-(in-package "SB-PCL")
-\f
-;;; FIXME: SB-PCL should probably USE-PACKAGE SB-KERNEL, since SB-PCL
-;;; is built on SB-KERNEL, and in the absence of USE-PACKAGE, it ends
-;;; up using a thundering herd of explicit prefixes to get to
-;;; SB-KERNEL symbols. Using the SB-INT and SB-EXT packages as well
-;;; would help reduce prefixing and make it more natural to reuse
-;;; things (ONCE-ONLY, *KEYWORD-PACKAGE*..) used in the main body of
-;;; the system. However, that would cause a conflict between the
-;;; SB-ITERATE:ITERATE macro and the SB-INT:ITERATE macro. (This could
-;;; be resolved by renaming SB-INT:ITERATE to SB-INT:NAMED-LET, or
-;;; with more gruntwork by punting the SB-ITERATE package and
-;;; replacing calls to SB-ITERATE:ITERATE with calls to CL:LOOP.
-;;; So perhaps:
-;;; * Do some sort of automated check for overlap of symbols to make
-;;; sure there wouldn't be any other clashes.
-;;; * Rename SB-INT:ITERATE to SB-INT:NAMED-LET.
-;;; * Make SB-PCL use SB-INT and SB-EXT.
-;;; * Grep for SB-INT: and SB-EXT: prefixes in the pcl/ directory
-;;; and delete them.
-
-;;; The caching algorithm implemented:
-;;;
-;;; << put a paper here >>
-;;;
-;;; For now, understand that as far as most of this code goes, a cache
-;;; has two important properties. The first is the number of wrappers
-;;; used as keys in each cache line. Throughout this code, this value
-;;; is always called NKEYS. The second is whether or not the cache
-;;; lines of a cache store a value. Throughout this code, this always
-;;; called VALUEP.
-;;;
-;;; Depending on these values, there are three kinds of caches.
-;;;
-;;; NKEYS = 1, VALUEP = NIL
-;;;
-;;; In this kind of cache, each line is 1 word long. No cache locking
-;;; is needed since all read's in the cache are a single value.
-;;; Nevertheless line 0 (location 0) is reserved, to ensure that
-;;; invalid wrappers will not get a first probe hit.
-;;;
-;;; To keep the code simpler, a cache lock count does appear in
-;;; location 0 of these caches, that count is incremented whenever
-;;; data is written to the cache. But, the actual lookup code (see
-;;; make-dlap) doesn't need to do locking when reading the cache.
-;;;
-;;; NKEYS = 1, VALUEP = T
-;;;
-;;; In this kind of cache, each line is 2 words long. Cache locking
-;;; must be done to ensure the synchronization of cache reads. Line 0
-;;; of the cache (location 0) is reserved for the cache lock count.
-;;; Location 1 of the cache is unused (in effect wasted).
-;;;
-;;; NKEYS > 1
-;;;
-;;; In this kind of cache, the 0 word of the cache holds the lock
-;;; count. The 1 word of the cache is line 0. Line 0 of these caches
-;;; is not reserved.
-;;;
-;;; This is done because in this sort of cache, the overhead of doing
-;;; the cache probe is high enough that the 1+ required to offset the
-;;; location is not a significant cost. In addition, because of the
-;;; larger line sizes, the space that would be wasted by reserving
-;;; line 0 to hold the lock count is more significant.
-\f
-;;; caches
-;;;
-;;; A cache is essentially just a vector. The use of the individual
-;;; `words' in the vector depends on particular properties of the
-;;; cache as described above.
-;;;
-;;; This defines an abstraction for caches in terms of their most
-;;; obvious implementation as simple vectors. But, please notice that
-;;; part of the implementation of this abstraction, is the function
-;;; lap-out-cache-ref. This means that most port-specific
-;;; modifications to the implementation of caches will require
-;;; corresponding port-specific modifications to the lap code
-;;; assembler.
