view tests/test-filecache.py @ 45121:b6269741ed42

config: add option to control creation of empty successors during rewrite

The default for many history-rewriting commands (e.g. rebase and absorb) is
that changesets which would become empty are not created in the target branch.
This makes sense if the source branch consists of small fix-up changes. For
more advanced workflows that make heavy use of history-editing to create
curated patch series, dropping empty changesets is not as important or even
undesirable.

Some users want to keep the meta-history, e.g. to make finding comments in a
code review tool easier or to avoid that divergent bookmarks are created. For
that, obsmarkers from the (to-be) empty changeset to the changeset(s) that
already made the changes should be added. If a to-be empty changeset is pruned
without a successor, adding the obsmarkers is hard because the changeset has to
be found within the hidden part of the history.

If rebasing in TortoiseHg, it’s easy to miss the fact that the to-be empty
changeset was pruned. An empty changeset will function as a reminder that
obsmarkers should be added.

Martin von Zweigbergk mentioned another advantage. Stripping the successor will
de-obsolete the predecessor. If no (empty) successor is created, this won’t be
possible.

In the future, we may want to consider other behaviors, like e.g. creating the
empty successor, but pruning it right away. Therefore this configuration
accepts 'skip' and 'keep' instead of being a boolean configuration.

from __future__ import absolute_import, print_function
import os
import stat
import subprocess
import sys

if subprocess.call(
    ['python', '%s/hghave' % os.environ['TESTDIR'], 'cacheable']
):
    sys.exit(80)

print_ = print


def print(*args, **kwargs):
    """print() wrapper that flushes stdout buffers to avoid py3 buffer issues

    We could also just write directly to sys.stdout.buffer the way the
    ui object will, but this was easier for porting the test.
    """
    print_(*args, **kwargs)
    sys.stdout.flush()


from mercurial import (
    extensions,
    hg,
    localrepo,
    pycompat,
    ui as uimod,
    util,
    vfs as vfsmod,
)

if pycompat.ispy3:
    xrange = range


class fakerepo(object):
    def __init__(self):
        self._filecache = {}

    class fakevfs(object):
        def join(self, p):
            return p

    vfs = fakevfs()

    def unfiltered(self):
        return self

    def sjoin(self, p):
        return p

    @localrepo.repofilecache('x', 'y')
    def cached(self):
        print('creating')
        return 'string from function'

    def invalidate(self):
        for k in self._filecache:
            try:
                delattr(self, pycompat.sysstr(k))
            except AttributeError:
                pass


def basic(repo):
    print("* neither file exists")
    # calls function
    repo.cached

    repo.invalidate()
    print("* neither file still exists")
    # uses cache
    repo.cached

    # create empty file
    f = open('x', 'w')
    f.close()
    repo.invalidate()
    print("* empty file x created")
    # should recreate the object
    repo.cached

    f = open('x', 'w')
    f.write('a')
    f.close()
    repo.invalidate()
    print("* file x changed size")
    # should recreate the object
    repo.cached

    repo.invalidate()
    print("* nothing changed with either file")
    # stats file again, reuses object
    repo.cached

    # atomic replace file, size doesn't change
    # hopefully st_mtime doesn't change as well so this doesn't use the cache
    # because of inode change
    f = vfsmod.vfs(b'.')(b'x', b'w', atomictemp=True)
    f.write(b'b')
    f.close()

    repo.invalidate()
    print("* file x changed inode")
    repo.cached

    # create empty file y
    f = open('y', 'w')
    f.close()
    repo.invalidate()
    print("* empty file y created")
    # should recreate the object
    repo.cached

    f = open('y', 'w')
    f.write('A')
    f.close()
    repo.invalidate()
    print("* file y changed size")
    # should recreate the object
    repo.cached

    f = vfsmod.vfs(b'.')(b'y', b'w', atomictemp=True)
    f.write(b'B')
    f.close()

    repo.invalidate()
    print("* file y changed inode")
    repo.cached

    f = vfsmod.vfs(b'.')(b'x', b'w', atomictemp=True)
    f.write(b'c')
    f.close()
    f = vfsmod.vfs(b'.')(b'y', b'w', atomictemp=True)
    f.write(b'C')
    f.close()

