Mercurial > hg
view tests/test-issue522.t @ 38893:23d582caae30
changegroup: capture revision delta in a data structure
The current changegroup generation code is tightly coupled to
the revlog API. This tight coupling makes it difficult to implement
alternate storage backends without requiring a large surface area
of the revlog API to be exposed. This is not desirable.
In order to support changegroup generation with non-revlog storage,
we'll need to abstract the concept of delta generation.
This commit is the first step down that road. We introduce a
data structure for representing a delta in a changegroup.
The API still leaves a lot to be desired. But at least we now
have separation between data and actions performed on it.
As part of this, we tweak behavior slightly: we no longer
concatenate the delta prefix with the metadata header. Instead,
we track and emit the prefix as a separate chunk. This shouldn't
have any meaningful impact since all the chunks just get sent to
the wire, the compressor, etc.
Because we're introducing a new object, this does add some
overhead to changegroup execution. `hg perfchangegroupchangelog`
on my clone of the Mercurial repo (~40,000 visible revisions in
the changelog) slows down a bit:
! wall 1.268600 comb 1.270000 user 1.270000 sys 0.000000 (best of 8)
! wall 1.419479 comb 1.410000 user 1.410000 sys 0.000000 (best of 8)
With for `hg bundle -t none-v2 -a /dev/null`:
before: real 6.610 secs (user 6.460+0.000 sys 0.140+0.000)
after: real 7.210 secs (user 7.060+0.000 sys 0.140+0.000)
I plan to claw back this regression in future commits. And I may
even do away with this data structure once the refactor is complete.
For now, it makes things easier to comprehend.
Differential Revision: https://phab.mercurial-scm.org/D4075
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 03 Aug 2018 10:05:26 -0700 |
parents | d4e62df1c73d |
children | 91a0bc50b288 |
line wrap: on
line source
https://bz.mercurial-scm.org/522 In the merge below, the file "foo" has the same contents in both parents, but if we look at the file-level history, we'll notice that the version in p1 is an ancestor of the version in p2. This test makes sure that we'll use the version from p2 in the manifest of the merge revision. $ hg init $ echo foo > foo $ hg ci -qAm 'add foo' $ echo bar >> foo $ hg ci -m 'change foo' $ hg backout -r tip -m 'backout changed foo' reverting foo changeset 2:4d9e78aaceee backs out changeset 1:b515023e500e $ hg up -C 0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ touch bar $ hg ci -qAm 'add bar' $ hg merge --debug searching for copies back to rev 1 unmatched files in local: bar resolving manifests branchmerge: True, force: False, partial: False ancestor: bbd179dfa0a7, local: 71766447bdbb+, remote: 4d9e78aaceee foo: remote is newer -> g getting foo 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg debugstate | grep foo m 0 -2 unset foo $ hg st -A foo M foo $ hg ci -m 'merge' $ hg manifest --debug | grep foo c6fc755d7e68f49f880599da29f15add41f42f5a 644 foo $ hg debugindex foo rev linkrev nodeid p1 p2 0 0 2ed2a3912a0b 000000000000 000000000000 1 1 6f4310b00b9a 2ed2a3912a0b 000000000000 2 2 c6fc755d7e68 6f4310b00b9a 000000000000