revset: optimize "draft() & ::x" pattern
The `draft() & ::x` type query could be common for selecting one or more
draft feature branches being worked on.
Before this patch, `::x` may travel through the changelog DAG for a long
distance until it gets a smaller revision number than `min(draft())`. It
could be very slow on long changelog with distant (in terms of revision
numbers) drafts.
This patch adds a fast path for this situation, and will stop traveling the
changelog DAG once `::x` hits a non-draft revision.
The fast path also works for `secret()` and `not public()`.
To measure the performance difference, I used drawdag to create a repo that
emulates distant drafts:
DRAFT4
|
DRAFT3 # draft
/
PUBLIC9999 # public
|
PUBLIC9998
|
. DRAFT2
. |
. DRAFT1 # draft
| /
PUBLIC0001 # public
And measured the performance using the repo:
(BEFORE)
$ hg perfrevset 'draft() & ::(DRAFT2+DRAFT4)'
! wall 0.017132 comb 0.010000 user 0.010000 sys 0.000000 (best of 156)
$ hg perfrevset 'draft() & ::(all())'
! wall 0.024221 comb 0.030000 user 0.030000 sys 0.000000 (best of 113)
(AFTER)
$ hg perfrevset 'draft() & ::(DRAFT2+DRAFT4)'
! wall 0.000243 comb 0.000000 user 0.000000 sys 0.000000 (best of 9303)
$ hg perfrevset 'draft() & ::(all())'
! wall 0.004319 comb 0.000000 user 0.000000 sys 0.000000 (best of 655)
Differential Revision: https://phab.mercurial-scm.org/D441
$ hg init empty-repo
$ cd empty-repo
Flags on revlog version 0 are rejected
>>> with open('.hg/store/00changelog.i', 'wb') as fh:
... fh.write('\x00\x01\x00\x00')
$ hg log
abort: unknown flags (0x01) in version 0 revlog 00changelog.i!
[255]
Unknown flags on revlog version 1 are rejected
>>> with open('.hg/store/00changelog.i', 'wb') as fh:
... fh.write('\x00\x04\x00\x01')
$ hg log
abort: unknown flags (0x04) in version 1 revlog 00changelog.i!
[255]
Unknown version is rejected
>>> with open('.hg/store/00changelog.i', 'wb') as fh:
... fh.write('\x00\x00\x00\x02')
$ hg log
abort: unknown version (2) in revlog 00changelog.i!
[255]
$ cd ..
Test for CVE-2016-3630
$ hg init
>>> open("a.i", "w").write(
... """eJxjYGZgZIAAYQYGxhgom+k/FMx8YKx9ZUaKSOyqo4cnuKb8mbqHV5cBCVTMWb1Cwqkhe4Gsg9AD
... Joa3dYtcYYYBAQ8Qr4OqZAYRICPTSr5WKd/42rV36d+8/VmrNpv7NP1jQAXrQE4BqQUARngwVA=="""
... .decode("base64").decode("zlib"))
$ hg debugindex a.i
rev offset length delta linkrev nodeid p1 p2
0 0 19 -1 2 99e0332bd498 000000000000 000000000000
1 19 12 0 3 6674f57a23d8 99e0332bd498 000000000000
$ hg debugdata a.i 1 2>&1 | egrep 'Error:.*decoded'
(mercurial\.\w+\.mpatch\.)?mpatchError: patch cannot be decoded (re)