Re: [PATCH iproute2-next v2] dpll: Send object per event in JSON monitor mode

[Petr Oros <poros@redhat.com>]

> Previously, monitor mode wrapped all events in a single JSON array
> inside a top-level object, which made piping the output to external
> tools (such as `jq`) impossible.
> Send a separate JSON object for each event in monitor mode,
> making the output suitable for line-by-line consumers. Skip the
> global JSON wrapper for monitor mode.
>
> Signed-off-by: Vitaly Grinberg <vgrinber@redhat.com>
> ---
> v2:
>    - Fixed indentation
> ---
>   dpll/dpll.c | 25 +++++++++++++++++--------
>   1 file changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/dpll/dpll.c b/dpll/dpll.c
> index 9893ca8c..49576d23 100644
> --- a/dpll/dpll.c
> +++ b/dpll/dpll.c
> @@ -571,8 +571,15 @@ int main(int argc, char **argv)
>   	argc -= optind;
>   	argv += optind;
>   
> -	new_json_obj_plain(json);
> -	open_json_object(NULL);
> +	/* Monitor emits one JSON object per event for streaming;
> +	 * other commands use a single JSON wrapper object.
> +	 */
> +	bool is_monitor = argc > 0 && strcmp(argv[0], "monitor") == 0;
> +
> +	if (!is_monitor) {
> +		new_json_obj_plain(json);
> +		open_json_object(NULL);
> +	}
>   
>   	/* Skip netlink init for help commands */
>   	bool need_nl = true;
> @@ -602,8 +609,10 @@ dpll_fini:
>   	if (need_nl)
>   		dpll_fini(dpll);
>   json_cleanup:
> -	close_json_object();
> -	delete_json_obj_plain();
> +	if (!is_monitor) {
> +		close_json_object();
> +		delete_json_obj_plain();
> +	}
>   dpll_free:
>   	dpll_free(dpll);
>   	return ret;
> @@ -2173,6 +2182,7 @@ static int cmd_monitor_cb(const struct nlmsghdr *nlh, void *data)
>   
>   		mnl_attr_parse(nlh, sizeof(struct genlmsghdr), attr_cb, tb);
>   
> +		new_json_obj_plain(json);
>   		open_json_object(NULL);
>   		print_string(PRINT_JSON, "name", NULL, json_name);
>   		open_json_object("msg");
> @@ -2182,6 +2192,7 @@ static int cmd_monitor_cb(const struct nlmsghdr *nlh, void *data)
>   
>   		close_json_object();
>   		close_json_object();
> +		delete_json_obj_plain();
>   		break;
>   	}
>   	case DPLL_CMD_PIN_CREATE_NTF:
> @@ -2200,6 +2211,7 @@ static int cmd_monitor_cb(const struct nlmsghdr *nlh, void *data)
>   			json_name = "pin-delete-ntf";
>   		}
>   
> +		new_json_obj_plain(json);
>   		open_json_object(NULL);
>   		print_string(PRINT_JSON, "name", NULL, json_name);
>   		open_json_object("msg");
> @@ -2209,6 +2221,7 @@ static int cmd_monitor_cb(const struct nlmsghdr *nlh, void *data)
>   
>   		close_json_object();
>   		close_json_object();
> +		delete_json_obj_plain();
>   		break;
>   	}
>   	default:
> @@ -2273,8 +2286,6 @@ static int cmd_monitor(struct dpll *dpll)
>   		goto err_signalfd;
>   	}
>   
> -	open_json_array(PRINT_JSON, "monitor");
> -
>   	pfds[0].fd = signal_fd;
>   	pfds[0].events = POLLIN;
>   	pfds[1].fd = netlink_fd;
> @@ -2307,8 +2318,6 @@ static int cmd_monitor(struct dpll *dpll)
>   		}
>   	}
>   
> -	close_json_array(PRINT_JSON, NULL);
> -
>   err_signalfd:
>   	if (signal_fd >= 0)
>   		close(signal_fd);
>
> ---
> base-commit: 36252727bfc653905bb39bec115a32869452beb1
> change-id: 20260328-dpll-mon-j-d88eb48c1f09
>
> Best regards,
> --
> Vitaly Grinberg <vgrinber@redhat.com>
>
>
Good idea, Thanks

Reviewed-by: Petr Oros <poros@redhat.com>