bundle2: extract logic for seeking bundle2 part into own class
Currently, unbundlepart classes support bi-directional seeking.
Most consumers of unbundlepart only ever seek forward - typically
as part of moving to the end of the bundle part so they can move
on to the next one. But regardless of the actual usage of the
part, instances maintain an index mapping offsets within the
underlying raw payload to offsets within the decoded payload.
Maintaining the mapping of offset data can be expensive in terms of
memory use. Furthermore, many bundle2 consumers don't have access
to an underlying seekable stream. This includes all compressed
bundles. So maintaining offset data when the underlying stream
can't be seeked anyway is wasteful. And since many bundle2 streams
can't be seeked, it seems like a bad idea to expose a seek API
in bundle2 parts by default. If you provide them, people will
attempt to use them.
Seekable bundle2 parts should be the exception, not the rule. This
commit starts the process dividing unbundlepart into 2 classes: a
base class that supports linear, one-time reads and a child class
that supports bi-directional seeking. In this first commit, we
split various methods and attributes out into a new
"seekableunbundlepart" class. Previous instantiators of "unbundlepart"
now instantiate "seekableunbundlepart." This preserves backwards
compatibility. The coupling between the classes is still tight:
"unbundlepart" cannot be used on its own. This will be addressed
in subsequent commits.
Differential Revision: https://phab.mercurial-scm.org/D1386
====================================
Testing head checking code: Case D-2
====================================
Mercurial checks for the introduction of new heads on push. Evolution comes
into play to detect if existing branches on the server are being replaced by
some of the new one we push.
This case is part of a series of tests checking this behavior.
Category D: remote head is "obs-affected" locally, but result is not part of the push
TestCase 1: remote branch has 2 changes, head is pruned, other is rewritten but result is not pushed
.. old-state:
..
.. * 1 changeset branch
..
.. new-state:
..
.. * old head is pruned
.. * 1 new branch succeeding to the other changeset in the old branch
.. * 1 new unrelated branch
..
.. expected-result:
..
.. * push allowed
.. * pushing only the unrelated branch: denied
..
.. graph-summary:
..
.. B ⊗
.. |
.. A ø⇠○ A'
.. |/
.. | ◔ C
.. |/
.. ●
$ . $TESTDIR/testlib/push-checkheads-util.sh
Test setup
----------
$ mkdir D2
$ cd D2
$ setuprepos
creating basic server and client repo
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd server
$ mkcommit B0
$ cd ../client
$ hg pull
pulling from $TESTTMP/D2/server (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets d73caddc5533
(run 'hg update' to get a working copy)
$ hg up 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ mkcommit A1
created new head
$ hg debugobsolete `getid "desc(A0)" ` `getid "desc(A1)"`
obsoleted 1 changesets
$ hg debugobsolete --record-parents `getid "desc(B0)"`
obsoleted 1 changesets
$ hg up 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ mkcommit C0
created new head
$ hg log -G --hidden
@ 0f88766e02d6 (draft): C0
|
| o f6082bc4ffef (draft): A1
|/
| x d73caddc5533 (draft): B0
| |
| x 8aaa48160adc (draft): A0
|/
o 1e4be0697311 (public): root
Actual testing
--------------
$ hg push --rev 'desc(C0)'
pushing to $TESTTMP/D2/server (glob)
searching for changes
abort: push creates new remote head 0f88766e02d6!
(merge or see 'hg help push' for details about pushing new heads)
[255]
$ cd ../..