    repo.invalidate()
    print("* both files changed inode")
    repo.cached


def fakeuncacheable():
    def wrapcacheable(orig, *args, **kwargs):
        return False

    def wrapinit(orig, *args, **kwargs):
        pass

    originit = extensions.wrapfunction(util.cachestat, '__init__', wrapinit)
    origcacheable = extensions.wrapfunction(
        util.cachestat, 'cacheable', wrapcacheable
    )

    for fn in ['x', 'y']:
        try:
            os.remove(fn)
        except OSError:
            pass

    basic(fakerepo())

    util.cachestat.cacheable = origcacheable
    util.cachestat.__init__ = originit


def test_filecache_synced():
    # test old behavior that caused filecached properties to go out of sync
    os.system('hg init && echo a >> a && hg ci -qAm.')
    repo = hg.repository(uimod.ui.load())
    # first rollback clears the filecache, but changelog to stays in __dict__
    repo.rollback()
    repo.commit(b'.')
    # second rollback comes along and touches the changelog externally
    # (file is moved)
    repo.rollback()
    # but since changelog isn't under the filecache control anymore, we don't
    # see that it changed, and return the old changelog without reconstructing
    # it
    repo.commit(b'.')


def setbeforeget(repo):
    os.remove('x')
    os.remove('y')
    repo.__class__.cached.set(repo, 'string set externally')
    repo.invalidate()
    print("* neither file exists")
    print(repo.cached)
    repo.invalidate()
    f = open('x', 'w')
    f.write('a')
    f.close()
    print("* file x created")
    print(repo.cached)

    repo.__class__.cached.set(repo, 'string 2 set externally')
    repo.invalidate()
    print("* string set externally again")
    print(repo.cached)

    repo.invalidate()
    f = open('y', 'w')
    f.write('b')
    f.close()
    print("* file y created")
    print(repo.cached)


def antiambiguity():
    filename = 'ambigcheck'

    # try some times, because reproduction of ambiguity depends on
    # "filesystem time"
    for i in xrange(5):
        fp = open(filename, 'w')
        fp.write('FOO')
        fp.close()

        oldstat = os.stat(filename)
        if oldstat[stat.ST_CTIME] != oldstat[stat.ST_MTIME]:
            # subsequent changing never causes ambiguity
            continue

        repetition = 3

        # repeat changing via checkambigatclosing, to examine whether
        # st_mtime is advanced multiple times as expected
        for i in xrange(repetition):
            # explicit closing
            fp = vfsmod.checkambigatclosing(open(filename, 'a'))
            fp.write('FOO')
            fp.close()

            # implicit closing by "with" statement
            with vfsmod.checkambigatclosing(open(filename, 'a')) as fp:
                fp.write('BAR')

        newstat = os.stat(filename)
        if oldstat[stat.ST_CTIME] != newstat[stat.ST_CTIME]:
            # timestamp ambiguity was naturally avoided while repetition
            continue

        # st_mtime should be advanced "repetition * 2" times, because
        # all changes occurred at same time (in sec)
        expected = (oldstat[stat.ST_MTIME] + repetition * 2) & 0x7FFFFFFF
        if newstat[stat.ST_MTIME] != expected:
            print(
                "'newstat[stat.ST_MTIME] %s is not %s (as %s + %s * 2)"
                % (
                    newstat[stat.ST_MTIME],
                    expected,
                    oldstat[stat.ST_MTIME],
                    repetition,
                )
            )

        # no more examination is needed regardless of result
        break
    else:
        # This platform seems too slow to examine anti-ambiguity
        # of file timestamp (or test happened to be executed at
        # bad timing). Exit silently in this case, because running
        # on other faster platforms can detect problems
        pass


print('basic:')
print()
basic(fakerepo())
print()
print('fakeuncacheable:')
print()
fakeuncacheable()
test_filecache_synced()
print()
print('setbeforeget:')
print()
setbeforeget(fakerepo())
print()
print('antiambiguity:')
print()
antiambiguity()