Mercurial > hg
view tests/test-newbranch.t @ 46149:294d5aca4ff5
copies: iterate over children directly (instead of parents)
Before this change we would gather all parent → child edges and iterate on
all parent, gathering copy information for children and aggregating them from
there.
They are not strict requirement for edges to be processed in that specific
order. We could also simply iterate over all "children" revision and aggregate
data from both parents at the same time. This patch does that.
It make various things simpler:
* since both parents are processed at the same time, we no longer need to
cache data for merge (see next changeset for details),
* we no longer need nested loop to process data,
* we no longer need to store partial merge data for a rev from distinct loop
interaction to another when processing merges,
* we no longer need to build a full parent -> children mapping (we only rely on
a simpler "parent -> number of children" map (for memory efficiency),
* the data access pattern is now simpler (from lower revisions to higher
revisions) and entirely predicable. That predictability open the way to
prefetching and parallel processing.
So that new iterations order requires simpler code and open the way to
interesting optimisation.
The effect on performance is quite good. In the worse case, we don't see any
significant negative impact. And in the best case, the reduction of roundtrip
to Python provide us with a significant speed. Some example below:
Repo Case Source-Rev Dest-Rev # of revisions old time new time Difference Factor time per rev
---------------------------------------------------------------------------------------------------------------------------------------------------------------
mozilla-try x00000_revs_x00000_added_0_copies dc8a3ca7010e d16fde900c9c : 34414 revs, 0.962867 s, 0.502584 s, -0.460283 s, × 0.5220, 14 µs/rev
mozilla-try x0000_revs_xx000_added_x_copies 156f6e2674f2 4d0f2c178e66 : 8598 revs, 0.110717 s, 0.076323 s, -0.034394 s, × 0.6894, 8 µs/rev
# full comparison between the previous changeset and this one
Repo Case Source-Rev Dest-Rev # of revisions old time new time Difference Factor time per rev
---------------------------------------------------------------------------------------------------------------------------------------------------------------
mercurial x_revs_x_added_0_copies ad6b123de1c7 39cfcef4f463 : 1 revs, 0.000048 s, 0.000041 s, -0.000007 s, × 0.8542, 41 µs/rev
mercurial x_revs_x_added_x_copies 2b1c78674230 0c1d10351869 : 6 revs, 0.000153 s, 0.000102 s, -0.000051 s, × 0.6667, 17 µs/rev
mercurial x000_revs_x000_added_x_copies 81f8ff2a9bf2 dd3267698d84 : 1032 revs, 0.004209 s, 0.004254 s, +0.000045 s, × 1.0107, 4 µs/rev
pypy x_revs_x_added_0_copies aed021ee8ae8 099ed31b181b : 9 revs, 0.000203 s, 0.000282 s, +0.000079 s, × 1.3892, 31 µs/rev
pypy x_revs_x000_added_0_copies 4aa4e1f8e19a 359343b9ac0e : 1 revs, 0.000059 s, 0.000048 s, -0.000011 s, × 0.8136, 48 µs/rev
pypy x_revs_x_added_x_copies ac52eb7bbbb0 72e022663155 : 7 revs, 0.000194 s, 0.000211 s, +0.000017 s, × 1.0876, 30 µs/rev
pypy x_revs_x00_added_x_copies c3b14617fbd7 ace7255d9a26 : 1 revs, 0.000380 s, 0.000375 s, -0.000005 s, × 0.9868, 375 µs/rev
pypy x_revs_x000_added_x000_copies df6f7a526b60 a83dc6a2d56f : 6 revs, 0.010588 s, 0.010574 s, -0.000014 s, × 0.9987, 1762 µs/rev
pypy x000_revs_xx00_added_0_copies 89a76aede314 2f22446ff07e : 4785 revs, 0.048961 s, 0.049974 s, +0.001013 s, × 1.0207, 10 µs/rev
