view tests/test-revlog-mmapindex.t @ 42486:35d674a3d5db

copies: don't filter out copy targets created on other side of merge commit

If file X is copied to Y on one side of merge and the other side
creates Y (no copy), we would not mark that as copy. In the
changeset-centric pathcopies() version, that was done by checking if
the copy target existed on the other branch. Even though merge commits
are pretty uncommon, it still turned out to be too expensive to load
the manifest of the parents of merge commits. In a repo of
mozilla-unified converted to storing copies in changesets, about 2m30s
of `hg debugpathcopies FIREFOX_BETA_59_END FIREFOX_BETA_60_BASE` is
spent on this check of merge commits.

I tried to think of a way of storing more information in the
changesets in order to cheaply detect these cases, but I couldn't
think of a solution. So this patch simply removes those checks.

For reference, these extra copies are reported from the aforementioned
command after this patch:

  browser/base/content/sanitize.js -> browser/modules/Sanitizer.jsm
  testing/mozbase/mozprocess/tests/process_normal_finish_python.ini -> testing/mozbase/mozprocess/tests/process_normal_finish.ini
  testing/mozbase/mozprocess/tests/process_waittimeout_python.ini -> testing/mozbase/mozprocess/tests/process_waittimeout.ini
  testing/mozbase/mozprocess/tests/process_waittimeout_10s_python.ini -> testing/mozbase/mozprocess/tests/process_waittimeout_10s.ini

Since these copies were created on one side of some merge, it still
seems reasonable to include them, so I'm not even sure it's worse than
filelog pathcopies(), just different.

Differential Revision: https://phab.mercurial-scm.org/D6420

create verbosemmap.py
  $ cat << EOF > verbosemmap.py
  > # extension to make util.mmapread verbose
  > 
  > from __future__ import absolute_import
  > 
  > from mercurial import (
  >     extensions,
  >     pycompat,
  >     util,
  > )
  > 
  > def extsetup(ui):
  >     def mmapread(orig, fp):
  >         ui.write(b"mmapping %s\n" % pycompat.bytestr(fp.name))
  >         ui.flush()
  >         return orig(fp)
  > 
  >     extensions.wrapfunction(util, 'mmapread', mmapread)
  > EOF

setting up base repo
  $ hg init a
  $ cd a
  $ touch a
  $ hg add a
  $ hg commit -qm base
  $ for i in `$TESTDIR/seq.py 1 100` ; do
  > echo $i > a
  > hg commit -qm $i
  > done

set up verbosemmap extension
  $ cat << EOF >> $HGRCPATH
  > [extensions]
  > verbosemmap=$TESTTMP/verbosemmap.py
  > EOF

mmap index which is now more than 4k long
  $ hg log -l 5 -T '{rev}\n' --config experimental.mmapindexthreshold=4k
  mmapping $TESTTMP/a/.hg/store/00changelog.i
  100
  99
  98
  97
  96

do not mmap index which is still less than 32k
  $ hg log -l 5 -T '{rev}\n' --config experimental.mmapindexthreshold=32k
  100
  99
  98
  97
  96

  $ cd ..