contrib/catapipe.py

pytype: import typing directly

First we no longer needs the pycompat layer, second having the types imported in
all case will allow to use them more directly in type annotation, something
important to upgrade the old "type comment" to proper type annotation.

A lot a stupid assert are needed to keep pyflakes happy. We should be able to
remove most of them once the type comment have been upgraded.

#!/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.
"""

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()