1.0.11.17: fixed dumb buglet in DEFMACRO NAMED-LET

[sbcl.git] / src / code / final.lisp

diff --git a/src/code/final.lisp b/src/code/final.lisp
index a2adcaf..c2ef070 100644 (file)
--- a/src/code/final.lisp
+++ b/src/code/final.lisp
@@ -13,46 +13,100 @@
 
 (defvar *finalizer-store* nil)
 
-(defvar *finalizer-store-lock* 
+(defvar *finalizer-store-lock*
   (sb!thread:make-mutex :name "Finalizer store lock."))
 
-(defun finalize (object function)
-  #!+sb-doc 
+(defmacro with-finalizer-store-lock (&body body)
+  `(sb!thread::call-with-system-mutex (lambda () ,@body)
+                                      *finalizer-store-lock*
+                                      t))
+
+(defun finalize (object function &key dont-save)
+  #!+sb-doc
   "Arrange for the designated FUNCTION to be called when there
-are no more references to OBJECT. In a multithreaded environment
-the finalizer may run in any thread."
-  (sb!thread:with-mutex (*finalizer-store-lock*)
-    (push (cons (make-weak-pointer object) function)
-         *finalizer-store*))
+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 (assumes 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)) ; causes GC and 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 for OBJECT."
   ;; Check for NIL to avoid deleting finalizers that are waiting to be
   ;; run.
   (when object
-    (sb!thread:with-mutex (*finalizer-store-lock*)
-      (setf *finalizer-store*
-           (delete object *finalizer-store*
-                   :key (lambda (pair) 
-                          (weak-pointer-value (car pair))))))
+    (with-finalizer-store-lock
+        (setf *finalizer-store*
+              (delete object *finalizer-store*
+                      :key (lambda (list)
+                             (weak-pointer-value (car list))))))
     object))
 
 (defun run-pending-finalizers ()
   (let (pending)
-    (sb!thread:with-mutex (*finalizer-store-lock*)
-      (setf *finalizer-store*
-           (delete-if  (lambda (pair)
-                         (when (null (weak-pointer-value (car pair)))
-                           (push (cdr pair) pending)
-                           t))
-                     *finalizer-store*)))
+    (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)))))
+          (funcall fun)
+        (error (c)
+          (warn "Error calling finalizer ~S:~%  ~S" fun c)))))
   nil)