X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Ftarget-thread.lisp;h=aedfa10bf5f99fda7e06981ecb7b76cc31827c0c;hb=428b60fff4247e34ff601810f33976908f22bbc0;hp=9142ee2728a7fee0a5fa47462d53a963c2a3d665;hpb=6893cb1b25387d1131371649b709398fea78d6f1;p=sbcl.git

diff --git a/src/code/target-thread.lisp b/src/code/target-thread.lisp
index 9142ee2..aedfa10 100644
--- a/src/code/target-thread.lisp
+++ b/src/code/target-thread.lisp
@@ -1,151 +1,120 @@
-(in-package "SB!THREAD")
+;;;; support for threads in the target machine
 
-(sb!alien::define-alien-routine ("create_thread" %create-thread)
-     sb!alien:unsigned-long
-  (lisp-fun-address sb!alien:unsigned-long))
+;;;; This software is part of the SBCL system. See the README file for
+;;;; more information.
+;;;;
+;;;; This software is derived from the CMU CL system, which was
+;;;; written at Carnegie Mellon University and released into the
+;;;; public domain. The software is in the public domain and is
+;;;; provided with absolutely no warranty. See the COPYING and CREDITS
+;;;; files for more information.
 
-(defun make-thread (function)
-  (let ((real-function (coerce function 'function)))
-    (%create-thread
-     (sb!kernel:get-lisp-obj-address
-      (lambda ()
-	;; in time we'll move some of the binding presently done in C
-	;; here too
-	(let ((sb!kernel::*restart-clusters* nil)
-	      (sb!impl::*descriptor-handlers* nil); serve-event
-	      (sb!impl::*available-buffers* nil)) ;for fd-stream
-	  ;; can't use handling-end-of-the-world, because that flushes
-	  ;; output streams, and we don't necessarily have any (or we
-	  ;; could be sharing them)
-	  (sb!sys:enable-interrupt :sigint :ignore)
-	  (sb!unix:unix-exit
-	   (catch 'sb!impl::%end-of-the-world 
-	     (with-simple-restart 
-		 (destroy-thread
-		  (format nil "~~@<Destroy this thread (~A)~~@:>"
-			  (current-thread-id)))
-	       (funcall real-function))
-	     0))))))))
+(in-package "SB!THREAD")
 
-(defun destroy-thread (thread-id)
-  (sb!unix:unix-kill thread-id :sigterm)
-  ;; may have been stopped for some reason, so now wake it up to
-  ;; deliver the TERM
-  (sb!unix:unix-kill thread-id :sigcont))
+;;; FIXME it would be good to define what a thread id is or isn't (our
+;;; current assumption is that it's a fixnum).  It so happens that on
+;;; Linux it's a pid, but it might not be on posix thread implementations
 
-;; Conventional wisdom says that it's a bad idea to use these unless
-;; you really need to.  Use a lock or a waitqueue instead
-(defun suspend-thread (thread-id)
-  (sb!unix:unix-kill thread-id :sigstop))
-(defun resume-thread (thread-id)
-  (sb!unix:unix-kill thread-id :sigcont))
+(define-alien-routine ("create_thread" %create-thread)
+    unsigned-long
+  (lisp-fun-address unsigned-long))
 
-(defun current-thread-id ()
-  (sb!sys:sap-int
-   (sb!vm::current-thread-offset-sap sb!vm::thread-pid-slot)))
+(define-alien-routine "signal_thread_to_dequeue"
+    unsigned-int
+  (thread-id unsigned-long))
 
-;;;; iterate over the in-memory threads
+(define-alien-routine reap-dead-threads void)
 
-(defun mapcar-threads (function)
-  "Call FUNCTION once for each known thread, giving it the thread structure as argument"
-  (let ((function (coerce function 'function)))
-    (loop for thread = (alien-sap (extern-alien "all_threads" (* t)))
-	  then  (sb!sys:sap-ref-sap thread (* 4 sb!vm::thread-next-slot))
-	  until (sb!sys:sap= thread (sb!sys:int-sap 0))
-	  collect (funcall function thread))))
+(defvar *session* nil)
 
