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Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
91 lines
2.4 KiB
Plaintext
91 lines
2.4 KiB
Plaintext
;; content-on-sx — snapshot cache over the op-log replay.
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;;
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;; Snapshots are a CACHE, never primary state: the op log stays the source of
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;; truth. A snapshot stores a materialised document at a sequence in the persist
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;; KV; cached reads start from it and replay only the tail of ops, so they return
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;; a document IDENTICAL to a full replay — just faster. Drop the snapshot and
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;; nothing is lost.
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;;
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;; Requires (loaded by harness): store.sx (+ doc.sx, persist event/log/kv/api).
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(define content/-snap-key (fn (doc-id) (str "content-snap:" doc-id)))
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;; take a snapshot of the current head at the current version. Returns the seq.
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(define
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content/snapshot!
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(fn
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(b doc-id)
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(let
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((seq (content/version-count b doc-id)))
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(begin (persist/kv-put b (content/-snap-key doc-id) {:doc (content/head b doc-id) :seq seq}) seq))))
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(define
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content/-snapshot
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(fn
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(b doc-id)
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(if
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(persist/kv-has? b (content/-snap-key doc-id))
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(persist/kv-get b (content/-snap-key doc-id))
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nil)))
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(define
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content/snapshot-seq
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(fn
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(b doc-id)
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(let
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((s (content/-snapshot b doc-id)))
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(if (= s nil) 0 (get s :seq)))))
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(define
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content/has-snapshot?
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(fn (b doc-id) (persist/kv-has? b (content/-snap-key doc-id))))
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(define
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content/drop-snapshot!
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(fn (b doc-id) (persist/kv-delete b (content/-snap-key doc-id))))
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;; ── cached reads (transparent: identical result to store.sx replay) ──
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(define
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content/-tail-ops
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(fn
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(b doc-id from to)
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(map
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(fn (ev) (persist/event-data ev))
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(filter
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(fn
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(ev)
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(and
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(> (persist/event-seq ev) from)
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(<= (persist/event-seq ev) to)))
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(content/log b doc-id)))))
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(define
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content/head-cached
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(fn
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(b doc-id)
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(let
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((snap (content/-snapshot b doc-id)))
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(if
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(= snap nil)
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(content/head b doc-id)
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(doc-apply-all
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(get snap :doc)
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(content/-tail-ops
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b
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doc-id
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(get snap :seq)
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(content/version-count b doc-id)))))))
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(define
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content/at-cached
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(fn
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(b doc-id seq)
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(let
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((snap (content/-snapshot b doc-id)))
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(if
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(or (= snap nil) (< seq (get snap :seq)))
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(content/at b doc-id seq)
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(doc-apply-all
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(get snap :doc)
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(content/-tail-ops b doc-id (get snap :seq) seq))))))
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