Re: [PATCH v2 07/20] kernel-shark: Add basic methods for Data streams

["Yordan Karadzhov (VMware)" <y.karadz@gmail.com>]

On 4.11.20 г. 17:41 ч., Steven Rostedt wrote:
> On Tue, 3 Nov 2020 15:38:33 +0200
> "Yordan Karadzhov (VMware)" <y.karadz@gmail.com> wrote:
> 
>> What if we define the interface to start with an integer identifier?
>>
>> /** Data interface identifier. */
>> typedef enum kshark_data_interface_id {
>> 	/** An interface with unknown type. */
>> 	KS_INVALIDE_INTERFACE,
>>
>> 	/** Generic interface suitable Ftrace data. */
>> 	KS_GENERIC_DATA_INTERFACE,
>> } kshark_data_interface_id;
>>
>> /**
>>    * Structure representing the interface of methods used to operate over
>>    * the data from a given stream.
>>    */
>> struct kshark_generic_stream_interface {
>> 	/** Interface version identifier. */
>> 	int			type; /* MUST BE FIRST ENTRY */
>>
>> 	/** Method used to retrieve the Process Id of the entry. */
>> 	stream_get_int_func	get_pid;
>>
>> 	/** Method used to retrieve the Event Id of the entry. */
>> 	stream_get_int_func	get_event_id;
>>
>> ....
>>
>> and it can be used like this:
>>
>> char *kshark_get_aux_field(const struct kshark_entry *entry)
>> {
>> 	struct kshark_generic_stream_interface *interface;
>> 	struct kshark_data_stream *stream =
>> 		kshark_get_stream_from_entry(entry);
>>
>> 	....
>>
>> 	interface = stream->interface;
>> 	if (interface->type == KS_GENERIC_DATA_INTERFACE &&
>> 	    interface->aux_field)
>> 		return interface->aux_field(stream, entry);
>>
>> 	return NULL;
>> }
>>
>> What do you think?
> 
> 
> This was actually what I was getting at ;-)
> 
> That is a common practice in the Linux kernel.

OK, thanks a lot!
Will be implemented in v3.

cheers,
Yordan

> 
> -- Steve
>