 ;;;; queues, locks 
 
 ;; spinlocks use 0 as "free" value: higher-level locks use NIL
+(declaim (inline get-spinlock release-spinlock))
+
 (defun get-spinlock (lock offset new-value)
   (declare (optimize (speed 3) (safety 0)))
   (loop until
 	(eql (sb!vm::%instance-set-conditional lock offset 0 new-value) 0)))
 
+;; this should do nothing if we didn't own the lock, so safe to use in
+;; unwind-protect cleanups when lock acquisition failed for some reason
+(defun release-spinlock (lock offset our-value)
+  (declare (optimize (speed 3) (safety 0)))
+  (sb!vm::%instance-set-conditional lock offset our-value 0))
+
 (defmacro with-spinlock ((queue) &body body)
   (with-unique-names (pid)
-    `(unwind-protect
-      (let ((,pid (current-thread-id)))
-	(get-spinlock ,queue 2 ,pid)
-	,@body)
-      (setf (waitqueue-lock ,queue) 0))))
+    `(let ((,pid (current-thread-id)))
+       (unwind-protect
+	    (progn
+	      (get-spinlock ,queue 2 ,pid)
+	      ,@body)
+	 (release-spinlock ,queue 2 ,pid)))))
+
 
 ;;;; the higher-level locking operations are based on waitqueues
 
+(declaim (inline waitqueue-data-address mutex-value-address))
+
 (defstruct waitqueue
-  (name nil :type (or null simple-base-string))
+  (name nil :type (or null simple-string))
   (lock 0)
   (data nil))
 
+;;; The bare 4 here and 5 below are offsets of the slots in the struct.
+;;; There ought to be some better way to get these numbers
+(defun waitqueue-data-address (lock)
+  (declare (optimize (speed 3)))
+  (sb!ext:truly-the
+   (unsigned-byte 32)
+   (+ (sb!kernel:get-lisp-obj-address lock)
+      (- (* 4 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag))))
+
 (defstruct (mutex (:include waitqueue))
   (value nil))
 
+(defun mutex-value-address (lock)
+  (declare (optimize (speed 3)))
+  (sb!ext:truly-the
+   (unsigned-byte 32)
+   (+ (sb!kernel:get-lisp-obj-address lock)
+      (- (* 5 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag))))
+
 (sb!alien:define-alien-routine "block_sigcont"  void)
 (sb!alien:define-alien-routine "unblock_sigcont_and_sleep"  void)
 
-;;; this should only be called while holding the queue spinlock.
-;;; it releases the spinlock before sleeping
-(defun wait-on-queue (queue &optional lock)
-  (let ((pid (current-thread-id)))
-    ;; FIXME what should happen if we get interrupted when we've blocked
-    ;; the sigcont?  For that matter, can we get interrupted?
-    (block-sigcont)
-    (when lock (release-mutex lock))
-    (sb!sys:without-interrupts
-     (pushnew pid (waitqueue-data queue)))
-    (setf (waitqueue-lock queue) 0)
-    (unblock-sigcont-and-sleep)))
-
-;;; this should only be called while holding the queue spinlock.  It doesn't
-;;; release it
-(defun dequeue (queue)
-  (let ((pid (current-thread-id)))
-    (sb!sys:without-interrupts     
-     (setf (waitqueue-data queue)
-	   (delete pid (waitqueue-data queue))))))
-
-;;; this should probably only be called while holding the queue spinlock.
-;;; not sure
-(defun signal-queue-head (queue)
-  (let ((p (car (waitqueue-data queue))))
-    (when p (sb!unix:unix-kill p  :sigcont))))
+(declaim (inline futex-wait futex-wake))
+(sb!alien:define-alien-routine
+    "futex_wait" int (word unsigned-long) (old-value unsigned-long))
+(sb!alien:define-alien-routine
+    "futex_wake" int (word unsigned-long) (n unsigned-long))
+
 
