CODEWITHSUNDEEP
javascriptarraysnode.jsredis
Slava
Slava

Reputation: 23

Get random element from redis set without duplicate

I'm making a game on Node.js with REDIS and Socket.io.

I have "rooms" in this game. There are from 1 to 9 players in room. They can join and leave whenever they want.

Also there is a loop (setInterval) in room that takes one player from Redis and makes this player a "leader".

Players stored in Redis as set (rooms:ROOMID:online). When user joins room I add him in this set. When user leaves, I remove him from set.

Maybe it's a dumb question, but...

How to get next user on every iteration WITHOUT DUPLICATE until I manually stop the loop, considering that the set could change on every iteration of the loop (can become smaller or bigger, users can join and leave).

Example of what I want: there are 3 users in set (0, 1, 2)

setInterval(function, 1000);

>0
>1
>2
> User 3 joined the room (added to set)
>0
>1
>2
>3
>0
>1
>2
> User 2 left the room (removed from set)
>3
>0
>1
>3
>...etc

Note: I can't SPOP from my main set (rooms:ROOMID:online).

Sorry for my English and thanks for any help.

Upvotes: 0

Views: 277

Answers (1)

Itamar Haber
Itamar Haber

Reputation: 50082

I suggest you keep another set, e.g. rooms:ROOMID:elected. Keep it in sync with the rooms:ROOMID:online set on every join/sync event. SPOP from it and once it is empty, copy contents rooms:ROOMID:online to it.

Upvotes: 0

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