1 ;;;; the basics of the PCL wrapper cache mechanism
3 ;;;; This software is part of the SBCL system. See the README file for
6 ;;;; This software is derived from software originally released by Xerox
7 ;;;; Corporation. Copyright and release statements follow. Later modifications
8 ;;;; to the software are in the public domain and are provided with
9 ;;;; absolutely no warranty. See the COPYING and CREDITS files for more
12 ;;;; copyright information from original PCL sources:
14 ;;;; Copyright (c) 1985, 1986, 1987, 1988, 1989, 1990 Xerox Corporation.
15 ;;;; All rights reserved.
17 ;;;; Use and copying of this software and preparation of derivative works based
18 ;;;; upon this software are permitted. Any distribution of this software or
19 ;;;; derivative works must comply with all applicable United States export
22 ;;;; This software is made available AS IS, and Xerox Corporation makes no
23 ;;;; warranty about the software, its performance or its conformity to any
28 ;;; Ye olde CMUCL comment follows, but it seems likely that the paper
29 ;;; that would be inserted would resemble Kiczales and Rodruigez,
30 ;;; Efficient Method Dispatch in PCL, ACM 1990. Some of the details
31 ;;; changed between that paper and "May Day PCL" of 1992; some other
32 ;;; details have changed since, but reading that paper gives the broad
35 ;;; The caching algorithm implemented:
37 ;;; << put a paper here >>
39 ;;; For now, understand that as far as most of this code goes, a cache
40 ;;; has two important properties. The first is the number of wrappers
41 ;;; used as keys in each cache line. Throughout this code, this value
42 ;;; is always called NKEYS. The second is whether or not the cache
43 ;;; lines of a cache store a value. Throughout this code, this always
46 ;;; Depending on these values, there are three kinds of caches.
48 ;;; NKEYS = 1, VALUEP = NIL
50 ;;; In this kind of cache, each line is 1 word long. No cache locking
51 ;;; is needed since all read's in the cache are a single value.
52 ;;; Nevertheless line 0 (location 0) is reserved, to ensure that
53 ;;; invalid wrappers will not get a first probe hit.
55 ;;; To keep the code simpler, a cache lock count does appear in
56 ;;; location 0 of these caches, that count is incremented whenever
57 ;;; data is written to the cache. But, the actual lookup code (see
58 ;;; make-dlap) doesn't need to do locking when reading the cache.
60 ;;; NKEYS = 1, VALUEP = T
62 ;;; In this kind of cache, each line is 2 words long. Cache locking
63 ;;; must be done to ensure the synchronization of cache reads. Line 0
64 ;;; of the cache (location 0) is reserved for the cache lock count.
65 ;;; Location 1 of the cache is unused (in effect wasted).
69 ;;; In this kind of cache, the 0 word of the cache holds the lock
70 ;;; count. The 1 word of the cache is line 0. Line 0 of these caches
73 ;;; This is done because in this sort of cache, the overhead of doing
74 ;;; the cache probe is high enough that the 1+ required to offset the
75 ;;; location is not a significant cost. In addition, because of the
76 ;;; larger line sizes, the space that would be wasted by reserving
77 ;;; line 0 to hold the lock count is more significant.
81 ;;; A cache is essentially just a vector. The use of the individual
82 ;;; `words' in the vector depends on particular properties of the
83 ;;; cache as described above.
85 ;;; This defines an abstraction for caches in terms of their most
86 ;;; obvious implementation as simple vectors. But, please notice that
87 ;;; part of the implementation of this abstraction, is the function
88 ;;; lap-out-cache-ref. This means that most port-specific
89 ;;; modifications to the implementation of caches will require
90 ;;; corresponding port-specific modifications to the lap code
92 (defmacro cache-vector-ref (cache-vector location)
93 `(svref (the simple-vector ,cache-vector)
94 (sb-ext:truly-the fixnum ,location)))
96 (defmacro cache-vector-size (cache-vector)
97 `(array-dimension (the simple-vector ,cache-vector) 0))
99 (defun allocate-cache-vector (size)
100 (make-array size :adjustable nil))
102 (defmacro cache-vector-lock-count (cache-vector)
103 `(cache-vector-ref ,cache-vector 0))
105 (defun flush-cache-vector-internal (cache-vector)
107 (fill (the simple-vector cache-vector) nil)
108 (setf (cache-vector-lock-count cache-vector) 0))
111 (defmacro modify-cache (cache-vector &body body)
113 (multiple-value-prog1
115 (let ((old-count (cache-vector-lock-count ,cache-vector)))
116 (declare (fixnum old-count))
117 (setf (cache-vector-lock-count ,cache-vector)
118 (if (= old-count most-positive-fixnum)
119 1 (the fixnum (1+ old-count))))))))
121 (deftype field-type ()
122 '(mod #.layout-clos-hash-length))
124 (eval-when (:compile-toplevel :load-toplevel :execute)
125 (defun power-of-two-ceiling (x)
127 ;;(expt 2 (ceiling (log x 2)))
128 (the fixnum (ash 1 (integer-length (1- x)))))
131 (defconstant +nkeys-limit+ 256)
133 (defstruct (cache (:constructor make-cache ())
134 (:copier copy-cache-internal))
136 (nkeys 1 :type (integer 1 #.+nkeys-limit+))
137 (valuep nil :type (member nil t))
138 (nlines 0 :type fixnum)
139 (field 0 :type field-type)
140 (limit-fn #'default-limit-fn :type function)
141 (mask 0 :type fixnum)
142 (size 0 :type fixnum)
143 (line-size 1 :type (integer 1 #.(power-of-two-ceiling (1+ +nkeys-limit+))))
144 (max-location 0 :type fixnum)
145 (vector #() :type simple-vector)
146 (overflow nil :type list))
148 #-sb-fluid (declaim (sb-ext:freeze-type cache))
150 (defmacro cache-lock-count (cache)
151 `(cache-vector-lock-count (cache-vector ,cache)))
153 ;;; Return a cache that has had FLUSH-CACHE-VECTOR-INTERNAL called on
154 ;;; it. This returns a cache of exactly the size requested, it won't
155 ;;; ever return a larger cache.
