filectx: use ctx.size comparisons to speed up ctx.cmp
Comparing sizes is cheaper than comparing file contents, as it does not
involve reading the file on disk or from the filelog.
It is however not always possible: some extensions, or encode filters,
change data when extracting it to the working directory.
$ 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 util
> def stripprefix(s, cmd, filename, **kwargs):
> header = '%s\n' % cmd
> if s[:len(header)] != header:
> raise util.Abort('missing header "%s" in %s' % (cmd, filename))
> return s[len(header):]
> def insertprefix(s, cmd):
> return '%s\n%s' % (cmd, s)
> def reposetup(ui, repo):
> repo.adddatafilter('stripprefix:', stripprefix)
> repo.adddatafilter('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