Re: [PATCH v4] receive-pack: Create a HEAD ref for ref namespace

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 15, 2015, 20:48 UTC
Message-ID: <xmqqlhfk7l6l.fsf@gitster.dls.corp.google.com>
In-Reply-To: <1433526142-2413-1-git-send-email-johannes@kyriasis.com>

Johannes Löthberg <johannes@kyriasis.com> writes:

Show 25 quoted lines

> diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
> index d2ec52b..0c18c92 100644
> --- a/builtin/receive-pack.c
> +++ b/builtin/receive-pack.c
> @@ -864,7 +864,9 @@ static const char *update(struct command *cmd, struct shallow_info *si)
>  {
>  	const char *name = cmd->ref_name;
>  	struct strbuf namespaced_name_buf = STRBUF_INIT;
> -	const char *namespaced_name, *ret;
> +	struct strbuf namespaced_head_buf = STRBUF_INIT;
> +	const char *namespaced_name, *ret, *namespace;
> +	const char *namespaced_head_path;
>  	unsigned char *old_sha1 = cmd->old_sha1;
>  	unsigned char *new_sha1 = cmd->new_sha1;
>  
> @@ -981,6 +983,14 @@ static const char *update(struct command *cmd, struct shallow_info *si)
>  		return NULL; /* good */
>  	}
>  	else {
> +		namespace = get_git_namespace();
> +		if (strcmp(namespace, "refs/namespaces/")) {
> +			strbuf_addf(&namespaced_head_buf, "%s%s", namespace, "HEAD");
> +			namespaced_head_path = strbuf_detach(&namespaced_head_buf, NULL);
> +
> +			create_symref(namespaced_head_path, namespaced_name, NULL);

In a normal environment without any namespace, get_git_namespace() will return an empty string, which is not "refs/namespaces/", so we create a symref HEAD (that is .git/HEAD) that points at whatever name the command is about. And this is done every time any ref is updated, flipping the HEAD to point at whatever was pushed the last, isn't it?

Why is this a good change?  I am puzzled...

> +		}
> +
>  		struct strbuf err = STRBUF_INIT;

This adds decl-after-stmt.

Going back to the proposed log message...

> Each ref namespace have their own separate branches, tags, and HEAD, so
> when pushing to a namespace we need to make sure that there exists a
> HEAD ref for the namespace, otherwise you will not be able to check out
> the repo after cloning from a namespace

What this paragraph describes is entirely correct, I think. But I do not think receive-pack is the "we" in that paragraph.

When setting up a "namespace" a and b, shouldn't you be doing essentially

	r=refs/namespaces/
	for ns in a b
        do
		git symbolic-ref $r$ns/HEAD $r$ns/refs/heads/master
	done

or something, which is an equivalent to what "git init" does to a normal repository?