156 (defun get-cache-vector (size)
157 (flush-cache-vector-internal (make-array size)))
160 ;;;; wrapper cache numbers
162 ;;; The constant WRAPPER-CACHE-NUMBER-ADDS-OK controls the number of
163 ;;; non-zero bits wrapper cache numbers will have.
165 ;;; The value of this constant is the number of wrapper cache numbers
166 ;;; which can be added and still be certain the result will be a
167 ;;; fixnum. This is used by all the code that computes primary cache
168 ;;; locations from multiple wrappers.
170 ;;; The value of this constant is used to derive the next two which
171 ;;; are the forms of this constant which it is more convenient for the
172 ;;; runtime code to use.
173 (defconstant wrapper-cache-number-length
174 (integer-length layout-clos-hash-max))
175 (defconstant wrapper-cache-number-mask layout-clos-hash-max)
176 (defconstant wrapper-cache-number-adds-ok
177 (truncate most-positive-fixnum layout-clos-hash-max))
179 ;;;; wrappers themselves
181 ;;; This caching algorithm requires that wrappers have more than one
182 ;;; wrapper cache number. You should think of these multiple numbers
183 ;;; as being in columns. That is, for a given cache, the same column
184 ;;; of wrapper cache numbers will be used.
186 ;;; If at some point the cache distribution of a cache gets bad, the
187 ;;; cache can be rehashed by switching to a different column.
189 ;;; The columns are referred to by field number which is that number
190 ;;; which, when used as a second argument to wrapper-ref, will return
191 ;;; that column of wrapper cache number.
193 ;;; This code is written to allow flexibility as to how many wrapper
194 ;;; cache numbers will be in each wrapper, and where they will be
195 ;;; located. It is also set up to allow port specific modifications to
196 ;;; `pack' the wrapper cache numbers on machines where the addressing
197 ;;; modes make that a good idea.
199 ;;; In SBCL, as in CMU CL, we want to do type checking as early as
200 ;;; possible; structures help this. The structures are hard-wired to
201 ;;; have a fixed number of cache hash values, and that number must
202 ;;; correspond to the number of cache lines we use.
203 (defconstant wrapper-cache-number-vector-length
204 layout-clos-hash-length)
206 (unless (boundp '*the-class-t*)
207 (setq *the-class-t* nil))
209 (defmacro wrapper-class (wrapper)
210 `(classoid-pcl-class (layout-classoid ,wrapper)))
211 (defmacro wrapper-no-of-instance-slots (wrapper)
212 `(layout-length ,wrapper))
214 ;;; FIXME: Why are these macros?
215 (defmacro wrapper-instance-slots-layout (wrapper)
216 `(%wrapper-instance-slots-layout ,wrapper))
217 (defmacro wrapper-class-slots (wrapper)
218 `(%wrapper-class-slots ,wrapper))
219 (defmacro wrapper-cache-number-vector (x) x)
221 ;;; This is called in BRAID when we are making wrappers for classes
222 ;;; whose slots are not initialized yet, and which may be built-in
223 ;;; classes. We pass in the class name in addition to the class.
224 (defun boot-make-wrapper (length name &optional class)
225 (let ((found (find-classoid name nil)))
228 (unless (classoid-pcl-class found)
229 (setf (classoid-pcl-class found) class))
230 (aver (eq (classoid-pcl-class found) class))
231 (let ((layout (classoid-layout found)))
235 (make-wrapper-internal
237 :classoid (make-standard-classoid
238 :name name :pcl-class class))))))
240 ;;; The following variable may be set to a STANDARD-CLASS that has
241 ;;; already been created by the lisp code and which is to be redefined
242 ;;; by PCL. This allows STANDARD-CLASSes to be defined and used for
243 ;;; type testing and dispatch before PCL is loaded.
244 (defvar *pcl-class-boot* nil)
246 ;;; In SBCL, as in CMU CL, the layouts (a.k.a wrappers) for built-in
247 ;;; and structure classes already exist when PCL is initialized, so we
248 ;;; don't necessarily always make a wrapper. Also, we help maintain
249 ;;; the mapping between CL:CLASS and SB-KERNEL:CLASSOID objects.
250 (defun make-wrapper (length class)
252 ((or (typep class 'std-class)
253 (typep class 'forward-referenced-class))
254 (make-wrapper-internal
257 (let ((owrap (class-wrapper class)))
259 (layout-classoid owrap))
260 ((or (*subtypep (class-of class) *the-class-standard-class*)
261 (*subtypep (class-of class) *the-class-funcallable-standard-class*)
262 (typep class 'forward-referenced-class))
263 (cond ((and *pcl-class-boot*
264 (eq (slot-value class 'name) *pcl-class-boot*))
265 (let ((found (find-classoid
266 (slot-value class 'name))))
267 (unless (classoid-pcl-class found)
268 (setf (classoid-pcl-class found) class))
269 (aver (eq (classoid-pcl-class found) class))
272 (let ((name (slot-value class 'name)))
273 (make-standard-classoid :pcl-class class
274 :name (and (symbolp name) name))))))
276 (bug "Got to T branch in ~S" 'make-wrapper))))))
278 (let* ((found (find-classoid (slot-value class 'name)))
279 (layout (classoid-layout found)))
280 (unless (classoid-pcl-class found)
281 (setf (classoid-pcl-class found) class))
282 (aver (eq (classoid-pcl-class found) class))
286 (defconstant +first-wrapper-cache-number-index+ 0)
288 (declaim (inline next-wrapper-cache-number-index))
289 (defun next-wrapper-cache-number-index (field-number)
290 (and (< field-number #.(1- wrapper-cache-number-vector-length))
293 ;;; FIXME: Why are there two layers here, with one operator trivially
294 ;;; defined in terms of the other? It'd be nice either to have a
295 ;;; comment explaining why the separation is valuable, or to collapse
296 ;;; it into a single layer.
