revlog: add a C implementation of `headrevsdiff`
Python implementation of `headrevsdiff` can be very slow in the worst
case compared with the `heads` computation it replaces, since the
latter is done in C.
Even the average case of this Python implementation is still
noticeable in the profiles.
This patch makes the computation much much faster by doing it in C.
Test adding .hgeol
$ cat >> $HGRCPATH <<EOF
> [diff]
> git = 1
> EOF
$ seteol () {
> if [ $1 = "LF" ]; then
> EOL='\n'
> else
> EOL='\r\n'
> fi
> }
$ makerepo () {
> echo
> echo "# ==== setup repository ===="
> echo '% hg init'
> hg init repo
> cd repo
> printf "first\nsecond\nthird\n" > a.txt
> hg commit -d '100 0' --addremove -m 'LF commit'
> cd ..
> }
$ dotest () {
> seteol $1
> echo
> echo "% hg clone repo repo-$1"
> hg clone repo repo-$1
> cd repo-$1
> cat > .hg/hgrc <<EOF
> [extensions]
> eol =
> [eol]
> native = LF
> EOF
> cat > .hgeol <<EOF
> [patterns]
> **.txt = native
> [repository]
> native = $1
> EOF
> echo '% hg add .hgeol'
> hg add .hgeol
> echo '% hg status'
> hg status
> echo '% hg commit'
> hg commit -d '200 0' -m 'Added .hgeol file'
> echo '% hg status'
> hg status
> echo '% hg tip -p'
> hg tip -p
> cd ..
> rm -r repo-$1
> }
$ makerepo
# ==== setup repository ====
% hg init
adding a.txt
$ dotest LF
% hg clone repo repo-LF
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg add .hgeol
% hg status
A .hgeol
% hg commit
% hg status
% hg tip -p
changeset: 1:33503edb53b0
tag: tip
user: test
date: Thu Jan 01 00:03:20 1970 +0000
summary: Added .hgeol file
diff --git a/.hgeol b/.hgeol
new file mode 100644
--- /dev/null
+++ b/.hgeol
@@ -0,0 +1,4 @@
+[patterns]
+**.txt = native
+[repository]
+native = LF
$ dotest CRLF
% hg clone repo repo-CRLF
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg add .hgeol
% hg status
M a.txt
A .hgeol
% hg commit
% hg status
% hg tip -p
changeset: 1:6e64eaa9eb23
tag: tip
user: test
date: Thu Jan 01 00:03:20 1970 +0000
summary: Added .hgeol file
diff --git a/.hgeol b/.hgeol
new file mode 100644
--- /dev/null
+++ b/.hgeol
@@ -0,0 +1,4 @@
+[patterns]
+**.txt = native
+[repository]
+native = CRLF
diff --git a/a.txt b/a.txt
--- a/a.txt
+++ b/a.txt
@@ -1,3 +1,3 @@
-first
-second
-third
+first\r (esc)
+second\r (esc)
+third\r (esc)
$ rm -r repo