(in-package "SB!THREAD")
+;;; Conditions
+
+(define-condition thread-error (error)
+ ((thread :reader thread-error-thread :initarg :thread))
+ #!+sb-doc
+ (:documentation
+ "Conditions of type THREAD-ERROR are signalled when thread operations fail.
+The offending thread is initialized by the :THREAD initialization argument and
+read by the function THREAD-ERROR-THREAD."))
+
+#!+sb-doc
+(setf
+ (fdocumentation 'thread-error-thread 'function)
+ "Return the offending thread that the THREAD-ERROR pertains to.")
+
+(define-condition symbol-value-in-thread-error (cell-error thread-error)
+ ((info :reader symbol-value-in-thread-error-info :initarg :info))
+ (:report
+ (lambda (condition stream)
+ (destructuring-bind (op problem)
+ (symbol-value-in-thread-error-info condition)
+ (format stream "Cannot ~(~A~) value of ~S in ~S: ~S"
+ op
+ (cell-error-name condition)
+ (thread-error-thread condition)
+ (ecase problem
+ (:unbound-in-thread "the symbol is unbound in thread.")
+ (:no-tls-value "the symbol has no thread-local value.")
+ (:thread-dead "the thread has exited.")
+ (:invalid-tls-value "the thread-local value is not valid."))))))
+ #!+sb-doc
+ (:documentation
+ "Signalled when SYMBOL-VALUE-IN-THREAD or its SETF version fails due to eg.
+the symbol not having a thread-local value, or the target thread having
+exited. The offending symbol can be accessed using CELL-ERROR-NAME, and the
+offending thread using THREAD-ERROR-THREAD."))
+
+(define-condition join-thread-error (thread-error) ()
+ (:report (lambda (c s)
+ (format s "Joining thread failed: thread ~A ~
+ did not return normally."
+ (thread-error-thread c))))
+ #!+sb-doc
+ (:documentation
+ "Signalled when joining a thread fails due to abnormal exit of the thread
+to be joined. The offending thread can be accessed using
+THREAD-ERROR-THREAD."))
+
+(defun join-thread-error-thread (condition)
+ (thread-error-thread condition))
+(define-compiler-macro join-thread-error-thread (condition)
+ (deprecation-warning 'join-thread-error-thread 'thread-error-thread)
+ `(thread-error-thread ,condition))
+
+#!+sb-doc
+(setf
+ (fdocumentation 'join-thread-error-thread 'function)
+ "The thread that we failed to join. Deprecated, use THREAD-ERROR-THREAD
+instead.")
+
+(define-condition interrupt-thread-error (thread-error) ()
+ (:report (lambda (c s)
+ (format s "Interrupt thread failed: thread ~A has exited."
+ (thread-error-thread c))))
+ #!+sb-doc
+ (:documentation
+ "Signalled when interrupting a thread fails because the thread has already
+exited. The offending thread can be accessed using THREAD-ERROR-THREAD."))
+
+(defun interrupt-thread-error-thread (condition)
+ (thread-error-thread condition))
+(define-compiler-macro interrupt-thread-error-thread (condition)
+ (deprecation-warning 'join-thread-error-thread 'thread-error-thread)
+ `(thread-error-thread ,condition))
+
+#!+sb-doc
+(setf
+ (fdocumentation 'interrupt-thread-error-thread 'function)
+ "The thread that was not interrupted. Deprecated, use THREAD-ERROR-THREAD
+instead.")
+
;;; Of the WITH-PINNED-OBJECTS in this file, not every single one is
;;; necessary because threads are only supported with the conservative
;;; gencgc and numbers on the stack (returned by GET-LISP-OBJ-ADDRESS)
(setf (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
- %alive-p
- os-thread
- interruptions
- (interruptions-lock (make-mutex :name "thread interruptions lock"))
- result
- (result-lock (make-mutex :name "thread result lock")))
-
#!+sb-doc
-(setf (fdocumentation 'thread-name 'function)
- "The name of the thread. Setfable.")
+(setf
+ (fdocumentation 'thread-name 'function)
+ "Name of the thread. Can be assigned to using SETF. Thread names can be
+arbitrary printable objects, and need not be unique.")
(def!method print-object ((thread thread) stream)
(print-unreadable-object (thread stream :type t :identity t)
(defun thread-alive-p (thread)
#!+sb-doc
- "Check if THREAD is running."
+ "Return T if THREAD is still alive. Note that the return value is
+potentially stale even before the function returns, as the thread may exit at
+any time."