-(defmacro cache-vector-ref (cache-vector location)
- `(svref (the simple-vector ,cache-vector)
- (sb-ext:truly-the fixnum ,location)))
-
-(defmacro cache-vector-size (cache-vector)
- `(array-dimension (the simple-vector ,cache-vector) 0))
-
-(defun allocate-cache-vector (size)
- (make-array size :adjustable nil))
-
-(defmacro cache-vector-lock-count (cache-vector)
- `(cache-vector-ref ,cache-vector 0))
-
-(defun flush-cache-vector-internal (cache-vector)
- (sb-sys:without-interrupts
- (fill (the simple-vector cache-vector) nil)
- (setf (cache-vector-lock-count cache-vector) 0))
- cache-vector)
-
-(defmacro modify-cache (cache-vector &body body)
- `(sb-sys:without-interrupts
- (multiple-value-prog1
- (progn ,@body)
- (let ((old-count (cache-vector-lock-count ,cache-vector)))
- (declare (fixnum old-count))
- (setf (cache-vector-lock-count ,cache-vector)
- (if (= old-count most-positive-fixnum)
- 1 (the fixnum (1+ old-count))))))))
-
-(deftype field-type ()
- '(mod #.sb-kernel:layout-clos-hash-length))
-
-(eval-when (:compile-toplevel :load-toplevel :execute)
-(defun power-of-two-ceiling (x)
- (declare (fixnum x))
- ;;(expt 2 (ceiling (log x 2)))
- (the fixnum (ash 1 (integer-length (1- x)))))
-) ; EVAL-WHEN
-
-(defconstant +nkeys-limit+ 256)
-
-(defstruct (cache (:constructor make-cache ())
- (:copier copy-cache-internal))
- (owner nil)
- (nkeys 1 :type (integer 1 #.+nkeys-limit+))
- (valuep nil :type (member nil t))
- (nlines 0 :type fixnum)
- (field 0 :type field-type)
- (limit-fn #'default-limit-fn :type function)
- (mask 0 :type fixnum)
- (size 0 :type fixnum)
- (line-size 1 :type (integer 1 #.(power-of-two-ceiling (1+ +nkeys-limit+))))
- (max-location 0 :type fixnum)
- (vector #() :type simple-vector)
- (overflow nil :type list))
-
-#-sb-fluid (declaim (sb-ext:freeze-type cache))
-
-(defmacro cache-lock-count (cache)
- `(cache-vector-lock-count (cache-vector ,cache)))
-\f
-;;; some facilities for allocation and freeing caches as they are needed
-
-;;; This is done on the assumption that a better port of PCL will
-;;; arrange to cons these all in the same static area. Given that, the
-;;; fact that PCL tries to reuse them should be a win.
-
-(defvar *free-cache-vectors* (make-hash-table :size 16 :test 'eql))
-
-;;; Return a cache that has had FLUSH-CACHE-VECTOR-INTERNAL called on
-;;; it. This returns a cache of exactly the size requested, it won't
-;;; ever return a larger cache.
-(defun get-cache-vector (size)
- (let ((entry (gethash size *free-cache-vectors*)))
- (sb-sys:without-interrupts
- (cond ((null entry)
- (setf (gethash size *free-cache-vectors*) (cons 0 nil))
- (get-cache-vector size))
- ((null (cdr entry))
- (incf (car entry))
- (flush-cache-vector-internal (allocate-cache-vector size)))
- (t
- (let ((cache (cdr entry)))
- (setf (cdr entry) (cache-vector-ref cache 0))
- (flush-cache-vector-internal cache)))))))
-
-(defun free-cache-vector (cache-vector)
- (let ((entry (gethash (cache-vector-size cache-vector) *free-cache-vectors*)))
- (sb-sys:without-interrupts
- (if (null entry)
- (error
- "attempt to free a cache-vector not allocated by GET-CACHE-VECTOR")
- (let ((thread (cdr entry)))
- (loop (unless thread (return))
- (when (eq thread cache-vector)
- (error "freeing a cache twice"))
- (setq thread (cache-vector-ref thread 0)))
- (flush-cache-vector-internal cache-vector) ; to help the GC
- (setf (cache-vector-ref cache-vector 0) (cdr entry))
- (setf (cdr entry) cache-vector)
- nil)))))
-
-;;; This is just for debugging and analysis. It shows the state of the
-;;; free cache resource.
