view contrib/pull_logger.py @ 50336:cf4d2f31660d stable

chg: populate CHGHG if not set

Normally, chg determines which `hg` executable to use by first consulting the
`$CHGHG` and `$HG` environment variables, and if neither are present defaults
to the `hg` found in the user's `$PATH`. If built with the `HGPATHREL` compiler
flag, chg will instead assume that there exists an `hg` executable in the same
directory as the `chg` binary and attempt to use that.

This can cause problems in situations where there are multiple actively-used
Mercurial installations on the same system. When a `chg` client connects to a
running command server, the server process performs some basic validation to
determine whether a new command server needs to be spawned. These checks include
things like checking certain "sensitive" environment variables and config
sections, as well as checking whether the mtime of the extensions, hg's
`__version__.py` module, and the Python interpreter have changed.

Crucially, the command server doesn't explicitly check whether the executable it
is running from matches the executable that the `chg` client would have
otherwise invoked had there been no existing command server process. Without
`HGPATHREL`, this still gets implicitly checked during the validation step,
because the only way to specify an alternate hg executable (apart from `$PATH`)
is via the `$CHGHG` and `$HG` environment variables, both of which are checked.

With `HGPATHREL`, however, the command server has no way of knowing which hg
executable the client would have run. This means that a client located at
`/version_B/bin/chg` will happily connect to a command server running
`/version_A/bin/hg` instead of `/version_B/bin/hg` as expected. A simple
solution is to have the client set `$CHGHG` itself, which then allows the
command server's environment validation to work as intended.

I have tested this manually using two locally built hg installations and it
seems to work with no ill effects. That said, I'm not sure how to write an
automated test for this since the `chg` available to the tests isn't even built
with the `HGPATHREL` compiler flag to begin with.

# pull_logger.py - Logs pulls to a JSON-line file in the repo's VFS.
#
# Copyright 2022  Pacien TRAN-GIRARD <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.


'''logs pull parameters to a file

This extension logs the pull parameters, i.e. the remote and common heads,
when pulling from the local repository.

The collected data should give an idea of the state of a pair of repositories
and allow replaying past synchronisations between them. This is particularly
useful for working on data exchange, bundling and caching-related
optimisations.

The record is a JSON-line file located in the repository's VFS at
.hg/pull_log.jsonl.

Log write failures are not considered fatal: log writes may be skipped for any
reason such as insufficient storage or a timeout.

Some basic log file rotation can be enabled by setting 'rotate-size' to a value
greater than 0. This causes the current log file to be moved to
.hg/pull_log.jsonl.rotated when this threshold is met, discarding any
previously rotated log file.

The timeouts of the exclusive lock used when writing to the lock file can be
configured through the 'timeout.lock' and 'timeout.warn' options of this
plugin. Those are not expected to be held for a significant time in practice.::

  [pull-logger]
  timeout.lock = 300
  timeout.warn = 100
  rotate-size = 1kb
'''


import json
import time

from mercurial.i18n import _
from mercurial.utils import stringutil
from mercurial import (
    error,
    extensions,
    lock,
    registrar,
    wireprotov1server,
)

EXT_NAME = b'pull-logger'
EXT_VERSION_CODE = 0

LOG_FILE = b'pull_log.jsonl'
OLD_LOG_FILE = LOG_FILE + b'.rotated'
LOCK_NAME = LOG_FILE + b'.lock'

configtable = {}
configitem = registrar.configitem(configtable)
configitem(EXT_NAME, b'timeout.lock', default=600)
configitem(EXT_NAME, b'timeout.warn', default=120)
configitem(EXT_NAME, b'rotate-size', default=b'100MB')


def wrap_getbundle(orig, repo, proto, others, *args, **kwargs):
    heads, common = extract_pull_heads(others)
    log_entry = {
        'timestamp': time.time(),
        'logger_version': EXT_VERSION_CODE,
        'heads': sorted(heads),
        'common': sorted(common),
    }

    try:
        write_to_log(repo, log_entry)
    except (IOError, error.LockError) as err:
        msg = stringutil.forcebytestr(err)
        repo.ui.warn(_(b'unable to append to pull log: %s\n') % msg)

    return orig(repo, proto, others, *args, **kwargs)


def extract_pull_heads(bundle_args):
    opts = wireprotov1server.options(
        b'getbundle',
        wireprotov1server.wireprototypes.GETBUNDLE_ARGUMENTS.keys(),
        bundle_args.copy(),  # this call consumes the args destructively
    )

    heads = opts.get(b'heads', b'').decode('utf-8').split(' ')
    common = opts.get(b'common', b'').decode('utf-8').split(' ')
    return (heads, common)


def write_to_log(repo, entry):
    locktimeout = repo.ui.configint(EXT_NAME, b'timeout.lock')
    lockwarntimeout = repo.ui.configint(EXT_NAME, b'timeout.warn')
    rotatesize = repo.ui.configbytes(EXT_NAME, b'rotate-size')

    with lock.trylock(
        ui=repo.ui,
        vfs=repo.vfs,
        lockname=LOCK_NAME,
        timeout=locktimeout,
        warntimeout=lockwarntimeout,
    ):
        if rotatesize > 0 and repo.vfs.exists(LOG_FILE):
            if repo.vfs.stat(LOG_FILE).st_size >= rotatesize:
                repo.vfs.rename(LOG_FILE, OLD_LOG_FILE)

        with repo.vfs.open(LOG_FILE, b'a+') as logfile:
            serialised = json.dumps(entry, sort_keys=True)
            logfile.write(serialised.encode('utf-8'))
            logfile.write(b'\n')
            logfile.flush()


def reposetup(ui, repo):
    if repo.local():
        repo._wlockfreeprefix.add(LOG_FILE)
        repo._wlockfreeprefix.add(OLD_LOG_FILE)


def uisetup(ui):
    del wireprotov1server.commands[b'getbundle']
    decorator = wireprotov1server.wireprotocommand(
        name=b'getbundle',
        args=b'*',
        permission=b'pull',
    )

    extensions.wrapfunction(
        container=wireprotov1server,
        funcname='getbundle',
        wrapper=wrap_getbundle,
    )

    decorator(wireprotov1server.getbundle)