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;; -*- mode: Lisp; Syntax: Common-Lisp; Package: cells; -*-
Cells -- Automatic Dataflow Managememnt
Copyright (C) 1995, 2006 by Kenneth Tilton
This library is free software; you can redistribute it and/or
modify it under the terms of the Lisp Lesser GNU Public License
(, known as the LLGPL.
This library is distributed WITHOUT ANY WARRANTY; without even
See the Lisp Lesser GNU Public License for more details.
(in-package :cells)
;----------------- change detection ---------------------------------
(defun c-no-news (c new-value old-value)
;;; (trc nil "c-no-news > checking news between" newvalue oldvalue)
(bif (test (c-unchanged-test (c-model c) (c-slot-name c)))
(funcall test new-value old-value)
(eql new-value old-value)))
(defmacro def-c-unchanged-test ((class slotname) &body test)
`(defmethod c-unchanged-test ((self ,class) (slotname (eql ',slotname)))
(defmethod c-unchanged-test (self slotname)
(declare (ignore self slotname))
; --- data pulse (change ID) management -------------------------------------
(defparameter *one-pulse?* nil)
(defun data-pulse-next (pulse-info)
(declare (ignorable pulse-info))
(unless *one-pulse?*
;(trc "dp-next> " (1+ *data-pulse-id*) pulse-info)
#+chill (when *c-debug*
(push (list :data-pulse-next pulse-info) *istack*))
(incf *data-pulse-id*)))
(defun c-currentp (c)
(eql (c-pulse c) *data-pulse-id*))
(defun c-pulse-update (c key)
(declare (ignorable key))
(unless (find key '(:valid-uninfluenced))
(trc nil "!!!!!!! c-pulse-update updating !!!!!!!!!!" *data-pulse-id* c key :prior-pulse (c-pulse c)))
(assert (>= *data-pulse-id* (c-pulse c)) ()
"Current DP ~a not GE pulse ~a of cell ~a" *data-pulse-id* (c-pulse c) c)
(setf (c-pulse c) *data-pulse-id*))
;--------------- propagate ----------------------------
; n.b. the cell argument may have been optimized away,
; though it is still receiving final processing here.
(defparameter *per-cell-handler* nil)
(defun c-propagate (c prior-value prior-value-supplied)
(when *one-pulse?*
(when *per-cell-handler*
(funcall *per-cell-handler* c prior-value prior-value-supplied)
(return-from c-propagate)))
(count-it :cpropagate)
(setf (c-pulse-last-changed c) *data-pulse-id*)
(when prior-value
(assert prior-value-supplied () "How can prior-value-supplied be nil if prior-value is not?!! ~a" c))
(let (*depender* *call-stack* ;; I think both need clearing, cuz we are neither depending nor calling when we prop to callers
(*c-prop-depth* (1+ *c-prop-depth*))
(*defer-changes* t))
(trc nil "c.propagate clearing *depender*" c)
;------ debug stuff ---------
(when *stop*
(princ #\.)(princ #\!)
(return-from c-propagate))
(trc nil "c.propagate> !!!!!!! propping" c (c-value c) :caller-ct (length (c-callers c)))
#+slow (trc nil "c.propagate> !!!! new value" (c-value c) :prior-value prior-value :caller-ct (length (c-callers c)) c)
(when *c-debug*
(when (> *c-prop-depth* 250)
(trc nil "c.propagate deep" *c-prop-depth* (c-model c) (c-slot-name c) #+nah c))
(when (> *c-prop-depth* 300)
(c-break "c.propagate looping ~c" c)))
; --- manifest new value as needed ---
; 20061030 Trying first because doomed instances may be interested in callers
; who will decide to propagate. If a family instance kids slot is changing, a doomed kid
; will be out of the kids but not yet quiesced. If the propagation to this rule asks the kid
; to look at its siblings (say a view instance being deleted from a stack who looks to the psib
; pb to decide its own pt), the doomed kid will still have a parent but not be in its kids slot
; when it goes looking for a sibling relative to its position.