pypy x000_revs_x000_added_x_copies 8a3b5bfd266e 2c68e87c3efe : 6780 revs, 0.083612 s, 0.084300 s, +0.000688 s, × 1.0082, 12 µs/rev
pypy x000_revs_x000_added_x000_copies 89a76aede314 7b3dda341c84 : 5441 revs, 0.058579 s, 0.060128 s, +0.001549 s, × 1.0264, 11 µs/rev
pypy x0000_revs_x_added_0_copies d1defd0dc478 c9cb1334cc78 : 43645 revs, 0.736783 s, 0.686542 s, -0.050241 s, × 0.9318, 15 µs/rev
pypy x0000_revs_xx000_added_0_copies bf2c629d0071 4ffed77c095c : 2 revs, 0.022050 s, 0.009277 s, -0.012773 s, × 0.4207, 4638 µs/rev
pypy x0000_revs_xx000_added_x000_copies 08ea3258278e d9fa043f30c0 : 11316 revs, 0.120800 s, 0.114733 s, -0.006067 s, × 0.9498, 10 µs/rev
netbeans x_revs_x_added_0_copies fb0955ffcbcd a01e9239f9e7 : 2 revs, 0.000140 s, 0.000081 s, -0.000059 s, × 0.5786, 40 µs/rev
netbeans x_revs_x000_added_0_copies 6f360122949f 20eb231cc7d0 : 2 revs, 0.000114 s, 0.000107 s, -0.000007 s, × 0.9386, 53 µs/rev
netbeans x_revs_x_added_x_copies 1ada3faf6fb6 5a39d12eecf4 : 3 revs, 0.000224 s, 0.000173 s, -0.000051 s, × 0.7723, 57 µs/rev
netbeans x_revs_x00_added_x_copies 35be93ba1e2c 9eec5e90c05f : 9 revs, 0.000723 s, 0.000698 s, -0.000025 s, × 0.9654, 77 µs/rev
netbeans x000_revs_xx00_added_0_copies eac3045b4fdd 51d4ae7f1290 : 1421 revs, 0.009665 s, 0.009248 s, -0.000417 s, × 0.9569, 6 µs/rev
netbeans x000_revs_x000_added_x_copies e2063d266acd 6081d72689dc : 1533 revs, 0.014820 s, 0.015446 s, +0.000626 s, × 1.0422, 10 µs/rev
netbeans x000_revs_x000_added_x000_copies ff453e9fee32 411350406ec2 : 5750 revs, 0.076049 s, 0.074373 s, -0.001676 s, × 0.9780, 12 µs/rev
netbeans x0000_revs_xx000_added_x000_copies 588c2d1ced70 1aad62e59ddd : 66949 revs, 0.683603 s, 0.639870 s, -0.043733 s, × 0.9360, 9 µs/rev
mozilla-central x_revs_x_added_0_copies 3697f962bb7b 7015fcdd43a2 : 2 revs, 0.000161 s, 0.000088 s, -0.000073 s, × 0.5466, 44 µs/rev
mozilla-central x_revs_x000_added_0_copies dd390860c6c9 40d0c5bed75d : 8 revs, 0.000234 s, 0.000199 s, -0.000035 s, × 0.8504, 24 µs/rev
mozilla-central x_revs_x_added_x_copies 8d198483ae3b 14207ffc2b2f : 9 revs, 0.000247 s, 0.000171 s, -0.000076 s, × 0.6923, 19 µs/rev
mozilla-central x_revs_x00_added_x_copies 98cbc58cc6bc 446a150332c3 : 7 revs, 0.000630 s, 0.000592 s, -0.000038 s, × 0.9397, 84 µs/rev
mozilla-central x_revs_x000_added_x000_copies 3c684b4b8f68 0a5e72d1b479 : 3 revs, 0.003286 s, 0.003151 s, -0.000135 s, × 0.9589, 1050 µs/rev
mozilla-central x_revs_x0000_added_x0000_copies effb563bb7e5 c07a39dc4e80 : 6 revs, 0.062441 s, 0.061612 s, -0.000829 s, × 0.9867, 10268 µs/rev
mozilla-central x000_revs_xx00_added_0_copies 6100d773079a 04a55431795e : 1593 revs, 0.005423 s, 0.005381 s, -0.000042 s, × 0.9923, 3 µs/rev
mozilla-central x000_revs_x000_added_x_copies 9f17a6fc04f9 2d37b966abed : 41 revs, 0.005919 s, 0.003742 s, -0.002177 s, × 0.6322, 91 µs/rev
mozilla-central x000_revs_x000_added_x000_copies 7c97034feb78 4407bd0c6330 : 7839 revs, 0.062597 s, 0.061983 s, -0.000614 s, × 0.9902, 7 µs/rev
mozilla-central x0000_revs_xx000_added_0_copies 9eec5917337d 67118cc6dcad : 615 revs, 0.043551 s, 0.019861 s, -0.023690 s, × 0.4560, 32 µs/rev
mozilla-central x0000_revs_xx000_added_x000_copies f78c615a656c 96a38b690156 : 30263 revs, 0.192475 s, 0.188101 s, -0.004374 s, × 0.9773, 6 µs/rev
mozilla-central x00000_revs_x0000_added_x0000_copies 6832ae71433c 4c222a1d9a00 : 153721 revs, 1.955575 s, 1.806696 s, -0.148879 s, × 0.9239, 11 µs/rev
