4cf95dc27c
Adds clojure.core.async's higher-level dataflow API as a Clojure overlay (stdlib/clojure/core/async.clj) over jolt's native channel primitives, plus clojure.core.async.lab. The native layer (host/chez/java/async.ss) gains offer!/poll!, put specs and :priority/:default in alts!, a transducer ex-handler arg to chan, unblocking-buffer?, promise-buffer, and on-caller? handling for put!/take!. The overlay covers alts!/pipe/pipeline/split/ reduce/transduce/into/take/mult/mix/pub-sub/map/merge/onto-chan/to-chan and the deprecated map</map>/filter>/... family (rewritten as go-loops since the JVM versions reify the impl handler protocol jolt doesn't expose). Loading: the native primitives pre-seed clojure.core.async, so the loader now drops it from the loaded set and a require pulls the overlay from the source roots like clojure.test (AOT-bundled into built binaries). Running clojure/core.async's own suite shook out two general bugs: - :refer with a list form, (:require [ns :refer (a b c)]), dropped the names (only the vector form was handled) — chez-register-spec! now accepts both. - (range 0) / (range 5 5) returned nil instead of the empty seq () — empty ranges now match Clojure, so (= () (range 0)) holds. Suite: async_test 15/20, pipeline_test 7/7, timers_test 2/2, lab_test 2/2. The five non-passing async_test cases all assert JVM go-machine limitations jolt's thread-based model is a superset of (the 1024 pending-op cap, parking ops that must throw outside a go block, expanding-transducer buffer backpressure) or dispatch-thread identity, not data semantics. make test green (0 new divergences, +4 range corpus rows), shakesmoke byte-identical.
315 lines
16 KiB
Scheme
315 lines
16 KiB
Scheme
;; async.ss — clojure.core.async channel primitives on real OS threads.
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;;
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;; A `go` block is an OS thread and a channel is a Chez mutex+condition blocking
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;; queue: <! / >! are the blocking <!! / >!! (they "park" by blocking the thread),
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;; and work ANYWHERE — no CPS transform, no go-only restriction. Real parallelism,
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;; shared heap. This is a superset of the JVM model: it has no fixed go-block
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;; thread pool, no MAX-QUEUE-SIZE on pending ops, and parking ops are legal outside
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;; a go block. One OS thread per go block (fine for typical use).
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;;
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;; Channel: an unbuffered channel is a rendezvous (the putter blocks until its
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;; value is taken); a buffered (chan n) put blocks only when full; dropping/sliding
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;; buffers never block the putter. A transducer is applied on the put side; an
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;; optional ex-handler catches a throw from the transducer step.
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;;
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;; This file provides the primitives; the higher-level dataflow API (mult, mix,
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;; pub/sub, pipeline, map, merge, reduce, …) is a Clojure overlay over them.
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;; go/go-loop/thread are macros (mark-macro!) expanding to go-spawn. Loaded after
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;; concurrency.ss (reuses ms->duration). Requires a threaded Chez build.
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;; --- buffers ----------------------------------------------------------------
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(define-record-type async-buffer (fields n kind) (nongenerative async-buffer-v1))
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(define (jolt-async-buffer n) (make-async-buffer n 'fixed))
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(define (jolt-async-dropping-buffer n) (make-async-buffer n 'dropping))
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(define (jolt-async-sliding-buffer n) (make-async-buffer n 'sliding))
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(define (jolt-async-unblocking-buffer? b)
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(if (and (async-buffer? b) (memq (async-buffer-kind b) '(dropping sliding promise))) #t #f))
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;; --- channels ---------------------------------------------------------------
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;; items: an amortized-O(1) FIFO held as a mutable #(out in len) — `out` is the
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;; front (pop from its head), `in` holds pushed entries reversed onto it, `len` is
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;; the count (an append-to-a-list FIFO is O(n) per push and O(n) to measure).
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;; Each entry is (value . box); box is #f for a buffered value or a 1-slot vector
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;; for an unbuffered rendezvous put (set #t when taken, waking the putter).
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;; cap 0 + kind 'unbuffered = rendezvous; cap>0 with kind fixed/dropping/sliding.
