-;;;; support for threads in the target machine common to uni- and
-;;;; multithread systems
+;;;; support for threads in the target machine
;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
(in-package "SB!THREAD")
+;;; set the doc here because in early-thread FDOCUMENTATION is not
+;;; available, yet
+#!+sb-doc
+(setf (sb!kernel:fdocumentation '*current-thread* 'variable)
+ "Bound in each thread to the thread itself.")
+
(defstruct (thread (:constructor %make-thread))
+ #!+sb-doc
+ "Thread type. Do not rely on threads being structs as it may change
+in future versions."
name
%sap)
+#!+sb-doc
+(setf (sb!kernel:fdocumentation 'thread-name 'function)
+ "The name of the thread. Setfable.")
+
(def!method print-object ((thread thread) stream)
(if (thread-name thread)
(print-unreadable-object (thread stream :type t :identity t)
(:dead #.(sb!vm:fixnumize 3))))))
(defun thread-alive-p (thread)
+ #!+sb-doc
+ "Check if THREAD is running."
(not (eq :dead (thread-state thread))))
;; A thread is eligible for gc iff it has finished and there are no
(defvar *all-threads-lock* (make-mutex :name "all threads lock"))
(defun list-all-threads ()
+ #!+sb-doc
+ "Return a list of the live threads."
(with-mutex (*all-threads-lock*)
(copy-list *all-threads*)))
;; in case we are in reinit since saving core with multiple
;; threads doesn't work.
(setq *all-threads* (list initial-thread))))
+
+;;;;
+
+#!+sb-thread
+(progn
+ (define-alien-routine ("create_thread" %create-thread)
+ system-area-pointer
+ (lisp-fun-address unsigned-long))
+
+ (define-alien-routine reap-dead-thread void
+ (thread-sap system-area-pointer))
+
+ (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)))
+
+;;; used by debug-int.lisp to access interrupt contexts
+#!-(and sb-fluid sb-thread) (declaim (inline sb!vm::current-thread-offset-sap))
+#!-sb-thread
+(defun sb!vm::current-thread-offset-sap (n)
+ (declare (type (unsigned-byte 27) n))
+ (sb!sys:sap-ref-sap (alien-sap (extern-alien "all_threads" (* t)))
+ (* n sb!vm:n-word-bytes)))
+
+;;;; spinlocks
+
+(defstruct spinlock
+ #!+sb-doc
+ "Spinlock type."
+ (name nil :type (or null simple-string))
+ (value 0))
+
+(declaim (inline get-spinlock release-spinlock))
+
+;;; The bare 2 here and below are offsets of the slots in the struct.
+;;; There ought to be some better way to get these numbers
+(defun get-spinlock (spinlock new-value)
+ (declare (optimize (speed 3) (safety 0))
+ #!-sb-thread
+ (ignore spinlock new-value))
+ ;; %instance-set-conditional can test for 0 (which is a fixnum) and
+ ;; store any value
+ #!+sb-thread
+ (loop until
+ (eql (sb!vm::%instance-set-conditional spinlock 2 0 new-value) 0)))
+
+(defun release-spinlock (spinlock)
+ (declare (optimize (speed 3) (safety 0))
+ #!-sb-thread (ignore spinlock))
+ ;; %instance-set-conditional cannot compare arbitrary objects
+ ;; meaningfully, so
+ ;; (sb!vm::%instance-set-conditional spinlock 2 our-value 0)
+ ;; does not work for bignum thread ids.
+ #!+sb-thread
+ (sb!vm::%instance-set spinlock 2 0))
+
+(defmacro with-spinlock ((spinlock) &body body)
+ (sb!int:with-unique-names (lock)
+ `(let ((,lock ,spinlock))
+ (get-spinlock ,lock *current-thread*)
+ (unwind-protect
+ (progn ,@body)
+ (release-spinlock ,lock)))))
+
+;;;; mutexes
+
+(defstruct mutex
+ #!+sb-doc
+ "Mutex type."
+ (name nil :type (or null simple-string))
+ (value nil))
+
+#!+sb-doc
+(setf (sb!kernel:fdocumentation 'make-mutex 'function)
+ "Create a mutex."
+ (sb!kernel:fdocumentation 'mutex-name 'function)
+ "The name of the mutex. Setfable."
+ (sb!kernel:fdocumentation 'mutex-value 'function)
+ "The value of the mutex. NIL if the mutex is free. Setfable.")
