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guile/module/oop/goops/dispatch.scm
Andy Wingo b6cf4d0265 a very big commit cleaning up structs & goops. also applicable structs.
I tried to split this one, and I know it's a bit disruptive, but this
stuff really is one big cobweb. So instead we'll pretend like these are
separate commits, by separating the changelog.

Applicable struct runtime support.

* libguile/debug.c (scm_procedure_source):
* libguile/eval.c (scm_trampoline_0, scm_trampoline_1)
  (scm_trampoline_2):
* libguile/eval.i.c (CEVAL):
* libguile/goops.c (scm_class_of):
* libguile/procprop.c (scm_i_procedure_arity):
* libguile/procs.c (scm_procedure_p, scm_procedure, scm_setter): Allow
  for applicable structs. Whee!

* libguile/deprecated.h (scm_vtable_index_vtable): Define as a synonym
  for scm_vtable_index_self.
  (scm_vtable_index_printer): Alias scm_vtable_index_instance_printer.
  (scm_struct_i_free): Alias scm_vtable_index_instance_finalize.
  (scm_struct_i_flags): Alias scm_vtable_index_flags.
  (SCM_STRUCTF_FLAGS): Be a -1 mask, we have a whole word now.
  (SCM_SET_VTABLE_DESTRUCTOR): Implement by hand.

Hidden slots.

* libguile/struct.c (scm_make_struct_layout): Add support for "hidden"
  fields, writable fields that are not visible to make-struct. This
  allows us to add fields to vtables and not break existing make-struct
  invocations.
  (scm_struct_ref, scm_struct_set_x): Always get struct length from the
  vtable. Support hidden fields.

* libguile/goops.c (scm_class_hidden, scm_class_protected_hidden): New
  slot classes, to correspond to the new vtable slots.
  (scm_sys_prep_layout_x): Turn hidden slots into 'h'.
  (build_class_class_slots): Reorder the class slots to account for
  vtable fields coming out of negative-land, for name as a vtable slot,
  and for hidden fields.
  (create_standard_classes): Define <hidden-slot> and
  <protected-hidden-slot>.

Clean up struct.h.

* libguile/struct.h: Lay things out cleaner. There are no more hidden
  (negative) words. Names are nicer. The exposition is nicer. But the
  basics are the same. The incompatibilities are that <vtable> has more
  slots now, and that scm_alloc_struct's signature has changed. The
  former is ameliorated by the "hidden" slots mentioned before, and the
  latter, well, it was always a very internal thing...
  (scm_t_struct_finalize): New type, a finalizer function to be run when
  instances of a vtable are collected.
  (scm_t_struct_free): Removed, structs' data is managed by the GC now,
  and not freed by vtable functions.

* libguile/struct.c: (scm_vtable_p): Now we keep flags on
  vtable-vtables, so this check is cheaper.
  (scm_alloc_struct): No hidden words. Yippee.
  (struct_finalizer_trampoline): Entersify.
  (scm_make_struct): No need to babysit extra words, though now we have
  to babysit flags. Propagate the vtable, applicable, and setter flags
  appropriately.
  (scm_make_vtable_vtable): Update for new simplicity.
  (scm_print_struct): A better printer.
  (scm_init_struct): Define <applicable-struct-vtable>, a magical vtable
  like CL's funcallable-standard-class. Also define
  <applicable-struct-with-setter-vtable>.

Remove foreign object implementation.

* libguile/goops.h:
* libguile/goops.c (scm_make_foreign_object, scm_make_class)
  (scm_add_slot, scm_wrap_object, scm_wrap_component): Remove, these
  were undocumented and unworking.

Clean up goops.h, a little.

