src/code/thread.lisp

   1 ;;;; support for threads needed at cross-compile time
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; This software is derived from the CMU CL system, which was
   7 ;;;; written at Carnegie Mellon University and released into the
   8 ;;;; public domain. The software is in the public domain and is
   9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  10 ;;;; files for more information.
  11
  12 (in-package "SB!THREAD")
  13
  14 (sb!xc:defmacro with-mutex ((mutex &key value (wait-p t)) &body body)
  15   #!-sb-thread (declare (ignore mutex value wait-p))
  16   #!+sb-thread
  17   (with-unique-names (got)
  18     `(let ((,got (get-mutex ,mutex ,value ,wait-p)))
  19       (when ,got
  20         (unwind-protect
  21              (locally ,@body)
  22           (release-mutex ,mutex)))))
  23   ;; KLUDGE: this separate expansion for (NOT SB-THREAD) is not
  24   ;; strictly necessary; GET-MUTEX and RELEASE-MUTEX are implemented.
  25   ;; However, there would be a (possibly slight) performance hit in
  26   ;; using them.
  27   #!-sb-thread
  28   `(locally ,@body))
  29
  30 (sb!xc:defmacro with-recursive-lock ((mutex) &body body)
  31   #!-sb-thread (declare (ignore mutex))
  32   #!+sb-thread
  33   (with-unique-names (cfp)
  34     `(let ((,cfp (sb!kernel:current-fp)))
  35       (unless (and (mutex-value ,mutex)
  36                    (sb!vm:control-stack-pointer-valid-p
  37                     (sb!sys:int-sap
  38                      (sb!kernel:get-lisp-obj-address (mutex-value ,mutex)))))
  39         ;; this punning with MAKE-LISP-OBJ depends for its safety on
  40         ;; the frame pointer being a lispobj-aligned integer.  While
  41         ;; it is, then MAKE-LISP-OBJ will always return a FIXNUM, so
  42         ;; we're safe to do that.  Should this ever change, this
  43         ;; MAKE-LISP-OBJ could return something that looks like a
  44         ;; pointer, but pointing into neverneverland, which will
  45         ;; confuse GC completely.  -- CSR, 2003-06-03
  46         (get-mutex ,mutex (sb!kernel:make-lisp-obj (sb!sys:sap-int ,cfp))))
  47       (unwind-protect
  48            (locally ,@body)
  49         (when (sb!sys:sap= (sb!sys:int-sap
  50                             (sb!kernel:get-lisp-obj-address
  51                              (mutex-value ,mutex)))
  52                            ,cfp)
  53           (release-mutex ,mutex)))))
  54   #!-sb-thread
  55   `(locally ,@body))