mozilla-central x00000_revs_x00000_added_x000_copies 76caed42cf7c 1daa622bbe42 : 204976 revs, 2.886501 s, 2.682987 s, -0.203514 s, × 0.9295, 13 µs/rev
mozilla-try x_revs_x_added_0_copies aaf6dde0deb8 9790f499805a : 2 revs, 0.001181 s, 0.000852 s, -0.000329 s, × 0.7214, 426 µs/rev
mozilla-try x_revs_x000_added_0_copies d8d0222927b4 5bb8ce8c7450 : 2 revs, 0.001189 s, 0.000859 s, -0.000330 s, × 0.7225, 429 µs/rev
mozilla-try x_revs_x_added_x_copies 092fcca11bdb 936255a0384a : 4 revs, 0.000563 s, 0.000150 s, -0.000413 s, × 0.2664, 37 µs/rev
mozilla-try x_revs_x00_added_x_copies b53d2fadbdb5 017afae788ec : 2 revs, 0.001548 s, 0.001158 s, -0.000390 s, × 0.7481, 579 µs/rev
mozilla-try x_revs_x000_added_x000_copies 20408ad61ce5 6f0ee96e21ad : 1 revs, 0.027782 s, 0.027240 s, -0.000542 s, × 0.9805, 27240 µs/rev
mozilla-try x_revs_x0000_added_x0000_copies effb563bb7e5 c07a39dc4e80 : 6 revs, 0.062781 s, 0.062824 s, +0.000043 s, × 1.0007, 10470 µs/rev
mozilla-try x000_revs_xx00_added_0_copies 6100d773079a 04a55431795e : 1593 revs, 0.005778 s, 0.005463 s, -0.000315 s, × 0.9455, 3 µs/rev
mozilla-try x000_revs_x000_added_x_copies 9f17a6fc04f9 2d37b966abed : 41 revs, 0.006192 s, 0.004238 s, -0.001954 s, × 0.6844, 103 µs/rev
mozilla-try x000_revs_x000_added_x000_copies 1346fd0130e4 4c65cbdabc1f : 6657 revs, 0.065391 s, 0.064113 s, -0.001278 s, × 0.9805, 9 µs/rev
mozilla-try x0000_revs_x_added_0_copies 63519bfd42ee a36a2a865d92 : 40314 revs, 0.317216 s, 0.294063 s, -0.023153 s, × 0.9270, 7 µs/rev
mozilla-try x0000_revs_x_added_x_copies 9fe69ff0762d bcabf2a78927 : 38690 revs, 0.303119 s, 0.281493 s, -0.021626 s, × 0.9287, 7 µs/rev
mozilla-try x0000_revs_xx000_added_x_copies 156f6e2674f2 4d0f2c178e66 : 8598 revs, 0.110717 s, 0.076323 s, -0.034394 s, × 0.6894, 8 µs/rev
mozilla-try x0000_revs_xx000_added_0_copies 9eec5917337d 67118cc6dcad : 615 revs, 0.045739 s, 0.020390 s, -0.025349 s, × 0.4458, 33 µs/rev
mozilla-try x0000_revs_xx000_added_x000_copies 89294cd501d9 7ccb2fc7ccb5 : 97052 revs, 3.098021 s, 3.023879 s, -0.074142 s, × 0.9761, 31 µs/rev
mozilla-try x0000_revs_x0000_added_x0000_copies e928c65095ed e951f4ad123a : 52031 revs, 0.771480 s, 0.735549 s, -0.035931 s, × 0.9534, 14 µs/rev
mozilla-try x00000_revs_x_added_0_copies 6a320851d377 1ebb79acd503 : 363753 revs, 18.813422 s, 18.568900 s, -0.244522 s, × 0.9870, 51 µs/rev
mozilla-try x00000_revs_x00000_added_0_copies dc8a3ca7010e d16fde900c9c : 34414 revs, 0.962867 s, 0.502584 s, -0.460283 s, × 0.5220, 14 µs/rev
mozilla-try x00000_revs_x_added_x_copies 5173c4b6f97c 95d83ee7242d : 362229 revs, 18.684923 s, 18.356645 s, -0.328278 s, × 0.9824, 50 µs/rev
mozilla-try x00000_revs_x000_added_x_copies 9126823d0e9c ca82787bb23c : 359344 revs, 18.296305 s, 18.250393 s, -0.045912 s, × 0.9975, 50 µs/rev
mozilla-try x00000_revs_x0000_added_x0000_copies 8d3fafa80d4b eb884023b810 : 192665 revs, 3.061887 s, 2.792459 s, -0.269428 s, × 0.9120, 14 µs/rev
mozilla-try x00000_revs_x00000_added_x0000_copies 1b661134e2ca 1ae03d022d6d : 228985 revs, 103.869641 s, 107.697264 s, +3.827623 s, × 1.0369, 470 µs/rev
mozilla-try x00000_revs_x00000_added_x000_copies 9b2a99adc05e 8e29777b48e6 : 382065 revs, 64.262957 s, 63.961040 s, -0.301917 s, × 0.9953, 167 µs/rev
Differential Revision: https://phab.mercurial-scm.org/D9422
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Mon, 14 Dec 2020 11:32:24 +0100 |
parents | 8d72e29ad1e0 |
children |
