[erlang-questions] ETS tables and pubsub

[Barco You]

Why don't you use gproc?


On Wed, Nov 13, 2013 at 2:38 AM, akonsu <akonsu@REDACTED> wrote:

> I have a pubsub system which has a single publisher process that maintains
> all its subscriber processes' Pid's in an ETS table.
>
> The publisher monitors its subscribers and when the publisher receives
> DOWN message, it removes the subscriber Pid from the table.
>
> The table entries are tuples of the form {MonitorRef, SubscriberPid}, and
> the MonitorRef is used as the key.
>
> Now I would like to make sure that if the publisher dies, and gets
> restarted by its supervisor, the subscriber table is preserved. So I
> created a process that creates the ETS table, sets the table's heir to
> self(), and then gives away the table to the publisher.
>
> The problem is that I do not know how to handle transfer of the table from
> the heir to the publisher:
>
> when publisher receives the table, the table contains a list of tuples
> {MonitorRef, SubscriberPid}, but the MonitorRefs were created by the
> previous publisher instance, so when the new publisher receives
> ETS_TRANSFER it needs to monitor all these SubscriberPids again.
>
> what is the best way to do it? Loop over all ETS entries, attach a monitor
> to each and reenter the new MonitorRefs into the table? This might be slow,
> no? Maybe my architecture can be improved? Any advice?
>
> thanks
> Konstantin
>
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