view hgext/logtoprocess.py @ 40622:d2c997b8001f

logtoprocess: drop support for ui.log() call with invalid msg arguments (BC)

Before, the logtoprocess extension put a formatted message into $MSG1, and
its arguments to $MSG2... If the specified arguments couldn't be formatted
because of a caller bug, an unformatted message was passed in to $MSG1
instead of exploding. This behavior doesn't make sense.

Since I'm planning to formalize the ui.log() interface such that we'll no
longer have to extend the ui class, I want to remove any features not
conforming to the ui.log() API. So this patch removes the support for
ill-formed arguments, and $MSG{n} (where n > 1) parameters which seems
useless as long as the message can be formatted. The $MSG1 variable isn't
renamed for the maximum compatibility.

In future patches, a formatted msg will be passed to a processlogger object,
instead of overriding the ui.log() function.

.. bc::

   The logtoprocess extension no longer supports invalid ``ui.log()``
   arguments. A log message is always formatted and passed in to the
   ``$MSG1`` environment variable.

# 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 import (
    pycompat,
)
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'

def uisetup(ui):

    class logtoprocessui(ui.__class__):
        def log(self, event, *msg, **opts):
            """Map log events to external commands

            Arguments are passed on as environment variables.

            """
            script = self.config('logtoprocess', event)
            if script:
                env = {
                    b'EVENT': event,
                    b'HGPID': os.getpid(),
                    b'MSG1': msg[0] % msg[1:],
                }
                # keyword arguments get prefixed with OPT_ and uppercased
                env.update((b'OPT_%s' % key.upper(), value)
                           for key, value in pycompat.byteskwargs(opts).items())
                fullenv = procutil.shellenviron(env)
                procutil.runbgcommand(script, fullenv, shell=True)
            return super(logtoprocessui, self).log(event, *msg, **opts)

    # Replace the class for this instance and all clones created from it:
    ui.__class__ = logtoprocessui