298 ;;; FIXME (?): These are logically inline functions, but they need to
299 ;;; be SETFable, and for now it seems not worth the trouble to DEFUN
300 ;;; both inline FOO and inline (SETF FOO) for each one instead of a
301 ;;; single macro. Perhaps the best thing would be to make them
302 ;;; immutable (since it seems sort of surprising and gross to be able
303 ;;; to modify hash values) so that they can become inline functions
304 ;;; with no muss or fuss. I (WHN) didn't do this only because I didn't
305 ;;; know whether any code anywhere depends on the values being
307 (defmacro cache-number-vector-ref (cnv n)
308 `(wrapper-cache-number-vector-ref ,cnv ,n))
309 (defmacro wrapper-cache-number-vector-ref (wrapper n)
310 `(layout-clos-hash ,wrapper ,n))
312 (declaim (inline wrapper-class*))
313 (defun wrapper-class* (wrapper)
314 (or (wrapper-class wrapper)
315 (ensure-non-standard-class
316 (classoid-name (layout-classoid wrapper)))))
318 ;;; The wrapper cache machinery provides general mechanism for
319 ;;; trapping on the next access to any instance of a given class. This
320 ;;; mechanism is used to implement the updating of instances when the
321 ;;; class is redefined (MAKE-INSTANCES-OBSOLETE). The same mechanism
322 ;;; is also used to update generic function caches when there is a
323 ;;; change to the superclasses of a class.
325 ;;; Basically, a given wrapper can be valid or invalid. If it is
326 ;;; invalid, it means that any attempt to do a wrapper cache lookup
327 ;;; using the wrapper should trap. Also, methods on
328 ;;; SLOT-VALUE-USING-CLASS check the wrapper validity as well. This is
329 ;;; done by calling CHECK-WRAPPER-VALIDITY.
331 (declaim (inline invalid-wrapper-p))
332 (defun invalid-wrapper-p (wrapper)
333 (not (null (layout-invalid wrapper))))
335 (defvar *previous-nwrappers* (make-hash-table))
337 (defun invalidate-wrapper (owrapper state nwrapper)
338 (aver (member state '(:flush :obsolete) :test #'eq))
339 (let ((new-previous ()))
340 ;; First off, a previous call to INVALIDATE-WRAPPER may have
341 ;; recorded OWRAPPER as an NWRAPPER to update to. Since OWRAPPER
342 ;; is about to be invalid, it no longer makes sense to update to
345 ;; We go back and change the previously invalidated wrappers so
346 ;; that they will now update directly to NWRAPPER. This
347 ;; corresponds to a kind of transitivity of wrapper updates.
348 (dolist (previous (gethash owrapper *previous-nwrappers*))
349 (when (eq state :obsolete)
350 (setf (car previous) :obsolete))
351 (setf (cadr previous) nwrapper)
352 (push previous new-previous))
354 (let ((ocnv (wrapper-cache-number-vector owrapper)))
355 (dotimes (i layout-clos-hash-length)
356 (setf (cache-number-vector-ref ocnv i) 0)))
358 (push (setf (layout-invalid owrapper) (list state nwrapper))
361 (setf (gethash owrapper *previous-nwrappers*) ()
362 (gethash nwrapper *previous-nwrappers*) new-previous)))
364 (defun check-wrapper-validity (instance)
365 (let* ((owrapper (wrapper-of instance))
366 (state (layout-invalid owrapper)))
367 (aver (not (eq state :uninitialized)))
370 ;; FIXME: I can't help thinking that, while this does cure the
371 ;; symptoms observed from some class redefinitions, this isn't
372 ;; the place to be doing this flushing. Nevertheless... --
376 ;; We assume in this case, that the :INVALID is from a
377 ;; previous call to REGISTER-LAYOUT for a superclass of
378 ;; INSTANCE's class. See also the comment above
379 ;; FORCE-CACHE-FLUSHES. Paul Dietz has test cases for this.
381 (force-cache-flushes (class-of instance))
382 (check-wrapper-validity instance))
386 (flush-cache-trap owrapper (cadr state) instance))
388 (obsolete-instance-trap owrapper (cadr state) instance)))))))
390 (declaim (inline check-obsolete-instance))
391 (defun check-obsolete-instance (instance)
392 (when (invalid-wrapper-p (layout-of instance))
393 (check-wrapper-validity instance)))
396 (defun get-cache (nkeys valuep limit-fn nlines)
397 (let ((cache (make-cache)))
398 (declare (type cache cache))
399 (multiple-value-bind (cache-mask actual-size line-size nlines)
400 (compute-cache-parameters nkeys valuep nlines)
401 (setf (cache-nkeys cache) nkeys
402 (cache-valuep cache) valuep
403 (cache-nlines cache) nlines
404 (cache-field cache) +first-wrapper-cache-number-index+
405 (cache-limit-fn cache) limit-fn
406 (cache-mask cache) cache-mask
407 (cache-size cache) actual-size
408 (cache-line-size cache) line-size
409 (cache-max-location cache) (let ((line (1- nlines)))
412 (1+ (* line line-size))))
413 (cache-vector cache) (get-cache-vector actual-size)
414 (cache-overflow cache) nil)
417 (defun get-cache-from-cache (old-cache new-nlines
418 &optional (new-field +first-wrapper-cache-number-index+))
419 (let ((nkeys (cache-nkeys old-cache))
420 (valuep (cache-valuep old-cache))
421 (cache (make-cache)))
422 (declare (type cache cache))
423 (multiple-value-bind (cache-mask actual-size line-size nlines)
424 (if (= new-nlines (cache-nlines old-cache))
425 (values (cache-mask old-cache) (cache-size old-cache)
426 (cache-line-size old-cache) (cache-nlines old-cache))
427 (compute-cache-parameters nkeys valuep new-nlines))
428 (setf (cache-owner cache) (cache-owner old-cache)
429 (cache-nkeys cache) nkeys
430 (cache-valuep cache) valuep
431 (cache-nlines cache) nlines
432 (cache-field cache) new-field
433 (cache-limit-fn cache) (cache-limit-fn old-cache)
434 (cache-mask cache) cache-mask
435 (cache-size cache) actual-size
436 (cache-line-size cache) line-size
437 (cache-max-location cache) (let ((line (1- nlines)))
440 (1+ (* line line-size))))
441 (cache-vector cache) (get-cache-vector actual-size)
442 (cache-overflow cache) nil)
445 (defun copy-cache (old-cache)
446 (let* ((new-cache (copy-cache-internal old-cache))
447 (size (cache-size old-cache))
448 (old-vector (cache-vector old-cache))
449 (new-vector (get-cache-vector size)))
450 (declare (simple-vector old-vector new-vector))
451 (dotimes-fixnum (i size)
452 (setf (svref new-vector i) (svref old-vector i)))
453 (setf (cache-vector new-cache) new-vector)
456 (defun compute-line-size (x)
457 (power-of-two-ceiling x))
459 (defun compute-cache-parameters (nkeys valuep nlines-or-cache-vector)
460 ;;(declare (values cache-mask actual-size line-size nlines))
461 (declare (fixnum nkeys))
463 (let* ((line-size (if valuep 2 1))
464 (cache-size (if (typep nlines-or-cache-vector 'fixnum)
468 (power-of-two-ceiling
469 nlines-or-cache-vector))))
470 (cache-vector-size nlines-or-cache-vector))))
471 (declare (fixnum line-size cache-size))
472 (values (logxor (the fixnum (1- cache-size)) (the fixnum (1- line-size)))
475 (the (values fixnum t) (floor cache-size line-size))))
476 (let* ((line-size (power-of-two-ceiling (if valuep (1+ nkeys) nkeys)))
477 (cache-size (if (typep nlines-or-cache-vector 'fixnum)
481 (power-of-two-ceiling
482 nlines-or-cache-vector))))
483 (1- (cache-vector-size nlines-or-cache-vector)))))
484 (declare (fixnum line-size cache-size))
485 (values (logxor (the fixnum (1- cache-size)) (the fixnum (1- line-size)))
486 (the fixnum (1+ cache-size))
488 (the (values fixnum t) (floor cache-size line-size))))))
490 ;;; the various implementations of computing a primary cache location from
491 ;;; wrappers. Because some implementations of this must run fast there are
492 ;;; several implementations of the same algorithm.
