Is pipelining atomic?
Joon Nick
we need a FIFO-queue, who will block duplicates.
Our solution:
- sorted Set with timestamp as score
- push member if not exists
- pop member with lowest score
PUSH:
ZSCORE queueKey member
if( nil ) ZADD queueKey time() member
POP
openPipeline
ZRANGE queueKey 0 0
ZREMRANGEBYRANK queueKey 0 0
executePipeline
or we need ?:
openPipeline
MULTI
ZRANGE queueKey 0 0
ZREMRANGEBYRANK queueKey 0 0
EXEC
executePipeline
Questions:
1. is this the right way or can we do it simpler, faster, better?
2. is pipelining atomic?
bugant
> PUSH:
> ZSCORE queueKey member
> if( nil ) ZADD queueKey time() member
This is not necessary since member in a set are always unique.
From the ZADD documentation (http://redis.io/commands/zadd):
"If a specified member is already a member of the sorted set, the
score is updated and the element reinserted at the right position to
ensure the correct ordering"
ciao ciao,
matteo.
Dvir Volk
--
You received this message because you are subscribed to the Google Groups "Redis DB" group.
To post to this group, send email to redi...@googlegroups.com.
To unsubscribe from this group, send email to redis-db+u...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/redis-db?hl=en.
ivan babrou
--
You received this message because you are subscribed to the Google Groups "Redis DB" group.
To post to this group, send email to redi...@googlegroups.com.
To unsubscribe from this group, send email to redis-db+u...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/redis-db?hl=en.
Regards, Ian Babrou
http://bobrik.name http://twitter.com/ibobrik skype:i.babrou
Joon Nick
> > PUSH:
> > ZSCORE queueKey member
> > if( nil ) ZADD queueKey time() member
>
> This is not necessary since member in a set are always unique.
break the FIFO-order!
--
so long Joon
www.schottenland.de
Joon Nick
On 15 Nov., 14:03, Dvir Volk <d...@doat.com> wrote:
> pipelining by itself without MULTI...EXEC is not atomic, so you need those.
BUT, what will the single thread do, i suppose he will process the
input until the buffer is empty, meens all commands in the pipeline,
then he will look for new data from any client.
Wrong?
Maybe if the pipeline-data is big and the process is processing the
incomming data faster as new packets arrive, he will switch to other
client-connections?!
(and i suppose my two commands fit in a single Datapacket.)
I know, this is not an API-Question, its only for practical
understandigs... ;-)
Salvatore Sanfilippo
yes it is possible that if your two queries are inside the same TCP
frame Redis will process it in an atomic fashion, but this is just a
side effect of the implementation and is not guaranteed.
Cheers,
Salvatore
> --
> You received this message because you are subscribed to the Google Groups "Redis DB" group.
> To post to this group, send email to redi...@googlegroups.com.
> To unsubscribe from this group, send email to redis-db+u...@googlegroups.com.
> For more options, visit this group at http://groups.google.com/group/redis-db?hl=en.
>
>
--
Salvatore 'antirez' Sanfilippo
open source developer - VMware
http://invece.org
"We are what we repeatedly do. Excellence, therefore, is not an act,
but a habit." -- Aristotele
Josiah Carlson
violation, except that a pair of racing queue entries will have almost
the same time, and it is unlikely that someone will consume the first
entered item before the second.
Generally, to do it properly requires one of 2 methods. Either using
WATCH/MULTI/EXEC
WATCH queue
score = ZSCORE queue member
if !score:
MULTI
ZADD queue time() member
EXEC
else:
UNWATCH queue
Or using the scripting branch.
- Josiah
Joon Nick
> yes it is possible that if your two queries are inside the same TCP
> frame Redis will process it in an atomic fashion, but this is just a
> side effect of the implementation and is not guaranteed.
thanks for the confirmation of my idea of the system.
Joon Nick
> Generally, to do it properly requires one of 2 methods. Either using
> WATCH/MULTI/EXEC
> WATCH queue
> score = ZSCORE queue member
> if !score:
> MULTI
> ZADD queue time() member
> EXEC
> else:
> UNWATCH queue
> Or using the scripting branch.
reciept.