view tests/test-push-checkheads-unpushed-D7.t @ 38661:8ac0c9cd4c48

fncache: avoid loading the filename cache when not actually modifying it

With time, fncache can become very large. The mozilla-central repo for example,
has a 31M and growing fncache file. Loading this file takes time (280ms for the
mozilla-central repository).

In many scenarios, we don't need to load fncache at all. For example, when
committing changes to existing files, or pushing such commits to another clone.
This patch detects when a name is added via store.vfs(), and only loads the
cache if a) the data metadata file doesn't already exist, or b) when opening
for appending, the data or metadata file exists but has size  (a transaction
rollback leaves behind such files).

Benchmarks (run on Macos 10.13 on a 2017-model Macbook Pro with Core i7 2.9GHz
and flash drive), each test without and with patch run 5 times:

* committing to an existing file, against the mozilla-central repository.
  Baseline real time average 2.3736, with patch 1.9884.

* unbundling a large changeset consisting *only* of existing-file modifications
  (159 revisions, 1050 modifications, mozilla-central
  4a250a0e4f29:beea9ac7d823), into a clone limited to the ancestor revision of
  that revset). Baseline real time average 1.5048, with patch 1.3108.

====================================
Testing head checking code: Case D-7
====================================

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 7: single changesets, superseeded multiple time then pruned (on a new changeset unpushed) changeset

This is a partial push variation of B6

.. old-state:
..
.. * 1 changeset branch
..
.. new-state:
..
.. * old branch is rewritten onto another one,
.. * The rewriting it again rewritten on the root
.. * the new version is then pruned.
..
.. expected-result:
..
.. * push allowed
..
.. graph-summary:
..
..       A'
..   A ø⇠ø⇠⊗ A''
..     | | |
.. C ◔ | ◔ | B
..    \|/ /
..     | /
..     |/
..     |
..     ●

  $ . $TESTDIR/testlib/push-checkheads-util.sh

Test setup
----------

  $ mkdir D7
  $ cd D7
  $ 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 up '0'
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ mkcommit A2
  created new head
  $ hg up '0'
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkcommit C0
  created new head
  $ hg debugobsolete `getid "desc(A0)"` `getid "desc(A1)"`
  obsoleted 1 changesets
  $ hg debugobsolete `getid "desc(A1)"` `getid "desc(A2)"`
  obsoleted 1 changesets
  $ hg debugobsolete --record-parents `getid "desc(A2)"`
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  0f88766e02d6 (draft): C0
  |
  | x  c1f8d089020f (draft): A2
  |/
  | x  ba93660aff8d (draft): A1
  | |
  | o  74ff5441d343 (draft): B0
  |/
  | x  8aaa48160adc (draft): A0
  |/
  o  1e4be0697311 (public): root
  

Actual testing
--------------

  $ hg push --rev 'desc(C0)'
  pushing to $TESTTMP/D7/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  3 new obsolescence markers
  obsoleted 1 changesets

  $ cd ../..