tests/test-ctxmanager.py

changelog: lazily parse date/extra field

This is probably the most complicated patch in the parsing
refactor.

Because the date and extras are encoded in the same field, we
stuff the entire field into a dedicated variable and add a
property for accessing the sub-components of each. There is
some duplicated code here. But the code is relatively simple,
so it shouldn't be a big deal.

We see revset performance wins across the board:

author(mpm)
0.896565
0.876713
0.822961

desc(bug)
0.887169
0.895514
0.847054

date(2015)
0.878797
0.820987
0.811613

extra(rebase_source)
0.865446
0.823811
0.797756

author(mpm) or author(greg)
1.801832
1.784160
1.668172

author(mpm) or desc(bug)
1.812438
1.822756
1.677608

date(2015) or branch(default)
0.968276
0.910981
0.896032

author(mpm) or desc(bug) or date(2015) or extra(rebase_source)
3.656193
3.516788
3.265024

We see a speed-up on revsets accessing date and extras because the new
parsing code only parses what you access. Even though they are stored
the same text field, we avoid parsing dates when accessing extras and
vice-versa.

But strangely revsets accessing both date and extras appeared to speed
up as well! I'm not sure if this is due to refactoring the parsing
code or due to an optimization in revsets. You can't argue with the
results!

from __future__ import absolute_import

import silenttestrunner
import unittest

from mercurial.util import ctxmanager

class contextmanager(object):
    def __init__(self, name, trace):
        self.name = name
        self.entered = False
        self.exited = False
        self.trace = trace

    def __enter__(self):
        self.entered = True
        self.trace(('enter', self.name))
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.exited = exc_type, exc_val, exc_tb
        self.trace(('exit', self.name))

    def __repr__(self):
        return '<ctx %r>' % self.name

class ctxerror(Exception):
    pass

class raise_on_enter(contextmanager):
    def __enter__(self):
        self.trace(('raise', self.name))
        raise ctxerror(self.name)

class raise_on_exit(contextmanager):
    def __exit__(self, exc_type, exc_val, exc_tb):
        self.trace(('raise', self.name))
        raise ctxerror(self.name)

def ctxmgr(name, trace):
    return lambda: contextmanager(name, trace)

class test_ctxmanager(unittest.TestCase):
    def test_basics(self):
        trace = []
        addtrace = trace.append
        with ctxmanager(ctxmgr('a', addtrace), ctxmgr('b', addtrace)) as c:
            a, b = c.enter()
            c.atexit(addtrace, ('atexit', 'x'))
            c.atexit(addtrace, ('atexit', 'y'))
        self.assertEqual(trace, [('enter', 'a'), ('enter', 'b'),
                                 ('atexit', 'y'), ('atexit', 'x'),
                                 ('exit', 'b'), ('exit', 'a')])

    def test_raise_on_enter(self):
        trace = []
        addtrace = trace.append
        def go():
            with ctxmanager(ctxmgr('a', addtrace),
                           lambda: raise_on_enter('b', addtrace)) as c:
                c.enter()
                addtrace('unreachable')
        self.assertRaises(ctxerror, go)
        self.assertEqual(trace, [('enter', 'a'), ('raise', 'b'), ('exit', 'a')])

    def test_raise_on_exit(self):
        trace = []
        addtrace = trace.append
        def go():
            with ctxmanager(ctxmgr('a', addtrace),
                           lambda: raise_on_exit('b', addtrace)) as c:
                c.enter()
                addtrace('running')
        self.assertRaises(ctxerror, go)
        self.assertEqual(trace, [('enter', 'a'), ('enter', 'b'), 'running',
                                 ('raise', 'b'), ('exit', 'a')])

if __name__ == '__main__':
    silenttestrunner.main(__name__)