rpush | The push notification service for Ruby | Notification library

I have a node backend REST API that will be deployed as multiple containers.

I have an array of users = ['u1', 'u2', 'u3', 'u4'] that can be stored in mongoDb or redis

I have a get endpoint that returns next user from this array.

Eg: for 1st request it should return u1, 2nd request should return u2, 5th request returns u1.

once this API is deployed as multiple containers, Lets say there are 10 containers running and 10 requests are concurrently made, how do I make sure that they are returned in order.

Im looking for a standard approach to handle this scenario. Following is an approach I have thought of

Store the array as list on redis.

Do LPOP and RPUSH on each request So that list after the first request would be

['u2', 'u3', 'u4', u1]

Concern here is that if 5 requests comes in parallel, there could be a scenario, where 5LPOP could be executed and array could be empty and RPUSH could be executed out of order.

What is the best approach to handle this issue?

I have a trouble with redis package. There's in it's docs:

This library is a 1 to 1 mapping of the Redis commands.

But I can not access Redis commands through this lib's client.

I'm creating a client like this:

I have the following setup:

A rails server, which has a basic user login using the devise gem. There I've defined a User and a Device model where each user may have multiple devices via a has_many relationship on the user. The Device model has a single attribute- a token which I would use to send push notifications to using the rpush gem.

A react-native app using the react-native-webview package and the react-native-firebase/messaging package. The thing is, that I don't really know how to send the firebase device token to the server correctly.

What I've got so far is that I've overridden the rails devise registrations#new view to the following:

Redis RPUSH docs here suggest that the return value of RPUSH is the length of the list after the push operation.

However, what's not clear to me is:

1. Is the result of RPUSH the length of the list after the push operation atomically, (so the result is definitely the index of the last item just added by RPUSH) or...
2. Is it possible other RPUSH operations from concurrent Redis clients could have executed before the RPUSH returns, so that you are indeed getting the new length of the list, but that length includes elements from other RPUSH commands?

Thanks!

I'm attemptign to use Redis cloud and push an Array of String values using below code:

I have a rather primitive use-case for streams: multiple producers and 1 consumer that periodically process messages in batches. Sometimes there will be more than 1 consumer and this is why I want to switch from "traditional" unreliable queue (rpush/lrange/ltrim) to streams.

There're actually 2 related questions:

1. When using Redis consumer groups I have to specify group name and consumer name. Is this good idea to use some hard-coded string as group's name and some random string as consumer name? Consumer is just 1 process and its name will be different on each start in this case. On some rare occasions there will be 2 or more consumers at a time.

2. Consumer group has to be created via xgroup create before I can xreadgroup from it. Each time a new consumer starts (with a random name) it gets added to a list of consumers, but it remains there even after the process died. My understanding that in this case I need to re-assign all pending messages from the dead consumers to the active one, and then delete old consumers. Is this correct?

I have a Django application that uses Celery with Redis broker for asynchronous task execution. Currently, the app has 3 queues (& 3 workers) that connect to a single Redis instance for communication. Here, the first two workers are prefork-based workers and the third one is a gevent-based worker.

The Celery setting variables regarding the broker and backend look like this:

I have a simple job queue on Redis where new jobs are pushed with RPUSH and consumed with BLPOP. The jobs are stringified JSON objects that have an id field among other things (the json string is parsed by the workers).

Each job takes some time to do, so there can be a meaningful wait time. I'd like to be able to find a job's current position in the queue, so that I can give an update to whatever is waiting on that job. That is, be able to do something like "your current position is 300... 250... 200... 100... 10... your job is now being processed".

It can be assumed that the list may grow long but never too long, i.e. possibly 1000 entries but not 1 million.

After looking through the docs a bit, it seems like this is maybe easier said than done. A possible naive solution seems to be to just loop through the list until the element is found. Are there any performance issues with calling LINDEX a couple hundred times at a time like that?

Would appreciate any suggestions on other ways this can be done (or confirmation that LINDEX is the only way). The whole structure (even the usage of a list, or addition of some helper map/list) can be changed if needed, only requirement is that it run on Redis.

so I am trying to manipulate this variable within an async function and i am aware that the variable is being returned before the data.map function i will show below is complete but i am curious why? I have the await keyword in front in attempt to pause the code until the .map function is complete and then it should return the count from the .map function, but it is not, i am curious what i am doing wrong and if there is a better way to do it? Thank you!

Code: