Hi,
one problem you have to keep in mind with what you want to do
(and i am not talking about the implementation that you suggest,
just the "delayed processing" aspects) is that sometimes data passed
through modules have a limited lifetime and might have become stale
by the time the consumer is scheduled to process them.
I had a similar problem with dummynet, related to route entries
that are passed around and might disappear. Same applies
to interface pointers (which, fortunately, are less dynamic).
cheers
luigi
> i'm in the middle of the project that uses Netgraph.
> everything is going pretty good, but there is one small
> issue. in five words it is "message and data delivery
> scheduling". here is an example:
>
> Node A --> Node B --> Node C
>
> Node "A" forwards data/messages to Node "B" and Node "B"
> in its turn forwards data/messages to Node "C". the issue
> is that Node "C" can handle only some small amount of
> data/messages at a time. Node "B" is aware of Node "C"'s
> limitation and must perform "leaking bucket" type of
> scheduling. i.e. Node "B" must queue data inside itself
> and then schedule later delivery to Node "C".
>
> but that is not all. sometimes it is required to send
> chunk of data (several messages) from Node "A" to Node "C".
> (via Node "B") and until this chunk of data is processed by
> Node "C", Node "B" is not allowed to send/accept any more
> data.
>
> i know about kernel threads and task queue, but i would really
> like to stay within Netgraph infrastructure and do not perform
> any extra synchronization.
>
> here is the proposal. every hook has two extra methods
> "hk_RcvDataShed" and "hk_RcvmMgSched" that performs scheduling.
> Node can turn on delivery scheduling on one of its hook by
> setting these methods. before actual data/message delivery
> Netgraph will call these methods and ask destination node "is
> that a good time to deliver this data/message". if it is then
> delivery is performed. otherwise depending on "HK_QUEUE" bit
> data/message gets queued or dropped. or perhaps turning on
> delivery scheduling must turn on "HK_QUEUE" bit automatically.
>
> thanks,
> max
>
> p.s. i think it should be easy to implement, if people are
> interested. i can prepare the patches.
>
> p.p.s. if anyone knows nice solution to this problem please
> let me know.
>
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