 ;;;; mutex
 
 (defun get-mutex (lock &optional new-value (wait-p t))
-  (declare (type mutex lock))
-  (let ((pid (current-thread-id)))
+  "Acquire LOCK, setting it to NEW-VALUE or some suitable default value 
+if NIL.  If WAIT-P is non-NIL and the lock is in use, sleep until it
+is available"
+  (declare (type mutex lock)  (optimize (speed 3)))
+  (let ((pid (current-thread-id))
+	old)
     (unless new-value (setf new-value pid))
-    (assert (not (eql new-value (mutex-value lock))))
-    (get-spinlock lock 2 pid)
+    (when (eql new-value (mutex-value lock))
+      (warn "recursive lock attempt ~S~%" lock))
     (loop
      (unless
-	 ;; args are object slot-num old-value new-value
-	 (sb!vm::%instance-set-conditional lock 4 nil new-value)
-       (dequeue lock)
-       (setf (waitqueue-lock lock) 0)
+	 (setf old (sb!vm::%instance-set-conditional lock 4 nil new-value))
        (return t))
-     (unless wait-p
-       (setf (waitqueue-lock lock) 0)
-       (return nil))
-     (wait-on-queue lock nil))))
+     (unless wait-p (return nil))
+     (futex-wait (mutex-value-address lock)
+		 (sb!kernel:get-lisp-obj-address old)))))
 
-(defun release-mutex (lock &optional (new-value nil))
+(defun release-mutex (lock)
   (declare (type mutex lock))
-  ;; we assume the lock is ours to release
-  (with-spinlock (lock)
-    (setf (mutex-value lock) new-value)
-    (signal-queue-head lock)))
-
-
-(defmacro with-mutex ((mutex &key value (wait-p t))  &body body)
-  (with-unique-names (got)
-    `(let ((,got (get-mutex ,mutex ,value ,wait-p)))
-      (when ,got
-	(unwind-protect
-	     (progn ,@body)
-	  (release-mutex ,mutex))))))
-
+  (setf (mutex-value lock) nil)
+  (futex-wake (mutex-value-address lock) 1))
 
 ;;;; condition variables
 
@@ -156,39 +125,272 @@ time we reacquire LOCK and return to the caller."
   (assert lock)
   (let ((value (mutex-value lock)))
     (unwind-protect
-	 (progn
-	   (get-spinlock queue 2 (current-thread-id))
-	   (wait-on-queue queue lock))
+	 (let ((me (current-thread-id)))
+	   ;; XXX we should do something to ensure that the result of this setf
+	   ;; is visible to all CPUs
+	   (setf (waitqueue-data queue) me)
+	   (release-mutex lock)
+	   ;; Now we go to sleep using futex-wait.  If anyone else
+	   ;; manages to grab LOCK and call CONDITION-NOTIFY during
+	   ;; this comment, it will change queue->data, and so
+	   ;; futex-wait returns immediately instead of sleeping.
+	   ;; Ergo, no lost wakeup
+	   (futex-wait (waitqueue-data-address queue)
+		       (sb!kernel:get-lisp-obj-address me)))
       ;; If we are interrupted while waiting, we should do these things
       ;; before returning.  Ideally, in the case of an unhandled signal,
       ;; we should do them before entering the debugger, but this is
       ;; better than nothing.
-      (with-spinlock (queue)
-	(dequeue queue))
       (get-mutex lock value))))
 