-#+sb-show
-(defun show-free-cache-vectors ()
- (let ((elements ()))
- (maphash #'(lambda (s e) (push (list s e) elements)) *free-cache-vectors*)
- (setq elements (sort elements #'< :key #'car))
- (dolist (e elements)
- (let* ((size (car e))
- (entry (cadr e))
- (allocated (car entry))
- (head (cdr entry))
- (free 0))
- (loop (when (null head) (return t))
- (setq head (cache-vector-ref head 0))
- (incf free))
- (format t
- "~&There ~4D are caches of size ~4D. (~D free ~3D%)"
- allocated
- size
- free
- (floor (* 100 (/ free (float allocated)))))))))
-\f
-;;;; wrapper cache numbers
-
-;;; The constant WRAPPER-CACHE-NUMBER-ADDS-OK controls the number of
-;;; non-zero bits wrapper cache numbers will have.
-;;;
-;;; The value of this constant is the number of wrapper cache numbers
-;;; which can be added and still be certain the result will be a
-;;; fixnum. This is used by all the code that computes primary cache
-;;; locations from multiple wrappers.
-;;;
-;;; The value of this constant is used to derive the next two which
-;;; are the forms of this constant which it is more convenient for the
-;;; runtime code to use.
-(defconstant wrapper-cache-number-length
- (integer-length sb-kernel:layout-clos-hash-max))
-(defconstant wrapper-cache-number-mask sb-kernel:layout-clos-hash-max)
-(defconstant wrapper-cache-number-adds-ok
- (truncate most-positive-fixnum sb-kernel:layout-clos-hash-max))
-\f
-;;;; wrappers themselves
-
-;;; This caching algorithm requires that wrappers have more than one
-;;; wrapper cache number. You should think of these multiple numbers
-;;; as being in columns. That is, for a given cache, the same column
-;;; of wrapper cache numbers will be used.
-;;;
-;;; If at some point the cache distribution of a cache gets bad, the
-;;; cache can be rehashed by switching to a different column.
-;;;
-;;; The columns are referred to by field number which is that number
-;;; which, when used as a second argument to wrapper-ref, will return
-;;; that column of wrapper cache number.
-;;;
-;;; This code is written to allow flexibility as to how many wrapper
-;;; cache numbers will be in each wrapper, and where they will be
-;;; located. It is also set up to allow port specific modifications to
-;;; `pack' the wrapper cache numbers on machines where the addressing
-;;; modes make that a good idea.
-
-;;; In SBCL, as in CMU CL, we want to do type checking as early as
-;;; possible; structures help this. The structures are hard-wired to
-;;; have a fixed number of cache hash values, and that number must
-;;; correspond to the number of cache lines we use.
-(defconstant wrapper-cache-number-vector-length
- sb-kernel:layout-clos-hash-length)
-
-(unless (boundp '*the-class-t*)
- (setq *the-class-t* nil))
-
-;;; Note that for SBCL, as for CMU CL, the WRAPPER of a built-in or
-;;; structure class will be some other kind of SB-KERNEL:LAYOUT, but
-;;; this shouldn't matter, since the only two slots that WRAPPER adds
-;;; are meaningless in those cases.
-(defstruct (wrapper
- (:include sb-kernel:layout
- ;; KLUDGE: In CMU CL, the initialization default
- ;; for LAYOUT-INVALID was NIL. In SBCL, that has
- ;; changed to :UNINITIALIZED, but PCL code might
- ;; still expect NIL for the initialization
- ;; default of WRAPPER-INVALID. Instead of trying
- ;; to find out, I just overrode the LAYOUT
- ;; default here. -- WHN 19991204
- (invalid nil))
- (:conc-name %wrapper-)
- (:constructor make-wrapper-internal))
- (instance-slots-layout nil :type list)
- (class-slots nil :type list))
-#-sb-fluid (declaim (sb-ext:freeze-type wrapper))
-
-(defmacro wrapper-class (wrapper)
- `(sb-kernel:class-pcl-class (sb-kernel:layout-class ,wrapper)))
-(defmacro wrapper-no-of-instance-slots (wrapper)
- `(sb-kernel:layout-length ,wrapper))
-
-;;; WRAPPER-STATE returns T (not generalized boolean, but T exactly)
-;;; iff the wrapper is valid. Any other return value denotes some
-;;; invalid state. Special conventions have been set up for certain
-;;; invalid states, e.g. obsoleteness or flushedness, but I (WHN
-;;; 19991204) haven't been motivated to reverse engineer them from the
-;;; code and document them here.