+
+#!+sb-thread
+(declaim (inline mutex-value-address))
+#!+sb-thread
+(defun mutex-value-address (mutex)
+ (declare (optimize (speed 3)))
+ (sb!ext:truly-the
+ sb!vm:word
+ (+ (sb!kernel:get-lisp-obj-address mutex)
+ (- (* 3 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag))))
+
+(defun get-mutex (mutex &optional new-value (wait-p t))
+ #!+sb-doc
+ "Acquire MUTEX, setting it to NEW-VALUE or some suitable default
+value if NIL. If WAIT-P is non-NIL and the mutex is in use, sleep
+until it is available"
+ (declare (type mutex mutex) (optimize (speed 3)))
+ (unless new-value (setf new-value *current-thread*))
+ #!-sb-thread
+ (let ((old-value (mutex-value mutex)))
+ (when (and old-value wait-p)
+ (error "In unithread mode, mutex ~S was requested with WAIT-P ~S and ~
+ new-value ~S, but has already been acquired (with value ~S)."
+ mutex wait-p new-value old-value))
+ (setf (mutex-value mutex) new-value)
+ t)
+ #!+sb-thread
+ (let (old)
+ (when (eql new-value (mutex-value mutex))
+ (warn "recursive lock attempt ~S~%" mutex)
+ (format *debug-io* "Thread: ~A~%" *current-thread*)
+ (sb!debug:backtrace most-positive-fixnum *debug-io*)
+ (force-output *debug-io*))
+ (loop
+ (unless
+ (setf old (sb!vm::%instance-set-conditional mutex 2 nil new-value))
+ (return t))
+ (unless wait-p (return nil))
+ (futex-wait (mutex-value-address mutex)
+ (sb!kernel:get-lisp-obj-address old)))))
+
+(defun release-mutex (mutex)
+ #!+sb-doc
+ "Release MUTEX by setting it to NIL. Wake up threads waiting for
+this mutex."
+ (declare (type mutex mutex))
+ (setf (mutex-value mutex) nil)
+ #!+sb-thread
+ (futex-wake (mutex-value-address mutex) 1))
+
+;;;; waitqueues/condition variables
+
+(defstruct (waitqueue (:constructor %make-waitqueue))
+ #!+sb-doc
+ "Waitqueue type."
+ (name nil :type (or null simple-string))
+ (data nil))
+
+(defun make-waitqueue (&key name)
+ #!+sb-doc
+ "Create a waitqueue."
+ (%make-waitqueue :name name))
+
+#!+sb-doc
+(setf (sb!kernel:fdocumentation 'waitqueue-name 'function)
+ "The name of the waitqueue. Setfable.")
+
+#!+sb-thread
+(declaim (inline waitqueue-data-address))
+#!+sb-thread
+(defun waitqueue-data-address (waitqueue)
+ (declare (optimize (speed 3)))
+ (sb!ext:truly-the
+ sb!vm:word
+ (+ (sb!kernel:get-lisp-obj-address waitqueue)
+ (- (* 3 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag))))
+
+(defun condition-wait (queue mutex)
+ #!+sb-doc
+ "Atomically release MUTEX and enqueue ourselves on QUEUE. Another
+thread may subsequently notify us using CONDITION-NOTIFY, at which
+time we reacquire MUTEX and return to the caller."
+ #!-sb-thread (declare (ignore queue))
+ (assert mutex)
+ #!-sb-thread (error "Not supported in unithread builds.")
+ #!+sb-thread
+ (let ((value (mutex-value mutex)))
+ (unwind-protect
+ (let ((me *current-thread*))
+ ;; 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 mutex)
+ ;; Now we go to sleep using futex-wait. If anyone else
+ ;; manages to grab MUTEX 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.
+ (get-mutex mutex value))))
+
+(defun condition-notify (queue)
+ #!+sb-doc
+ "Notify one of the threads waiting on QUEUE."
+ #!-sb-thread (declare (ignore queue))
+ #!-sb-thread (error "Not supported in unithread builds.")
+ #!+sb-thread
+ (let ((me *current-thread*))
+ ;; 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)
+ #!+sb-doc
+ "Notify all threads waiting on QUEUE."
+ #!-sb-thread (declare (ignore queue))
+ #!-sb-thread (error "Not supported in unithread builds.")