(thread-%alive-p thread))
;; A thread is eligible for gc iff it has finished and there are no
(defun list-all-threads ()
#!+sb-doc
- "Return a list of the live threads."
+ "Return a list of the live threads. Note that the return value is
+potentially stale even before the function returns, as new threads may be
+created and old ones may exit at any time."
(with-all-threads-lock
(copy-list *all-threads*)))
(declaim (inline current-thread-os-thread))
(defun current-thread-os-thread ()
- (sap-int
- (sb!vm::current-thread-offset-sap sb!vm::thread-os-thread-slot)))
+ #!+sb-thread
+ (sap-int (sb!vm::current-thread-offset-sap sb!vm::thread-os-thread-slot))
+ #!-sb-thread
+ 0)
(defun init-initial-thread ()
(/show0 "Entering INIT-INITIAL-THREAD")
;;;; Aliens, low level stuff
+(define-alien-routine "kill_safely"
+ integer
+ (os-thread #!-alpha unsigned-long #!+alpha unsigned-int)
+ (signal int))
+
#!+sb-thread
(progn
;; FIXME it would be good to define what a thread id is or isn't
(define-alien-routine ("create_thread" %create-thread)
unsigned-long (lisp-fun-address unsigned-long))
- (define-alien-routine "signal_interrupt_thread"
- integer (os-thread unsigned-long))
+ (declaim (inline %block-deferrable-signals))
+ (define-alien-routine ("block_deferrable_signals" %block-deferrable-signals)
+ void
+ (where sb!alien:unsigned-long)
+ (old sb!alien:unsigned-long))
- (define-alien-routine "block_deferrable_signals"
- void)
+ (defun block-deferrable-signals ()
+ (%block-deferrable-signals 0 0))
#!+sb-lutex
(progn
(if (and (not *interrupts-enabled*) *allow-with-interrupts*)
;; If interrupts are disabled, but we are allowed to
;; enabled them, check for pending interrupts every once
- ;; in a while.
- (loop
- (loop repeat 128 do (cas)) ; 128 is arbitrary here
- (sb!unix::%check-interrupts))
+ ;; in a while. %CHECK-INTERRUPTS is taking shortcuts, make
+ ;; sure that deferrables are unblocked by doing an empty
+ ;; WITH-INTERRUPTS once.
+ (progn
+ (with-interrupts)
+ (loop
+ (loop repeat 128 do (cas)) ; 128 is arbitrary here
+ (sb!unix::%check-interrupts)))
(loop (cas)))))
t))
(setf (mutex-%owner mutex) new-owner)
t)
#!-sb-lutex
- ;; This is a direct tranlation of the Mutex 2 algorithm from
+ ;; This is a direct translation of the Mutex 2 algorithm from
;; "Futexes are Tricky" by Ulrich Drepper.
(let ((old (sb!ext:compare-and-swap (mutex-state mutex)
+lock-free+
+lock-taken+
+lock-contested+))))
;; Wait on the contested lock.
- (multiple-value-bind (to-sec to-usec) (decode-timeout nil)
- (when (= 1 (with-pinned-objects (mutex)
- (futex-wait (mutex-state-address mutex)
- (get-lisp-obj-address +lock-contested+)
- (or to-sec -1)
- (or to-usec 0))))
- (signal-deadline))))
+ (loop
+ (multiple-value-bind (to-sec to-usec) (decode-timeout nil)
+ (case (with-pinned-objects (mutex)
+ (futex-wait (mutex-state-address mutex)
+ (get-lisp-obj-address +lock-contested+)
+ (or to-sec -1)
+ (or to-usec 0)))
+ ((1) (signal-deadline))
+ ((2))
+ (otherwise (return))))))
(setf old (sb!ext:compare-and-swap (mutex-state mutex)
+lock-free+
+lock-contested+))
(waitp
(bug "Failed to acquire lock with WAITP."))))))
-(defun release-mutex (mutex)
+(defun release-mutex (mutex &key (if-not-owner :punt))
#!+sb-doc
"Release MUTEX by setting it to NIL. Wake up threads waiting for
this mutex.
RELEASE-MUTEX is not interrupt safe: interrupts should be disabled
around calls to it.
-Signals a WARNING if current thread is not the current owner of the
-mutex."
+If the current thread is not the owner of the mutex then it silently
+returns without doing anything (if IF-NOT-OWNER is :PUNT), signals a
+WARNING (if IF-NOT-OWNER is :WARN), or releases the mutex anyway (if
+IF-NOT-OWNER is :FORCE)."