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;; takew counts threads parked in a blocking take (so a non-blocking offer! to an
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;; unbuffered channel can tell a taker is waiting). xrf is the transducer reducing
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;; fn (or #f); exh the ex-handler (or #f).
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(define-record-type async-chan
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(fields mu cv (mutable items) cap kind (mutable closed?) (mutable xrf) (mutable takew) exh)
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(nongenerative async-chan-v2))
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(define (ac-qnew) (vector '() '() 0))
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(define (ac-qlen ch) (vector-ref (async-chan-items ch) 2))
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(define (ac-qempty? ch) (fx=? 0 (vector-ref (async-chan-items ch) 2)))
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(define (ac-qpush! ch entry)
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(let ((q (async-chan-items ch)))
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(vector-set! q 1 (cons entry (vector-ref q 1)))
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(vector-set! q 2 (fx+ 1 (vector-ref q 2)))))
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(define (ac-qfront! q) ; ensure `out` is non-empty: out := reverse in
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(when (null? (vector-ref q 0))
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(vector-set! q 0 (reverse (vector-ref q 1)))
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(vector-set! q 1 '())))
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(define (ac-qpop! ch)
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(let ((q (async-chan-items ch)))
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(ac-qfront! q)
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(let ((out (vector-ref q 0)))
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(vector-set! q 0 (cdr out))
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(vector-set! q 2 (fx- (vector-ref q 2) 1))
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(car out))))
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(define (ac-qdrop-oldest! ch)
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(let ((q (async-chan-items ch)))
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(ac-qfront! q)
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(vector-set! q 0 (cdr (vector-ref q 0)))
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(vector-set! q 2 (fx- (vector-ref q 2) 1))))
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;; enqueue honoring the buffer kind (used by the transducer step + buffered puts).
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(define (ac-buf-give! ch v)
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(case (async-chan-kind ch)
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((dropping) (when (< (ac-qlen ch) (async-chan-cap ch)) (ac-qpush! ch (cons v #f))))
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((sliding) (when (>= (ac-qlen ch) (async-chan-cap ch)) (ac-qdrop-oldest! ch))
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(ac-qpush! ch (cons v #f)))
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(else (ac-qpush! ch (cons v #f)))) ; fixed: caller ensured room
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(condition-broadcast (async-chan-cv ch)))
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;; A transducer is a jolt fn (xform); (xform add-rf) yields the channel's reducing
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;; fn. add-rf: 0-arg init, 1-arg completion, 2-arg step (enqueue the output). A
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;; `reduced` step result closes the channel.
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(define (ac-make-add-rf ch)
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(lambda args
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(cond ((null? args) ch) ; init
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((null? (cdr args)) (car args)) ; completion
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(else (ac-buf-give! ch (cadr args)) (car args))))) ; step
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;; run the transducer step (or completion) guarded by the channel's ex-handler:
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;; if the xform throws and exh returns non-nil, that value is added to the buffer.
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(define (ac-xrf-apply ch . v)
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(let ((xrf (async-chan-xrf ch)) (exh (async-chan-exh ch)))
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(guard (e (#t (if exh
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(let ((else (jolt-invoke exh e)))
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(unless (jolt-nil? else) (ac-buf-give! ch else))
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(async-chan-xrf ch)) ; treat as non-reduced
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(raise e))))
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(apply jolt-invoke xrf ch v))))
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(define (ac-make cap kind xrf) (make-async-chan (make-mutex) (make-condition) (ac-qnew) cap kind #f xrf 0 #f))
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(define (ac-make/exh cap kind exh) (make-async-chan (make-mutex) (make-condition) (ac-qnew) cap kind #f #f 0 exh))
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;; (chan) | (chan n) | (chan buf) | (chan n|buf xform) | (chan n|buf xform exh)
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(define (jolt-async-chan . args)
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(let ((buf (if (pair? args) (car args) jolt-nil))
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(xform (if (and (pair? args) (pair? (cdr args))) (cadr args) jolt-nil))
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(exh (if (and (pair? args) (pair? (cdr args)) (pair? (cddr args))) (caddr args) jolt-nil)))
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(let-values (((cap kind)
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(cond ((async-buffer? buf) (values (async-buffer-n buf) (async-buffer-kind buf)))
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((and (number? buf) (> buf 0)) (values buf 'fixed))
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(else (values 0 'unbuffered)))))
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(let ((ch (ac-make/exh cap kind (if (jolt-nil? exh) #f exh))))
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(unless (jolt-nil? xform)
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(async-chan-xrf-set! ch (jolt-invoke xform (ac-make-add-rf ch))))
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ch))))
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;; close! (idempotent): mark closed, flush a stateful transducer's completion, and
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;; wake everyone. ac-close! assumes the lock is held; the public form takes it.
