X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Ffinal.lisp;h=cfa36f1dba686f94c4daae37f504563c9fab543e;hb=18dc0069cd514c976042766ab9a785c970fe1603;hp=1fdffda1ba1e1239f63f2adfcd4f86a98a1c6844;hpb=a530bbe337109d898d5b4a001fc8f1afa3b5dc39;p=sbcl.git

diff --git a/src/code/final.lisp b/src/code/final.lisp
index 1fdffda..cfa36f1 100644
--- a/src/code/final.lisp
+++ b/src/code/final.lisp
@@ -9,48 +9,105 @@
 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
 ;;;; files for more information.
 
-(in-package "SB!EXT")
+(in-package "SB!IMPL")
 
-(file-comment
-  "$Header$")
+(defglobal **finalizer-store** nil)
 
-(defvar *objects-pending-finalization* nil)
+(defglobal **finalizer-store-lock**
+  (sb!thread:make-mutex :name "Finalizer store lock."))
 
-(defun finalize (object function)
+(defmacro with-finalizer-store-lock (&body body)
+  `(sb!thread::with-system-mutex (**finalizer-store-lock** :without-gcing t)
+     ,@body))
+
+(defun finalize (object function &key dont-save)
   #!+sb-doc
-  "Arrange for FUNCTION to be called when there are no more references to
-   OBJECT."
-  (declare (type function function))
-  (sb!sys:without-gcing
-   (push (cons (make-weak-pointer object) function)
-	 *objects-pending-finalization*))
+  "Arrange for the designated FUNCTION to be called when there
+are no more references to OBJECT, including references in
+FUNCTION itself.
+
+If DONT-SAVE is true, the finalizer will be cancelled when
+SAVE-LISP-AND-DIE is called: this is useful for finalizers
+deallocating system memory, which might otherwise be called
+with addresses from the old image.
+
+In a multithreaded environment FUNCTION may be called in any
+thread. In both single and multithreaded environments FUNCTION
+may be called in any dynamic scope: consequences are unspecified
+if FUNCTION is not fully re-entrant.
+
+Errors from FUNCTION are handled and cause a WARNING to be
+signalled in whichever thread the FUNCTION was called in.
+
+Examples:
+
+  ;;; GOOD, assuming RELEASE-HANDLE is re-entrant.
+  (let* ((handle (get-handle))
+         (object (make-object handle)))
+   (finalize object (lambda () (release-handle handle)))
+   object)
+
+  ;;; BAD, finalizer refers to object being finalized, causing
+  ;;; it to be retained indefinitely!
+  (let* ((handle (get-handle))
+         (object (make-object handle)))
+    (finalize object
+              (lambda ()
+                (release-handle (object-handle object)))))
+
+  ;;; BAD, not re-entrant!
+  (defvar *rec* nil)
+
+  (defun oops ()
+   (when *rec*
+     (error \"recursive OOPS\"))
+   (let ((*rec* t))
+     (gc))) ; or just cons enough to cause one
+
+  (progn
+    (finalize \"oops\" #'oops)
+    (oops)) ; GC causes re-entry to #'oops due to the finalizer
+            ; -> ERROR, caught, WARNING signalled"
+  (unless object
+    (error "Cannot finalize NIL."))
+  (with-finalizer-store-lock
+    (push (list (make-weak-pointer object) function dont-save)
+          **finalizer-store**))
   object)
 
+(defun deinit-finalizers ()
+  ;; remove :dont-save finalizers
+  (with-finalizer-store-lock
+    (setf **finalizer-store** (delete-if #'third **finalizer-store**)))
+  nil)
+
 (defun cancel-finalization (object)
   #!+sb-doc
-  "Cancel any finalization registers for OBJECT."
+  "Cancel any finalization for OBJECT."
+  ;; Check for NIL to avoid deleting finalizers that are waiting to be
+  ;; run.
   (when object
-    ;; We check to make sure object isn't nil because if there are any
-    ;; broken weak pointers, their value will show up as nil. Therefore,
-    ;; they would be deleted from the list, but not finalized. Broken
-    ;; weak pointers shouldn't be left in the list, but why take chances?
-    (sb!sys:without-gcing
-     (setf *objects-pending-finalization*
-	   (delete object *objects-pending-finalization*
-		   :key #'(lambda (pair)
-			    (values (weak-pointer-value (car pair))))))))
-  nil)
+    (with-finalizer-store-lock
+        (setf **finalizer-store**
+              (delete object **finalizer-store**
+                      :key (lambda (list)
+                             (weak-pointer-value (car list))))))
+    object))
 
-(defun finalize-corpses ()
-  (setf *objects-pending-finalization*
-	(delete-if #'(lambda (pair)
-		       (multiple-value-bind (object valid)
-			   (weak-pointer-value (car pair))
-			 (declare (ignore object))
-			 (unless valid
-			   (funcall (cdr pair))
-			   t)))
-		   *objects-pending-finalization*))
+(defun run-pending-finalizers ()
+  (let (pending)
+    (with-finalizer-store-lock
+        (setf **finalizer-store**
+              (delete-if (lambda (list)
+                           (when (null (weak-pointer-value (car list)))
+                             (push (second list) pending)
+                             t))
+                         **finalizer-store**)))
+    ;; We want to run the finalizer bodies outside the lock in case
+    ;; finalization of X causes finalization to be added for Y.
+    (dolist (fun pending)
+      (handler-case
+          (funcall fun)
+        (error (c)
+          (warn "Error calling finalizer ~S:~%  ~S" fun c)))))
   nil)
-
-(pushnew 'finalize-corpses *after-gc-hooks*)