(declare (type mutex mutex))
;; Order matters: set owner to NIL before releasing state.
(let* ((self *current-thread*)
(old-owner (sb!ext:compare-and-swap (mutex-%owner mutex) self nil)))
- (unless (eql self old-owner)
- (warn "Releasing ~S, owned by another thread: ~S" mutex old-owner)
- (setf (mutex-%owner mutex) nil)))
- #!+sb-thread
- (progn
- #!+sb-lutex
- (with-lutex-address (lutex (mutex-lutex mutex))
- (%lutex-unlock lutex))
- #!-sb-lutex
- ;; FIXME: once ATOMIC-INCF supports struct slots with word sized
- ;; unsigned-byte type this can be used:
- ;;
- ;; (let ((old (sb!ext:atomic-incf (mutex-state mutex) -1)))
- ;; (unless (eql old +lock-free+)
- ;; (setf (mutex-state mutex) +lock-free+)
- ;; (with-pinned-objects (mutex)
- ;; (futex-wake (mutex-state-address mutex) 1))))
- (let ((old (sb!ext:compare-and-swap (mutex-state mutex)
- +lock-taken+ +lock-free+)))
- (when (eql old +lock-contested+)
- (sb!ext:compare-and-swap (mutex-state mutex)
- +lock-contested+ +lock-free+)
- (with-pinned-objects (mutex)
- (futex-wake (mutex-state-address mutex) 1))))
- nil))
+ (unless (eql self old-owner)
+ (ecase if-not-owner
+ ((:punt) (return-from release-mutex nil))
+ ((:warn)
+ (warn "Releasing ~S, owned by another thread: ~S" mutex old-owner))
+ ((:force))))
+ #!+sb-thread
+ (when old-owner
+ (setf (mutex-%owner mutex) nil)
+ #!+sb-lutex
+ (with-lutex-address (lutex (mutex-lutex mutex))
+ (%lutex-unlock lutex))
+ #!-sb-lutex
+ ;; FIXME: once ATOMIC-INCF supports struct slots with word sized
+ ;; unsigned-byte type this can be used:
+ ;;
+ ;; (let ((old (sb!ext:atomic-incf (mutex-state mutex) -1)))
+ ;; (unless (eql old +lock-free+)
+ ;; (setf (mutex-state mutex) +lock-free+)
+ ;; (with-pinned-objects (mutex)
+ ;; (futex-wake (mutex-state-address mutex) 1))))
+ (let ((old (sb!ext:compare-and-swap (mutex-state mutex)
+ +lock-taken+ +lock-free+)))
+ (when (eql old +lock-contested+)
+ (sb!ext:compare-and-swap (mutex-state mutex)
+ +lock-contested+ +lock-free+)
+ (with-pinned-objects (mutex)
+ (futex-wake (mutex-state-address mutex) 1))))
+ nil)))
\f
;;;; Waitqueues/condition variables
#!+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."
+time we reacquire MUTEX and return to the caller.
+
+Note that if CONDITION-WAIT unwinds (due to eg. a timeout) instead of
+returning normally, it may do so without holding the mutex."
#!-sb-thread (declare (ignore queue))
(assert mutex)
#!-sb-thread (error "Not supported in unithread builds.")
;; Need to disable interrupts so that we don't miss grabbing the
;; mutex on our way out.
(without-interrupts
- (unwind-protect
- (let ((me *current-thread*))
- ;; This setf becomes visible to other CPUS due to the
- ;; usual memory barrier semantics of lock
- ;; acquire/release.
- (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. We may get spurious wakeups, but
- ;; that's ok.
- (multiple-value-bind (to-sec to-usec) (decode-timeout nil)
- (when (= 1 (with-pinned-objects (queue me)
- (allow-with-interrupts
- (futex-wait (waitqueue-data-address queue)
- (get-lisp-obj-address me)
- ;; our way if saying "no
- ;; timeout":
- (or to-sec -1)
- (or to-usec 0)))))
- (signal-deadline))))
- ;; 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)))))
+ (let ((me nil))
+ ;; This setf becomes visible to other CPUS due to the usual
+ ;; memory barrier semantics of lock acquire/release. This must
+ ;; not be moved into the loop else wakeups may be lost upon
+ ;; continuing after a deadline or EINTR.
