

Use bytearray instead. I don't know what's changed since Python 2, but bytes
concatenation is 100x slow on Python 3.

  % python2.7 -m timeit -s "s = b''" "for i in range(10000): s += b'line'"
  1000 loops, best of 3: 321 usec per loop

  % python3.9 -m timeit -s "s = b''" "for i in range(10000): s += b'line'"
  5 loops, best of 5: 39.2 msec per loop

Benchmark using tailwind.css (measuring the fast path, a is empty):

  % HGRCPATH=/dev/null python2.7 ./hg log -R /tmp/issue6445 -p --time \
  --color=always --config diff.word-diff=true >/dev/null
  (prev) time: real 1.580 secs (user 1.560+0.000 sys 0.020+0.000)
  (this) time: real 1.610 secs (user 1.570+0.000 sys 0.030+0.000)

  % HGRCPATH=/dev/null python3.9 ./hg log -R /tmp/issue6445 -p --time \
  --color=always --config diff.word-diff=true >/dev/null
  (prev) time: real 114.500 secs (user 114.460+0.000 sys 0.030+0.000)
  (this) time: real 2.180 secs (user 2.140+0.000 sys 0.040+0.000)

Benchmark using random tabular text data (not the fast path):

  % dd if=/dev/urandom bs=1k count=1000 | hexdump -v -e '16/1 "%3u," "\n"' > ttf
  % hg ci -ma
  % dd if=/dev/urandom bs=1k count=1000 | hexdump -v -e '16/1 "%3u," "\n"' > ttf
  % hg ci -mb

  % HGRCPATH=/dev/null python2.7 ./hg log -R /tmp/issue6445 -p --time \
  --color=always --config diff.word-diff=true >/dev/null
  (prev) time: real 3.240 secs (user 3.040+0.000 sys 0.200+0.000
  (this) time: real 3.230 secs (user 3.070+0.000 sys 0.160+0.000)

  % HGRCPATH=/dev/null python3.9 ./hg log -R /tmp/issue6445 -p --time \
  --color=always --config diff.word-diff=true >/dev/null
  (prev) time: real 44.130 secs (user 43.850+0.000 sys 0.270+0.000)
  (this) time: real 4.170 secs (user 3.850+0.000 sys 0.310+0.000)

# 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 = b'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]
        maxmsg = 100000
        if len(msg) > maxmsg:
            # Each env var has a 128KiB limit on linux. msg can be long, in
            # particular for command event, where it's the full command line.
            # Prefer truncating the message than raising "Argument list too
            # long" error.
            msg = msg[:maxmsg] + b' (truncated)'
        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))