fix: retry on R2 ETag mismatch when client sends If-Match: * - #276
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If-Match: * asserts document existence only (already verified before the R2 write). When a concurrent write changes the ETag between the existence check and the PutObjectCommand, R2 returns 412. The previous code treated any If-Match value as a non-retriable client conditional, so this spurious 412 propagated to the caller (da-collab) instead of being retried silently. Fix: treat If-Match: * the same as the no-conditional path on R2 ETag mismatch — re-fetch the current state and retry. Only a specific ETag (If-Match: "<hash>") means the caller requires a precise version and warrants a non-retriable 412. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Codecov Report✅ All modified and coverable lines are covered by tests. 📢 Thoughts on this report? Let us know! |
| const shouldRetry = !effectiveConditionals?.ifMatch | ||
| || effectiveConditionals.ifMatch === '*'; | ||
| if (shouldRetry) { | ||
| return putObjectWithVersion(env, daCtx, update, body, guid, clientConditionals); |
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Old code mentions "retry limit" though I don't see code for that. Seems like there should be a limit otherwise it might be possible to stack overflow?
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I agree. I do not really understand the original code.
I do not think the "under retry limit" was there before. No behavior change but it is worth understanding why.
@karlpauls could you please review and comment ?
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## [1.8.1](v1.8.0...v1.8.1) (2026-05-12) ### Bug Fixes * retry on R2 ETag mismatch when client sends If-Match: * ([#276](#276)) ([3634d98](3634d98))
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🎉 This PR is included in version 1.8.1 🎉 The release is available on:
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Problem
When da-collab sends
PUTwithIf-Match: *, da-admin correctly checks document existence first. It then uses the document's current ETag for the actual R2 write (If-Match: <etag>). If a concurrent write (e.g. during a Durable Object live migration) changes the ETag between the existence check and thePutObjectCommand, R2 returns 412.The previous code treated any
If-Matchvalue as a non-retriable client conditional:This conflates two distinct semantics:
If-Match: *— wildcard, asserts existence only (already verified before the write)If-Match: "<etag>"— specific version lock, caller requires that exact versionFor the wildcard case, the document still exists after the ETag mismatch — the retry behaviour should be identical to the no-conditional (internal) path.
Fix
Retry on R2 ETag mismatch when the client sent
If-Match: *, exactly as internal writes do. Only a specific ETag value keeps the non-retriable 412.Tests
putObjectWithVersion retries on ETag mismatch when If-Match: * is sent— verifies the retry succeeds (was failing before this fix)putObjectWithVersion returns 412 without retry when client sends specific ETag— verifies specific-ETag behaviour is unchanged🤖 Generated with Claude Code