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Evan JarrettandClaude Fable 5.1
f4343d7956
Every blob went through the multipart machinery: an S3 multipart started on Docker's initial POST, a hold round trip per part, and a complete on the hold that finished the multipart, HEADed the temp object, copied it to its final key, and deleted the temp. For a 2KB config blob that was three hold calls and six S3 operations. On production data 86% of distinct layers and every config blob fit in a 16MB buffer, and 49% of image manifests have no layer larger than that. The writer now buffers up to 16MB (also the multipart part size) and makes no hold call until it has to. A blob that never overflows the buffer is written at Commit with a single presigned PUT to its final key, via the hold's existing method=PUT presign; the multipart only starts on the first flush. The hold's completeUpload does nothing the direct path skips: quota, layer records, stats and scan dispatch all hang off notifyManifest, which is unchanged. The buffer starts empty and grows on demand, with the doubling capped so capacity never overshoots 16MB: a config blob costs kilobytes, and only layers that approach the threshold fill it. Bytes are hashed as they arrive. Commit compares the computed sha256 to the digest the client claimed before any network call, and returns DIGEST_INVALID on mismatch, aborting a multipart if one was started. Previously nothing verified the content, so a pusher could store wrong bytes under a digest in the shared content-addressed space. Tests observe request counts on a fake hold and fake S3 rather than return values. The growth test streams in 24KB chunks because power-of-two chunks land on 16MB by luck and hid an earlier weaker guard. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_018Yf1ZVA7sXYhQNb9tCo1m5