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(define (ac-close! ch)
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(unless (async-chan-closed? ch)
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(async-chan-closed?-set! ch #t)
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(when (async-chan-xrf ch) (guard (e (#t #f)) (ac-xrf-apply ch)))
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(condition-broadcast (async-chan-cv ch)))
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jolt-nil)
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(define (jolt-async-close! ch) (with-mutex (async-chan-mu ch) (ac-close! ch)))
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;; >! / >!! — put, blocking. false if closed; nil may not be put. With a
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;; transducer the value is run through it (one put -> zero or more channel values);
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;; a `reduced` result closes the channel.
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(define (jolt-async-give ch v)
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(when (jolt-nil? v) (jolt-throw (jolt-host-throwable "java.lang.IllegalArgumentException" "Can't put nil on a channel")))
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(with-mutex (async-chan-mu ch)
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(cond
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((async-chan-closed? ch) #f)
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((async-chan-xrf ch)
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(let ((r (ac-xrf-apply ch v)))
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(when (jolt-reduced? r) (ac-close! ch))
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#t))
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(else
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(case (async-chan-kind ch)
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((dropping sliding) (ac-buf-give! ch v) #t)
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;; a promise channel takes ONE value, delivered to every taker; further
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;; puts are dropped. Never blocks.
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((promise) (when (ac-qempty? ch)
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(ac-qpush! ch (cons v #f)) (condition-broadcast (async-chan-cv ch)))
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#t)
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(else
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(if (> (async-chan-cap ch) 0)
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(let loop () ; buffered fixed: wait for room
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(cond ((async-chan-closed? ch) #f)
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((< (ac-qlen ch) (async-chan-cap ch))
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(ac-qpush! ch (cons v #f)) (condition-broadcast (async-chan-cv ch)) #t)
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(else (condition-wait (async-chan-cv ch) (async-chan-mu ch)) (loop))))
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(let ((box (vector #f))) ; unbuffered: rendezvous
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(ac-qpush! ch (cons v box))
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(condition-broadcast (async-chan-cv ch))
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(let loop ()
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(cond ((vector-ref box 0) #t)
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((async-chan-closed? ch) #f)
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(else (condition-wait (async-chan-cv ch) (async-chan-mu ch)) (loop))))))))))))
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;; remove + return the head value, waking a parked rendezvous putter.
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(define (ac-take-head! ch)
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(let* ((entry (ac-qpop! ch)) (v (car entry)) (box (cdr entry)))
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(when box (vector-set! box 0 #t))
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(condition-broadcast (async-chan-cv ch))
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v))
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;; peek the front value without removing it (promise channels keep their value).
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(define (ac-peek ch)
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(let ((q (async-chan-items ch)))
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(ac-qfront! q)
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(car (car (vector-ref q 0)))))
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;; <! / <!! — take, blocking. Drains buffered values, then nil once closed + empty.
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;; A promise channel PEEKS — its one value stays for every taker.
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(define (jolt-async-take ch)
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(with-mutex (async-chan-mu ch)
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(let loop ()
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(cond ((eq? (async-chan-kind ch) 'promise)
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(cond ((not (ac-qempty? ch)) (ac-peek ch))
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((async-chan-closed? ch) jolt-nil)
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(else (ac-take-wait ch) (loop))))
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((not (ac-qempty? ch)) (ac-take-head! ch))
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((async-chan-closed? ch) jolt-nil)
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(else (ac-take-wait ch) (loop))))))
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;; park in a take, tracking the waiter count so a concurrent offer! to an
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;; unbuffered channel can see that a taker is ready.