* libguile/goops.h:
* libguile/goops.c: Also clean up.
* module/oop/goops/dispatch.scm (hashset-index): Adapt for new hashset
  index.
2009-11-26 00:24:58 +01:00

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;;;; Copyright (C) 1999, 2000, 2001, 2003, 2006, 2009 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 3 of the License, or (at your option) any later version.
;;;;
;;;; This library is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;;; Lesser General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;;;
;; There are circularities here; you can't import (oop goops compile)
;; before (oop goops). So when compiling, make sure that things are
;; kosher.
(eval-when (compile) (resolve-module '(oop goops)))
(define-module (oop goops dispatch)
:use-module (oop goops)
:use-module (oop goops util)
:use-module (oop goops compile)
:export (memoize-method!)
:no-backtrace
)
;;;
;;; This file implements method memoization. It will finally be
;;; implemented on C level in order to obtain fast generic function
;;; application also during the first pass through the code.
;;;
;;;
;;; Constants
;;;
(define hashsets 8)
(define hashset-index 9)
(define hash-threshold 3)
(define initial-hash-size 4) ;must be a power of 2 and >= hash-threshold
(define initial-hash-size-1 (- initial-hash-size 1))
(define the-list-of-no-method '(no-method))
;;;
;;; Method cache
;;;
;; (#@dispatch args N-SPECIALIZED #((TYPE1 ... . CMETHOD) ...) GF)
;; (#@dispatch args N-SPECIALIZED HASHSET MASK
;; #((TYPE1 ... . CMETHOD) ...)
;; GF)
;;; Representation
;; non-hashed form
(define method-cache-entries cadddr)
(define (set-method-cache-entries! mcache entries)
(set-car! (cdddr mcache) entries))
(define (method-cache-n-methods exp)
(n-cache-methods (method-cache-entries exp)))
(define (method-cache-methods exp)
(cache-methods (method-cache-entries exp)))
;; hashed form
(define (set-hashed-method-cache-hashset! exp hashset)
(set-car! (cdddr exp) hashset))
(define (set-hashed-method-cache-mask! exp mask)
(set-car! (cddddr exp) mask))
(define (hashed-method-cache-entries exp)
(list-ref exp 5))
(define (set-hashed-method-cache-entries! exp entries)
(set-car! (list-cdr-ref exp 5) entries))
;; either form
(define (method-cache-generic-function exp)
(list-ref exp (if (method-cache-hashed? exp) 6 4)))
;;; Predicates
(define (method-cache-hashed? x)
(integer? (cadddr x)))
(define max-non-hashed-index (- hash-threshold 2))
(define (passed-hash-threshold? exp)
(and (> (vector-length (method-cache-entries exp)) max-non-hashed-index)
(struct? (car (vector-ref (method-cache-entries exp)
max-non-hashed-index)))))
;;; Converting a method cache to hashed form
(define (method-cache->hashed! exp)
(set-cdr! (cddr exp) (cons 0 (cons initial-hash-size-1 (cdddr exp))))
exp)
;;;
;;; Cache entries
;;;
(define (n-cache-methods entries)
(do ((i (- (vector-length entries) 1) (- i 1)))
((or (< i 0) (struct? (car (vector-ref entries i))))
(+ i 1))))
(define (cache-methods entries)
(do ((i (- (vector-length entries) 1) (- i 1))
(methods '() (let ((entry (vector-ref entries i)))
(if (or (not (pair? entry)) (struct? (car entry)))
(cons entry methods)
methods))))
((< i 0) methods)))
;;;
;;; Method insertion
;;;
(define (method-cache-insert! exp entry)
(let* ((entries (method-cache-entries exp))
(n (n-cache-methods entries)))
(if (>= n (vector-length entries))
;; grow cache
(let ((new-entries (make-vector (* 2 (vector-length entries))
the-list-of-no-method)))
(do ((i 0 (+ i 1)))
((= i n))
(vector-set! new-entries i (vector-ref entries i)))
(vector-set! new-entries n entry)
(set-method-cache-entries! exp new-entries))
