+;;;; 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))
-
-(sb!alien::define-alien-routine "signal_thread_to_dequeue"
- sb!alien:unsigned-int
- (thread-pid sb!alien:unsigned-long))
-
-
-(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 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))))))))
-
-;;; 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-alien-routine ("create_thread" %create-thread)
+ unsigned-long
+ (lisp-fun-address unsigned-long))
-(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))))
-(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))))
+(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
(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))
-
-;;;; multiple independent listeners
-
-(defvar *session-lock* nil)
+(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))))))
+ (when (zerop tid) (error "Can't create a new thread"))
+ (with-mutex ((session-lock *session*))
+ (pushnew tid (session-threads *session*)))
+ tid))
-(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*
- (sb!sys:make-fd-stream in :input t :buffering :line))
- (sb!impl::*stdout*
- (sb!sys:make-fd-stream out :output t :buffering :line))
- (sb!impl::*stderr*
- (sb!sys:make-fd-stream err :output t :buffering :line))
- (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 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
+;;; 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))))
-(defvar *interactive-threads-lock*
- (make-mutex :name "*interactive-threads* lock"))
-(defvar *interactive-threads* nil)
-(defvar *interactive-threads-queue*
- (make-waitqueue :name "All threads that need the terminal. First ID on this list is running, the others are waiting"))
+(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 ()
- (with-mutex (*interactive-threads-lock*)
- (setf *interactive-threads* (list (current-thread-id)))
- (return-from init-job-control t)))
+ (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 (*interactive-threads-lock*)
- (not (member (current-thread-id) *interactive-threads*)))
+ (with-mutex ((session-lock *session*))
+ (not (member (current-thread-id)
+ (session-interactive-threads *session*))))
(get-foreground)))
-(defun thread-repl-prompt-fun (out-stream)
- (get-foreground)
- (let ((stopped-threads (cdr *interactive-threads*)))
- (when stopped-threads
- (format out-stream "~{~&Thread ~A suspended~}~%" stopped-threads))
- (sb!impl::repl-prompt-fun out-stream)))
(defun get-foreground ()
- (loop
- (with-mutex (*interactive-threads-lock*)
- (let ((tid (current-thread-id)))
- (when (eql (car *interactive-threads*) tid)
- (sb!sys:enable-interrupt sb!unix:sigint #'sb!unix::sigint-handler)
- (return-from get-foreground t))
- (unless (member tid *interactive-threads*)
- (setf (cdr (last *interactive-threads*)) (list tid)))
- (condition-wait
- *interactive-threads-queue* *interactive-threads-lock* )))))
+ (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 (*interactive-threads-lock*)
+ (with-mutex ((session-lock *session*))
(let ((tid (current-thread-id)))
- (setf *interactive-threads* (delete tid *interactive-threads*))
+ (setf (session-interactive-threads *session*)
+ (delete tid (session-interactive-threads *session*)))
(sb!sys:enable-interrupt sb!unix:sigint :ignore)
- (when next (setf *interactive-threads*
- (list* next (delete next *interactive-threads*))))
- (condition-broadcast *interactive-threads-queue*))))
\ No newline at end of file
+ (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))
+ (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* ((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))
+ (sb!impl::*stderr*
+ (sb!sys:make-fd-stream err :output t :buffering :line))
+ (sb!impl::*tty*
+ (sb!sys:make-fd-stream err :input t :output t :buffering :line))
+ (sb!impl::*descriptor-handlers* nil))
+ (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))))
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