[Deliverable] Create Rate Limit Manager

[fryorcraken]

Owner: App/Chat Dev

Feature: Rate Limit Manager

FURPS:

• F1. Rate limit the number of messages passed to the delivery service.

• F2. The rate limit is set in a form of number of messages per epoch; same format as RLN Relay.

• F3. Tracks current quota and usage.

• F4. Messages can be flagged with three priorities level: critical, normal, optional.

• F5. When remaining message quota is low, critical messages are sent, normal messages are queued and optional messages are dropped.

• F6. When message quote is exhausted, critical messages are queued on top, normal messages are queued, optional messages are dropped.

• U1. Developer can mark messages with relevant priority.

• U2. Developer can pass messages by batch; with an all-or-none sending strategy.

• U3. Developer can access total quota and remaining quota values.

• U4. Message status is available to the developer (queued, dropped, passed to delivery service).

• R1. Errors and status from the underlying delivery service are available to the developer.

• R2. Queued messages are persisted across restart.

• R3. Quota status is persisted across restart.

• S1. Nim library.

• +1. Nimble package manager is used to build.

Checklist:

• Specs: link to specs
  • N/A (using FURPS as specs/docs)
• Code: link to GitHub issues/PRs/Epic
• Dogfood: link to dogfooding session/artefact
  • N/A for now up until chat-sdk poc or mvp ready
• Docs: links to README.md or docs.waku.org (TBD)
  • https://github.com/waku-org/nim-chat-sdk/blob/main/ratelimit/README.md

Tasks

• feat: to use token_bucket as rate limiter we need to expose the currenct budget and cap logos-messaging-nim#3497 <- copy/pasted a version with this to remove the blocker, tracking the swith in here
• feat: rate limit (wip: no storage) nim-chat-sdk#3
• Feat/rate-limit-store-state nim-chat-sdk#5
• Feat/ratelimit store queue nim-chat-sdk#6
• Feat/expose data nim-chat-sdk#9

[fryorcraken]

@plopezlpz as discussed, add a README to show how to use the rate limit manager (I would suggest one in https://github.com/waku-org/nim-chat-sdk/tree/main/ratelimit).

[jazzz]

This deliverable is functionally complete, as it relates to the Milestone.

There is a blocked integration task waiting on upstream approval - tracked nim-chat-sdk#8 - but is not critical for this deliverable.

Once nim-chronos#582 is completed, the implementation can be updated to point to the correct location.