(vector-set! entries n entry))))
(define (hashed-method-cache-insert! exp entry)
(let* ((cache (hashed-method-cache-entries exp))
(size (vector-length cache)))
(let* ((entries (cons entry (cache-methods cache)))
(size (if (<= (length entries) size)
size
;; larger size required
(let ((new-size (* 2 size)))
(set-hashed-method-cache-mask! exp (- new-size 1))
new-size)))
(min-misses size)
(best #f))
(do ((hashset 0 (+ 1 hashset)))
((= hashset hashsets))
(let* ((test-cache (make-vector size the-list-of-no-method))
(misses (cache-try-hash! min-misses hashset test-cache entries)))
(cond ((zero? misses)
(set! min-misses 0)
(set! best hashset)
(set! cache test-cache)
(set! hashset (- hashsets 1)))
((< misses min-misses)
(set! min-misses misses)
(set! best hashset)
(set! cache test-cache)))))
(set-hashed-method-cache-hashset! exp best)
(set-hashed-method-cache-entries! exp cache))))
;;;
;;; Caching
;;;
(define (cache-hashval hashset entry)
(let ((hashset-index (+ hashset-index hashset)))
(do ((sum 0)
(classes entry (cdr classes)))
((not (and (pair? classes) (struct? (car classes))))
sum)
(set! sum (+ sum (struct-ref (car classes) hashset-index))))))
(define (cache-try-hash! min-misses hashset cache entries)
(let ((mask (- (vector-length cache) 1)))
(let outer ((in entries) (max-misses 0))
(if (null? in)
max-misses
(let inner ((i (logand mask (cache-hashval hashset (car in))))
(misses 0))
(cond
((and (pair? (vector-ref cache i))
(eq? (car (vector-ref cache i)) 'no-method))
(vector-set! cache i (car in))
(outer (cdr in) (if (> misses max-misses) misses max-misses)))
(else
(let ((misses (+ 1 misses)))
(if (>= misses min-misses)
misses ;; this is a return, yo.
(inner (logand mask (+ i 1)) misses))))))))))
;;;
;;; Memoization
;;;
;; Backward compatibility
(define (lookup-create-cmethod gf args)
(no-applicable-method (car args) (cadr args)))
(define (memoize-method! gf args exp)
(if (not (slot-ref gf 'used-by))
(slot-set! gf 'used-by '()))
(let ((applicable ((if (eq? gf compute-applicable-methods)
%compute-applicable-methods
compute-applicable-methods)
gf args)))
(cond (applicable
;; *fixme* dispatch.scm needs rewriting Since the current
;; code mutates the method cache, we have to work on a
;; copy. Otherwise we might disturb another thread
;; currently dispatching on the cache. (No need to copy
;; the vector.)
(let* ((new (list-copy exp))
(res
(cond ((method-cache-hashed? new)
(method-cache-install! hashed-method-cache-insert!
new args applicable))
((passed-hash-threshold? new)
(method-cache-install! hashed-method-cache-insert!
(method-cache->hashed! new)
args
applicable))
(else
(method-cache-install! method-cache-insert!
new args applicable)))))
(set-cdr! (cdr exp) (cddr new))
res))
((null? args)
(lookup-create-cmethod no-applicable-method (list gf '())))
(else
;; Mutate arglist to fit no-applicable-method
(set-cdr! args (list (cons (car args) (cdr args))))
(set-car! args gf)
(lookup-create-cmethod no-applicable-method args)))))
(set-procedure-property! memoize-method! 'system-procedure #t)
(define method-cache-install!
(letrec ((first-n
(lambda (ls n)
(if (or (zero? n) (null? ls))
'()
(cons (car ls) (first-n (cdr ls) (- n 1)))))))
(lambda (insert! exp args applicable)
(let* ((specializers (method-specializers (car applicable)))
(n-specializers
(if (list? specializers)
(length specializers)
(+ 1 (slot-ref (method-cache-generic-function exp)
'n-specialized)))))
(let* ((types (map class-of (first-n args n-specializers)))
(cmethod (compute-cmethod applicable types)))
(insert! exp (append types cmethod)) ; entry = types + cmethod
cmethod))))) ; cmethod