feat: add half-open state to circuit breaker#33
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xakep666 merged 2 commits intoplatacard:mainfrom Mar 30, 2026
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The circuit breaker now periodically probes the upstream after tripping, allowing recovery if the remote cache server comes back during a long build. Uses a timestamp-based approach with CompareAndSwap to ensure only one concurrent request acts as the probe. Configurable via --retry-after / REMOTE_STORAGE_RETRY_AFTER (default 15s). Set to 0 to disable and preserve the previous permanently-open behavior.
xakep666
reviewed
Mar 27, 2026
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Some requests here:
Also I thought about adding a functests scenario (IMHO it should present for such feature). But it requires to compile large-scale project which need to be find at first. Simulating network problems here shouldn't be an issue because functests setup already includes toxiproxy. |
- Remove now func() field, use time.Now() directly with synctest fake time - Add test verifying only one probe request in half-open state - Add changelog entry - Fix linter issues
xakep666
approved these changes
Mar 30, 2026
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The circuit breaker currently stays permanently open once tripped, remote storage is disabled for the rest of the build. For long CI builds, the server may recover mid-build but cacheprog won't try again.
This adds a half-open state: after the circuit trips, it periodically allows a single probe request through. If the probe succeeds, the circuit closes and remote storage resumes. If it fails, the circuit stays open and the timer resets.
Implementation uses a timestamp +
CompareAndSwapso only one concurrent request wins the probe, no background goroutines or lifecycle management needed.New config:
--retry-after/REMOTE_STORAGE_RETRY_AFTER(default15s). Set to0to disable recovery and preserve the current behavior.