tests/test-extensions-wrapfunction.py

perf: add perfchangegroupchangelog command

This command can be used for testing the performance of producing the
changelog portion of a changegroup.

We could use additional perf* commands for testing other parts of
changegroup. Those can be written another time, when they are needed.
(And those may want to refactor the changegroup generation API so code
can be reused.) Speaking of code reuse, yes, this command does reinvent
a small wheel. I didn't want to scope bloat to change the changegroup
API because that will invite bikeshedding.

from __future__ import absolute_import, print_function

from mercurial import extensions

def genwrapper(x):
    def f(orig, *args, **kwds):
        return [x] + orig(*args, **kwds)
    f.x = x
    return f

def getid(wrapper):
    return getattr(wrapper, 'x', '-')

wrappers = [genwrapper(i) for i in range(5)]

class dummyclass(object):
    def getstack(self):
        return ['orig']

dummy = dummyclass()

def batchwrap(wrappers):
    for w in wrappers:
        extensions.wrapfunction(dummy, 'getstack', w)
        print('wrap %d: %s' % (getid(w), dummy.getstack()))

def batchunwrap(wrappers):
    for w in wrappers:
        result = None
        try:
            result = extensions.unwrapfunction(dummy, 'getstack', w)
            msg = str(dummy.getstack())
        except (ValueError, IndexError) as e:
            msg = e.__class__.__name__
        print('unwrap %s: %s: %s' % (getid(w), getid(result), msg))

batchwrap(wrappers + [wrappers[0]])
batchunwrap([(wrappers[i] if i >= 0 else None)
             for i in [3, None, 0, 4, 0, 2, 1, None]])