view tests/test-context.py.out @ 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.

workingfilectx.date = (1000, 0)
ASCII   : Gr?ezi!
Latin-1 : Grüezi!
UTF-8   : Grüezi!
<status modified=['foo'], added=[], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
diff --git a/foo b/foo
--- a/foo
+++ b/foo
@@ -1,1 +1,2 @@
 foo
+bar
= checking context.status():
== checking workingctx.status:
wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "pattern match":
<status modified=['bar-m'], added=[], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-m'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "always match" and "listclean=True":
<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=['foo']>
wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-a', 'bar-m'], removed=[], deleted=[], unknown=[], ignored=[], clean=['foo']>
wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>
== checking workingcommitctx.status:
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "always match":
<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-a', 'bar-m', 'bar-r'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "always match" and "listclean=True":
<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=['bar-r', 'foo']>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-a', 'bar-m', 'bar-r'], removed=[], deleted=[], unknown=[], ignored=[], clean=['foo']>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "pattern match":
<status modified=['bar-m'], added=[], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-m'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "pattern match" and "listclean=True":
<status modified=[], added=[], removed=[], deleted=[], unknown=[], ignored=[], clean=['bar-r', 'foo']>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-r'], removed=[], deleted=[], unknown=[], ignored=[], clean=['foo']>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
== commit with manifestlog invalidated
commit 1: 2efe531a913fa648867ab8824360371679d05a65
commit 2: 2caca91f6362020334384ebe27bae67315298abf
commit 3: abd6b0f49f338be22b094ef2b7425e8048f8337b