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$ branchcache=.hg/cache/branch2 $ listbranchcaches() { > for f in .hg/cache/branch2*; > do echo === $f ===; > cat $f; > done; > } $ purgebranchcaches() { > rm .hg/cache/branch2* > } $ hg init t $ cd t $ hg branches $ echo foo > a $ hg add a $ hg ci -m "initial" $ hg branch foo marked working directory as branch foo (branches are permanent and global, did you want a bookmark?) $ hg branch foo $ hg ci -m "add branch name" $ hg branch bar marked working directory as branch bar $ hg ci -m "change branch name" Branch shadowing: $ hg branch default abort: a branch of the same name already exists (use 'hg update' to switch to it) [10] $ hg branch -f default marked working directory as branch default $ hg ci -m "clear branch name" created new head There should be only one default branch head $ hg heads . changeset: 3:1c28f494dae6 tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: clear branch name Merging and branches $ hg co foo 0 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg branch foo set existing branch name fails unless force - setting existing parent branch works without force: $ hg branch bar abort: a branch of the same name already exists (use 'hg update' to switch to it) [10] $ hg branch -f bar marked working directory as branch bar $ hg branch foo marked working directory as branch foo $ echo bleah > a $ hg ci -m "modify a branch" $ hg merge default 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg branch foo set existing branch name where branch head is ancestor: $ hg branch bar abort: a branch of the same name already exists (use 'hg update' to switch to it) [10] set (other) parent branch as branch name $ hg branch default marked working directory as branch default set (first) parent branch as branch name $ hg branch foo marked working directory as branch foo $ hg ci -m "merge" $ hg log -G -T '{rev}:{node|short} {branch} {desc}\n' @ 5:530046499edf foo merge |\ | o 4:adf1a74a7f7b foo modify a branch | | o | 3:1c28f494dae6 default clear branch name | | o | 2:c21617b13b22 bar change branch name |/ o 1:6c0e42da283a foo add branch name | o 0:db01e8ea3388 default initial $ hg branches foo 5:530046499edf default 3:1c28f494dae6 (inactive) bar 2:c21617b13b22 (inactive) $ hg branches -q foo default bar Test for invalid branch cache: $ hg rollback repository tip rolled back to revision 4 (undo commit) working directory now based on revisions 4 and 3 $ cp ${branchcache}-served .hg/bc-invalid $ hg log -r foo changeset: 4:adf1a74a7f7b branch: foo tag: tip parent: 1:6c0e42da283a user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: modify a branch $ cp .hg/bc-invalid $branchcache $ hg --debug log -r foo changeset: 4:adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 branch: foo tag: tip phase: draft parent: 1:6c0e42da283a56b5edc5b4fadb491365ec7f5fa8 parent: -1:0000000000000000000000000000000000000000 manifest: 1:8c342a37dfba0b3d3ce073562a00d8a813c54ffe user: test date: Thu Jan 01 00:00:00 1970 +0000 files: a extra: branch=foo description: modify a branch $ purgebranchcaches $ echo corrupted > $branchcache $ hg log -qr foo 4:adf1a74a7f7b $ listbranchcaches === .hg/cache/branch2 === corrupted === .hg/cache/branch2-served === adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 4 c21617b13b220988e7a2e26290fbe4325ffa7139 o bar 1c28f494dae69a2f8fc815059d257eccf3fcfe75 o default adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 o foo Push should update the branch cache: $ hg