+ #!+sb-thread
+ (let ((me *current-thread*))
+ (setf (waitqueue-data queue) me)
+ (futex-wake (waitqueue-data-address queue) (ash 1 30))))
+
+;;;; job control, independent listeners
+
+(defstruct session
+ (lock (make-mutex :name "session lock"))
+ (threads nil)
+ (interactive-threads nil)
+ (interactive-threads-queue (make-waitqueue)))
+
+(defvar *session* nil)
+
+;;; the debugger itself tries to acquire the session lock, don't let
+;;; funny situations (like getting a sigint while holding the session
+;;; lock) occur
+(defmacro with-session-lock ((session) &body body)
+ #!-sb-thread (declare (ignore session))
+ #!-sb-thread
+ `(locally ,@body)
+ #!+sb-thread
+ `(sb!sys:without-interrupts
+ (with-mutex ((session-lock ,session))
+ ,@body)))
+
+(defun new-session ()
+ (make-session :threads (list *current-thread*)
+ :interactive-threads (list *current-thread*)))
+
+(defun init-job-control ()
+ (setf *session* (new-session)))
+
+(defun %delete-thread-from-session (thread session)
+ (with-session-lock (session)
+ (setf (session-threads session)
+ (delete thread (session-threads session))
+ (session-interactive-threads session)
+ (delete thread (session-interactive-threads session)))))
+
+(defun call-with-new-session (fn)
+ (%delete-thread-from-session *current-thread* *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 from its session, if it has one.
+#!+sb-thread
+(defun handle-thread-exit (thread)
+ (with-mutex (*all-threads-lock*)
+ (setq *all-threads* (delete thread *all-threads*)))
+ (when *session*
+ (%delete-thread-from-session thread *session*)))
+
+(defun terminate-session ()
+ #!+sb-doc
+ "Kill all threads in session except for this one. Does nothing if current
+thread is not the foreground thread."
+ ;; FIXME: threads created in other threads may escape termination
+ (let ((to-kill
+ (with-session-lock (*session*)
+ (and (eq *current-thread*
+ (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 (thread to-kill)
+ (unless (eq thread *current-thread*)
+ ;; terminate the thread but don't be surprised if it has
+ ;; exited in the meantime
+ (handler-case (terminate-thread thread)
+ (interrupt-thread-error ()))))))
+
+;;; 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))
+ #!-sb-thread nil
+ #!+sb-thread
+ (prog1
+ (with-session-lock (*session*)
+ (not (member *current-thread*
+ (session-interactive-threads *session*))))
+ (get-foreground)))
+
+(defun get-foreground ()
+ #!-sb-thread t
+ #!+sb-thread
+ (let ((was-foreground t))
+ (loop
+ (with-session-lock (*session*)
+ (let ((int-t (session-interactive-threads *session*)))
+ (when (eq (car int-t) *current-thread*)
+ (unless was-foreground
+ (format *query-io* "Resuming thread ~A~%" *current-thread*))
+ (return-from get-foreground t))
+ (setf was-foreground nil)
+ (unless (member *current-thread* int-t)
+ (setf (cdr (last int-t))
+ (list *current-thread*)))
+ (condition-wait
+ (session-interactive-threads-queue *session*)
+ (session-lock *session*)))))))
+
+(defun release-foreground (&optional next)
+ #!+sb-doc
+ "Background this thread. If NEXT is supplied, arrange for it to
+have the foreground next"
+ #!-sb-thread (declare (ignore next))
+ #!-sb-thread nil
+ #!+sb-thread
+ (with-session-lock (*session*)
+ (setf (session-interactive-threads *session*)
+ (delete *current-thread* (session-interactive-threads *session*)))
+ (when next
+ (setf (session-interactive-threads *session*)
+ (list* next
+ (delete next (session-interactive-threads *session*)))))
+ (condition-broadcast (session-interactive-threads-queue *session*))))
+
+(defun foreground-thread ()
+ (car (session-interactive-threads *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
+ :dual-channel-p t))
+ (sb!impl::*stdout*
+ (sb!sys:make-fd-stream out :output t :buffering :line
+ :dual-channel-p t))
+ (sb!impl::*stderr*
+ (sb!sys:make-fd-stream err :output t :buffering :line
+ :dual-channel-p t))
+ (sb!impl::*tty*
+ (sb!sys:make-fd-stream err :input t :output t
+ :buffering :line
+ :dual-channel-p t))
+ (sb!impl::*descriptor-handlers* nil))
+ (with-new-session ()
+ (unwind-protect
+ (sb!impl::toplevel-repl nil)
+ (sb!int:flush-standard-output-streams))))))
+ (make-thread #'thread-repl))))
+
+;;;; the beef
+
+(defun make-thread (function &key name)
+ #!+sb-doc
+ "Create a new thread of NAME that runs FUNCTION. When the function
+returns the thread exits."
