1.0.4.49: revert debugger hackery

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

diff --git a/src/code/signal.lisp b/src/code/signal.lisp
index 91d7a13..41be48f 100644 (file)
--- a/src/code/signal.lisp
+++ b/src/code/signal.lisp
@@ -42,38 +42,44 @@
 
 (sb!xc:defmacro without-interrupts (&body body)
   #!+sb-doc
-  "Execute BODY in a context impervious to interrupts."
+  "Execute BODY with all deferrable interrupts deferred. Deferrable interrupts
+include most blockable POSIX signals, and SB-THREAD:INTERRUPT-THREAD. Does not
+interfere with garbage collection, and unlike in many traditional Lisps using
+userspace threads, in SBCL WITHOUT-INTERRUPTS does not inhibit scheduling of
+other threads."
   (let ((name (gensym "WITHOUT-INTERRUPTS-BODY-")))
     `(flet ((,name () ,@body))
        (if *interrupts-enabled*
-          (unwind-protect
-               (let ((*interrupts-enabled* nil))
-                 (,name))
-            ;; FIXME: Does it matter that an interrupt coming in here
-            ;; could be executed before any of the pending interrupts?
-            ;; Or do incoming interrupts have the good grace to check
-            ;; whether interrupts are pending before executing themselves
-            ;; immediately?
-            ;;
-            ;; FIXME: from the kernel's POV we've already handled the
-            ;; signal the moment we return from the handler having
-            ;; decided to defer it, meaning that the kernel is free
-            ;; to deliver _more_ signals to us... of which we save,
-            ;; and subsequently handle here, only the last one.
-            ;; PSEUDO-ATOMIC has the same issue. -- NS 2005-05-19
-            (when *interrupt-pending*
-              (receive-pending-interrupt)))
-          (,name)))))
+           (unwind-protect
+                (let ((*interrupts-enabled* nil))
+                  (,name))
+             ;; If we were interrupted in the protected section, then
+             ;; the interrupts are still blocked and it remains so
+             ;; until the pending interrupt is handled.
+             ;;
+             ;; If we were not interrupted in the protected section,
+             ;; but here, then even if the interrupt handler enters
+             ;; another WITHOUT-INTERRUPTS, the pending interrupt will
+             ;; be handled immediately upon exit from said
+             ;; WITHOUT-INTERRUPTS, so it is as if nothing has
+             ;; happened.
+             (when *interrupt-pending*
+               (receive-pending-interrupt)))
+           (,name)))))
 
 (sb!xc:defmacro with-interrupts (&body body)
   #!+sb-doc
   "Allow interrupts while executing BODY. As interrupts are normally allowed,
-  this is only useful inside a WITHOUT-INTERRUPTS."
+this is only useful inside a SB-SYS:WITHOUT-INTERRUPTS. Signals a runtime
+warning if used inside the dynamic countour of SB-SYS:WITHOUT-GCING."
   (let ((name (gensym)))
     `(flet ((,name () ,@body))
        (if *interrupts-enabled*
-          (,name)
-          (let ((*interrupts-enabled* t))
-            (when *interrupt-pending*
-              (receive-pending-interrupt))
-            (,name))))))
+           (,name)
+           (progn
+             (when sb!kernel:*gc-inhibit*
+               (warn "Re-enabling interrupts while GC is inhibited."))
+             (let ((*interrupts-enabled* t))
+               (when *interrupt-pending*
+                 (receive-pending-interrupt))
+               (,name)))))))