view contrib/catapipe.py @ 42669:36c692eb28d3

transaction: leave unfinished without crashing when not properly released

I think the transaction.__del__ is there just as a last resort in case
we (or an extension) forgot to release the transaction. When that
happens, the repo can (or will on Python 3?) get deleted before the
transaction. This leads to a crash in test-devel-warnings.t on Python
3 because we tried to access repo.dirstate, where repo was retried
from a weak reference. There's not much we can do here, but let's at
least avoid the crash. The user will have run `hg recover` afterwards
regardless.

Differential Revision: https://phab.mercurial-scm.org/D6664

#!/usr/bin/env python3
#
# Copyright 2018 Google LLC.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""Tool read primitive events from a pipe to produce a catapult trace.

Usage:
    Terminal 1: $ catapipe.py /tmp/mypipe /tmp/trace.json
    Terminal 2: $ HGCATAPULTSERVERPIPE=/tmp/mypipe hg root
    <ctrl-c catapipe.py in Terminal 1>
    $ catapult/tracing/bin/trace2html /tmp/trace.json  # produce /tmp/trace.html
    <open trace.html in your browser of choice; the WASD keys are very useful>
    (catapult is located at https://github.com/catapult-project/catapult)

For now the event stream supports

  START $SESSIONID ...

and

  END $SESSIONID ...

events. Everything after the SESSIONID (which must not contain spaces)
is used as a label for the event. Events are timestamped as of when
they arrive in this process and are then used to produce catapult
traces that can be loaded in Chrome's about:tracing utility. It's
important that the event stream *into* this process stay simple,
because we have to emit it from the shell scripts produced by
run-tests.py.

Typically you'll want to place the path to the named pipe in the
HGCATAPULTSERVERPIPE environment variable, which both run-tests and hg
understand. To trace *only* run-tests, use HGTESTCATAPULTSERVERPIPE instead.
"""
from __future__ import absolute_import, print_function

import argparse
import json
import os
import timeit

_TYPEMAP = {
    'START': 'B',
    'END': 'E',
    'COUNTER': 'C',
}

_threadmap = {}

# Timeit already contains the whole logic about which timer to use based on
# Python version and OS
timer = timeit.default_timer

def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('pipe', type=str, nargs=1,
                        help='Path of named pipe to create and listen on.')
    parser.add_argument('output', default='trace.json', type=str, nargs='?',
                        help='Path of json file to create where the traces '
                             'will be stored.')
    parser.add_argument('--debug', default=False, action='store_true',
                        help='Print useful debug messages')
    args = parser.parse_args()
    fn = args.pipe[0]
    os.mkfifo(fn)
    try:
        with open(fn) as f, open(args.output, 'w') as out:
            out.write('[\n')
            start = timer()
            while True:
                ev = f.readline().strip()
                if not ev:
                    continue
                now = timer()
                if args.debug:
                    print(ev)
                verb, session, label = ev.split(' ', 2)
                if session not in _threadmap:
                    _threadmap[session] = len(_threadmap)
                if verb == 'COUNTER':
                    amount, label = label.split(' ', 1)
                    payload_args = {'value': int(amount)}
                else:
                    payload_args = {}
                pid = _threadmap[session]
                ts_micros = (now - start) * 1000000
                out.write(json.dumps(
                    {
                        "name": label,
                        "cat": "misc",
                        "ph": _TYPEMAP[verb],
                        "ts": ts_micros,
                        "pid": pid,
                        "tid": 1,
                        "args": payload_args,
                    }))
                out.write(',\n')
    finally:
        os.unlink(fn)

if __name__ == '__main__':
    main()