494 ;;; The algorithm is:
496 ;;; SUM over the wrapper cache numbers,
497 ;;; ENSURING that the result is a fixnum
498 ;;; MASK the result against the mask argument.
500 ;;; The basic functional version. This is used by the cache miss code to
501 ;;; compute the primary location of an entry.
502 (defun compute-primary-cache-location (field mask wrappers)
504 (declare (type field-type field) (fixnum mask))
505 (if (not (listp wrappers))
507 (the fixnum (wrapper-cache-number-vector-ref wrappers field)))
508 (let ((location 0) (i 0))
509 (declare (fixnum location i))
510 (dolist (wrapper wrappers)
511 ;; First add the cache number of this wrapper to location.
512 (let ((wrapper-cache-number (wrapper-cache-number-vector-ref wrapper
514 (declare (fixnum wrapper-cache-number))
515 (if (zerop wrapper-cache-number)
516 (return-from compute-primary-cache-location 0)
518 (the fixnum (+ location wrapper-cache-number)))))
519 ;; Then, if we are working with lots of wrappers, deal with
520 ;; the wrapper-cache-number-mask stuff.
521 (when (and (not (zerop i))
522 (zerop (mod i wrapper-cache-number-adds-ok)))
524 (logand location wrapper-cache-number-mask)))
526 (the fixnum (1+ (logand mask location))))))
528 ;;; This version is called on a cache line. It fetches the wrappers
529 ;;; from the cache line and determines the primary location. Various
530 ;;; parts of the cache filling code call this to determine whether it
531 ;;; is appropriate to displace a given cache entry.
533 ;;; If this comes across a wrapper whose CACHE-NO is 0, it returns the
534 ;;; symbol invalid to suggest to its caller that it would be provident
535 ;;; to blow away the cache line in question.
536 (defun compute-primary-cache-location-from-location (to-cache
539 (from-cache to-cache))
540 (declare (type cache to-cache from-cache) (fixnum from-location))
542 (cache-vector (cache-vector from-cache))
543 (field (cache-field to-cache))
544 (mask (cache-mask to-cache))
545 (nkeys (cache-nkeys to-cache)))
546 (declare (type field-type field) (fixnum result mask nkeys)
547 (simple-vector cache-vector))
548 (dotimes-fixnum (i nkeys)
549 (let* ((wrapper (cache-vector-ref cache-vector (+ i from-location)))
550 (wcn (wrapper-cache-number-vector-ref wrapper field)))
551 (declare (fixnum wcn))
552 (setq result (+ result wcn)))
553 (when (and (not (zerop i))
554 (zerop (mod i wrapper-cache-number-adds-ok)))
555 (setq result (logand result wrapper-cache-number-mask))))
558 (the fixnum (1+ (logand mask result))))))
560 ;;; NIL: means nothing so far, no actual arg info has NILs in the
563 ;;; CLASS: seen all sorts of metaclasses (specifically, more than one
564 ;;; of the next 5 values) or else have seen something which doesn't
565 ;;; fall into a single category (SLOT-INSTANCE, FORWARD).
567 ;;; T: means everything so far is the class T
568 ;;; STANDARD-INSTANCE: seen only standard classes
569 ;;; BUILT-IN-INSTANCE: seen only built in classes
570 ;;; STRUCTURE-INSTANCE: seen only structure classes
571 ;;; CONDITION-INSTANCE: seen only condition classes
572 (defun raise-metatype (metatype new-specializer)
573 (let ((slot (find-class 'slot-class))
574 (standard (find-class 'standard-class))
575 (fsc (find-class 'funcallable-standard-class))
576 (condition (find-class 'condition-class))
577 (structure (find-class 'structure-class))
578 (built-in (find-class 'built-in-class))
579 (frc (find-class 'forward-referenced-class)))
580 (flet ((specializer->metatype (x)
581 (let ((meta-specializer
582 (if (eq *boot-state* 'complete)
583 (class-of (specializer-class x))
586 ((eq x *the-class-t*) t)
587 ((*subtypep meta-specializer standard) 'standard-instance)
588 ((*subtypep meta-specializer fsc) 'standard-instance)
589 ((*subtypep meta-specializer condition) 'condition-instance)
590 ((*subtypep meta-specializer structure) 'structure-instance)
591 ((*subtypep meta-specializer built-in) 'built-in-instance)
592 ((*subtypep meta-specializer slot) 'slot-instance)
593 ((*subtypep meta-specializer frc) 'forward)
594 (t (error "~@<PCL cannot handle the specializer ~S ~
595 (meta-specializer ~S).~@:>"
596 new-specializer meta-specializer))))))
597 ;; We implement the following table. The notation is
598 ;; that X and Y are distinct meta specializer names.