+ (setf (waitqueue-data queue) me)
+ (loop
+ (multiple-value-bind (to-sec to-usec)
+ (allow-with-interrupts (decode-timeout nil))
+ (case (unwind-protect
+ (with-pinned-objects (queue me)
+ ;; RELEASE-MUTEX is purposefully as close to
+ ;; FUTEX-WAIT as possible to reduce the size
+ ;; of the window where WAITQUEUE-DATA may be
+ ;; set by a notifier.
+ (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. We may get spurious
+ ;; wakeups, but that's ok.
+ (allow-with-interrupts
+ (futex-wait (waitqueue-data-address queue)
+ (get-lisp-obj-address me)
+ ;; our way of saying "no
+ ;; timeout":
+ (or to-sec -1)
+ (or to-usec 0))))
+ ;; 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.
+ (allow-with-interrupts (get-mutex mutex)))
+ ;; ETIMEDOUT; we know it was a timeout, yet we cannot
+ ;; signal a deadline unconditionally here because the
+ ;; call to GET-MUTEX may already have signaled it.
+ ((1))
+ ;; EINTR
+ ((2))
+ ;; EWOULDBLOCK, -1 here, is the possible spurious wakeup
+ ;; case. 0 is the normal wakeup.
+ (otherwise (return)))))))))
(defun condition-notify (queue &optional (n 1))
#!+sb-doc
"Notify N threads waiting on QUEUE. The same mutex that is used in
-the correspoinding condition-wait must be held by this thread during
+the corresponding CONDITION-WAIT must be held by this thread during
this call."
#!-sb-thread (declare (ignore queue n))
#!-sb-thread (error "Not supported in unithread builds.")
do (condition-wait (semaphore-queue semaphore)
(semaphore-mutex semaphore)))
(setf (semaphore-%count semaphore) (1- count)))
- (decf (semaphore-waitcount semaphore)))))))
+ ;; Need to use ATOMIC-DECF instead of DECF, as CONDITION-WAIT
+ ;; may unwind without the lock being held due to timeouts.
+ (atomic-decf (semaphore-waitcount semaphore)))))))
+
+(defun try-semaphore (semaphore)
+ #!+sb-doc
+ "Try to decrement the count of SEMAPHORE if the count would not be
+negative. Else return NIL."
+ ;; No need for disabling interrupts; the mutex prevents interleaved
+ ;; modifications, and we don't leave temporarily inconsistent state
+ ;; around.
+ (with-mutex ((semaphore-mutex semaphore))
+ (let ((count (semaphore-%count semaphore)))
+ (when (plusp count)
+ (setf (semaphore-%count semaphore) (1- count))))))
(defun signal-semaphore (semaphore &optional (n 1))
#!+sb-doc
(setup-sem (make-semaphore :name "Thread setup semaphore"))
(real-function (coerce function 'function))
(initial-function
- (lambda ()
+ (named-lambda initial-thread-function ()
;; In time we'll move some of the binding presently done in C
;; here too.
;;
;; internal printer variables
(sb!impl::*previous-case* nil)
(sb!impl::*previous-readtable-case* nil)
- (empty (vector))
- (sb!impl::*merge-sort-temp-vector* empty)
- (sb!impl::*zap-array-data-temp* empty)
(sb!impl::*internal-symbol-output-fun* nil)
(sb!impl::*descriptor-handlers* nil)) ; serve-event
;; Binding from C
(wait-on-semaphore setup-sem)
thread)))))
-(define-condition join-thread-error (error)
- ((thread :reader join-thread-error-thread :initarg :thread))
- #!+sb-doc
- (:documentation "Joining thread failed.")
- (:report (lambda (c s)
- (format s "Joining thread failed: thread ~A ~
- has not returned normally."
- (join-thread-error-thread c)))))
-
-#!+sb-doc
-(setf (fdocumentation 'join-thread-error-thread 'function)
- "The thread that we failed to join.")
-
(defun join-thread (thread &key (default nil defaultp))
#!+sb-doc
"Suspend current thread until THREAD exits. Returns the result
"Deprecated. Same as TERMINATE-THREAD."
(terminate-thread thread))
-(define-condition interrupt-thread-error (error)
- ((thread :reader interrupt-thread-error-thread :initarg :thread))
- #!+sb-doc
- (:documentation "Interrupting thread failed.")
- (:report (lambda (c s)
- (format s "Interrupt thread failed: thread ~A has exited."
- (interrupt-thread-error-thread c)))))
-
-#!+sb-doc
-(setf (fdocumentation 'interrupt-thread-error-thread 'function)
- "The thread that was not interrupted.")
