X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Ftimer.lisp;h=53523859208eafbb2425e281a2f726072ddf4f99;hb=fd324a9d981355d8bc10d2bd469cb54c4c9108fd;hp=7f49302e9de247fe10ca22ab07eb0eaa9ef97d08;hpb=1aee76da48edafa210f60e852913041a843428b7;p=sbcl.git

diff --git a/src/code/timer.lisp b/src/code/timer.lisp
index 7f49302..5352385 100644
--- a/src/code/timer.lisp
+++ b/src/code/timer.lisp
@@ -208,9 +208,9 @@ from now. For timers with a repeat interval it returns true."
       ,@body)))
 
 (defun under-scheduler-lock-p ()
-  #!-sb!thread
+  #!-sb-thread
   t
-  #!+sb!thread
+  #!+sb-thread
   (eq sb!thread:*current-thread* (sb!thread:mutex-value *scheduler-lock*)))
 
 (defparameter *schedule* (make-priority-queue :key #'%timer-expire-time))
@@ -337,28 +337,50 @@ triggers."
            (handler-case
                (sb!thread:interrupt-thread thread function)
              (sb!thread:interrupt-thread-error (c)
-               (warn c)))))))
+               (declare (ignore c))
+               (warn "Timer ~S failed to interrupt thread ~S."
+                     timer thread)))))))
 
+;; Called from the signal handler.
 (defun run-expired-timers ()
   (unwind-protect
-       (let (timer)
-         (loop
-          (with-scheduler-lock ()
-            (setq timer (peek-schedule))
-            (unless (and timer
-                         (> (get-internal-real-time)
-                            (%timer-expire-time timer)))
-              (return-from run-expired-timers nil))
-            (assert (eq timer (priority-queue-extract-maximum *schedule*))))
-          ;; run the timer without the lock
-          (run-timer timer)))
+       (with-interrupts
+         (let (timer)
+           (loop
+            (with-scheduler-lock ()
+              (setq timer (peek-schedule))
+              (unless (and timer
+                           (> (get-internal-real-time)
+                              (%timer-expire-time timer)))
+                (return-from run-expired-timers nil))
+              (assert (eq timer (priority-queue-extract-maximum *schedule*))))
+            ;; run the timer without the lock
+            (run-timer timer))))
     (with-scheduler-lock ()
       (set-system-timer))))
 
 (defmacro sb!ext:with-timeout (expires &body body)
   #!+sb-doc
-  "Execute the body, asynchronously interrupting it and signalling a
-TIMEOUT condition after at least EXPIRES seconds have passed."
+  "Execute the body, asynchronously interrupting it and signalling a TIMEOUT
+condition after at least EXPIRES seconds have passed.
+
+Note that it is never safe to unwind from an asynchronous condition. Consider:
+
+  (defun call-with-foo (function)
+    (let (foo)
+      (unwind-protect
+         (progn
+           (setf foo (get-foo))
+           (funcall function foo))
+       (when foo
+         (release-foo foo)))))
+
+If TIMEOUT occurs after GET-FOO has executed, but before the assignment, then
+RELEASE-FOO will be missed. While individual sites like this can be made proof
+against asynchronous unwinds, this doesn't solve the fundamental issue, as all
+the frames potentially unwound through need to be proofed, which includes both
+system and application code -- and in essence proofing everything will make
+the system uninterruptible."
   (with-unique-names (timer)
     ;; FIXME: a temporary compatibility workaround for CLX, if unsafe
     ;; unwinds are handled revisit it.