600 ;; NIL <anything> ===> <anything>
603 (let ((new-metatype (specializer->metatype new-specializer)))
604 (cond ((eq new-metatype 'slot-instance) 'class)
605 ((eq new-metatype 'forward) 'class)
606 ((null metatype) new-metatype)
607 ((eq metatype new-metatype) new-metatype)
610 (defmacro with-dfun-wrappers ((args metatypes)
611 (dfun-wrappers invalid-wrapper-p
612 &optional wrappers classes types)
613 invalid-arguments-form
615 `(let* ((args-tail ,args) (,invalid-wrapper-p nil) (invalid-arguments-p nil)
616 (,dfun-wrappers nil) (dfun-wrappers-tail nil)
618 `((wrappers-rev nil) (types-rev nil) (classes-rev nil))))
619 (dolist (mt ,metatypes)
621 (setq invalid-arguments-p t)
623 (let* ((arg (pop args-tail))
626 `((class *the-class-t*)
629 (setq wrapper (wrapper-of arg))
630 (when (invalid-wrapper-p wrapper)
631 (setq ,invalid-wrapper-p t)
632 (setq wrapper (check-wrapper-validity arg)))
633 (cond ((null ,dfun-wrappers)
634 (setq ,dfun-wrappers wrapper))
635 ((not (consp ,dfun-wrappers))
636 (setq dfun-wrappers-tail (list wrapper))
637 (setq ,dfun-wrappers (cons ,dfun-wrappers dfun-wrappers-tail)))
639 (let ((new-dfun-wrappers-tail (list wrapper)))
640 (setf (cdr dfun-wrappers-tail) new-dfun-wrappers-tail)
641 (setf dfun-wrappers-tail new-dfun-wrappers-tail))))
643 `((setq class (wrapper-class* wrapper))
644 (setq type `(class-eq ,class)))))
646 `((push wrapper wrappers-rev)
647 (push class classes-rev)
648 (push type types-rev)))))
649 (if invalid-arguments-p
650 ,invalid-arguments-form
651 (let* (,@(when wrappers
652 `((,wrappers (nreverse wrappers-rev))
653 (,classes (nreverse classes-rev))
654 (,types (mapcar (lambda (class)
659 ;;;; some support stuff for getting a hold of symbols that we need when
660 ;;;; building the discriminator codes. It's OK for these to be interned
661 ;;;; symbols because we don't capture any user code in the scope in which
662 ;;;; these symbols are bound.
664 (defvar *dfun-arg-symbols* '(.ARG0. .ARG1. .ARG2. .ARG3.))
666 (defun dfun-arg-symbol (arg-number)
667 (or (nth arg-number (the list *dfun-arg-symbols*))
668 (format-symbol *pcl-package* ".ARG~A." arg-number)))
670 (defvar *slot-vector-symbols* '(.SLOTS0. .SLOTS1. .SLOTS2. .SLOTS3.))
672 (defun slot-vector-symbol (arg-number)
673 (or (nth arg-number (the list *slot-vector-symbols*))
674 (format-symbol *pcl-package* ".SLOTS~A." arg-number)))
676 ;; FIXME: There ought to be a good way to factor out the idiom:
678 ;; (dotimes (i (length metatypes))
679 ;; (push (dfun-arg-symbol i) lambda-list))
681 ;; used in the following four functions into common code that we can
682 ;; declare inline or something. --njf 2001-12-20
683 (defun make-dfun-lambda-list (metatypes applyp)
684 (let ((lambda-list nil))
685 (dotimes (i (length metatypes))
686 (push (dfun-arg-symbol i) lambda-list))
688 (push '&rest lambda-list)
689 (push '.dfun-rest-arg. lambda-list))
690 (nreverse lambda-list)))
692 (defun make-dlap-lambda-list (metatypes applyp)
693 (let ((lambda-list nil))
694 (dotimes (i (length metatypes))
695 (push (dfun-arg-symbol i) lambda-list))
696 ;; FIXME: This is translated directly from the old PCL code.
697 ;; It didn't have a (PUSH '.DFUN-REST-ARG. LAMBDA-LIST) or
698 ;; something similar, so we don't either. It's hard to see how
699 ;; this could be correct, since &REST wants an argument after
700 ;; it. This function works correctly because the caller
701 ;; magically tacks on something after &REST. The calling functions
702 ;; (in dlisp.lisp) should be fixed and this function rewritten.
705 (push '&rest lambda-list))
706 (nreverse lambda-list)))
708 ;; FIXME: The next two functions suffer from having a `.DFUN-REST-ARG.'
709 ;; in their lambda lists, but no corresponding `&REST' symbol. We assume
710 ;; this should be the case by analogy with the previous two functions.
711 ;; It works, and I don't know why. Check the calling functions and
712 ;; fix these too. --njf 2001-12-20
713 (defun make-emf-call (metatypes applyp fn-variable &optional emf-type)
715 (let ((required nil))
716 (dotimes (i (length metatypes))
717 (push (dfun-arg-symbol i) required))
718 (nreverse required))))
719 `(,(if (eq emf-type 'fast-method-call)
720 'invoke-effective-method-function-fast
721 'invoke-effective-method-function)
722 ,fn-variable ,applyp ,@required ,@(when applyp `(.dfun-rest-arg.)))))
724 (defun make-fast-method-call-lambda-list (metatypes applyp)
725 (let ((reversed-lambda-list nil))
726 (push '.pv-cell. reversed-lambda-list)
727 (push '.next-method-call. reversed-lambda-list)
728 (dotimes (i (length metatypes))
729 (push (dfun-arg-symbol i) reversed-lambda-list))
731 (push '.dfun-rest-arg. reversed-lambda-list))
732 (nreverse reversed-lambda-list)))
734 (defmacro with-local-cache-functions ((cache) &body body)
735 `(let ((.cache. ,cache))
736 (declare (type cache .cache.))
737 (labels ((cache () .cache.)
738 (nkeys () (cache-nkeys .cache.))
739 (line-size () (cache-line-size .cache.))
740 (vector () (cache-vector .cache.))
741 (valuep () (cache-valuep .cache.))
742 (nlines () (cache-nlines .cache.))
743 (max-location () (cache-max-location .cache.))
744 (limit-fn () (cache-limit-fn .cache.))
745 (size () (cache-size .cache.))