(when (and prior-value-supplied
(md-slot-owning? (type-of (c-model c)) (c-slot-name c)))
(trc nil "c.propagate> contemplating lost" (qci c))
(flet ((listify (x) (if (listp x) x (list x))))
(bif (lost (set-difference (listify prior-value) (listify (c-value c))))
(trc nil "prop nailing owned!!!!!!!!!!!" (qci c) :lost (length lost)) ;; :leaving (c-value c))
(loop for l in lost
when (numberp l)
do (break "got num ~a" (list l (type-of (c-model c))(c-slot-name c)
(md-slot-owning? (type-of (c-model c)) (c-slot-name c)))))
(mapcar 'not-to-be lost))
(trc nil "no owned lost!!!!!"))))
; propagation to callers jumps back in front of client slot-value-observe handling in cells3
; because model adopting (once done by the kids change handler) can now be done in
; shared-initialize (since one is now forced to supply the parent to make-instance).
; we wnat it here to support (eventually) state change rollback. change handlers are
; expected to have side-effects, so we want to propagate fully and be sure no rule
; wants a rollback before starting with the side effects.
(progn ;; unless (member (c-lazy c) '(t :always :once-asked)) ;; 2006-09-26 still fuzzy on this
(c-propagate-to-callers c))
(trc nil "c.propagate observing" c)
; this next assertion is just to see if we can ever come this way twice. If so, just
; make it a condition on whether to observe
(when t ; breaks algebra (> *data-pulse-id* (c-pulse-observed c))
(setf (c-pulse-observed c) *data-pulse-id*)
(slot-value-observe (c-slot-name c) (c-model c)
(c-value c) prior-value prior-value-supplied c))
; with propagation done, ephemerals can be reset. we also do this in c-awaken, so
; let the fn decide if C really is ephemeral. Note that it might be possible to leave
; this out and use the datapulse to identify obsolete ephemerals and clear them
; when read. That would avoid ever making again bug I had in which I had the reset inside slot-value-observe,
; thinking that that always followed propagation to callers. It would also make
; debugging easier in that I could find the last ephemeral value in the inspector.
; would this be bad for persistent CLOS, in which a DB would think there was still a link
; between two records until the value actually got cleared?
(ephemeral-reset c)))
; --- slot change -----------------------------------------------------------
(defmacro defobserver (slotname &rest args &aux (aroundp (eq :around (first args))))
(when aroundp (setf args (cdr args)))
(when (find slotname '(value kids))
(break "d: did you mean .value or .kids when you coded ~a?" slotname))
(destructuring-bind ((&optional (self-arg 'self) (new-varg 'new-value)
(oldvarg 'old-value) (oldvargboundp 'old-value-boundp) (cell-arg 'c))
&body output-body) args
(eval-when (:compile-toplevel :load-toplevel :execute)
(setf (get ',slotname :output-defined) t))
,(if (eql (last1 output-body) :test)
(let ((temp1 (gensym))
(loc-self (gensym)))
`(defmethod slot-value-observe #-(or cormanlisp) ,(if aroundp :around 'progn)
((slotname (eql ',slotname)) ,self-arg ,new-varg ,oldvarg ,oldvargboundp ,cell-arg)
(let ((,temp1 (bump-output-count ,slotname))
(,loc-self ,(if (listp self-arg)
(car self-arg)
(when (and ,oldvargboundp ,oldvarg)
(format t "~&output ~d (~a ~a) old: ~a" ,temp1 ',slotname ,loc-self ,oldvarg ,cell-arg))
(format t "~&output ~d (~a ~a) new: ~a" ,temp1 ',slotname ,loc-self ,new-varg ,cell-arg))))
`(defmethod slot-value-observe
#-(or cormanlisp) ,(if aroundp :around 'progn)
((slotname (eql ',slotname)) ,self-arg ,new-varg ,oldvarg ,oldvargboundp ,cell-arg)
(declare (ignorable
,@(flet ((arg-name (arg-spec)
(etypecase arg-spec
(list (car arg-spec))
(atom arg-spec))))
(list (arg-name self-arg)(arg-name new-varg)
(arg-name oldvarg)(arg-name oldvargboundp) (arg-name cell-arg)))))
(defmacro bump-output-count (slotname) ;; pure test func
`(if (get ',slotname :outputs)
(incf (get ',slotname :outputs))
(setf (get ',slotname :outputs) 1)))
; --- recalculate dependents ----------------------------------------------------
(defmacro cll-outer (val &body body)
`(let ((outer-val ,val))
(defmacro cll-inner (expr)
`(,expr outer-val))
(export! cll-outer cll-inner)
(defun c-propagate-to-callers (c)
; We must defer propagation to callers because of an edge case in which:
; - X tells A to recalculate
; - A asks B for its current value
; - B must recalculate because it too uses X
; - if B propagates to its callers after recalculating instead of deferring it
; - B might tell H to reclaculate, where H decides this time to use A
; - but A is in the midst of recalculating, and cannot complete until B returns.
