Re: [PATCH v2 03/11] serve: add "receive" method for v2 capabilities table

On Wed, Sep 15, 2021 at 09:41:28AM -0700, Junio C Hamano wrote:

Jeff King [off-list ref] writes:

quoted

+	/*
+	 * Function called when a client requests the capability as a
+	 * non-command. This may be NULL if the capability does nothing.
+	 *
+	 * For a capability of the form "foo=bar", the value string points to
+	 * the content after the "=" (i.e., "bar"). For simple capabilities
+	 * (just "foo"), it is NULL.
+	 */
+	void (*receive)(struct repository *r, const char *value);

What does "as a non-command" mean?  To put it another way, when a
client requests the capability as a command, what does the receive
method do differently?

For each entry in this capability table, clients can say:

  command=foo

or just:

  foo

The latter is a non-command. The "receive" function is not called at all
if it is a "command". I think this is a bit more clear when read
together with the existing function just above (which you can't see in
the diff context):

        /*
         * Function called when a client requests the capability as a command.
         * Will be provided a struct packet_reader 'request' which it should
         * use to read the command specific part of the request.  Every command
         * MUST read until a flush packet is seen before sending a response.
         *
         * This field should be NULL for capabilities which are not commands.
         */
        int (*command)(struct repository *r, struct packet_reader *request);

I guess these could define "as a command", but I think it's pretty clear
in the context.

quoted

 static int parse_command(const char *key, struct protocol_capability **command)

@@ -262,7 +277,7 @@ static int process_request(void)
 		case PACKET_READ_NORMAL:
 			/* collect request; a sequence of keys and values */

The comment tentatively gets slightly stale here, but that will be
corrected at the end, so it would be fine ;-)

Hmm. I think it is not stale here, as we are still collecting the "keys"
strvec. But it _does_ get stale by the end, when we stop doing so.

I'm preparing a re-roll for the test issues Eric noted, so I'll drop
that comment in the appropriate patch.

-Peff