746 (mask () (cache-mask .cache.))
747 (field () (cache-field .cache.))
748 (overflow () (cache-overflow .cache.))
750 ;; Return T IFF this cache location is reserved. The
751 ;; only time this is true is for line number 0 of an
754 (line-reserved-p (line)
755 (declare (fixnum line))
759 (location-reserved-p (location)
760 (declare (fixnum location))
764 ;; Given a line number, return the cache location.
765 ;; This is the value that is the second argument to
766 ;; cache-vector-ref. Basically, this deals with the
767 ;; offset of nkeys>1 caches and multiplies by line
770 (line-location (line)
771 (declare (fixnum line))
772 (when (line-reserved-p line)
773 (error "line is reserved"))
775 (the fixnum (* line (line-size)))
776 (the fixnum (1+ (the fixnum (* line (line-size)))))))
778 ;; Given a cache location, return the line. This is
779 ;; the inverse of LINE-LOCATION.
781 (location-line (location)
782 (declare (fixnum location))
784 (floor location (line-size))
785 (floor (the fixnum (1- location)) (line-size))))
787 ;; Given a line number, return the wrappers stored at
788 ;; that line. As usual, if nkeys=1, this returns a
789 ;; single value. Only when nkeys>1 does it return a
790 ;; list. An error is signalled if the line is
793 (line-wrappers (line)
794 (declare (fixnum line))
795 (when (line-reserved-p line) (error "Line is reserved."))
796 (location-wrappers (line-location line)))
798 (location-wrappers (location) ; avoid multiplies caused by line-location
799 (declare (fixnum location))
801 (cache-vector-ref (vector) location)
802 (let ((list (make-list (nkeys)))
804 (declare (simple-vector vector))
805 (dotimes (i (nkeys) list)
808 (cache-vector-ref vector (+ location i)))))))
810 ;; Given a line number, return true IFF the line's
811 ;; wrappers are the same as wrappers.
813 (line-matches-wrappers-p (line wrappers)
814 (declare (fixnum line))
815 (and (not (line-reserved-p line))
816 (location-matches-wrappers-p (line-location line)
819 (location-matches-wrappers-p (loc wrappers) ; must not be reserved
820 (declare (fixnum loc))
821 (let ((cache-vector (vector)))
822 (declare (simple-vector cache-vector))
824 (eq wrappers (cache-vector-ref cache-vector loc))
825 (dotimes (i (nkeys) t)
827 (unless (eq (pop wrappers)
828 (cache-vector-ref cache-vector (+ loc i)))
831 ;; Given a line number, return the value stored at that line.
832 ;; If valuep is NIL, this returns NIL. As with line-wrappers,
833 ;; an error is signalled if the line is reserved.
836 (declare (fixnum line))
837 (when (line-reserved-p line) (error "Line is reserved."))
838 (location-value (line-location line)))
840 (location-value (loc)
841 (declare (fixnum loc))
843 (cache-vector-ref (vector) (+ loc (nkeys)))))
845 ;; Given a line number, return true IFF that line has data in
846 ;; it. The state of the wrappers stored in the line is not
847 ;; checked. An error is signalled if line is reserved.
849 (when (line-reserved-p line) (error "Line is reserved."))
850 (not (null (cache-vector-ref (vector) (line-location line)))))
852 ;; Given a line number, return true IFF the line is full and
853 ;; there are no invalid wrappers in the line, and the line's
854 ;; wrappers are different from wrappers.
855 ;; An error is signalled if the line is reserved.
857 (line-valid-p (line wrappers)
858 (declare (fixnum line))
859 (when (line-reserved-p line) (error "Line is reserved."))
860 (location-valid-p (line-location line) wrappers))
862 (location-valid-p (loc wrappers)
863 (declare (fixnum loc))
864 (let ((cache-vector (vector))
865 (wrappers-mismatch-p (null wrappers)))
866 (declare (simple-vector cache-vector))
867 (dotimes (i (nkeys) wrappers-mismatch-p)
869 (let ((wrapper (cache-vector-ref cache-vector (+ loc i))))
870 (when (or (null wrapper)
871 (invalid-wrapper-p wrapper))
873 (unless (and wrappers
878 (setq wrappers-mismatch-p t))))))
880 ;; How many unreserved lines separate line-1 and line-2.
882 (line-separation (line-1 line-2)
883 (declare (fixnum line-1 line-2))
884 (let ((diff (the fixnum (- line-2 line-1))))
885 (declare (fixnum diff))
887 (setq diff (+ diff (nlines)))
888 (when (line-reserved-p 0)
889 (setq diff (1- diff))))
892 ;; Given a cache line, get the next cache line. This will not
893 ;; return a reserved line.
896 (declare (fixnum line))
897 (if (= line (the fixnum (1- (nlines))))
898 (if (line-reserved-p 0) 1 0)
899 (the fixnum (1+ line))))
902 (declare (fixnum loc))
903 (if (= loc (max-location))
907 (the fixnum (+ loc (line-size)))))
909 ;; Given a line which has a valid entry in it, this
910 ;; will return the primary cache line of the wrappers
911 ;; in that line. We just call
912 ;; COMPUTE-PRIMARY-CACHE-LOCATION-FROM-LOCATION, this
913 ;; is an easier packaging up of the call to it.
916 (declare (fixnum line))
917 (location-line (line-primary-location line)))
919 (line-primary-location (line)
920 (declare (fixnum line))
921 (compute-primary-cache-location-from-location
922 (cache) (line-location line))))
923 (declare (ignorable #'cache #'nkeys #'line-size #'vector #'valuep
924 #'nlines #'max-location #'limit-fn #'size
925 #'mask #'field #'overflow #'line-reserved-p
926 #'location-reserved-p #'line-location
927 #'location-line #'line-wrappers #'location-wrappers
928 #'line-matches-wrappers-p
929 #'location-matches-wrappers-p
930 #'line-value #'location-value #'line-full-p
931 #'line-valid-p #'location-valid-p
932 #'line-separation #'next-line #'next-location
933 #'line-primary #'line-primary-location))
936 ;;; Here is where we actually fill, recache and expand caches.
938 ;;; The functions FILL-CACHE and PROBE-CACHE are the ONLY external
939 ;;; entrypoints into this code.