init ../target Pushing just rev 0: $ hg push -qr 0 ../target $ (cd ../target/; listbranchcaches) === .hg/cache/branch2-base === db01e8ea3388fd3c7c94e1436ea2bd6a53d581c5 0 db01e8ea3388fd3c7c94e1436ea2bd6a53d581c5 o default Pushing everything: $ hg push -qf ../target $ (cd ../target/; listbranchcaches) === .hg/cache/branch2-base === adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 4 c21617b13b220988e7a2e26290fbe4325ffa7139 o bar 1c28f494dae69a2f8fc815059d257eccf3fcfe75 o default adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 o foo Update with no arguments: tipmost revision of the current branch: $ hg up -q -C 0 $ hg up -q $ hg id 1c28f494dae6 $ hg up -q 1 $ hg up -q $ hg id adf1a74a7f7b (foo) tip $ hg branch foobar marked working directory as branch foobar $ hg up 0 files updated, 0 files merged, 0 files removed, 0 files unresolved Fast-forward merge: $ hg branch ff marked working directory as branch ff $ echo ff > ff $ hg ci -Am'fast forward' adding ff $ hg up foo 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg merge ff 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg branch foo $ hg commit -m'Merge ff into foo' $ hg parents changeset: 6:185ffbfefa30 branch: foo tag: tip parent: 4:adf1a74a7f7b parent: 5:1a3c27dc5e11 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: Merge ff into foo $ hg manifest a ff Test merging, add 3 default heads and one test head: $ cd .. $ hg init merges $ cd merges $ echo a > a $ hg ci -Ama adding a $ echo b > b $ hg ci -Amb adding b $ hg up 0 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ echo c > c $ hg ci -Amc adding c created new head $ hg up 0 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ echo d > d $ hg ci -Amd adding d created new head $ hg up 0 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg branch test marked working directory as branch test (branches are permanent and global, did you want a bookmark?) $ echo e >> e $ hg ci -Ame adding e $ hg log changeset: 4:3a1e01ed1df4 branch: test tag: tip parent: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: e changeset: 3:980f7dc84c29 parent: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: d changeset: 2:d36c0562f908 parent: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: c changeset: 1:d2ae7f538514 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: b changeset: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: a Implicit merge with test branch as parent: $ hg merge abort: branch 'test' has one head - please merge with an explicit rev (run 'hg heads' to see all heads, specify rev with -r) [255] $ hg up -C default 1 files updated, 0 files merged, 1 files removed, 0 files unresolved Implicit merge with default branch as parent: $ hg merge abort: branch 'default' has 3 heads - please merge with an explicit rev (run 'hg heads .' to see heads, specify rev with -r) [255] 3 branch heads, explicit merge required: $ hg merge 2 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -m merge 2 branch heads, implicit merge works: $ hg merge 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cd .. We expect that bare update on new branch, updates to parent $ hg init bareupdateonnewbranch $ cd bareupdateonnewbranch $ hg update 0 files updated, 0 files merged, 0 files removed, 0 files unresolved $ touch a $ hg commit -A -m "a" adding a $ touch b $ hg commit -A -m "b" adding b $ touch c $ hg commit -A -m "c" adding c $ hg update -r 1 