Program to test the performance of Lisp file I/O.

slow.lisp

;; It is often said that Lisp macros need not be used for optimization purposes. This
;; is an exception. SBCL issued the following warning when compiling the MAKE-ARRAY call
;; below:

;; ; note: unable to optimize because: ELEMENT-TYPE is not constant.

;; I don't want to lose the ability to decide which ELEMENT-TYPE to use by using
;; an :ELEMENT-TYPE argument, so I have to arrange for this argument to be processed
;; at compile time.

(defmacro define-test-file-functions ()
  (let* ((element-type* (gensym))
	 (function-name (gensym))
	 (template `(defun ,function-name (infile outfile)
		     (declare (optimize (speed 3) (safety 0)))
		     (ignore-errors (delete-file outfile))
		     (time
		      (with-open-file (in infile :element-type ,element-type*)
			(with-open-file (out outfile :direction :output :element-type ,element-type*)
			  (let ((buffer (make-array (file-length in) :element-type ,element-type*)))
			    (read-sequence buffer in)
			    (write-sequence buffer out)))))))
	 (types/defs-alist (loop for type in '((unsigned-byte 8) character)
			      for realname = (gensym)
			      collect (cons type (subst (list 'quote type) element-type*
							(subst realname function-name
							       template))))))
    `(progn
       ,@(mapcar #'cdr types/defs-alist)
       (defparameter *test-file-functions* ',(loop for (type . (defun name)) in types/defs-alist
						collect (cons type name))))))

(define-test-file-functions)

(defmacro test-file (infile outfile &key (element-type '(unsigned-byte 8)))
  `(time (,(cdr (assoc element-type *test-file-functions* :test #'equal)) ,infile ,outfile)))