git branches and compilation

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On Saturday, May 18, 2013, Phil Pennock wrote:

> On 2013-05-18 at 16:24 -0700, Bart Schaefer wrote:
> > (One of the few things I'm finding annoying about git is that
> > a cloned repository doesn't preserve file timestamps.)
>
> There's a post-checkout hook [...]

Having been annoyed a couple of times by things not recompiling when a
different branch is checked out (especially the texinfo inputs in Doc/,
leading to reams of bad node errors when doing "make info") I dug into
this a bit further and found "metastore".

http://david.hardeman.nu/software.php

It's available as a Debian package and seems so far to do what I want,
although I haven't really been able to test it thoroughly because no one
else has pushed anything in the past couple of days.

The following patch adds a couple of more lines to the .*ignore files
and three functions in Util/, two of which are git hooks and the third
of which creates symlinks in .git/hooks for the first two.  I'm curious
if anyone has any opinions/examples on whether this approach is best,
or if something requiring "git clone --template ..." is preferred.

It might also be ideal to have the metadata stored when stashing or at
least (in the old branch) before checkout (of the new), but there don't
seem to be hooks for either of those.

I won't push this patch without some discussion from the list first.

diff --git a/.cvsignore b/.cvsignore
index 95cdc58..a5f7191 100644
--- a/.cvsignore
+++ b/.cvsignore
@@ -14,3 +14,4 @@ stamp-h.in
 autom4te.cache
 *.swp
 .git
+.metadata
diff --git a/.gitignore b/.gitignore
index d0172e3..b89a5cc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,6 +9,7 @@ TAGS
 *~
 .*.sw?
 \#*
+.metadata
 
 /META-FAQ
 /config.cache
diff --git a/Util/add-git-hooks b/Util/add-git-hooks
new file mode 100755
index 0000000..77b2ac2
--- /dev/null
+++ b/Util/add-git-hooks
@@ -0,0 +1,38 @@
+#! /bin/sh
+
+HOOKS="pre-commit post-checkout"
+
+case `pwd` in
+*/Util) cd ..;;
+esac
+
+if ! [ -d .git/hooks ]
+then
+	echo "No directory for git hooks" >&2
+	exit 1
+fi
+
+if metastore -h 2>/dev/null 1>&2
+then
+	echo "Installing in `pwd`/.git/hooks ..." >&2
+	cd .git/hooks
+	for hook in $HOOKS
+	do
+		if [ -e $hook ]
+		then
+			if cmp -s ../../Util/git-$hook $hook
+			then
+				echo "$hook is already installed" >&2
+			else
+				echo "Another $hook already exists" >&2
+			fi
+		else
+			ln -s ../../Util/git-$hook $hook
+			chmod +x $hook
+		fi
+	done
+else
+	echo "Did not find metastore, skipping hooks" >&2
+fi
+
+exit 0
diff --git a/Util/git-post-checkout b/Util/git-post-checkout
new file mode 100755
index 0000000..a15d1d9
--- /dev/null
+++ b/Util/git-post-checkout
@@ -0,0 +1,24 @@
+#!/bin/bash
+#
+# Hook script to restore metadata information using metastore
+# following each checkout.
+
+# Do not restore metadata on a checkout from index
+if [ "$3" -eq 0 ]
+then
+	exit 0
+fi
+
+STOREFILE=".metadata/$(git symbolic-ref HEAD)/.metadata"
+
+if [ ! -e "$STOREFILE" ]; then
+	echo "No .metadata yet" >&2
+	exit 0
+fi
+
+if ! metastore -q -a -f "$STOREFILE"; then
+	echo "Failed to execute metastore -a" >&2
+	exit 1
+fi
+
+exit 0
diff --git a/Util/git-pre-commit b/Util/git-pre-commit
new file mode 100755
index 0000000..6030d12
--- /dev/null
+++ b/Util/git-pre-commit
@@ -0,0 +1,25 @@
+#!/bin/bash
+#
+# Hook script to store metadata information using metastore
+# before each commit.
+
+STOREPATH=".metadata/$(git symbolic-ref HEAD)"
+STOREFILE="$STOREPATH/.metadata"
+
+if [ ! -d "$STOREPATH" ] && ! mkdir -p "$STOREPATH"
+then
+	echo "Cannot create $STOREPATH, committing anyway" >&2
+	exit 0
+fi
+
+if ! metastore -s -f "$STOREFILE"; then
+	echo "Failed to execute metastore -s" >&2
+	exit 1
+fi
+
+if [ ! -e "$STOREFILE" ]; then
+	echo ".metadata missing after metastore -s" >&2
+	exec test \! -x .git/hooks/post-checkout
+fi
+
+exit 0

-- 
Barton E. Schaefer