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(define (ac-take-wait ch)
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(async-chan-takew-set! ch (fx+ 1 (async-chan-takew ch)))
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(condition-wait (async-chan-cv ch) (async-chan-mu ch))
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(async-chan-takew-set! ch (fx- (async-chan-takew ch) 1)))
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;; non-blocking take for alts!/poll!: a value, jolt-nil (closed+empty), or ac-poll-empty.
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(define ac-poll-empty (list 'empty))
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(define (ac-poll! ch)
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(with-mutex (async-chan-mu ch)
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(cond ((and (eq? (async-chan-kind ch) 'promise) (not (ac-qempty? ch))) (ac-peek ch))
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((not (ac-qempty? ch)) (ac-take-head! ch))
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((async-chan-closed? ch) jolt-nil)
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(else ac-poll-empty))))
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;; non-blocking give: 'ok (accepted), 'full (would block), or 'closed.
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(define (ac-try-give! ch v)
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(when (jolt-nil? v) (jolt-throw (jolt-host-throwable "java.lang.IllegalArgumentException" "Can't put nil on a channel")))
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(with-mutex (async-chan-mu ch)
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(cond
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((async-chan-closed? ch) 'closed)
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((async-chan-xrf ch) (let ((r (ac-xrf-apply ch v)))
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(when (jolt-reduced? r) (ac-close! ch)) 'ok))
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(else
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(case (async-chan-kind ch)
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((dropping sliding) (ac-buf-give! ch v) 'ok)
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((promise) (when (ac-qempty? ch) (ac-qpush! ch (cons v #f))
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(condition-broadcast (async-chan-cv ch))) 'ok)
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(else
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(cond
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((> (async-chan-cap ch) 0)
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(if (< (ac-qlen ch) (async-chan-cap ch))
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(begin (ac-qpush! ch (cons v #f)) (condition-broadcast (async-chan-cv ch)) 'ok)
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'full))
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;; unbuffered: only immediate if a taker is parked to receive it.
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((> (async-chan-takew ch) 0)
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(let ((box (vector #f)))
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(ac-qpush! ch (cons v box))
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(condition-broadcast (async-chan-cv ch))
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'ok))
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(else 'full))))))))
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;; offer! / poll! — never block. offer! returns #t/#f(closed) on completion, nil if
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;; it would block; poll! returns a value, nil (closed+empty), or the ::none sentinel.
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(define cca-none (keyword "clojure.core.async" "none"))
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(define (jolt-async-offer! ch v)
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(case (ac-try-give! ch v) ((ok) #t) ((closed) #f) (else jolt-nil)))
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(define (jolt-async-poll! ch)
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(let ((r (ac-poll! ch))) (if (eq? r ac-poll-empty) cca-none r)))
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;; (timeout ms) — a channel that closes after ms milliseconds.
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(define (jolt-async-timeout ms)
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(let ((w (ac-make 0 'unbuffered #f)))
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(fork-thread (lambda () (sleep (ms->duration ms)) (jolt-async-close! w)))
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w))
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;; (put! ch v [cb [on-caller?]]) — async put, optional completion callback. If the
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;; put completes immediately and on-caller? (default #t), the callback runs on the
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;; calling thread; otherwise on another thread. Returns true unless already closed.
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(define (jolt-async-put! ch v . rest)
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(let* ((cb (if (pair? rest) (car rest) jolt-nil))
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(on-caller? (if (and (pair? rest) (pair? (cdr rest))) (jolt-truthy? (cadr rest)) #t))
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(call-cb (lambda (ok) (unless (jolt-nil? cb) (jolt-invoke cb ok)))))
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(case (ac-try-give! ch v)
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((ok) (if on-caller? (call-cb #t) (fork-thread (lambda () (call-cb #t)))) #t)
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((closed) (if on-caller? (call-cb #f) (fork-thread (lambda () (call-cb #f)))) #f)
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(else (fork-thread (lambda () (call-cb (jolt-async-give ch v)))) #t))))
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;; (take! ch cb [on-caller?]) — async take. Same on-caller? rule as put!.
