cborutil: change buffering strategy
Profiling revealed that we were spending a lot of time on the
line that was concatenating the old buffer with the incoming data
when attempting to decode long byte strings, such as manifest
revisions.
Essentially, we were feeding N chunks of size len(X) << len(Y) into
decode() and continuously allocating a new, larger buffer to hold
the undecoded input. This created substantial memory churn and
slowed down execution.
Changing the code to aggregate pending chunks in a list until we
have enough data to fully decode the next atom makes things much
more efficient.
I don't have exact data, but I recall the old code spending >1s
on manifest fulltexts from the mozilla-unified repo. The new code
doesn't significantly appear in profile output.
Differential Revision: https://phab.mercurial-scm.org/D4854
====================================
Testing head checking code: Case A-5
====================================
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 A: simple case involving a branch being superceeded by another.
TestCase 5: New changeset as parent of the successor
.. old-state:
..
.. * 1-changeset branch
..
.. new-state:
..
.. * 2rchangeset branch, head is a successor, but other is new
..
.. expected-result:
..
.. * push allowed
..
.. graph-summary:
..
.. A ø⇠◔ A'
.. | |
.. | ◔ B
.. |/
.. ●
$ . $TESTDIR/testlib/push-checkheads-util.sh
Test setup
----------
$ mkdir A5
$ cd A5
$ setuprepos
creating basic server and client repo
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd client
$ hg up 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ mkcommit B0
created new head
$ mkcommit A1
$ hg debugobsolete `getid "desc(A0)" ` `getid "desc(A1)"`
obsoleted 1 changesets
$ hg log -G --hidden
@ ba93660aff8d (draft): A1
|
o 74ff5441d343 (draft): B0
|
| x 8aaa48160adc (draft): A0
|/
o 1e4be0697311 (public): root
Actual testing
--------------
$ hg push
pushing to $TESTTMP/A5/server
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files (+1 heads)
1 new obsolescence markers
obsoleted 1 changesets
$ cd ../..