+
 (defun condition-notify (queue)
   "Notify one of the processes waiting on QUEUE"
-  (with-spinlock (queue) (signal-queue-head queue)))
+  (let ((me (current-thread-id)))
+    ;; no problem if >1 thread notifies during the comment in
+    ;; condition-wait: as long as the value in queue-data isn't the
+    ;; waiting thread's id, it matters not what it is
+    ;; XXX we should do something to ensure that the result of this setf
+    ;; is visible to all CPUs
+    (setf (waitqueue-data queue) me)
+    (futex-wake (waitqueue-data-address queue) 1)))
+
+(defun condition-broadcast (queue)
+  (let ((me (current-thread-id)))
+    (setf (waitqueue-data queue) me)
+    (futex-wake (waitqueue-data-address queue) (ash 1 30))))
+
+(defun make-thread (function)
+  (let* ((real-function (coerce function 'function))
+	 (tid
+	  (%create-thread
+	   (sb!kernel:get-lisp-obj-address
+	    (lambda ()
+	      ;; in time we'll move some of the binding presently done in C
+	      ;; here too
+	      (let ((sb!kernel::*restart-clusters* nil)
+		    (sb!kernel::*handler-clusters* nil)
+		    (sb!kernel::*condition-restarts* nil)
+		    (sb!impl::*descriptor-handlers* nil) ; serve-event
+		    (sb!impl::*available-buffers* nil)) ;for fd-stream
+		;; can't use handling-end-of-the-world, because that flushes
+		;; output streams, and we don't necessarily have any (or we
+		;; could be sharing them)
+		(sb!sys:enable-interrupt sb!unix:sigint :ignore)
+		(catch 'sb!impl::%end-of-the-world 
+		  (with-simple-restart 
+		      (destroy-thread
+		       (format nil "~~@<Destroy this thread (~A)~~@:>"
+			       (current-thread-id)))
+		    (funcall real-function))
+		  0))
+	      (values))))))
+    (with-mutex ((session-lock *session*))
+      (pushnew tid (session-threads *session*)))
+    tid))
+
+;;; Really, you don't want to use these: they'll get into trouble with
+;;; garbage collection.  Use a lock or a waitqueue instead
+(defun suspend-thread (thread-id)
+  (sb!unix:unix-kill thread-id sb!unix:sigstop))
+(defun resume-thread (thread-id)
+  (sb!unix:unix-kill thread-id sb!unix:sigcont))
+;;; Note warning about cleanup forms
+(defun destroy-thread (thread-id)
+  "Destroy the thread identified by THREAD-ID abruptly, without running cleanup forms"
+  (sb!unix:unix-kill thread-id sb!unix:sigterm)
+  ;; may have been stopped for some reason, so now wake it up to
+  ;; deliver the TERM
+  (sb!unix:unix-kill thread-id sb!unix:sigcont))
+
+     
+     
+
+;;; a moderate degree of care is expected for use of interrupt-thread,
+;;; due to its nature: if you interrupt a thread that was holding
+;;; important locks then do something that turns out to need those
+;;; locks, you probably won't like the effect.  Used with thought
+;;; though, it's a good deal gentler than the last-resort functions above
+
+(define-condition interrupt-thread-error (error)
+  ((thread :reader interrupt-thread-error-thread :initarg :thread)
+   (errno :reader interrupt-thread-error-errno :initarg :errno))
+  (:report (lambda (c s)
+	     (format s "interrupt thread ~A failed (~A: ~A)"
+		     (interrupt-thread-error-thread c)
+		     (interrupt-thread-error-errno c)
+		     (strerror (interrupt-thread-error-errno c))))))
+
+(defun interrupt-thread (thread function)
+  "Interrupt THREAD and make it run FUNCTION."
+  (let ((function (coerce function 'function)))
+    (sb!sys:with-pinned-objects 
+     (function)
+     (multiple-value-bind (res err)
+	 (sb!unix::syscall ("interrupt_thread"
+			    sb!alien:unsigned-long  sb!alien:unsigned-long)
+			   thread
+			   thread 
+			   (sb!kernel:get-lisp-obj-address function))
+       (unless res
+	 (error 'interrupt-thread-error :thread thread :errno err))))))
+
+
+(defun terminate-thread (thread-id)
+  "Terminate the thread identified by THREAD-ID, by causing it to run
+SB-EXT:QUIT - the usual cleanup forms will be evaluated"
+  (interrupt-thread thread-id 'sb!ext:quit))
+
+(declaim (inline current-thread-id))
+(defun current-thread-id ()
+  (logand 
+   (sb!sys:sap-int
+    (sb!vm::current-thread-offset-sap sb!vm::thread-pid-slot))
+   ;; KLUDGE pids are 16 bit really.  Avoid boxing the return value
+   (1- (ash 1 16))))
+
+;;;; iterate over the in-memory threads
+
+(defun mapcar-threads (function)
+  "Call FUNCTION once for each known thread, giving it the thread structure as argument"
+  (let ((function (coerce function 'function)))
+    (loop for thread = (alien-sap (extern-alien "all_threads" (* t)))
+	  then  (sb!sys:sap-ref-sap thread (* sb!vm:n-word-bytes
+					      sb!vm::thread-next-slot))
+	  until (sb!sys:sap= thread (sb!sys:int-sap 0))
+	  collect (funcall function thread))))
 
