bug: add concurrency protection to AssignmentCache (FF-4172) #53
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rasendubi
approved these changes
Mar 24, 2025
Sources/eppo/AssignmentCache.swift
Outdated
| @@ -13,6 +13,7 @@ public struct AssignmentCacheKey { | |||
| } | |||
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| public class InMemoryAssignmentCache: AssignmentCache { | |||
| private let queue = DispatchQueue(label: "com.eppo.assignmentcache", attributes: .concurrent) | |||
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minor: have you considered using a Mutex instead? Given our sync blocks are very short, I would expect it to be a better fit here
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I did give this a read - https://swiftrocks.com/thread-safety-in-swift
Does seem like an NSLock is the fastest but I value my understanding of this API and feel comfortable with it working, but would be open to re-implementing the usage here now that we have a test that demonstrates the bug.
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Thanks for the quick turnaround @leoromanovsky |
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Observation
Customer report of crash #52
Description
Dictionary access in Swift is not thread-safe; the implementation of AssignmentCache has no protection against concurrent access.
DispatchQueueto guard access to the classTest plan
Wrote a test first to reproduce the issue
✔️ Implementation is passing the test
Rollout plan
This PR is opened against
mainbranch and we need to back port this change to the3.xbranch and make a new release against it.