+;;;; support for threads in the target machine
+
+;;;; 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.
+
(in-package "SB!THREAD")
;;; 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
-(sb!alien::define-alien-routine ("create_thread" %create-thread)
- sb!alien:unsigned-long
- (lisp-fun-address sb!alien:unsigned-long))
+(define-alien-routine ("create_thread" %create-thread)
+ unsigned-long
+ (lisp-fun-address unsigned-long))
+
+(define-alien-routine "signal_thread_to_dequeue"
+ unsigned-int
+ (thread-id unsigned-long))
-(sb!alien::define-alien-routine "signal_thread_to_dequeue"
- sb!alien:unsigned-int
- (thread-id sb!alien:unsigned-long))
+(define-alien-routine reap-dead-threads void)
(defvar *session* nil)
(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))
(sb!alien:define-alien-routine "block_sigcont" void)
(sb!alien:define-alien-routine "unblock_sigcont_and_sleep" void)
-#!+sb-futex
(declaim (inline futex-wait futex-wake))
-#!+sb-futex
(sb!alien:define-alien-routine
"futex_wait" int (word unsigned-long) (old-value unsigned-long))
-#!+sb-futex
(sb!alien:define-alien-routine
"futex_wake" int (word unsigned-long) (n unsigned-long))
-;;; 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)))
- (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 only be called while holding the queue spinlock.
-(defun signal-queue-head (queue)
- (let ((p (car (waitqueue-data queue))))
- (when p (signal-thread-to-dequeue p))))
-
;;;; mutex
-;;; i suspect there may be a race still in this: the futex version requires
-;;; the old mutex value before sleeping, so how do we get away without it
(defun get-mutex (lock &optional new-value (wait-p t))
- (declare (type mutex lock) (optimize (speed 3)))
- (let ((pid (current-thread-id)))
- (unless new-value (setf new-value pid))
- (assert (not (eql new-value (mutex-value lock))))
- (get-spinlock lock 2 pid)
- (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)
- (return t))
- (unless wait-p
- (setf (waitqueue-lock lock) 0)
- (return nil))
- (wait-on-queue lock nil))))
-
-#!+sb-futex
-(defun get-mutex/futex (lock &optional new-value (wait-p t))
+ "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))))
+ (when (eql new-value (mutex-value lock))
+ (warn "recursive lock attempt ~S~%" lock))
(loop
(unless
(setf old (sb!vm::%instance-set-conditional lock 4 nil new-value))
(futex-wait (mutex-value-address lock)
(sb!kernel:get-lisp-obj-address old)))))
-(defun release-mutex (lock &optional (new-value nil))
- (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)))
-
-#!+sb-futex
-(defun release-mutex/futex (lock)
+(defun release-mutex (lock)
(declare (type mutex lock))
(setf (mutex-value lock) nil)
(futex-wake (mutex-value-address lock) 1))
-
-(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))))))
-
-
;;;; condition variables
(defun condition-wait (queue lock)
(assert lock)
(let ((value (mutex-value lock)))
(unwind-protect
- (progn
- (get-spinlock queue 2 (current-thread-id))
- (wait-on-queue queue lock))
- ;; 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))))
-
-#!+sb-futex
-(defun condition-wait/futex (queue lock)
- (assert lock)
- (let ((value (mutex-value lock)))
- (unwind-protect
(let ((me (current-thread-id)))
;; XXX we should do something to ensure that the result of this setf
;; is visible to all CPUs
(defun condition-notify (queue)
"Notify one of the processes waiting on QUEUE"
- (with-spinlock (queue) (signal-queue-head queue)))
-
-#!+sb-futex
-(defun condition-notify/futex (queue)
- "Notify one of the processes waiting on 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
(setf (waitqueue-data queue) me)
(futex-wake (waitqueue-data-address queue) 1)))
-#!+sb-futex
-(defun condition-broadcast/futex (queue)
+(defun condition-broadcast (queue)
(let ((me (current-thread-id)))
(setf (waitqueue-data queue) me)
(futex-wake (waitqueue-data-address queue) (ash 1 30))))
-(defun condition-broadcast (queue)
- "Notify all of the processes waiting on QUEUE."
- (with-spinlock (queue)
- (map nil #'signal-thread-to-dequeue (waitqueue-data queue))))
-
-;;; Futexes may be available at compile time but not runtime, so we
-;;; default to not using them unless os_init says they're available
-(defun maybe-install-futex-functions ()
- #!+sb-futex
- (unless (zerop (extern-alien "linux_supports_futex" int))
- (setf (fdefinition 'get-mutex) #'get-mutex/futex
- (fdefinition 'release-mutex) #'release-mutex/futex
- (fdefinition 'condition-wait) #'condition-wait/futex
- (fdefinition 'condition-broadcast) #'condition-broadcast/futex
- (fdefinition 'condition-notify) #'condition-notify/futex)
- t))
-
(defun make-thread (function)
(let* ((real-function (coerce function 'function))
(tid
;; 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)
- (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))))))))
+ (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))
;;; 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. "
- (sb!unix::syscall* ("interrupt_thread"
- sb!alien:unsigned-long sb!alien:unsigned-long)
- thread
- thread (sb!kernel:get-lisp-obj-address
- (coerce function '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"
"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))
+ 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
(defun init-job-control ()
(setf *session* (new-session)))
-(defun %delete-thread-from-session (tid)
- (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 %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))
+ (%delete-thread-from-session (current-thread-id) *session*)
(let ((*session* (new-session))) (funcall fn)))
(defmacro with-new-session (args &body forms)
`(labels ((,fb-name () ,@forms))
(call-with-new-session (function ,fb-name)))))
-;;; this is called from a C signal handler: some signals may be masked
+;;; 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)
- "Remove thread id TID from the session, if it's there"
- (%delete-thread-from-session 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 exept for this one. Does nothing if current
+ "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*))
(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)
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