+(defun thread-sap-from-id (id)
+  (let ((thread (alien-sap (extern-alien "all_threads" (* t)))))
+    (loop 
+     (when (sb!sys:sap= thread (sb!sys:int-sap 0)) (return nil))
+     (let ((pid (sb!sys:sap-ref-32 thread (* sb!vm:n-word-bytes
+					     sb!vm::thread-pid-slot))))
+       (when (= pid id) (return thread))
+       (setf thread (sb!sys:sap-ref-sap thread (* sb!vm:n-word-bytes
+						  sb!vm::thread-next-slot)))))))
+
+;;; internal use only.  If you think you need to use this, either you
+;;; are an SBCL developer, are doing something that you should discuss
+;;; with an SBCL developer first, or are doing something that you
+;;; should probably discuss with a professional psychiatrist first
+(defun symbol-value-in-thread (symbol thread-id)
+  (let ((thread (thread-sap-from-id thread-id)))
+    (when thread
+      (let* ((index (sb!vm::symbol-tls-index symbol))
+	     (tl-val (sb!sys:sap-ref-word thread
+					  (* sb!vm:n-word-bytes index))))
+	(if (eql tl-val sb!vm::unbound-marker-widetag)
+	    (sb!vm::symbol-global-value symbol)
+	    (sb!kernel:make-lisp-obj tl-val))))))
+
+;;;; job control, independent listeners
+
+(defstruct session 
+  (lock (make-mutex))
+  (threads nil)
+  (interactive-threads nil)
+  (interactive-threads-queue (make-waitqueue)))
+
+(defun new-session ()
+  (let ((tid (current-thread-id)))
+    (make-session :threads (list tid)
+		  :interactive-threads (list tid))))
+
+(defun init-job-control ()
+  (setf *session* (new-session)))
+
+(defun %delete-thread-from-session (tid session)
+  (with-mutex ((session-lock session))
+    (setf (session-threads session)
+	  (delete tid (session-threads session))
+	  (session-interactive-threads session)
+	  (delete tid (session-interactive-threads session)))))
+
+(defun call-with-new-session (fn)
+  (%delete-thread-from-session (current-thread-id) *session*)
+  (let ((*session* (new-session)))  (funcall fn)))
+
+(defmacro with-new-session (args &body forms)
+  (declare (ignore args))		;for extensibility
+  (sb!int:with-unique-names (fb-name)
+    `(labels ((,fb-name () ,@forms))
+      (call-with-new-session (function ,fb-name)))))
+
+;;; Remove thread id TID from its session, if it has one.  This is
+;;; called from C reap_dead_threads() so is run in the context of
+;;; whichever thread called that (usually after a GC), which may not have 
+;;; any meaningful parent/child/sibling relationship with the dead thread
+(defun handle-thread-exit (tid)
+  (let ((session (symbol-value-in-thread '*session* tid)))
+    (and session (%delete-thread-from-session tid session))))
+  
+(defun terminate-session ()
+  "Kill all threads in session except for this one.  Does nothing if current
+thread is not the foreground thread"
+  (reap-dead-threads)
+  (let* ((tid (current-thread-id))
+	 (to-kill
+	  (with-mutex ((session-lock *session*))
+	    (and (eql tid (car (session-interactive-threads *session*)))
+		 (session-threads *session*)))))
+    ;; do the kill after dropping the mutex; unwind forms in dying
+    ;; threads may want to do session things
+    (dolist (p to-kill)
+      (unless (eql p tid) (terminate-thread p)))))
+
+;;; called from top of invoke-debugger
+(defun debugger-wait-until-foreground-thread (stream)
+  "Returns T if thread had been running in background, NIL if it was
+interactive."
+  (declare (ignore stream))
+  (prog1
+      (with-mutex ((session-lock *session*))
+	(not (member (current-thread-id) 
+		     (session-interactive-threads *session*))))
+    (get-foreground)))
 
