1 ;;;; Copyright (C) 1999, 2000, 2001, 2003, 2006 Free Software Foundation, Inc.
3 ;;;; This library is free software; you can redistribute it and/or
4 ;;;; modify it under the terms of the GNU Lesser General Public
5 ;;;; License as published by the Free Software Foundation; either
6 ;;;; version 2.1 of the License, or (at your option) any later version.
8 ;;;; This library is distributed in the hope that it will be useful,
9 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
10 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 ;;;; Lesser General Public License for more details.
13 ;;;; You should have received a copy of the GNU Lesser General Public
14 ;;;; License along with this library; if not, write to the Free Software
15 ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 (define-module (oop goops dispatch)
20 :use-module (oop goops)
21 :use-module (oop goops util)
22 :use-module (oop goops compile)
23 :export (memoize-method!)
28 ;;; This file implements method memoization. It will finally be
29 ;;; implemented on C level in order to obtain fast generic function
30 ;;; application also during the first pass through the code.
38 (define hashset-index 6)
40 (define hash-threshold 3)
41 (define initial-hash-size 4) ;must be a power of 2 and >= hash-threshold
43 (define initial-hash-size-1 (- initial-hash-size 1))
45 (define the-list-of-no-method '(no-method))
51 ;; (#@dispatch args N-SPECIALIZED #((TYPE1 ... ENV FORMALS FORM1 ...) ...) GF)
52 ;; (#@dispatch args N-SPECIALIZED HASHSET MASK
53 ;; #((TYPE1 ... ENV FORMALS FORM1 ...) ...)
60 (define method-cache-entries cadddr)
62 (define (set-method-cache-entries! mcache entries)
63 (set-car! (cdddr mcache) entries))
65 (define (method-cache-n-methods exp)
66 (n-cache-methods (method-cache-entries exp)))
68 (define (method-cache-methods exp)
69 (cache-methods (method-cache-entries exp)))
73 (define (set-hashed-method-cache-hashset! exp hashset)
74 (set-car! (cdddr exp) hashset))
76 (define (set-hashed-method-cache-mask! exp mask)
77 (set-car! (cddddr exp) mask))
79 (define (hashed-method-cache-entries exp)
82 (define (set-hashed-method-cache-entries! exp entries)
83 (set-car! (list-cdr-ref exp 5) entries))
87 (define (method-cache-generic-function exp)
88 (list-ref exp (if (method-cache-hashed? exp) 6 4)))
92 (define (method-cache-hashed? x)
93 (integer? (cadddr x)))
95 (define max-non-hashed-index (- hash-threshold 2))
97 (define (passed-hash-threshold? exp)
98 (and (> (vector-length (method-cache-entries exp)) max-non-hashed-index)
99 (struct? (car (vector-ref (method-cache-entries exp)
100 max-non-hashed-index)))))
102 ;;; Converting a method cache to hashed form
104 (define (method-cache->hashed! exp)
105 (set-cdr! (cddr exp) (cons 0 (cons initial-hash-size-1 (cdddr exp))))
112 (define (n-cache-methods entries)
113 (do ((i (- (vector-length entries) 1) (- i 1)))
114 ((or (< i 0) (struct? (car (vector-ref entries i))))
117 (define (cache-methods entries)
118 (do ((i (- (vector-length entries) 1) (- i 1))
119 (methods '() (let ((entry (vector-ref entries i)))
120 (if (struct? (car entry))
129 (define (method-cache-insert! exp entry)
130 (let* ((entries (method-cache-entries exp))
131 (n (n-cache-methods entries)))
132 (if (>= n (vector-length entries))
134 (let ((new-entries (make-vector (* 2 (vector-length entries))
135 the-list-of-no-method)))
138 (vector-set! new-entries i (vector-ref entries i)))
139 (vector-set! new-entries n entry)
140 (set-method-cache-entries! exp new-entries))
