- (defconstant micro-seconds-per-internal-time-unit
- (/ 1000000 sb!xc:internal-time-units-per-second))
-
- (declaim (inline system-internal-real-time system-internal-run-time))
- (defun system-internal-real-time ()
- (multiple-value-bind (ignore seconds useconds) (unix-gettimeofday)
- (declare (ignore ignore) (type (unsigned-byte 32) seconds useconds))
- (let ((uint (truncate useconds
- micro-seconds-per-internal-time-unit)))
- (declare (type (unsigned-byte 32) uint))
- (+ (* seconds sb!xc:internal-time-units-per-second)
- uint))))
+ (declaim (inline system-internal-run-time
+ system-real-time-values))
+
+ (defun system-real-time-values ()
+ (multiple-value-bind (_ sec usec) (unix-gettimeofday)
+ (declare (ignore _) (type (unsigned-byte 32) sec usec))
+ (values sec (truncate usec micro-seconds-per-internal-time-unit))))
+
+ ;; There are two optimizations here that actually matter (on 32-bit
+ ;; systems): substract the epoch from seconds and milliseconds
+ ;; separately, as those should remain fixnums for the first 17 years
+ ;; or so of runtime. Also, avoid doing consing a new bignum if the
+ ;; result would be = to the last result given.
+ ;;
+ ;; Note: the next trick would be to spin a separate thread to update
+ ;; a global value once per internal tick, so each individual call to
+ ;; get-internal-real-time would be just a memory read... but that is
+ ;; probably best left for user-level code. ;)
+ ;;
+ ;; Thanks to James Anderson for the optimization hint.
+ ;;
+ ;; Yes, it is possible to a computation to be GET-INTERNAL-REAL-TIME
+ ;; bound.
+ ;;
+ ;; --NS 2007-04-05
+ (let ((e-sec 0)
+ (e-msec 0)
+ (c-sec 0)
+ (c-msec 0)
+ (now 0))
+ (declare (type (unsigned-byte 32) e-sec c-sec)
+ (type fixnum e-msec c-msec)
+ (type unsigned-byte now))
+ (defun reinit-internal-real-time ()
+ (setf (values e-sec e-msec) (system-real-time-values)
+ c-sec 0
+ c-msec 0))
+ ;; If two threads call this at the same time, we're still safe, I believe,
+ ;; as long as NOW is updated before either of C-MSEC or C-SEC. Same applies
+ ;; to interrupts. --NS
+ (defun get-internal-real-time ()
+ (multiple-value-bind (sec msec) (system-real-time-values)
+ (unless (and (= msec c-msec) (= sec c-sec))
+ (setf now (+ (* (- sec e-sec)
+ sb!xc:internal-time-units-per-second)
+ (- msec e-msec))
+ c-msec msec
+ c-sec sec))
+ now)))