-;;;; multiple independent listeners
 
-(defvar *session-lock* nil)
+(defun get-foreground ()
+  (let ((was-foreground t))
+    (loop
+     (with-mutex ((session-lock *session*))
+       (let ((tid (current-thread-id))
+	     (int-t (session-interactive-threads *session*)))
+	 (when (eql (car int-t) tid)
+	   (unless was-foreground
+	     (format *query-io* "Resuming thread ~A~%" tid))
+	   (sb!sys:enable-interrupt sb!unix:sigint #'sb!unix::sigint-handler)
+	   (return-from get-foreground t))
+	 (setf was-foreground nil)
+	 (unless (member tid int-t)
+	   (setf (cdr (last int-t))
+		 (list tid)))
+	 (condition-wait
+	  (session-interactive-threads-queue *session*)
+	  (session-lock *session*)))))))
+
+(defun release-foreground (&optional next)
+  "Background this thread.  If NEXT is supplied, arrange for it to have the foreground next"
+  (with-mutex ((session-lock *session*))
+    (let ((tid (current-thread-id)))
+      (setf (session-interactive-threads *session*)
+	    (delete tid (session-interactive-threads *session*)))
+      (sb!sys:enable-interrupt sb!unix:sigint :ignore)
+      (when next 
+	(setf (session-interactive-threads *session*)
+	      (list* next 
+		     (delete next (session-interactive-threads *session*)))))
+      (condition-broadcast (session-interactive-threads-queue *session*)))))
 
