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One IRef seam: watches/validators/meta over atom, var, and agent

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add-watch/remove-watch/set-validator!/get-validator were atom-only; the
atom ctor ignored :meta and :validator; watching a var crashed. Now the
ARef contract is one seam: atoms keep their record slots (hot path
unchanged), every other reference type registers a predicate and stores
watches/validators in identity-keyed side tables, and notifies at its
mutation points. Vars notify on root changes (def on a watched var,
var-set outside a thread binding, alter-var-root — thread-binding sets
don't notify, like the JVM); agents notify per action. The def-var! wrap
costs two weak-table probes per def and does IRef work only on a watched
var.

Ctor options follow ARef: the validator gates the initial value
(IllegalStateException 'Invalid reference state' — also the class for
rejected swap!/reset!), :meta must be a map (else ClassCastException),
nil allowed. meta reads any reference through the identity side-table
(the type-gated fall-through is gone); alter-meta!/reset-meta! work on
non-var references.

Runtime-only (no re-mint). 9 JVM-certified corpus rows; spec entry; cts
baseline 5781 -> 5805 pass, 73 baselined namespaces (the residual error
in the watch namespaces is their STM ref section — refs stay out of
scope).
This commit is contained in:
Yogthos 2026-07-02 09:07:00 -04:00
parent 257f822825
commit f80f9aab4b
8 changed files with 203 additions and 42 deletions
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35
host/chez/java/concurrency.ss
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@ -151,16 +151,31 @@
(mutable queue) (mutable running?) mu cv)
(nongenerative jolt-agent-v1))
;; (agent state) / (agent state :validator f :error-mode m :meta x): only :validator
;; has runtime behaviour here; other opts are accepted/ignored.
;; (agent state :meta m :validator f :error-mode e): the ARef ctor contract like
;; atom's — the validator runs against the initial state, :meta must be a map.
;; :error-mode is accepted/ignored (jolt agents are always :fail).
(define (jolt-agent-new state . opts)
(let loop ((o opts) (validator jolt-nil))
(let loop ((o opts) (validator jolt-nil) (m #f))
(cond
((or (null? o) (null? (cdr o)))
(make-jolt-agent state jolt-nil validator (vector '() '()) #f (make-mutex) (make-condition)))
(let ((a (make-jolt-agent state jolt-nil validator (vector '() '()) #f (make-mutex) (make-condition))))
(when (and (not (jolt-nil? validator)) (jolt-not (jolt-invoke validator state)))
(jolt-iref-state-throw))
(when (and m (not (jolt-nil? m)))
(unless (jolt-map? m)
(jolt-throw (jolt-host-throwable
"java.lang.ClassCastException"
(string-append "class " (jolt-class-name m)
" cannot be cast to class clojure.lang.IPersistentMap"))))
(hashtable-set! meta-table a m))
a))
((and (keyword-t? (car o)) (string=? (keyword-t-name (car o)) "validator"))
(loop (cddr o) (cadr o)))
(else (loop (cddr o) validator)))))
(loop (cddr o) (cadr o) m))
((and (keyword-t? (car o)) (string=? (keyword-t-name (car o)) "meta"))
(loop (cddr o) validator (cadr o)))
(else (loop (cddr o) validator m)))))
;; agents are watchable IRefs; the worker notifies on each state change.
(register-iref-arm! jolt-agent?)
;; The action queue is an amortized-O(1) FIFO held as a mutable #(out in): `out` is
;; the front, `in` holds sends reversed onto it (an append-to-a-list send was O(n)).
@ -189,11 +204,13 @@
(guard (e (#t (with-mutex (jolt-agent-mu a)
(jolt-agent-err-set! a e)
(condition-broadcast (jolt-agent-cv a)))))
(let ((nv (apply jolt-invoke (car act) (jolt-agent-state a) (cdr act))))
(let* ((old (jolt-agent-state a))
(nv (apply jolt-invoke (car act) old (cdr act))))
(let ((vf (jolt-agent-validator a)))
(when (and (not (jolt-nil? vf)) (jolt-not (jolt-invoke vf nv)))
(error #f "Invalid reference state")))
(jolt-agent-state-set! a nv)))
(jolt-iref-state-throw)))
(jolt-agent-state-set! a nv)
(iref-notify a old nv)))
(loop)))))
;; send / send-off: enqueue the action, start the worker if idle. (jolt treats them