Refactor directory and source file layout.

darcs-hash:0eb031a60f3b86a678869960867410811ca5325c

1 files changed, 93 insertions, 0 deletions

diff --git a/Lisp/memory-management.lisp b/Lisp/memory-management.lisp
new file mode 100644
index 0000000..4476957
--- /dev/null
+++ b/Lisp/memory-management.lisp
@@ -0,0 +1,93 @@
+(in-package #:mulk.objective-cl)
+
+
+(defvar *skip-finalization* nil)
+(defvar *skip-retaining*    nil)
+
+(defvar *id-objects* (make-weak-value-hash-table))
+(defvar *class-objects* (make-weak-value-hash-table))
+(defvar *exception-objects* (make-weak-value-hash-table))
+
+
+#+cmu
+(progn
+  (declaim (inline make-weak-value-hash-table))
+
+  (defun make-weak-value-hash-table ()
+    (make-hash-table :test 'eql))
+
+  (defun weak-gethash (key hash-table &optional (default nil))
+    (let ((pointer (gethash key hash-table default)))
+      (or (and (trivial-garbage:weak-pointer-p pointer)
+               (trivial-garbage:weak-pointer-value pointer))
+          (prog1 default
+            ;; Clean up.
+            (remhash key hash-table)))))
+
+  (defun (setf weak-gethash) (value key hash-table)
+    (setf (gethash key hash-table)
+          (trivial-garbage:make-weak-pointer value))))
+
+#-cmu
+(progn
+  (declaim (inline make-weak-value-hash-table))
+
+  (defun make-weak-value-hash-table ()
+    (trivial-garbage:make-weak-hash-table :weakness :value
+                                          :test 'eql))
+
+  (setf (fdefinition 'weak-gethash)        (fdefinition 'gethash)
+        (fdefinition '(setf weak-gethash)) (fdefinition '(setf gethash))))
+
+;; We call the `retain' method on every object that we receive from a
+;; method call or otherwise except non-convenience constructor methods
+;; (i.e. those whose name starts with `alloc' or `new').  Upon
+;; Lisp-side finalization of an object, wie `release' it.
+(eval-when (:load-toplevel)
+  (dolist (type '(objc-id objc-class objc-exception))
+    (funcall
+     (compile
+      nil
+      `(lambda ()
+         (defmethod make-instance ((class (eql ',type)) &rest initargs &key)
+           (let* ((hash-table ,(ecase type
+                                 ((objc-id)        '*id-objects*)
+                                 ((objc-class)     '*class-objects*)
+                                 ((objc-exception) '*exception-objects*)))
+                  (hash-key (pointer-address (getf initargs :pointer)))
+                  (obj (weak-gethash hash-key hash-table nil)))
+             (typecase obj
+               (keyword (assert (eq :incomplete obj))
+                        (call-next-method))
+               (null (setf (weak-gethash hash-key hash-table)
+                           :incomplete)
+                     (let ((new-obj (call-next-method)))
+                       (setf (weak-gethash hash-key hash-table) new-obj)
+                       (unless *skip-retaining*
+                         (objcl-invoke-class-method new-obj "retain"))
+                       (unless *skip-finalization*
+                         (assert (not (null (pointer-to new-obj))))
+                         (let ((saved-pointer (pointer-to new-obj))
+                               (saved-type    (type-of new-obj)))
+                           (flet ((finalizer ()
+                                    ;; In order to send the `release'
+                                    ;; message to the newly GC'd object,
+                                    ;; we have to create a temporary
+                                    ;; container object for the final
+                                    ;; message delivery.  Note that this
+                                    ;; can cause an infinite recursion
+                                    ;; or even memory corruption if we
+                                    ;; don't take measure to skip both
+                                    ;; finalization and retaining of the
+                                    ;; temporary object.
+                                    (let ((temp (let ((*skip-finalization* t)
+                                                      (*skip-retaining*    t))
+                                                  (make-instance saved-type
+                                                                 :pointer saved-pointer))))
+                                      (objcl-invoke-class-method temp "release"))))
+                             (trivial-garbage:finalize new-obj #'finalizer))))
+                       new-obj))
+               (t obj))))
+
+         (defmethod initialize-instance ((obj ,type) &key)
+           (call-next-method)))))))