 (defun make-listener-thread (tty-name)  
   (assert (probe-file tty-name))
-  ;; FIXME probably still need to do some tty stuff to get signals
-  ;; delivered correctly.
-  ;; FIXME 
   (let* ((in (sb!unix:unix-open (namestring tty-name) sb!unix:o_rdwr #o666))
 	 (out (sb!unix:unix-dup in))
 	 (err (sb!unix:unix-dup in)))
     (labels ((thread-repl () 
 	       (sb!unix::unix-setsid)
-	       (let* ((*session-lock*
-		       (make-mutex :name (format nil "lock for ~A" tty-name)))
-		      (sb!impl::*stdin* 
+	       (let* ((sb!impl::*stdin* 
 		       (sb!sys:make-fd-stream in :input t :buffering :line))
 		      (sb!impl::*stdout* 
 		       (sb!sys:make-fd-stream out :output t :buffering :line))
@@ -197,179 +399,9 @@ time we reacquire LOCK and return to the caller."
 		      (sb!impl::*tty* 
 		       (sb!sys:make-fd-stream err :input t :output t :buffering :line))
 		      (sb!impl::*descriptor-handlers* nil))
-		 (get-mutex *session-lock*)
-		 (sb!sys:enable-interrupt :sigint #'sb!unix::sigint-handler)
-		 (unwind-protect
-		      (sb!impl::toplevel-repl nil)
-		   (sb!int:flush-standard-output-streams)))))
+		 (with-new-session ()
+		   (sb!sys:enable-interrupt sb!unix:sigint #'sb!unix::sigint-handler)
+		   (unwind-protect
+			(sb!impl::toplevel-repl nil)
+		     (sb!int:flush-standard-output-streams))))))
       (make-thread #'thread-repl))))
-  
-;;;; job control
-
-(defvar *background-threads-wait-for-debugger* t)
-;;; may be T, NIL, or a function called with a stream and thread id 
-;;; as its two arguments, returning NIl or T
-
-;;; called from top of invoke-debugger
-(defun debugger-wait-until-foreground-thread (stream)
-  "Returns T if thread had been running in background, NIL if it was
-already the foreground thread, or transfers control to the first applicable
-restart if *BACKGROUND-THREADS-WAIT-FOR-DEBUGGER* says to do that instead"
-  (let* ((wait-p *background-threads-wait-for-debugger*)
-	 (*background-threads-wait-for-debugger* nil)
-	 (lock *session-lock*))
-    (when (not (eql (mutex-value lock)   (CURRENT-THREAD-ID)))
-      (when (functionp wait-p) 
-	(setf wait-p 
-	      (funcall wait-p stream (CURRENT-THREAD-ID))))
-      (cond (wait-p (get-foreground))
-	    (t  (invoke-restart (car (compute-restarts))))))))
-
-;;; install this with (setf SB!INT:*REPL-PROMPT-FUN* #'thread-prompt-fun)
-;;; One day it will be default
-(defun thread-repl-prompt-fun (out-stream)
-  (let ((lock *session-lock*))
-    (get-foreground)
-    (let ((stopped-threads (waitqueue-data lock)))
-      (when stopped-threads
-	(format out-stream "~{~&Thread ~A suspended~}~%" stopped-threads))
-      (sb!impl::repl-prompt-fun out-stream))))
-
-(defun resume-stopped-thread (id)
-  (let ((pid (current-thread-id))
-	(lock *session-lock*)) 
-    (with-spinlock (lock)
-      (setf (waitqueue-data lock)
-	    (cons id (delete id  (waitqueue-data lock)))))
-    (release-foreground)))
-
-(defstruct rwlock
-  (name nil :type (or null simple-base-string))
-  (value 0 :type fixnum)
-  (max-readers nil :type (or fixnum null))
-  (max-writers 1 :type fixnum))
-#+nil
-(macrolet
-    ((make-rwlocking-function (lock-fn unlock-fn increment limit test)
-       (let ((do-update '(when (eql old-value
-				(sb!vm::%instance-set-conditional
-				 lock 2 old-value new-value))
-			  (return (values t old-value))))
-	     (vars `((timeout (and timeout (+ (get-internal-real-time) timeout)))
-		     old-value
-		     new-value
-		     (limit ,limit))))
-	 (labels ((do-setfs (v) `(setf old-value (rwlock-value lock)
-				  new-value (,v old-value ,increment))))
-	   `(progn
-	     (defun ,lock-fn (lock timeout)