-;;;
-;;; FIXME: This is awkward and unmnemonic. There is a function
-;;; (INVALID-WRAPPER-P) to test this return result abstractly for
-;;; invalidness but it's not called consistently; the functions that
-;;; need to know whether a wrapper is invalid often test (EQ
-;;; (WRAPPER-STATE X) T), ick. It would be good to use the abstract
-;;; test instead. It would probably be even better to switch the sense
-;;; of the WRAPPER-STATE function, renaming it to WRAPPER-INVALID and
-;;; making it synonymous with LAYOUT-INVALID. Then the
-;;; INVALID-WRAPPER-P function would become trivial and would go away
-;;; (replaced with WRAPPER-INVALID), since all the various invalid
-;;; wrapper states would become generalized boolean "true" values. --
-;;; WHN 19991204
-#-sb-fluid (declaim (inline wrapper-state (setf wrapper-state)))
-(defun wrapper-state (wrapper)
- (let ((invalid (sb-kernel:layout-invalid wrapper)))
- (cond ((null invalid)
- t)
- ((atom invalid)
- ;; some non-PCL object. INVALID is probably :INVALID. We
- ;; should arguably compute the new wrapper here instead of
- ;; returning NIL, but we don't bother, since
- ;; OBSOLETE-INSTANCE-TRAP can't use it.
- '(:obsolete nil))
- (t
- invalid))))
-(defun (setf wrapper-state) (new-value wrapper)
- (setf (sb-kernel:layout-invalid wrapper)
- (if (eq new-value t)
- nil
- new-value)))
-
-(defmacro wrapper-instance-slots-layout (wrapper)
- `(%wrapper-instance-slots-layout ,wrapper))
-(defmacro wrapper-class-slots (wrapper)
- `(%wrapper-class-slots ,wrapper))
-(defmacro wrapper-cache-number-vector (x) x)
-
-;;; This is called in BRAID when we are making wrappers for classes
-;;; whose slots are not initialized yet, and which may be built-in
-;;; classes. We pass in the class name in addition to the class.
-(defun boot-make-wrapper (length name &optional class)
- (let ((found (cl:find-class name nil)))
- (cond
- (found
- (unless (sb-kernel:class-pcl-class found)
- (setf (sb-kernel:class-pcl-class found) class))
- (assert (eq (sb-kernel:class-pcl-class found) class))
- (let ((layout (sb-kernel:class-layout found)))
- (assert layout)
- layout))
- (t
- (make-wrapper-internal
- :length length
- :class (sb-kernel:make-standard-class :name name :pcl-class class))))))
-
-;;; The following variable may be set to a standard-class that has
-;;; already been created by the lisp code and which is to be redefined
-;;; by PCL. This allows standard-classes to be defined and used for
-;;; type testing and dispatch before PCL is loaded.
-(defvar *pcl-class-boot* nil)
-
-;;; In SBCL, as in CMU CL, the layouts (a.k.a wrappers) for built-in
-;;; and structure classes already exist when PCL is initialized, so we
-;;; don't necessarily always make a wrapper. Also, we help maintain
-;;; the mapping between cl:class and pcl::class objects.