+ #!-sb-thread (declare (ignore function name))
+ #!-sb-thread (error "Not supported in unithread builds.")
+ #!+sb-thread
+ (let* ((thread (%make-thread :name name))
+ (setup-p nil)
+ (real-function (coerce function 'function))
+ (thread-sap
+ (%create-thread
+ (sb!kernel:get-lisp-obj-address
+ (lambda ()
+ ;; FIXME: use semaphores?
+ (loop until setup-p)
+ ;; in time we'll move some of the binding presently done in C
+ ;; here too
+ (let ((*current-thread* thread)
+ (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)
+ (unwind-protect
+ (catch 'sb!impl::toplevel-catcher
+ (catch 'sb!impl::%end-of-the-world
+ (with-simple-restart
+ (terminate-thread
+ (format nil "~~@<Terminate this thread (~A)~~@:>"
+ *current-thread*))
+ ;; now that most things have a chance to work
+ ;; properly without messing up other threads, it's
+ ;; time to enable signals
+ (sb!unix::reset-signal-mask)
+ (unwind-protect
+ (funcall real-function)
+ ;; we're going down, can't handle
+ ;; interrupts sanely anymore
+ (sb!unix::block-blockable-signals)))))
+ ;; mark the thread dead, so that the gc does not
+ ;; wait for it to handle sig-stop-for-gc
+ (%set-thread-state thread :dead)
+ ;; and remove what can be the last reference to
+ ;; the thread object
+ (handle-thread-exit thread)
+ 0))
+ (values))))))
+ (when (sb!sys:sap= thread-sap (sb!sys:int-sap 0))
+ (error "Can't create a new thread"))
+ (setf (thread-%sap thread) thread-sap)
+ (with-mutex (*all-threads-lock*)
+ (push thread *all-threads*))
+ (with-session-lock (*session*)
+ (push thread (session-threads *session*)))
+ (setq setup-p t)
+ (sb!impl::finalize thread (lambda () (reap-dead-thread thread-sap)))
+ thread))
+
+(defun destroy-thread (thread)
+ #!+sb-doc
+ "Deprecated. Same as TERMINATE-THREAD."
+ (terminate-thread thread))
+
+(define-condition interrupt-thread-error (error)
+ ((thread :reader interrupt-thread-error-thread :initarg :thread)
+ (errno :reader interrupt-thread-error-errno :initarg :errno))
+ #!+sb-doc
+ (:documentation "Interrupting thread failed.")
+ (: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))))))
+
+#!+sb-doc
+(setf (sb!kernel:fdocumentation 'interrupt-thread-error-thread 'function)
+ "The thread that was not interrupted."
+ (sb!kernel:fdocumentation 'interrupt-thread-error-errno 'function)
+ "The reason why the interruption failed.")
+
+(defun interrupt-thread (thread function)
+ #!+sb-doc
+ "Interrupt the live THREAD and make it run FUNCTION. 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."
+ #!-sb-thread (declare (ignore thread))
+ ;; not quite perfect, because it does not take WITHOUT-INTERRUPTS
+ ;; into account
+ #!-sb-thread
+ (funcall function)
+ #!+sb-thread
+ (let ((function (coerce function 'function)))
+ (multiple-value-bind (res err)
+ (sb!unix::syscall ("interrupt_thread"
+ system-area-pointer sb!alien:unsigned-long)
+ thread
+ (thread-%sap thread)
+ (sb!kernel:get-lisp-obj-address function))
+ (unless res
+ (error 'interrupt-thread-error :thread thread :errno err)))))
+
+(defun terminate-thread (thread)
+ #!+sb-doc
+ "Terminate the thread identified by THREAD, by causing it to run
+SB-EXT:QUIT - the usual cleanup forms will be evaluated"
+ (interrupt-thread thread 'sb!ext:quit))
+
+;;; 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
+#!+sb-thread
+(defun symbol-value-in-thread (symbol thread)
+ (let ((thread-sap (thread-%sap thread)))
+ (let* ((index (sb!vm::symbol-tls-index symbol))
+ (tl-val (sb!sys:sap-ref-word thread-sap
+ (* 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)))))
projects / sbcl.git / blobdiff