-	       (declare (type rwlock lock))
-	       (let ,vars
-		 (loop
-		  ,(do-setfs '+)
-		  (when ,test
-		    ,do-update)
-		  (when (sleep-a-bit timeout) (return nil)) ;expired
-		  )))
-	     ;; unlock doesn't need timeout or test-in-range
-	     (defun ,unlock-fn (lock)
-	       (declare (type rwlock lock))
-	       (declare (ignorable limit))
-	       (let ,(cdr vars)
-		 (loop
-		  ,(do-setfs '-)
-		  ,do-update))))))))
-    
-  (make-rwlocking-function %lock-for-reading %unlock-for-reading 1
-			   (rwlock-max-readers lock)
-			   (and (>= old-value 0)
-				(or (null limit) (<= new-value limit))))
-  (make-rwlocking-function %lock-for-writing %unlock-for-writing -1
-			   (- (rwlock-max-writers lock))
-			   (and (<= old-value 0)
-				(>= new-value limit))))
-#+nil  
-(defun get-rwlock (lock direction &optional timeout)
-  (ecase direction
-    (:read (%lock-for-reading lock timeout))
-    (:write (%lock-for-writing lock timeout))))
-#+nil
-(defun free-rwlock (lock direction)
-  (ecase direction
-    (:read (%unlock-for-reading lock))
-    (:write (%unlock-for-writing lock))))
-
-;;;; beyond this point all is commented.
-
-;;; Lock-Wait-With-Timeout  --  Internal
-;;;
-;;; Wait with a timeout for the lock to be free and acquire it for the
-;;; *current-process*.
-;;;
-#+nil
-(defun lock-wait-with-timeout (lock whostate timeout)
-  (declare (type lock lock))
-  (process-wait-with-timeout
-   whostate timeout
-   #'(lambda ()
-       (declare (optimize (speed 3)))
-       #-i486
-       (unless (lock-process lock)
-	 (setf (lock-process lock) *current-process*))
-       #+i486
-       (null (kernel:%instance-set-conditional
-	      lock 2 nil *current-process*)))))
-
-;;; With-Lock-Held  --  Public
-;;;
-#+nil
-(defmacro with-lock-held ((lock &optional (whostate "Lock Wait")
-				&key (wait t) timeout)
-			  &body body)
-  "Execute the body with the lock held. If the lock is held by another
-  process then the current process waits until the lock is released or
-  an optional timeout is reached. The optional wait timeout is a time in
-  seconds acceptable to process-wait-with-timeout.  The results of the
-  body are return upon success and NIL is return if the timeout is
-  reached. When the wait key is NIL and the lock is held by another
-  process then NIL is return immediately without processing the body."
-  (let ((have-lock (gensym)))
-    `(let ((,have-lock (eq (lock-process ,lock) *current-process*)))
-      (unwind-protect
-	   ,(cond ((and timeout wait)
-		   `(progn
-		      (when (and (error-check-lock-p ,lock) ,have-lock)
-			(error "Dead lock"))
-		      (when (or ,have-lock
-				 #+i486 (null (kernel:%instance-set-conditional
-					       ,lock 2 nil *current-process*))
-				 #-i486 (seize-lock ,lock)
-				 (if ,timeout
-				     (lock-wait-with-timeout
-				      ,lock ,whostate ,timeout)
-				     (lock-wait ,lock ,whostate)))
-			,@body)))
-		  (wait
-		   `(progn
-		      (when (and (error-check-lock-p ,lock) ,have-lock)
-		        (error "Dead lock"))
-		      (unless (or ,have-lock
-				 #+i486 (null (kernel:%instance-set-conditional
-					       ,lock 2 nil *current-process*))
-				 #-i486 (seize-lock ,lock))
-			(lock-wait ,lock ,whostate))
-		      ,@body))
-		  (t
-		   `(when (or (and (recursive-lock-p ,lock) ,have-lock)
-			      #+i486 (null (kernel:%instance-set-conditional
-					    ,lock 2 nil *current-process*))
-			      #-i486 (seize-lock ,lock))
-		      ,@body)))
-	(unless ,have-lock
-	  #+i486 (kernel:%instance-set-conditional
-		  ,lock 2 *current-process* nil)
-	  #-i486 (when (eq (lock-process ,lock) *current-process*)
-		   (setf (lock-process ,lock) nil)))))))
-
-
-