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.
Test applying context diffs
$ cat > writepatterns.py <<EOF
> import sys
>
> path = sys.argv[1]
> lasteol = sys.argv[2] == '1'
> patterns = sys.argv[3:]
>
> fp = open(path, 'wb')
> for i, pattern in enumerate(patterns):
> count = int(pattern[0:-1])
> char = pattern[-1].encode('utf8') + b'\n'
> if not lasteol and i == len(patterns) - 1:
> fp.write((char * count)[:-1])
> else:
> fp.write(char * count)
> fp.close()
> EOF
$ cat > cat.py <<EOF
> import sys
> from mercurial.utils import procutil, stringutil
> procutil.stdout.write(b'%s\n'
> % stringutil.pprint(open(sys.argv[1], 'rb').read()))
> EOF
Initialize the test repository
$ hg init repo
$ cd repo
$ "$PYTHON" ../writepatterns.py a 0 5A 1B 5C 1D
$ "$PYTHON" ../writepatterns.py b 1 1A 1B
$ "$PYTHON" ../writepatterns.py c 1 5A
$ "$PYTHON" ../writepatterns.py d 1 5A 1B
$ hg add
adding a
adding b
adding c
adding d
$ hg ci -m addfiles
Add file, missing a last end of line
$ hg import --no-commit - <<EOF
> *** /dev/null 2010-10-16 18:05:49.000000000 +0200
> --- b/newnoeol 2010-10-16 18:23:26.000000000 +0200
> ***************
> *** 0 ****
> --- 1,2 ----
> + a
> + b
> \ No newline at end of file
> *** a/a Sat Oct 16 16:35:51 2010
> --- b/a Sat Oct 16 16:35:51 2010
> ***************
> *** 3,12 ****
> A
> A
> A
> ! B
> C
> C
> C
> C
> C
> ! D
> \ No newline at end of file
> --- 3,13 ----
> A
> A
> A
> ! E
> C
> C
> C
> C
> C
> ! F
> ! F
>
> *** a/b 2010-10-16 18:40:38.000000000 +0200
> --- /dev/null 2010-10-16 18:05:49.000000000 +0200
> ***************
> *** 1,2 ****
> - A
> - B
> --- 0 ----
> *** a/c Sat Oct 16 21:34:26 2010
> --- b/c Sat Oct 16 21:34:27 2010
> ***************
> *** 3,5 ****
> --- 3,7 ----
> A
> A
> A
> + B
> + B
> *** a/d Sat Oct 16 21:47:20 2010
> --- b/d Sat Oct 16 21:47:22 2010
> ***************
> *** 2,6 ****
> A
> A
> A
> - A
> - B
> --- 2,4 ----
> EOF
applying patch from stdin
$ hg st
M a
M c
M d
A newnoeol
R b
What's in a
$ "$PYTHON" ../cat.py a
'A\nA\nA\nA\nA\nE\nC\nC\nC\nC\nC\nF\nF\n'
$ "$PYTHON" ../cat.py newnoeol
'a\nb'
$ "$PYTHON" ../cat.py c
'A\nA\nA\nA\nA\nB\nB\n'
$ "$PYTHON" ../cat.py d
'A\nA\nA\nA\n'
$ cd ..