branchcache: skip entries that are topological heads in the on disk file
In the majority of cases, topological heads are also branch heads. We have
efficient way to get the topological heads and efficient way to retrieve
their branch information. So there is little value in putting them in the branch
cache file explicitly. On the contrary, writing them explicitly tend to create
very large cache file that are inefficient to read and update.
So the branch cache v3 format is no longer including them. This changeset focus
on the format aspect and have no focus on the performance aspect. We will cover
that later.
A script that implements uppercasing all letters in a file.
$ UPPERCASEPY="$TESTTMP/uppercase.py"
$ cat > $UPPERCASEPY <<EOF
> import sys
> from mercurial.utils.procutil import setbinary
> setbinary(sys.stdin)
> setbinary(sys.stdout)
> sys.stdout.write(sys.stdin.read().upper())
> EOF
$ TESTLINES="foo\nbar\nbaz\n"
$ printf $TESTLINES | "$PYTHON" $UPPERCASEPY
FOO
BAR
BAZ
This file attempts to test our workarounds for pickle's lack of
support for short reads.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> fix =
> [fix]
> uppercase-whole-file:command="$PYTHON" $UPPERCASEPY
> uppercase-whole-file:pattern=set:**
> EOF
$ hg init repo
$ cd repo
# Create a file that's large enough that it seems to not fit in
# pickle's buffer, making it use the code path that expects our
# _blockingreader's read() method to return bytes.
$ echo "some stuff" > file
$ for i in $($TESTDIR/seq.py 13); do
> cat file file > tmp
> mv -f tmp file
> done
$ hg commit -Am "add large file"
adding file
Check that we don't get a crash
$ hg fix -r .
saved backup bundle to $TESTTMP/repo/.hg/strip-backup/*-fix.hg (glob)