-(defun make-wrapper (length class)
- (cond
- ((typep class 'std-class)
- (make-wrapper-internal
- :length length
- :class
- (let ((owrap (class-wrapper class)))
- (cond (owrap
- (sb-kernel:layout-class owrap))
- ((*subtypep (class-of class)
- *the-class-standard-class*)
- (cond ((and *pcl-class-boot*
- (eq (slot-value class 'name) *pcl-class-boot*))
- (let ((found (cl:find-class (slot-value class 'name))))
- (unless (sb-kernel:class-pcl-class found)
- (setf (sb-kernel:class-pcl-class found) class))
- (assert (eq (sb-kernel:class-pcl-class found) class))
- found))
- (t
- (sb-kernel:make-standard-class :pcl-class class))))
- (t
- (sb-kernel:make-random-pcl-class :pcl-class class))))))
- (t
- (let* ((found (cl:find-class (slot-value class 'name)))
- (layout (sb-kernel:class-layout found)))
- (unless (sb-kernel:class-pcl-class found)
- (setf (sb-kernel:class-pcl-class found) class))
- (assert (eq (sb-kernel:class-pcl-class found) class))
- (assert layout)
- layout))))
-
-;;; FIXME: The immediately following macros could become inline functions.
-
-(defmacro first-wrapper-cache-number-index ()
- 0)
-
-(defmacro next-wrapper-cache-number-index (field-number)
- `(and (< ,field-number #.(1- wrapper-cache-number-vector-length))
- (1+ ,field-number)))
-
-(defmacro cache-number-vector-ref (cnv n)
- `(wrapper-cache-number-vector-ref ,cnv ,n))
-
-(defmacro wrapper-cache-number-vector-ref (wrapper n)
- `(sb-kernel:layout-clos-hash ,wrapper ,n))
-
-(defmacro class-no-of-instance-slots (class)
- `(wrapper-no-of-instance-slots (class-wrapper ,class)))
-
-(defmacro wrapper-class* (wrapper)
- `(let ((wrapper ,wrapper))
- (or (wrapper-class wrapper)
- (find-structure-class
- (cl:class-name (sb-kernel:layout-class wrapper))))))
-
-;;; The wrapper cache machinery provides general mechanism for
-;;; trapping on the next access to any instance of a given class. This
-;;; mechanism is used to implement the updating of instances when the
-;;; class is redefined (MAKE-INSTANCES-OBSOLETE). The same mechanism
-;;; is also used to update generic function caches when there is a
-;;; change to the superclasses of a class.
-;;;
-;;; Basically, a given wrapper can be valid or invalid. If it is
-;;; invalid, it means that any attempt to do a wrapper cache lookup
-;;; using the wrapper should trap. Also, methods on
-;;; SLOT-VALUE-USING-CLASS check the wrapper validity as well. This is
-;;; done by calling CHECK-WRAPPER-VALIDITY.
-
-;;; FIXME: could become inline function
-(defmacro invalid-wrapper-p (wrapper)
- `(neq (wrapper-state ,wrapper) t))
-
-(defvar *previous-nwrappers* (make-hash-table))
-
-(defun invalidate-wrapper (owrapper state nwrapper)
- (ecase state
- ((:flush :obsolete)
- (let ((new-previous ()))
- ;; First off, a previous call to INVALIDATE-WRAPPER may have
- ;; recorded OWRAPPER as an NWRAPPER to update to. Since
- ;; OWRAPPER is about to be invalid, it no longer makes sense to
- ;; update to it.
- ;;
- ;; We go back and change the previously invalidated wrappers so
- ;; that they will now update directly to NWRAPPER. This
- ;; corresponds to a kind of transitivity of wrapper updates.
- (dolist (previous (gethash owrapper *previous-nwrappers*))
- (when (eq state ':obsolete)
- (setf (car previous) ':obsolete))
- (setf (cadr previous) nwrapper)
- (push previous new-previous))
-
- (let ((ocnv (wrapper-cache-number-vector owrapper)))
- (dotimes (i sb-kernel:layout-clos-hash-length)
- (setf (cache-number-vector-ref ocnv i) 0)))
- (push (setf (wrapper-state owrapper) (list state nwrapper))
- new-previous)
-
- (setf (gethash owrapper *previous-nwrappers*) ()
- (gethash nwrapper *previous-nwrappers*) new-previous)))))
-
-(defun check-wrapper-validity (instance)
- (let* ((owrapper (wrapper-of instance))
- (state (wrapper-state owrapper)))
- (if (eq state t)
- owrapper
- (let ((nwrapper
- (ecase (car state)
- (:flush
- (flush-cache-trap owrapper (cadr state) instance))
- (:obsolete
- (obsolete-instance-trap owrapper (cadr state) instance)))))
- ;; This little bit of error checking is superfluous. It only
- ;; checks to see whether the person who implemented the trap
- ;; handling screwed up. Since that person is hacking
- ;; internal PCL code, and is not a user, this should be
- ;; needless. Also, since this directly slows down instance
- ;; update and generic function cache refilling, feel free to
- ;; take it out sometime soon.
