view hgext/logtoprocess.py @ 46393:66e8e279133b

hghave: list the module needed for the `vcr` check

I'm tired of having to look up modules each time I setup a system, and try to
distinguish between similar package names to get the right one.  Now that the
search API has been disabled, it's even harder.  There are other python packages
here that should be listed like this, but this is the one that came up missing
today, so it's a start.

Differential Revision: https://phab.mercurial-scm.org/D9879

# 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))