Re: xenstore - Suggestion of batching watch events

[Andriy Sultanov <sultanovandriy@xxxxxxxxx>]

On 6/24/25 3:51 PM, Andriy Sultanov wrote:

> Suggestion:
> WATCH_EVENT's req_id and tx_id are currently 0. Could it be possible, for
> example, to modify this such that watch events coming as a result of a
> transaction commit (a "batch") have tx_id of the corresponding 
> transaction
> and req_id of, say, 2 if it's the last such watch event of a batch and 1
> otherwise? Old clients would still ignore these values, but it would 
> allow
> some others to detect if an update is part of a logical batch that 
> doesn't end
> until its last event. 
Come to think of it, since clients could watch arbitrary parts of
what the transaction touched, this wouldn't be as simple, xenstored
would have to issue the "batch ended" packet per token, tracking
that somehow internally... Perhaps transaction_start and transaction_end
could produce WATCH_EVENT (or some other similar packet) as well so
that this tracking could be done client-side? (standard WATCH_EVENT
would still need their tx_id to be modified)