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rose-ash/lib/artdag/plan.sx
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artdag: Phase 3 Plan — topological batches + parallelism cap + dirty plan + 18 tests
plan.sx schedules a dag into Kahn-wave batches (parallel-safe), splits waves
wider than a cap into sub-batches, and plans incrementally over the dirty
closure only (out-of-set deps treated as satisfied cache hits). plan 18/18,
total 54/54.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-07 11:56:13 +00:00

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; lib/artdag/plan.sx — Phase 3: schedule a DAG (or its dirty subset) into
; topological batches under a max-parallelism cap. A batch is a set of nodes
; whose deps are all satisfied by earlier batches, so they run in parallel.
; cap <= 0 means unlimited width. Depends on dag.sx and analyze.sx.
; inputs of id that also lie inside the scheduled set (out-of-set deps are
; treated as already satisfied — e.g. clean cache hits in an incremental plan).
(define
artdag/-deps-in
(fn
(dag id sset)
(filter
(fn (in) (artdag/member? in sset))
(artdag/node-inputs (artdag/dag-get dag id)))))
(define
artdag/-ready-in
(fn
(dag sset placed)
(filter
(fn
(id)
(and
(not (artdag/member? id placed))
(artdag/all-in? (artdag/-deps-in dag id sset) placed)))
(artdag/sort-strings sset))))
(define
artdag/-batch-loop
(fn
(dag sset placed batches)
(if
(= (len placed) (len sset))
batches
(let
((wave (artdag/-ready-in dag sset placed)))
(artdag/-batch-loop
dag
sset
(concat placed wave)
(concat batches (list wave)))))))
; split a wave into consecutive chunks of at most n (sorted order preserved).
(define
artdag/-chunk
(fn
(xs n)
(if
(<= (len xs) n)
(list xs)
(cons
(slice xs 0 n)
(artdag/-chunk (slice xs n (len xs)) n)))))
(define
artdag/-cap-split
(fn
(batches cap)
(if
(<= cap 0)
batches
(reduce
(fn (acc b) (concat acc (artdag/-chunk b cap)))
(list)
batches))))
; schedule an explicit set of node-ids into capped topological batches.
(define
artdag/plan-subset
(fn
(dag node-ids cap)
(artdag/-cap-split (artdag/-batch-loop dag node-ids (list) (list)) cap)))
; full plan over every node in the dag.
(define
artdag/plan
(fn (dag cap) (artdag/plan-subset dag (keys (artdag/dag-nodes dag)) cap)))
; incremental plan: schedule only the dirty closure of the changed nodes.
(define
artdag/plan-dirty
(fn
(dag changed cap)
(artdag/plan-subset dag (artdag/dirty-closure dag changed) cap)))
; ---- plan inspection ----
(define artdag/plan-batches (fn (plan) (len plan)))
(define
artdag/plan-width
(fn
(plan)
(reduce (fn (m b) (if (> (len b) m) (len b) m)) 0 plan)))
(define
artdag/plan-flatten
(fn (plan) (reduce (fn (acc b) (concat acc b)) (list) plan)))
(define artdag/plan-size (fn (plan) (len (artdag/plan-flatten plan))))