Re: [PATCH 7/7] Implement git commit as a builtin command.

Kristian Høgsberg [off-list ref] writes:

quoted

quoted

+
+	/* update the user index file */
+	add_files_to_cache(fd, files, prefix);
+
+	if (!initial_commit) {
+		tree = parse_tree_indirect(head_sha1);
+		if (!tree)
+			die("failed to unpack HEAD tree object");
+		if (read_tree(tree, 0, NULL))
+			die("failed to read HEAD tree object");
+	}

Huh?  Doesn't this read_tree() defeat the add_files_to_cache()
you did earlier?

This is the case where we add the files on the command line
to .git/index, but commit from a clean index file corresponding to HEAD
with the files from the command line added (partial commit?).  The first
add_files_to_cache() updates .git/index, then we do read_tree() to build
a tmp index from HEAD and then we add the files again.  The tmp index is
written to a tmp index file.

Still, if you are doing read_tree() that reads into the same
in-core cache you have just prepared in the add_fiels_to_cache()
above, potentially overwriting whatever you did, doesn't it?
That was what I was puzzled about...

...  As for just using an in-memory
index, I wanted to do it that way originally, but you have to write it
to disk after all for the pre-commit hook.

Ah, I completely forgot about the hook.  Ok, scratch the idea of
not using a temporary index file.  The is not much potential for
performance gain anyway.