-
(defmacro with-interruptions-lock ((thread) &body body)
`(with-system-mutex ((thread-interruptions-lock ,thread))
,@body))
-;;; Called from the signal handler in C.
+;;; Called from the signal handler.
+#!-win32
(defun run-interruption ()
- (in-interruption ()
- (loop
- (let ((interruption (with-interruptions-lock (*current-thread*)
- (pop (thread-interruptions *current-thread*)))))
- ;; Resignalling after popping one works fine, because from the
- ;; OS's point of view we have returned from the signal handler
- ;; (thanks to arrange_return_to_lisp_function) so at least one
- ;; more signal will be delivered.
- (when (thread-interruptions *current-thread*)
- (signal-interrupt-thread (thread-os-thread *current-thread*)))
- (if interruption
- (with-interrupts
- (funcall interruption))
- (return))))))
-
-;;; The order of interrupt execution is peculiar. If thread A
-;;; interrupts thread B with I1, I2 and B for some reason receives I1
-;;; when FUN2 is already on the list, then it is FUN2 that gets to run
-;;; first. But when FUN2 is run SIG_INTERRUPT_THREAD is enabled again
-;;; and I2 hits pretty soon in FUN2 and run FUN1. This is of course
-;;; just one scenario, and the order of thread interrupt execution is
-;;; undefined.
+ (let ((interruption (with-interruptions-lock (*current-thread*)
+ (pop (thread-interruptions *current-thread*)))))
+ ;; If there is more to do, then resignal and let the normal
+ ;; interrupt deferral mechanism take care of the rest. From the
+ ;; OS's point of view the signal we are in the handler for is no
+ ;; longer pending, so the signal will not be lost.
+ (when (thread-interruptions *current-thread*)
+ (kill-safely (thread-os-thread *current-thread*) sb!unix:sigpipe))
+ (when interruption
+ (funcall interruption))))
+
(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))
- #!-sb-thread
+won't like the effect. FUNCTION runs with interrupts disabled, but
+WITH-INTERRUPTS is allowed in it. Keep in mind that many things may
+enable interrupts (GET-MUTEX when contended, for instance) so the
+first thing to do is usually a WITH-INTERRUPTS or a
+WITHOUT-INTERRUPTS. Within a thread interrupts are queued, they are
+run in same the order they were sent."
+ #!+win32
+ (declare (ignore thread))
+ #!+win32
(with-interrupt-bindings
(with-interrupts (funcall function)))
- #!+sb-thread
- (if (eq thread *current-thread*)
- (with-interrupt-bindings
- (with-interrupts (funcall function)))
- (let ((os-thread (thread-os-thread thread)))
- (cond ((not os-thread)
- (error 'interrupt-thread-error :thread thread))
- (t
- (with-interruptions-lock (thread)
- (push function (thread-interruptions thread)))
- (when (minusp (signal-interrupt-thread os-thread))
- (error 'interrupt-thread-error :thread thread)))))))
+ #!-win32
+ (let ((os-thread (thread-os-thread thread)))
+ (cond ((not os-thread)
+ (error 'interrupt-thread-error :thread thread))
+ (t
+ (with-interruptions-lock (thread)
+ ;; Append to the end of the interruptions queue. It's
+ ;; O(N), but it does not hurt to slow interruptors down a
+ ;; bit when the queue gets long.
+ (setf (thread-interruptions thread)
+ (append (thread-interruptions thread)
+ (list (lambda ()
+ (without-interrupts
+ (allow-with-interrupts
+ (funcall function))))))))
+ (when (minusp (kill-safely os-thread sb!unix:sigpipe))
+ (error 'interrupt-thread-error :thread thread))))))
(defun terminate-thread (thread)
#!+sb-doc
sb!vm::thread-next-slot)))))))
(defun %symbol-value-in-thread (symbol thread)
- (tagbody
- ;; Prevent the dead from dying completely while we look for the
- ;; TLS area...
- (with-all-threads-lock
- (if (thread-alive-p thread)
- (let* ((offset (* sb!vm:n-word-bytes
- (sb!vm::symbol-tls-index symbol)))
- (tl-val (sap-ref-word (%thread-sap thread) offset)))
- (if (eql tl-val sb!vm::no-tls-value-marker-widetag)
- (go :unbound)
- (return-from %symbol-value-in-thread
- (values (make-lisp-obj tl-val) t))))
- (return-from %symbol-value-in-thread (values nil nil))))
- :unbound
- (error "Cannot read thread-local symbol value: ~S unbound in ~S"
- symbol thread)))
+ ;; Prevent the thread from dying completely while we look for the TLS
+ ;; area...
