view tests/test-revlog-mmapindex.t @ 40390:7e3b6c4f01a2

localrepo: support marking repos as having shallow file storage

Various operations against repositories need to know if repository
storage is full or partial. For example, a checkout (including possibly
a widening of a sparse checkout), needs to know if it can assume all file
revisions are available or whether to look for missing revisions first.

This commit lays the plumbing for doing that.

We define a repo creation option that indicates that shallow file storage
is desired.

The SQLite store uses this creation option to add an extra repo requirement
indicating file storage is shallow.

A new repository feature has been added to indicate that file storage is
shallow. The SQLite store adds this feature when the shallow file store
requirement is present.

Code can now look at repo.features to determine if repo file storage may
be shallow and take additional actions if so.

While we're here, we also teach the SQLite store to handle the narrow repo
requirement, which gets added when making narrow clones.

Differential Revision: https://phab.mercurial-scm.org/D5166

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 ..