941 ;;; FILL-CACHE returns 1 value: a new cache
943 ;;; a wrapper field number
946 ;;; an absolute cache size (the size of the actual vector)
947 ;;; It tries to re-adjust the cache every time it makes a new fill.
948 ;;; The intuition here is that we want uniformity in the number of
949 ;;; probes needed to find an entry. Furthermore, adjusting has the
950 ;;; nice property of throwing out any entries that are invalid.
951 (defvar *cache-expand-threshold* 1.25)
953 (defun fill-cache (cache wrappers value)
954 ;; FILL-CACHE won't return if WRAPPERS is nil, might as well check..
957 (or (fill-cache-p nil cache wrappers value)
958 (and (< (ceiling (* (cache-count cache) *cache-expand-threshold*))
959 (if (= (cache-nkeys cache) 1)
960 (1- (cache-nlines cache))
961 (cache-nlines cache)))
962 (adjust-cache cache wrappers value))
963 (expand-cache cache wrappers value)))
965 (defvar *check-cache-p* nil)
967 (defmacro maybe-check-cache (cache)
969 (when *check-cache-p*
970 (check-cache ,cache))
973 (defun check-cache (cache)
974 (with-local-cache-functions (cache)
975 (let ((location (if (= (nkeys) 1) 0 1))
976 (limit (funcall (limit-fn) (nlines))))
977 (dotimes-fixnum (i (nlines) cache)
978 (when (and (not (location-reserved-p location))
980 (let* ((home-loc (compute-primary-cache-location-from-location
982 (home (location-line (if (location-reserved-p home-loc)
983 (next-location home-loc)
985 (sep (when home (line-separation home i))))
986 (when (and sep (> sep limit))
987 (error "bad cache ~S ~@
988 value at location ~W: ~W lines from its home. The limit is ~W."
989 cache location sep limit))))
990 (setq location (next-location location))))))
992 (defun probe-cache (cache wrappers &optional default limit-fn)
993 ;;(declare (values value))
995 (with-local-cache-functions (cache)
996 (let* ((location (compute-primary-cache-location (field) (mask) wrappers))
997 (limit (funcall (or limit-fn (limit-fn)) (nlines))))
998 (declare (fixnum location limit))
999 (when (location-reserved-p location)
1000 (setq location (next-location location)))
1001 (dotimes-fixnum (i (1+ limit))
1002 (when (location-matches-wrappers-p location wrappers)
1003 (return-from probe-cache (or (not (valuep))
1004 (location-value location))))
1005 (setq location (next-location location)))
1006 (dolist (entry (overflow))
1007 (when (equal (car entry) wrappers)
1008 (return-from probe-cache (or (not (valuep))
1012 (defun map-cache (function cache &optional set-p)
1013 (with-local-cache-functions (cache)
1014 (let ((set-p (and set-p (valuep))))
1015 (dotimes-fixnum (i (nlines) cache)
1016 (unless (or (line-reserved-p i) (not (line-valid-p i nil)))
1017 (let ((value (funcall function (line-wrappers i) (line-value i))))
1019 (setf (cache-vector-ref (vector) (+ (line-location i) (nkeys)))
1021 (dolist (entry (overflow))
1022 (let ((value (funcall function (car entry) (cdr entry))))
1024 (setf (cdr entry) value))))))
1027 (defun cache-count (cache)
1028 (with-local-cache-functions (cache)
1030 (declare (fixnum count))
1031 (dotimes-fixnum (i (nlines) count)
1032 (unless (line-reserved-p i)
1033 (when (line-full-p i)
1036 (defun entry-in-cache-p (cache wrappers value)
1037 (declare (ignore value))
1038 (with-local-cache-functions (cache)
1039 (dotimes-fixnum (i (nlines))
1040 (unless (line-reserved-p i)
1041 (when (equal (line-wrappers i) wrappers)
1044 ;;; returns T or NIL
1045 (defun fill-cache-p (forcep cache wrappers value)
1046 (with-local-cache-functions (cache)
1047 (let* ((location (compute-primary-cache-location (field) (mask) wrappers))
1048 (primary (location-line location)))
1049 (declare (fixnum location primary))
1050 ;; FIXME: I tried (aver (> location 0)) and (aver (not
1051 ;; (location-reserved-p location))) here, on the basis that
1052 ;; particularly passing a LOCATION of 0 for a cache with more
1053 ;; than one key would cause PRIMARY to be -1. However, the
1054 ;; AVERs triggered during the bootstrap, and removing them
1055 ;; didn't cause anything to break, so I've left them removed.
1056 ;; I'm still confused as to what is right. -- CSR, 2006-04-20
1057 (multiple-value-bind (free emptyp)
1058 (find-free-cache-line primary cache wrappers)
1059 (when (or forcep emptyp)
1061 (push (cons (line-wrappers free) (line-value free))
1062 (cache-overflow cache)))
1063 ;;(fill-line free wrappers value)
1065 (declare (fixnum line))
1066 (when (line-reserved-p line)
1067 (error "attempt to fill a reserved line"))
1068 (let ((loc (line-location line))
1069 (cache-vector (vector)))
1070 (declare (fixnum loc) (simple-vector cache-vector))
1071 (cond ((= (nkeys) 1)
1072 (setf (cache-vector-ref cache-vector loc) wrappers)
1074 (setf (cache-vector-ref cache-vector (1+ loc)) value)))
1077 (declare (fixnum i))
1078 (dolist (w wrappers)
1079 (setf (cache-vector-ref cache-vector (+ loc i)) w)
1080 (setq i (the fixnum (1+ i)))))
1082 (setf (cache-vector-ref cache-vector (+ loc (nkeys)))
1084 (maybe-check-cache cache))))))))
1086 (defun fill-cache-from-cache-p (forcep cache from-cache from-line)
1087 (declare (fixnum from-line))
1088 (with-local-cache-functions (cache)
1089 (let ((primary (location-line
1090 (compute-primary-cache-location-from-location
1091 cache (line-location from-line) from-cache))))
1092 (declare (fixnum primary))
1093 (multiple-value-bind (free emptyp)
1094 (find-free-cache-line primary cache)
1095 (when (or forcep emptyp)
1097 (push (cons (line-wrappers free) (line-value free))
1098 (cache-overflow cache)))
1099 ;;(transfer-line from-cache-vector from-line cache-vector free)
1100 (let ((from-cache-vector (cache-vector from-cache))
1101 (to-cache-vector (vector))
1103 (declare (fixnum to-line))
1104 (if (line-reserved-p to-line)
1105 (error "transferring something into a reserved cache line")
1106 (let ((from-loc (line-location from-line))
1107 (to-loc (line-location to-line)))
1108 (declare (fixnum from-loc to-loc))
1109 (modify-cache to-cache-vector
1110 (dotimes-fixnum (i (line-size))
1111 (setf (cache-vector-ref to-cache-vector
1113 (cache-vector-ref from-cache-vector
1114 (+ from-loc i)))))))
1115 (maybe-check-cache cache)))))))
1117 ;;; Returns NIL or (values <field> <cache-vector>)
1119 ;;; This is only called when it isn't possible to put the entry in the
1120 ;;; cache the easy way. That is, this function assumes that
1121 ;;; FILL-CACHE-P has been called as returned NIL.