141 (vector-set! entries n entry))))
143 (define (hashed-method-cache-insert! exp entry)
144 (let* ((cache (hashed-method-cache-entries exp))
145 (size (vector-length cache)))
146 (let* ((entries (cons entry (cache-methods cache)))
147 (size (if (<= (length entries) size)
149 ;; larger size required
150 (let ((new-size (* 2 size)))
151 (set-hashed-method-cache-mask! exp (- new-size 1))
155 (do ((hashset 0 (+ 1 hashset)))
156 ((= hashset hashsets))
157 (let* ((test-cache (make-vector size the-list-of-no-method))
158 (misses (cache-try-hash! min-misses hashset test-cache entries)))
159 (cond ((zero? misses)
162 (set! cache test-cache)
163 (set! hashset (- hashsets 1)))
164 ((< misses min-misses)
165 (set! min-misses misses)
167 (set! cache test-cache)))))
168 (set-hashed-method-cache-hashset! exp best)
169 (set-hashed-method-cache-entries! exp cache))))
175 (define (cache-hashval hashset entry)
176 (let ((hashset-index (+ hashset-index hashset)))
178 (classes entry (cdr classes)))
179 ((not (struct? (car classes))) sum)
180 (set! sum (+ sum (struct-ref (car classes) hashset-index))))))
182 (define (cache-try-hash! min-misses hashset cache entries)
184 (mask (- (vector-length cache) 1)))
187 (do ((ls entries (cdr ls))
189 ((null? ls) max-misses)
190 (do ((i (logand mask (cache-hashval hashset (car ls)))
191 (logand mask (+ i 1))))
192 ((not (struct? (car (vector-ref cache i))))
193 (vector-set! cache i (car ls)))
194 (set! misses (+ 1 misses))
195 (if (>= misses min-misses)
196 (throw 'misses misses)))
197 (if (> misses max-misses)
198 (set! max-misses misses))))
206 ;; Backward compatibility
207 (if (not (defined? 'lookup-create-cmethod))
208 (define (lookup-create-cmethod gf args)
209 (no-applicable-method (car args) (cadr args))))
211 (define (memoize-method! gf args exp)
212 (if (not (slot-ref gf 'used-by))
213 (slot-set! gf 'used-by '()))
214 (let ((applicable ((if (eq? gf compute-applicable-methods)
215 %compute-applicable-methods
216 compute-applicable-methods)
219 ;; *fixme* dispatch.scm needs rewriting Since the current
220 ;; code mutates the method cache, we have to work on a
221 ;; copy. Otherwise we might disturb another thread
222 ;; currently dispatching on the cache. (No need to copy
224 (let* ((new (list-copy exp))
226 (cond ((method-cache-hashed? new)
227 (method-cache-install! hashed-method-cache-insert!
228 new args applicable))
229 ((passed-hash-threshold? new)
230 (method-cache-install! hashed-method-cache-insert!
231 (method-cache->hashed! new)
235 (method-cache-install! method-cache-insert!
236 new args applicable)))))
237 (set-cdr! (cdr exp) (cddr new))
240 (lookup-create-cmethod no-applicable-method (list gf '())))
242 ;; Mutate arglist to fit no-applicable-method
243 (set-cdr! args (list (cons (car args) (cdr args))))
245 (lookup-create-cmethod no-applicable-method args)))))
247 (set-procedure-property! memoize-method! 'system-procedure #t)
249 (define method-cache-install!
252 (if (or (zero? n) (null? ls))
254 (cons (car ls) (first-n (cdr ls) (- n 1)))))))
255 (lambda (insert! exp args applicable)
256 (let* ((specializers (method-specializers (car applicable)))
258 (if (list? specializers)
259 (length specializers)
260 (+ 1 (slot-ref (method-cache-generic-function exp)
262 (let* ((types (map class-of (first-n args n-specializers)))
263 (entry+cmethod (compute-entry-with-cmethod applicable types)))
264 (insert! exp (car entry+cmethod)) ; entry = types + cmethod
265 (cdr entry+cmethod) ; cmethod