tests/test-largefiles-small-disk.t

localrepo: don't refresh filecache entries that aren't in __dict__

We call invalidate to remove properties from __dict__ because they're
possibly outdated and we'd like to check for a new version. Next time
the property is accessed the filecache mechanism checks the current stat
info with the one recorded at the last time the property was read, if
they're different it recreates the property.

Previously we refreshed the stat info on all properties in the filecache
when the lock is released, including properties that are missing from
__dict__. This is a problem because:

  l = repo.lock()
  repo.P          # stat info S for P is recorded in _filecache
  <changes are made to repo.P indirectly, e.g. underlying file is replaced>
                  # P's new stat info = S'
  l.release()     # filecache refreshes, records S' as P's stat info

At this point our filecache contains P with stat info S', but P's
version is from S, which is outdated.

The above happens during _rollback and strip. Currently we're wiping the
filecache and forcing everything to reload from scratch which works but
isn't the right solution.

Test how largefiles abort in case the disk runs full

  $ cat > criple.py <<EOF
  > import os, errno, shutil
  > from mercurial import util
  > #
  > # this makes the original largefiles code abort:
  > def copyfileobj(fsrc, fdst, length=16*1024):
  >     fdst.write(fsrc.read(4))
  >     raise IOError(errno.ENOSPC, os.strerror(errno.ENOSPC))
  > shutil.copyfileobj = copyfileobj
  > #
  > # this makes the rewritten code abort:
  > def filechunkiter(f, size=65536, limit=None):
  >     yield f.read(4)
  >     raise IOError(errno.ENOSPC, os.strerror(errno.ENOSPC))
  > util.filechunkiter = filechunkiter
  > #
  > def oslink(src, dest):
  >     raise OSError("no hardlinks, try copying instead")
  > util.oslink = oslink
  > EOF

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "largefiles =" >> $HGRCPATH

  $ hg init alice
  $ cd alice
  $ echo "this is a very big file" > big
  $ hg add --large big
  $ hg commit --config extensions.criple=$TESTTMP/criple.py -m big
  abort: No space left on device
  [255]

The largefile is not created in .hg/largefiles:

  $ ls .hg/largefiles
  dirstate

The user cache is not even created:

  >>> import os; os.path.exists("$HOME/.cache/largefiles/")
  False

Make the commit with space on the device:

  $ hg commit -m big

Now make a clone with a full disk, and make sure lfutil.link function
makes copies instead of hardlinks:

  $ cd ..
  $ hg --config extensions.criple=$TESTTMP/criple.py clone --pull alice bob
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  getting changed largefiles
  abort: No space left on device
  [255]

The largefile is not created in .hg/largefiles:

  $ ls bob/.hg/largefiles