; but B is busy eagerly propagating. "This time" is important because it means
; there is no way one can reliably be sure H will not ask for A
(when (find-if-not (lambda (caller)
(and (c-lazy caller) ;; slight optimization
(member (c-lazy caller) '(t :always :once-asked))))
(c-callers c))
(let ((causation (cons c *causation*))) ;; in case deferred
#+slow (trc nil "c.propagate-to-callers > queueing notifying callers" (c-callers c))
(with-integrity (:tell-dependents c)
(assert (null *call-stack*))
(assert (null *depender*))
(if (mdead (c-model c))
(trc nil "WHOAA!!!! dead by time :tell-deps dispatched; bailing" c)
(let ((*causation* causation))
(trc nil "c.propagate-to-callers > actually notifying callers of" c (c-callers c))
#+c-debug (dolist (caller (c-callers c))
(assert (find c (cd-useds caller)) () "test 1 failed ~a ~a" c caller))
#+c-debug (dolist (caller (copy-list (c-callers c))) ;; following code may modify c-callers list...
(trc nil "PRE-prop-CHECK " c :caller caller (c-state caller) (c-lazy caller))
(unless (or (eq (c-state caller) :quiesced) ;; watch for quiesced
(member (c-lazy caller) '(t :always :once-asked)))
(assert (find c (cd-useds caller))() "Precheck Caller ~a of ~a does not have it as used" caller c)
(dolist (caller (c-callers c))
(trc nil "propagating to caller iterates" c :caller caller (c-state caller) (c-lazy caller))
(block do-a-caller
(unless (or (eq (c-state caller) :quiesced) ;; watch for quiesced
(member (c-lazy caller) '(t :always :once-asked)))
(unless (find c (cd-useds caller))
(trc "WHOA!!!! Bailing on Known caller:" caller :does-not-in-its-used c)
(return-from do-a-caller))
#+slow (trc nil "propagating to caller is used" c :caller caller (c-currentp c))
(let ((*trc-ensure* (trcp c)))
; we just calculate-and-set at the first level of dependency because
; we do not need to check the next level (as ensure-value-is-current does)
; because we already know /this/ notifying dependency has changed, so yeah,
; any first-level cell /has to/ recalculate. (As for ensuring other dependents
; of the first level guy are current, that happens automatically anyway JIT on
; any read.) This is a minor efficiency enhancement since ensure-value-is-current would
; very quickly decide it has to re-run, but maybe it makes the logic clearer.
;(ensure-value-is-current caller :prop-from c) <-- next was this, but see above change reason
(unless (c-currentp caller) ; happens if I changed when caller used me in current pulse
(calculate-and-set caller :propagate c))))))))))))
(defparameter *the-unpropagated* nil)
(defmacro with-one-datapulse ((&key (per-cell nil per-cell?) (finally nil finally?)) &body body)
`(call-with-one-datapulse (lambda () ,@body)
,@(when per-cell? `(:per-cell (lambda (c prior-value prior-value-boundp)
(declare (ignorable c prior-value prior-value-boundp))
,@(when finally? `(:finally (lambda (cs) (declare (ignorable cs)) ,finally)))))
(defun call-with-one-datapulse
(f &key
(per-cell (lambda (c prior-value prior-value?)
(unless (find c *the-unpropagated* :key 'car)
(pushnew (list c prior-value prior-value?) *the-unpropagated*))))
(finally (lambda (cs)
(print `(finally sees ,*data-pulse-id* ,cs))
;(trace c-propagate ensure-value-is-current)
(loop for (c prior-value prior-value?) in (nreverse cs) do
(c-propagate c prior-value prior-value?)))))
(assert (not *one-pulse?*))
(data-pulse-next :client-prop)
(trc "call-with-one-datapulse bumps pulse" *data-pulse-id*)
(funcall finally
(let ((*one-pulse?* t)
(*per-cell-handler* per-cell)
(*the-unpropagated* nil))
(funcall f)
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