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improve multipart part retries with exponential backoff & preserve root errors - #44
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… upload errors - Fix abort state in NetworkFacade to preserve and propagate actual abort errors instead of masking them as UploadNotSuccessful. - Implement exponential backoff with jitter and selective error filtering (isRetryableChunkError) in UploadPartOperation. - Pass HTTP status code in PartUploadFailed for non-200 S3 responses in UploadMultipart. - Conform UploadError to LocalizedError for clean string descriptions.
sg-gs
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Jul 22, 2026
sg-gs
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Jul 22, 2026
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📌 Summary
Fixes an issue where multipart upload failures were masked as
UploadNotSuccessfuldue to unhandled abort states inNetworkFacade.Previously, part-level retries were only triggered during offline states (
notConnectedToInternet/networkConnectionLost), while transient network issues like S3 request timeouts (-1001), server errors (5xx), or rate limits (429) failed immediately without retrying.This PR improves part-level resilience by introducing Exponential Backoff with Jitter, selective error classification for transient failures, preserving underlying root-cause errors, conforming
UploadErrortoLocalizedError.🛠️ Changes Introduced
Smart Part-Level Retry & Error Classification:
notConnectedToInternet/networkConnectionLost) and retried immediately without delay.isRetryableChunkErrorto retry transient network conditions (timeouts-1001, host unreachable-1003/-1004, HTTP5xx, HTTP429, HTTP status-1) while immediately aborting non-retryable errors (e.g. HTTP4xx).Exponential Backoff & Jitter:
pow(2.0, attempt)) with random jitter inUploadPartOperation.uploadPartWithRetry()to prevent request storms against S3 endpoints during transient hiccups.Error Preservation & Propagation:
uploadState.setAborted(error: partError)andencryptFileIntoChunksinNetworkFacade.swiftto preserve and propagate the actualPartUploadFailederror instead of falling back to genericUploadError.UploadNotSuccessful.HTTP Status Code Exposure & Localized Errors:
UploadMultipart.swiftto return non-200 S3 responses wrapped inPartUploadFailedcontaining the actual HTTP status code.UploadErrortoLocalizedErrorfor descriptive string representations in system logs (PartUploadFailed(partIndex: X, error: Y)).