OSConsistencyManager & IAM fetch read-your-write consistency implementation
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rgomezp
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OSConsistencyManager & IAM fetch read-your-write consistency implementation
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Motivation: Manages (kafka) offsets that function as read-your-write tokens for more accurate segment membership calculation. The manager works based on conditions & offsets. Offsets are stored in a nested map indexed by a unique id (e.g. `onesignalId`) and offset key (e.g. `USER_UPDATE`). This allows us to track offsets on a per-user basis (e.g. handle switching users). Conditions work by creating a blocking mechanism with customizable offset retrieval until a pre-defined condition is met (e.g. at least two specific offsets are available). OSCondition interface: allows extensibility for future applications to control offset blocking mechanism in consistency use-cases.
Motivation: custom condition to block offset retrieval until condition is met: user & subscription offsets are both available or just the user offset is available. This is because we always make a user update call (update the session count) but not always for subscription.
Motivation: commit new file references
…ager` Motivation: move into `OSSessionManager` to be accessible from other modules
Motivation: we need to pass the offset, session duration, & retry count to the GET IAM request.
Motivation: we need to flush the delta queue on start in order to immediately trigger updates that would return a RYW token so we can unblock IAM fetch as soon as possible.
Motivation: executors make the update or create requests and get back an offset which is saved in the consistency manager
Motivation: retry logic should work as follows: 1. initial request with offset --> failure 2. get retry limit & retry after from response & start retrying 3. if hit limit, make one final request with the offset: 0 The final request tells the backend, just show me what you got. Example: If the retry limit is 3 & we never get a successful response retrying, we should end up with 5 total requests.
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Description
One Line Summary
Introduce and integrate a ConsistencyManager to manage read-your-write tokens for improved segment membership calculation.
Details
Motivation
This update introduces the ConsistencyManager to manage RYW tokens. The goal is to improve the accuracy of segment membership calculations by providing an open-ended & highly customizable blocking mechanism for operations that rely on having successfully synchronized client & server state.
For a first use-case, we want to block the fetching of IAMs until we have tokens for a user or subscription state update.
Scope
OSConsistencyManagerimplementationOSConsistencyManager.OSConsistencyManager.OSMessagingControllerto delay IAM fetch until the token is available. Implements the retry logic.Testing
Unit testing
Manual Testing
Affected code checklist
Checklist
Overview
Testing
Final pass
This change is