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(define (jolt-async-take! ch cb . rest)
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(let* ((on-caller? (if (pair? rest) (jolt-truthy? (car rest)) #t))
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(call-cb (lambda (v) (unless (jolt-nil? cb) (jolt-invoke cb v))))
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(r (ac-poll! ch)))
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(cond
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((eq? r ac-poll-empty) (fork-thread (lambda () (call-cb (jolt-async-take ch)))))
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(on-caller? (call-cb r))
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(else (fork-thread (lambda () (call-cb r)))))
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jolt-nil))
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;; (go-spawn thunk) — run thunk on a thread; return a buffered(1) channel that
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;; conveys its value once then closes (a nil result just closes). Dynamic bindings
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;; are conveyed (Chez inherits the thread-parameter at fork; we install explicitly).
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(define (async-go-spawn thunk)
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(let ((w (ac-make 1 'fixed #f)) (snap (dyn-binding-stack)))
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(fork-thread
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(lambda ()
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(dyn-binding-stack snap)
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(let ((r (guard (e (#t (cons #f e))) (cons #t (jolt-invoke thunk)))))
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(when (and (car r) (not (jolt-nil? (cdr r)))) (jolt-async-give w (cdr r)))
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(jolt-async-close! w))))
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w))
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;; --- macros (expander fns over the reader forms) ----------------------------
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(define cca-go-spawn-sym (jolt-symbol "clojure.core.async" "go-spawn"))
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(define cca-go-sym (jolt-symbol "clojure.core.async" "go"))
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(define cca-fn*-sym (jolt-symbol #f "fn*"))
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(define cca-loop-sym (jolt-symbol #f "loop"))
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;; (go body...) -> (clojure.core.async/go-spawn (fn* [] body...))
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(define (cca-go-macro . body)
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(jolt-list cca-go-spawn-sym (apply jolt-list cca-fn*-sym empty-pvec body)))
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;; (go-loop bindings body...) -> (go (loop bindings body...))
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(define (cca-go-loop-macro bindings . body)
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(jolt-list cca-go-sym (apply jolt-list cca-loop-sym bindings body)))
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;; (thread body...) — a real OS thread (same shape as go here).
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(define (cca-thread-macro . body)
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(jolt-list cca-go-spawn-sym (apply jolt-list cca-fn*-sym empty-pvec body)))
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;; --- install clojure.core.async ---------------------------------------------
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(define (cca-def! name v) (def-var! "clojure.core.async" name v))
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(cca-def! "chan" jolt-async-chan)
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(cca-def! "promise-chan" (lambda args (ac-make 1 'promise #f)))
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(cca-def! "chan?" async-chan?)
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(cca-def! "buffer" jolt-async-buffer)
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(cca-def! "dropping-buffer" jolt-async-dropping-buffer)
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(cca-def! "sliding-buffer" jolt-async-sliding-buffer)
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(cca-def! "__promise-buffer" (lambda () (make-async-buffer 1 'promise)))
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(cca-def! "unblocking-buffer?" jolt-async-unblocking-buffer?)
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(cca-def! "close!" jolt-async-close!)
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(cca-def! "<!" jolt-async-take) (cca-def! "<!!" jolt-async-take)
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(cca-def! ">!" jolt-async-give) (cca-def! ">!!" jolt-async-give)
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(cca-def! "timeout" jolt-async-timeout)
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(cca-def! "put!" jolt-async-put!)
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(cca-def! "take!" jolt-async-take!)
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(cca-def! "offer!" jolt-async-offer!)
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(cca-def! "go-spawn" async-go-spawn)
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;; non-blocking primitives the Clojure overlay's do-alts polls over.
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(cca-def! "__poll!" jolt-async-poll!)
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(cca-def! "__offer!" jolt-async-offer!)
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(cca-def! "go" cca-go-macro) (mark-macro! "clojure.core.async" "go")
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(cca-def! "go-loop" cca-go-loop-macro) (mark-macro! "clojure.core.async" "go-loop")
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(cca-def! "thread" cca-thread-macro) (mark-macro! "clojure.core.async" "thread")
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