Detect own-leaked lock on PreconditionFailed in acquire_lock (#2)#67
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Darksinian wants to merge 1 commit into
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Detect own-leaked lock on PreconditionFailed in acquire_lock (#2)#67Darksinian wants to merge 1 commit into
Darksinian wants to merge 1 commit into
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When boto3 silently retries a PutObject that already succeeded server-side (transient 5xx after write, lost response, connection reset, etc.), the retry returns 412 PreconditionFailed because the lock now exists. The helper previously treated this as "another client holds the lock" and only recovered after the 60s TTL expired. Write a per-call uuid into the lock body. On 412 PreconditionFailed read the existing body — if it matches our token, boto3 must have retried our own successful PUT and we own the lock. Take it via the same delete + re-acquire path the staleness check already uses. Concurrent clients still serialise correctly: each call generates its own uuid, so a foreign client's lock body never matches our token. Callers who also need to recover locks across reinvocations of the helper (e.g. an outer-loop retry of git push) can set GIT_REMOTE_S3_OWNER_TOKEN to a stable per-client value.
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When boto3 silently retries a PutObject that already succeeded server-side (transient 5xx after write, lost response, connection reset, etc.), the retry returns 412 PreconditionFailed because the lock now exists. The helper previously treated this as "another client holds the lock" and only recovered after the 60s TTL expired.
This solves the issue by writing a per-call identifier (uuid by default) into the lock body. On 412 PreconditionFailed we read the existing lock and if it matches our token, boto3 must have retried our own successful PUT and we own the lock. Take it via the same delete + re-acquire path the staleness check already uses.
Concurrent clients still serialise correctly: each call generates its own uuid, so a foreign client's lock body never matches our token. Callers who also need to recover locks across reinvocations of the helper (e.g. an outer-loop retry of git push) can set GIT_REMOTE_S3_OWNER_TOKEN to a stable per-client value.