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg log -G o changeset: 2:991a3460af53 | tag: tip | user: test | date: Thu Jan 01 00:00:00 1970 +0000 | summary: c | @ changeset: 1:0e067c57feba | user: test | date: Thu Jan 01 00:00:00 1970 +0000 | summary: b | o changeset: 0:3903775176ed user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: a $ hg branch dev marked working directory as branch dev (branches are permanent and global, did you want a bookmark?) $ hg update 0 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg summary parent: 1:0e067c57feba b branch: dev commit: (new branch) update: (current) phases: 3 draft $ cd .. We need special handling for repositories with no "default" branch because "null" revision belongs to non-existent "default" branch. $ hg init nodefault $ cd nodefault $ hg branch -q foo $ touch 0 $ hg ci -Aqm0 $ touch 1 $ hg ci -Aqm1 $ hg update -qr0 $ hg branch -q bar $ touch 2 $ hg ci -Aqm2 $ hg update -qr0 $ hg branch -q baz $ touch 3 $ hg ci -Aqm3 $ hg ci --close-branch -m 'close baz' $ hg update -q null $ hg log -GT'{rev} {branch}\n' _ 4 baz | o 3 baz | | o 2 bar |/ | o 1 foo |/ o 0 foo a) updating from "null" should bring us to the tip-most branch head as there is no "default" branch: $ hg update -q null $ hg id -bn -1 default $ hg update 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg id -bn 2 bar b) but if we are at uncommitted "default" branch, we should stick to the current revision: $ hg update -q 0 $ hg branch default marked working directory as branch default $ hg id -bn 0 default $ hg update 0 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg id -bn 0 default c) also, if we have uncommitted branch at "null", we should stick to it: $ hg update -q null $ hg branch new marked working directory as branch new $ hg id -bn -1 new $ hg update 0 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg id -bn -1 new $ cd .. We expect that update --clean discard changes in working directory, and updates to the head of parent branch. $ hg init updatebareclean $ cd updatebareclean $ hg update --clean 0 files updated, 0 files merged, 0 files removed, 0 files unresolved $ touch a $ hg commit -A -m "a" adding a $ touch b $ hg commit -A -m "b" adding b $ touch c $ hg commit -A -m "c" adding c $ hg log changeset: 2:991a3460af53 tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: c changeset: 1:0e067c57feba user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: b changeset: 0:3903775176ed user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: a $ hg update -r 1 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg branch new-branch marked working directory as branch new-branch (branches are permanent and global, did you want a bookmark?) $ echo "aa" >> a $ hg update --clean 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg status $ hg branch default $ hg parent changeset: 2:991a3460af53 tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: c We expect that update --clean on non existing parent discards a new branch and updates to the tipmost non-closed branch head $ hg update null 0 files updated, 0 files merged, 3 files removed, 0 files unresolved $ hg branch newbranch marked working directory as branch newbranch (branches are permanent and global, did you want a bookmark?) $ hg update -C 3 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg summary parent: 2:991a3460af53 tip c branch: default commit: (clean) update: (current) phases: 3 draft