Subscribe to keys update

[Arnaud Tanguy]

Hi guys,

I'm wondering if there is a simple way to receive notification when a counter on a key is updated (via INCR or DECR).
I don't think that Redis can push the value of a counter directly to clients.
That's why, I'm thinking about publishing a notification on a channel (the channel is the key name) so clients will receive a notification and query Redis to get the value.

Is that the right way to do it?

Thanks for your feedback.

Arnaud.

[Dvir Volk]

yes this is definitely the way to go.

Arnaud.

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Dvir Volk

System Architect, The Everything Project (formerly DoAT)

http://everything.me

[Josiah Carlson]

On Thu, Feb 9, 2012 at 1:31 AM, Arnaud Tanguy <arnaud...@gmail.com> wrote:
> Hi guys,
>
> I'm wondering if there is a simple way to receive notification when a
> counter on a key is updated (via INCR or DECR).

There is no current way, but at least one request for notifications.

> I don't think that Redis can push the value of a counter directly to
> clients.
> That's why, I'm thinking about publishing a notification on a channel (the
> channel is the key name) so clients will receive a notification and query
> Redis to get the value.
>
> Is that the right way to do it?

That will work. Alternatively, if you want to go a bit over the top,
you could use MONITOR and build a system that automatically broadcasts
updates when certain operations are performed. With such a system, any
client that is updating data doesn't need to be updated to also
publish information.

Here's a quick hack that will publish the name of a key being
incremented to a channel of the same name for INCR operations.
redis-cli monitor | sed -e 's/"//g;s/(db ..*)//g' | grep INCR | awk
'{print "publish", $3, $3}' | redis-cli

It doesn't really support multiple databases, as it discards database
information and posts publish information into DB 0, but adding that
functionality shouldn't be that bad.

Regards,
- Josiah