feat(ofrep): add close to OFREP core

[beeme1mr]

This PR

This pull request focuses on resource management, graceful shutdown, and test coverage. The most significant changes ensure that in-flight requests can be aborted, timers are properly cleaned up, and the provider can be safely closed, preventing further evaluations.

Resource management and graceful shutdown:

• Added a close() method to the OFREPApi class that aborts any in-flight requests and prevents further usage after shutdown. The doFetchRequest method now checks for shutdown and rejects requests if the provider has been closed. (libs/shared/ofrep-core/src/lib/api/ofrep-api.ts) [1] [2]
• Updated the OFREPProvider and OFREPWebProvider classes to call the API's close() method in their onClose() implementations, ensuring proper resource release. (libs/providers/ofrep/src/lib/ofrep-provider.ts, libs/providers/ofrep-web/src/lib/ofrep-web-provider.ts) [1] [2]

Bug fixes:

• Fixed a missing return statement in the isomorphicFetch function to ensure correct fetch implementation selection. (libs/shared/ofrep-core/src/lib/api/ofrep-api.ts)

Related Issues

Fixes #1479

Follow-up Tasks

We'll need to release core prior to the other libraries and update the minimum dependency version in OFREP and OFREP Web.

How to test

• Added tests to verify that timers are cleaned up after requests, that in-flight requests are aborted on close, and that no pending timers remain after completion. (libs/shared/ofrep-core/src/lib/api/ofrep-api.spec.ts)
• Added tests to ensure the provider's onClose method can be called and that evaluations are rejected after closure. (libs/providers/ofrep/src/lib/ofrep-provider.spec.ts)

[gemini-code-assist]

Summary of Changes

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This pull request significantly enhances the robustness and resource management of the OFREP providers by introducing a comprehensive shutdown mechanism. It ensures that all in-flight requests are gracefully terminated and resources are properly released when a provider is closed, preventing potential memory leaks or unexpected behavior. This change improves the overall stability and reliability of the OpenFeature OFREP integration.

Highlights

• Graceful Shutdown: Implemented a close() method in OFREPApi to abort in-flight requests and prevent further evaluations, ensuring proper resource release.
• Provider Integration: Updated OFREPProvider and OFREPWebProvider to utilize the new OFREPApi.close() method within their onClose() implementations.
• Bug Fix: Corrected a missing return statement in the isomorphicFetch function for accurate fetch implementation selection.
• Dependency Update: Upgraded the @openfeature/ofrep-core dependency to version 2.1.0 in both provider packages.
• Enhanced Test Coverage: Added comprehensive tests for timer cleanup, in-flight request abortion, and post-closure evaluation rejection.

Changelog

• libs/providers/ofrep-web/package.json
  • Updated @openfeature/ofrep-core dependency from ^2.0.0 to ^2.1.0.
• libs/providers/ofrep-web/src/lib/ofrep-web-provider.ts
  • Added a call to this._ofrepAPI.close() within the onClose() method to ensure proper resource cleanup.
• libs/providers/ofrep/package.json
  • Updated @openfeature/ofrep-core dependency from ^2.0.0 to ^2.1.0.
• libs/providers/ofrep/src/lib/ofrep-provider.spec.ts
  • Added a test to verify that the onClose method is defined and can be called without throwing an error.
  • Added a test to confirm that evaluations are rejected after the onClose method has been invoked.
• libs/providers/ofrep/src/lib/ofrep-provider.ts
  • Implemented the onClose() method to delegate the closing operation to the ofrepApi instance.
• libs/shared/ofrep-core/src/lib/api/ofrep-api.spec.ts
  • Added tests to ensure clearTimeout is called after both successful and failed requests, verifying proper timer cleanup.
  • Included a test to confirm no pending timers remain after a request completes.
  • Added a test to verify that in-flight requests are aborted when the close() method is called.
• libs/shared/ofrep-core/src/lib/api/ofrep-api.ts
  • Corrected a missing return statement in the isomorphicFetch function for the self context.
  • Introduced a _shutdownController (an AbortController) to manage the shutdown state of the API.
  • Added a public close() method that triggers the _shutdownController to abort any pending operations.
  • Modified doFetchRequest to check if the provider is closed, rejecting new requests if it is.
  • Integrated the _shutdownController's signal with individual request controllers to allow global abortion.
  • Ensured clearTimeout is called and the shutdown event listener is removed in a finally block for robust resource management.

Activity

• The author, beeme1mr, initiated the pull request to add proper shutdown cleanup to OFREP.
• Tests were added to verify timer cleanup after requests, abortion of in-flight requests on close, and the absence of pending timers.
• Tests were also added to ensure the provider's onClose method functions correctly and that evaluations are rejected after closure.

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[gemini-code-assist]

Code Review

This pull request introduces graceful shutdown capabilities to the OFREP providers. A close() method has been added to OFREPApi which aborts in-flight requests using an AbortController. The OFREPProvider and OFREPWebProvider are updated to call this new method on close. The changes also include a bugfix for a missing return statement and comprehensive tests for the new shutdown logic. My review focuses on the implementation of the shutdown mechanism. I've found one minor opportunity for code simplification to improve readability.

[lukas-reining]

This looks good to me!

[jonathannorris]

Looks good, I would probably change the PR title to fix(ofrep):

[beeme1mr]

Looks good, I would probably change the PR title to fix(ofrep):

Maybe I should split this into two separate PRs because the fix adds a new method to core and we'll need to bump the min version in the consuming providers. FYI @toddbaert

[toddbaert]

Looks good, I would probably change the PR title to fix(ofrep):

Maybe I should split this into two separate PRs because the fix adds a new method to core and we'll need to bump the min version in the consuming providers. FYI @toddbaert

I'll just merge this as is, but make separate fixes to absorb this in the providers, and update the min version + release.