Mercurial > hg
view tests/test-parseindex.t @ 32697:19b9fc40cc51
revlog: skeleton support for version 2 revlogs
There are a number of improvements we want to make to revlogs
that will require a new version - version 2. It is unclear what the
full set of improvements will be or when we'll be done with them.
What I do know is that the process will likely take longer than a
single release, will require input from various stakeholders to
evaluate changes, and will have many contentious debates and
bikeshedding.
It is unrealistic to develop revlog version 2 up front: there
are just too many uncertainties that we won't know until things
are implemented and experiments are run. Some changes will also
be invasive and prone to bit rot, so sitting on dozens of patches
is not practical.
This commit introduces skeleton support for version 2 revlogs in
a way that is flexible and not bound by backwards compatibility
concerns.
An experimental repo requirement for denoting revlog v2 has been
added. The requirement string has a sub-version component to it.
This will allow us to declare multiple requirements in the course
of developing revlog v2. Whenever we change the in-development
revlog v2 format, we can tweak the string, creating a new
requirement and locking out old clients. This will allow us to
make as many backwards incompatible changes and experiments to
revlog v2 as we want. In other words, we can land code and make
meaningful progress towards revlog v2 while still maintaining
extreme format flexibility up until the point we freeze the
format and remove the experimental labels.
To enable the new repo requirement, you must supply an experimental
and undocumented config option. But not just any boolean flag
will do: you need to explicitly use a value that no sane person
should ever type. This is an additional guard against enabling
revlog v2 on an installation it shouldn't be enabled on. The
specific scenario I'm trying to prevent is say a user with a
4.4 client with a frozen format enabling the option but then
downgrading to 4.3 and accidentally creating repos with an
outdated and unsupported repo format. Requiring a "challenge"
string should prevent this.
Because the format is not yet finalized and I don't want to take
any chances, revlog v2's version is currently 0xDEAD. I figure
squatting on a value we're likely never to use as an actual revlog
version to mean "internal testing only" is acceptable. And
"dead" is easily recognized as something meaningful.
There is a bunch of cleanup that is needed before work on revlog
v2 begins in earnest. I plan on doing that work once this patch
is accepted and we're comfortable with the idea of starting down
this path.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 19 May 2017 20:29:11 -0700 |
parents | 6d44de27790c |
children | 75be14993fda |
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revlog.parseindex must be able to parse the index file even if an index entry is split between two 64k blocks. The ideal test would be to create an index file with inline data where 64k < size < 64k + 64 (64k is the size of the read buffer, 64 is the size of an index entry) and with an index entry starting right before the 64k block boundary, and try to read it. We approximate that by reducing the read buffer to 1 byte. $ hg init a $ cd a $ echo abc > foo $ hg add foo $ hg commit -m 'add foo' $ echo >> foo $ hg commit -m 'change foo' $ hg log -r 0: changeset: 0:7c31755bf9b5 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: add foo changeset: 1:26333235a41c tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: change foo $ cat >> test.py << EOF > from mercurial import changelog, vfs > from mercurial.node import * > > class singlebyteread(object): > def __init__(self, real): > self.real = real > > def read(self, size=-1): > if size == 65536: > size = 1 > return self.real.read(size) > > def __getattr__(self, key): > return getattr(self.real, key) > > def opener(*args): > o = vfs.vfs(*args) > def wrapper(*a): > f = o(*a) > return singlebyteread(f) > return wrapper > > cl = changelog.changelog(opener('.hg/store')) > print len(cl), 'revisions:' > for r in cl: > print short(cl.node(r)) > EOF $ python test.py 2 revisions: 7c31755bf9b5 26333235a41c $ cd .. #if no-pure Test SEGV caused by bad revision passed to reachableroots() (issue4775): $ cd a $ python <<EOF > from mercurial import changelog, vfs > cl = changelog.changelog(vfs.vfs('.hg/store')) > print 'good heads:' > for head in [0, len(cl) - 1, -1]: > print'%s: %r' % (head, cl.reachableroots(0, [head], [0])) > print 'bad heads:' > for head in [len(cl), 10000, -2, -10000, None]: > print '%s:' % head, > try: > cl.reachableroots(0, [head], [0]) > print 'uncaught buffer overflow?' > except (IndexError, TypeError) as inst: > print inst > print 'good roots:' > for root in [0, len(cl) - 1, -1]: > print '%s: %r' % (root, cl.reachableroots(root, [len(cl) - 1], [root])) > print 'out-of-range roots are ignored:' > for root in [len(cl), 10000, -2, -10000]: > print '%s: %r' % (root, cl.reachableroots(root, [len(cl) - 1], [root])) > print 'bad roots:' > for root in [None]: > print '%s:' % root, > try: > cl.reachableroots(root, [len(cl) - 1], [root]) > print 'uncaught error?' > except TypeError as inst: > print inst > EOF good heads: 0: [0] 1: [0] -1: [] bad heads: 2: head out of range 10000: head out of range -2: head out of range -10000: head out of range None: an integer is required good roots: 0: [0] 1: [1] -1: [-1] out-of-range roots are ignored: 2: [] 10000: [] -2: [] -10000: [] bad roots: None: an integer is required $ cd .. Test corrupted p1/p2 fields that could cause SEGV at parsers.c: $ mkdir invalidparent $ cd invalidparent $ hg clone --pull -q --config phases.publish=False ../a limit $ hg clone --pull -q --config phases.publish=False ../a segv $ rm -R limit/.hg/cache segv/.hg/cache $ python <<EOF > data = open("limit/.hg/store/00changelog.i", "rb").read() > for n, p in [('limit', '\0\0\0\x02'), ('segv', '\0\x01\0\0')]: > # corrupt p1 at rev0 and p2 at rev1 > d = data[:24] + p + data[28:127 + 28] + p + data[127 + 32:] > open(n + "/.hg/store/00changelog.i", "wb").write(d) > EOF $ hg debugindex -f1 limit/.hg/store/00changelog.i rev flag offset length size base link p1 p2 nodeid 0 0000 0 63 62 0 0 2 -1 7c31755bf9b5 1 0000 63 66 65 1 1 0 2 26333235a41c $ hg debugindex -f1 segv/.hg/store/00changelog.i rev flag offset length size base link p1 p2 nodeid 0 0000 0 63 62 0 0 65536 -1 7c31755bf9b5 1 0000 63 66 65 1 1 0 65536 26333235a41c $ cat <<EOF > test.py > import sys > from mercurial import changelog, vfs > cl = changelog.changelog(vfs.vfs(sys.argv[1])) > n0, n1 = cl.node(0), cl.node(1) > ops = [ > ('reachableroots', > lambda: cl.index.reachableroots2(0, [1], [0], False)), > ('compute_phases_map_sets', lambda: cl.computephases([[0], []])), > ('index_headrevs', lambda: cl.headrevs()), > ('find_gca_candidates', lambda: cl.commonancestorsheads(n0, n1)), > ('find_deepest', lambda: cl.ancestor(n0, n1)), > ] > for l, f in ops: > print l + ':', > try: > f() > print 'uncaught buffer overflow?' > except ValueError, inst: > print inst > EOF $ python test.py limit/.hg/store reachableroots: parent out of range compute_phases_map_sets: parent out of range index_headrevs: parent out of range find_gca_candidates: parent out of range find_deepest: parent out of range $ python test.py segv/.hg/store reachableroots: parent out of range compute_phases_map_sets: parent out of range index_headrevs: parent out of range find_gca_candidates: parent out of range find_deepest: parent out of range $ cd .. #endif