view tests/test-custom-filters.t @ 39494:e72130f58f5d

snapshot: consider all snapshots in the parents' chains

There are no reasons to only consider full snapshot as a possible base for an
intermediate snapshot.  Now that the basic principles have been set, we can
start adding more levels of snapshots.

We now consider all snapshots in the parent's chains (full or intermediate).
This creates a chain of intermediate snapshots, each smaller than the previous
one.

# Effect On The Test Repository

In the test repository, we can see a decrease in the revlog size and slightly
shorter delta chain.

However, that approach creates snapshots more frequently, increasing the risk
of ending into problematic cases in very branchy repositories (not triggered
by the test repository). The next changesets will remove that risk by adding
logic that increases deltas reuse.

  $ hg init

  $ cat > .hg/hgrc <<EOF
  > [extensions]
  > prefixfilter = prefix.py
  > [encode]
  > *.txt = stripprefix: Copyright 2046, The Masters
  > [decode]
  > *.txt = insertprefix: Copyright 2046, The Masters
  > EOF

  $ cat > prefix.py <<EOF
  > from mercurial import error
  > def stripprefix(s, cmd, filename, **kwargs):
  >     header = b'%s\n' % cmd
  >     if s[:len(header)] != header:
  >         raise error.Abort(b'missing header "%s" in %s' % (cmd, filename))
  >     return s[len(header):]
  > def insertprefix(s, cmd):
  >     return b'%s\n%s' % (cmd, s)
  > def reposetup(ui, repo):
  >     repo.adddatafilter(b'stripprefix:', stripprefix)
  >     repo.adddatafilter(b'insertprefix:', insertprefix)
  > EOF

  $ cat > .hgignore <<EOF
  > .hgignore
  > prefix.py
  > prefix.pyc
  > EOF

  $ cat > stuff.txt <<EOF
  > Copyright 2046, The Masters
  > Some stuff to ponder very carefully.
  > EOF
  $ hg add stuff.txt
  $ hg ci -m stuff

Repository data:

  $ hg cat stuff.txt
  Some stuff to ponder very carefully.

Fresh checkout:

  $ rm stuff.txt
  $ hg up -C
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat stuff.txt
  Copyright 2046, The Masters
  Some stuff to ponder very carefully.
  $ echo "Very very carefully." >> stuff.txt
  $ hg stat
  M stuff.txt

  $ echo "Unauthorized material subject to destruction." > morestuff.txt

Problem encoding:

  $ hg add morestuff.txt
  $ hg ci -m morestuff
  abort: missing header "Copyright 2046, The Masters" in morestuff.txt
  [255]
  $ hg stat
  M stuff.txt
  A morestuff.txt