1123 ;;; If this returns NIL, it means that it wasn't possible to find a
1124 ;;; wrapper field for which all of the entries could be put in the
1125 ;;; cache (within the limit).
1126 (defun adjust-cache (cache wrappers value)
1127 (with-local-cache-functions (cache)
1128 (let ((ncache (get-cache-from-cache cache (nlines) (field))))
1129 (do ((nfield (cache-field ncache)
1130 (next-wrapper-cache-number-index nfield)))
1132 (setf (cache-field ncache) nfield)
1133 (labels ((try-one-fill-from-line (line)
1134 (fill-cache-from-cache-p nil ncache cache line))
1135 (try-one-fill (wrappers value)
1136 (fill-cache-p nil ncache wrappers value)))
1137 (if (and (dotimes-fixnum (i (nlines) t)
1138 (when (and (null (line-reserved-p i))
1139 (line-valid-p i wrappers))
1140 (unless (try-one-fill-from-line i) (return nil))))
1141 (dolist (wrappers+value (cache-overflow cache) t)
1142 (unless (try-one-fill (car wrappers+value) (cdr wrappers+value))
1144 (try-one-fill wrappers value))
1145 (return (maybe-check-cache ncache))
1146 (flush-cache-vector-internal (cache-vector ncache))))))))
1148 ;;; returns: (values <cache>)
1149 (defun expand-cache (cache wrappers value)
1150 ;;(declare (values cache))
1151 (with-local-cache-functions (cache)
1152 (let ((ncache (get-cache-from-cache cache (* (nlines) 2))))
1153 (labels ((do-one-fill-from-line (line)
1154 (unless (fill-cache-from-cache-p nil ncache cache line)
1155 (do-one-fill (line-wrappers line) (line-value line))))
1156 (do-one-fill (wrappers value)
1157 (setq ncache (or (adjust-cache ncache wrappers value)
1158 (fill-cache-p t ncache wrappers value))))
1159 (try-one-fill (wrappers value)
1160 (fill-cache-p nil ncache wrappers value)))
1161 (dotimes-fixnum (i (nlines))
1162 (when (and (null (line-reserved-p i))
1163 (line-valid-p i wrappers))
1164 (do-one-fill-from-line i)))
1165 (dolist (wrappers+value (cache-overflow cache))
1166 (unless (try-one-fill (car wrappers+value) (cdr wrappers+value))
1167 (do-one-fill (car wrappers+value) (cdr wrappers+value))))
1168 (unless (try-one-fill wrappers value)
1169 (do-one-fill wrappers value))
1170 (maybe-check-cache ncache)))))
1172 (defvar *pcl-misc-random-state* (make-random-state))
1174 ;;; This is the heart of the cache filling mechanism. It implements
1175 ;;; the decisions about where entries are placed.
1177 ;;; Find a line in the cache at which a new entry can be inserted.
1180 ;;; <empty?> is <line> in fact empty?
1181 (defun find-free-cache-line (primary cache &optional wrappers)
1182 ;;(declare (values line empty?))
1183 (declare (fixnum primary))
1184 (with-local-cache-functions (cache)
1185 (when (line-reserved-p primary) (setq primary (next-line primary)))
1186 (let ((limit (funcall (limit-fn) (nlines)))
1189 (p primary) (s primary))
1190 (declare (fixnum p s limit))
1193 ;; Try to find a free line starting at <s>. <p> is the
1194 ;; primary line of the entry we are finding a free
1195 ;; line for, it is used to compute the separations.
1196 (do* ((line s (next-line line))
1197 (nsep (line-separation p s) (1+ nsep)))
1199 (declare (fixnum line nsep))
1200 (when (null (line-valid-p line wrappers)) ;If this line is empty or
1201 (push line lines) ;invalid, just use it.
1202 (return-from find-free))
1203 (when (and wrappedp (>= line primary))
1204 ;; have gone all the way around the cache, time to quit
1205 (return-from find-free-cache-line (values primary nil)))
1206 (let ((osep (line-separation (line-primary line) line)))
1207 (when (>= osep limit)
1208 (return-from find-free-cache-line (values primary nil)))
1209 (when (cond ((= nsep limit) t)
1211 (zerop (random 2 *pcl-misc-random-state*)))
1214 ;; See whether we can displace what is in this line so that we
1215 ;; can use the line.
1216 (when (= line (the fixnum (1- (nlines)))) (setq wrappedp t))
1217 (setq p (line-primary line))
1218 (setq s (next-line line))
1221 (when (= line (the fixnum (1- (nlines)))) (setq wrappedp t)))))
1222 ;; Do all the displacing.
1224 (when (null (cdr lines)) (return nil))
1225 (let ((dline (pop lines))
1227 (declare (fixnum dline line))
1228 ;;Copy from line to dline (dline is known to be free).
1229 (let ((from-loc (line-location line))
1230 (to-loc (line-location dline))
1231 (cache-vector (vector)))
1232 (declare (fixnum from-loc to-loc) (simple-vector cache-vector))
1233 (modify-cache cache-vector
1234 (dotimes-fixnum (i (line-size))
1235 (setf (cache-vector-ref cache-vector
1237 (cache-vector-ref cache-vector
1239 (setf (cache-vector-ref cache-vector
1242 (values (car lines) t))))
1244 (defun default-limit-fn (nlines)