tests/blackbox-readonly-dispatch.py

revlog: add a C implementation of `headrevsdiff`

Python implementation of `headrevsdiff` can be very slow in the worst
case compared with the `heads` computation it replaces, since the
latter is done in C.

Even the average case of this Python implementation is still
noticeable in the profiles.

This patch makes the computation much much faster by doing it in C.

import os
from mercurial import (
    dispatch,
    extensions,
    ui as uimod,
)


def testdispatch(cmd):
    """Simple wrapper around dispatch.dispatch()

    Prints command and result value, but does not handle quoting.
    """
    ui = uimod.ui.load()
    extensions.populateui(ui)
    ui.statusnoi18n(b"running: %s\n" % cmd)
    req = dispatch.request(cmd.split(), ui)
    result = dispatch.dispatch(req)
    ui.statusnoi18n(b"result: %r\n" % result)


# create file 'foo', add and commit
f = open(b'foo', 'wb')
f.write(b'foo\n')
f.close()
testdispatch(b"--debug add foo")
testdispatch(b"--debug commit -m commit1 -d 2000-01-01 foo")

# append to file 'foo' and commit
f = open(b'foo', 'ab')
f.write(b'bar\n')
f.close()
# remove blackbox.log directory (proxy for readonly log file)
os.rmdir(b".hg/blackbox.log")
# replace it with the real blackbox.log file
os.rename(b".hg/blackbox.log-", b".hg/blackbox.log")
testdispatch(b"--debug commit -m commit2 -d 2000-01-02 foo")

# check 88803a69b24 (fancyopts modified command table)
testdispatch(b"--debug log -r 0")
testdispatch(b"--debug log -r tip")