- ;;
- ;; FIXME: We probably need to add a #+SB-PARANOID feature to
- ;; make stuff like this optional. Until then, it stays in.
- (cond ((neq nwrapper (wrapper-of instance))
- (error "wrapper returned from trap not wrapper of instance"))
- ((invalid-wrapper-p nwrapper)
- (error "wrapper returned from trap invalid")))
- nwrapper))))
-
-(defmacro check-wrapper-validity1 (object)
- (let ((owrapper (gensym)))
- `(let ((,owrapper (sb-kernel:layout-of object)))
- (if (sb-kernel:layout-invalid ,owrapper)
- (check-wrapper-validity ,object)
- ,owrapper))))
-\f
-(defvar *free-caches* nil)
-
-(defun get-cache (nkeys valuep limit-fn nlines)
- (let ((cache (or (sb-sys:without-interrupts (pop *free-caches*))
- (make-cache))))
- (declare (type cache cache))
- (multiple-value-bind (cache-mask actual-size line-size nlines)
- (compute-cache-parameters nkeys valuep nlines)
- (setf (cache-nkeys cache) nkeys
- (cache-valuep cache) valuep
- (cache-nlines cache) nlines
- (cache-field cache) (first-wrapper-cache-number-index)
- (cache-limit-fn cache) limit-fn
- (cache-mask cache) cache-mask
- (cache-size cache) actual-size
- (cache-line-size cache) line-size
- (cache-max-location cache) (let ((line (1- nlines)))
- (if (= nkeys 1)
- (* line line-size)
- (1+ (* line line-size))))
- (cache-vector cache) (get-cache-vector actual-size)
- (cache-overflow cache) nil)
- cache)))
-
-(defun get-cache-from-cache (old-cache new-nlines
- &optional (new-field (first-wrapper-cache-number-index)))
- (let ((nkeys (cache-nkeys old-cache))
- (valuep (cache-valuep old-cache))
- (cache (or (sb-sys:without-interrupts (pop *free-caches*))
- (make-cache))))
- (declare (type cache cache))
- (multiple-value-bind (cache-mask actual-size line-size nlines)
- (if (= new-nlines (cache-nlines old-cache))
- (values (cache-mask old-cache) (cache-size old-cache)
- (cache-line-size old-cache) (cache-nlines old-cache))
- (compute-cache-parameters nkeys valuep new-nlines))
- (setf (cache-owner cache) (cache-owner old-cache)
- (cache-nkeys cache) nkeys
- (cache-valuep cache) valuep
- (cache-nlines cache) nlines
- (cache-field cache) new-field
- (cache-limit-fn cache) (cache-limit-fn old-cache)
- (cache-mask cache) cache-mask
- (cache-size cache) actual-size
- (cache-line-size cache) line-size
- (cache-max-location cache) (let ((line (1- nlines)))
- (if (= nkeys 1)
- (* line line-size)
- (1+ (* line line-size))))
- (cache-vector cache) (get-cache-vector actual-size)
- (cache-overflow cache) nil)
- cache)))
-
-(defun copy-cache (old-cache)
- (let* ((new-cache (copy-cache-internal old-cache))
- (size (cache-size old-cache))
- (old-vector (cache-vector old-cache))
- (new-vector (get-cache-vector size)))
- (declare (simple-vector old-vector new-vector))
- (dotimes-fixnum (i size)
- (setf (svref new-vector i) (svref old-vector i)))
- (setf (cache-vector new-cache) new-vector)
- new-cache))
-
-(defun free-cache (cache)
- (free-cache-vector (cache-vector cache))
- (setf (cache-vector cache) #())
- (setf (cache-owner cache) nil)
- (push cache *free-caches*)
- nil)