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cxymds
f52dde87d1
* fix(object): make version undo preconditions atomic * fix(object): fence metadata-only undo copies * fix(object): order versions by commit time
42 lines
1.7 KiB
Markdown
42 lines
1.7 KiB
Markdown
# Atomic object undo precondition
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RustFS supports a destination-side version precondition for the two S3
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operations used to undo changes in a versioned bucket:
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```text
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x-rustfs-expected-current-version-id: <version-id>
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```
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This is a RustFS extension, not a standard S3 header.
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## Restore a historical object version
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Send a same-object `CopyObject` request whose copy source includes the
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historical `versionId`, and set the extension header to the version that was
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current when the undo was planned. RustFS holds the destination namespace write
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lock while it compares the current version and creates the restored version.
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The request fails without creating a version when the source is not a
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historical version, the source and destination differ, or the destination
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current version no longer matches.
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## Remove a delete marker
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Send a version-specific `DeleteObject` request for the delete marker and set the
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extension header to the same version ID. RustFS removes it only when it is still
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the current version and is a delete marker. The namespace write lock covers the
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check and deletion.
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## Responses and retries
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- A stale, missing, non-current, or non-delete-marker version returns HTTP 412
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`PreconditionFailed` and does not mutate object history.
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- An empty or malformed version header returns HTTP 400 `InvalidArgument`.
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- A mismatched operation shape returns HTTP 400 `InvalidRequest`.
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- A successful retry using an old expected version returns HTTP 412 because the
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first successful request changed the current version.
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Object Lock retention, legal hold, authorization, replication, and ordinary S3
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behavior remain unchanged. The extension only adds a precondition; it does not
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bypass existing validation.
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