fix: Handle closed EventChannel from multiprovider

[saleemrashid]

This PR

This fixes a bug where the multiprovider is briefly READY, then becomes NOT_READY.

The multiprovider closes the event channel under certain circumstances, e.g.:

	if len(handlers) > 0 {
		p.workerGroup.Add(1)
		go p.forwardProviderEvents(workerCtx, handlers)
	} else {
		// we don't emit any events so we can just close the channel
		close(p.outboundEvents)
	}

But the eventExecutor goroutine copying from the provider's event channel was not checking if it was closed, so it was constantly reading zero-value events. This resulted in triggerEvent being called constantly with zero-value events, for which stateFromEvent returns NotReady.

[gemini-code-assist]

Summary of Changes

Hello @saleemrashid, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves an intermittent state management problem within the multiprovider, preventing it from incorrectly reporting a NOT_READY status. The fix ensures that the system gracefully handles closed event channels, thereby maintaining accurate provider state and preventing the processing of spurious events that could lead to erroneous state transitions.

Highlights

• Bug Fix: Multiprovider State: Addresses a bug where the multiprovider would briefly become READY and then incorrectly transition to NOT_READY.
• Root Cause: Unhandled Closed Channel: The issue stemmed from the eventExecutor goroutine continuously reading zero-value events from a closed provider event channel, leading to constant NotReady state updates.
• Solution: Channel Closure Check: Implemented a check for channel closure (ok value) when reading from the event channel in eventExecutor, ensuring that processing stops when the channel is closed.

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[gemini-code-assist]

Code Review

The pull request modifies openfeature/event_executor.go to enhance robustness when handling events. Specifically, a check if !ok { return } was added when receiving from v.EventChannel() within the startListeningAndShutdownOld function. This ensures that the goroutine gracefully exits if the event channel is closed, preventing potential panics or unexpected behavior.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.11%. Comparing base (4ee43eb) to head (92a0346).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #461   +/-   ##
=======================================
  Coverage   83.11%   83.11%           
=======================================
  Files          27       27           
  Lines        2097     2097           
=======================================
  Hits         1743     1743           
  Misses        305      305           
  Partials       49       49           

Flag	Coverage Δ
e2e	83.11% <100.00%> (ø)
unit	83.11% <100.00%> (ø)

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[erka]

@saleemrashid What a bug...

Could you please merge this PR into your branch?

[dangra]

Could you please merge this PR into your branch?

@erka : Saleem is away until later today. I merged it in case we can save another sun cycle :) thanks!

[erka]

/gemini review

[gemini-code-assist]

Code Review

This pull request correctly fixes a bug where a closed event channel from a multiprovider would cause an infinite loop of zero-value events. The fix involves checking the second return value from the channel receive operation to detect when the channel is closed, and the associated goroutine is now only started if the provider is an EventHandler. A comprehensive test case is added to verify this fix. My main feedback is to maintain consistency in the testing style by avoiding the introduction of a new testing library and instead using the existing helper functions and standard library assertions.

[erka]

thank you @saleemrashid @dangra

[erka]

@toddbaert @sahidvelji could you please take a look?