+ (with-all-threads-lock
+ (loop
+ (if (thread-alive-p thread)
+ (let* ((epoch sb!kernel::*gc-epoch*)
+ (offset (* sb!vm:n-word-bytes
+ (sb!vm::symbol-tls-index symbol)))
+ (tl-val (sap-ref-word (%thread-sap thread) offset)))
+ (cond ((zerop offset)
+ (return (values nil :no-tls-value)))
+ ((or (eql tl-val sb!vm:no-tls-value-marker-widetag)
+ (eql tl-val sb!vm:unbound-marker-widetag))
+ (return (values nil :unbound-in-thread)))
+ (t
+ (multiple-value-bind (obj ok) (make-lisp-obj tl-val nil)
+ ;; The value we constructed may be invalid if a GC has
+ ;; occurred. That is harmless, though, since OBJ is
+ ;; either in a register or on stack, and we are
+ ;; conservative on both on GENCGC -- so a bogus object
+ ;; is safe here as long as we don't return it. If we
+ ;; ever port threads to a non-conservative GC we must
+ ;; pin the TL-VAL address before constructing OBJ, or
+ ;; make WITH-ALL-THREADS-LOCK imply WITHOUT-GCING.
+ ;;
+ ;; The reason we don't just rely on TL-VAL pinning the
+ ;; object is that the call to MAKE-LISP-OBJ may cause
+ ;; bignum allocation, at which point TL-VAL might not
+ ;; be alive anymore -- hence the epoch check.
+ (when (eq epoch sb!kernel::*gc-epoch*)
+ (if ok
+ (return (values obj :ok))
+ (return (values obj :invalid-tls-value))))))))
+ (return (values nil :thread-dead))))))
(defun %set-symbol-value-in-thread (symbol thread value)
- (tagbody
- (with-pinned-objects (value)
- ;; Prevent the dead from dying completely while we look for
- ;; the TLS area...
- (with-all-threads-lock
- (if (thread-alive-p thread)
- (let* ((offset (* sb!vm:n-word-bytes
- (sb!vm::symbol-tls-index symbol)))
- (sap (%thread-sap thread))
- (tl-val (sap-ref-word sap offset)))
- (if (eql tl-val sb!vm::no-tls-value-marker-widetag)
- (go :unbound)
- (setf (sap-ref-word sap offset)
- (get-lisp-obj-address value)))
- (return-from %set-symbol-value-in-thread (values value t)))
- (return-from %set-symbol-value-in-thread (values nil nil)))))
- :unbound
- (error "Cannot set thread-local symbol value: ~S unbound in ~S"
- symbol thread))))
+ (with-pinned-objects (value)
+ ;; Prevent the thread from dying completely while we look for the TLS
+ ;; area...
+ (with-all-threads-lock
+ (if (thread-alive-p thread)
+ (let ((offset (* sb!vm:n-word-bytes
+ (sb!vm::symbol-tls-index symbol))))
+ (cond ((zerop offset)
+ (values nil :no-tls-value))
+ (t
+ (setf (sap-ref-word (%thread-sap thread) offset)
+ (get-lisp-obj-address value))
+ (values value :ok))))
+ (values nil :thread-dead))))))
+
+(defun symbol-value-in-thread (symbol thread &optional (errorp t))
+ "Return the local value of SYMBOL in THREAD, and a secondary value of T
+on success.
+
+If the value cannot be retrieved (because the thread has exited or because it
+has no local binding for NAME) and ERRORP is true signals an error of type
+SYMBOL-VALUE-IN-THREAD-ERROR; if ERRORP is false returns a primary value of
+NIL, and a secondary value of NIL.
+
+Can also be used with SETF to change the thread-local value of SYMBOL.
+
+SYMBOL-VALUE-IN-THREAD is primarily intended as a debugging tool, and not as a
+mechanism for inter-thread communication."
+ (declare (symbol symbol) (thread thread))
+ #!+sb-thread
+ (multiple-value-bind (res status) (%symbol-value-in-thread symbol thread)
+ (if (eq :ok status)
+ (values res t)
+ (if errorp
+ (error 'symbol-value-in-thread-error
+ :name symbol
+ :thread thread
+ :info (list :read status))
+ (values nil nil))))
+ #!-sb-thread
+ (if (boundp symbol)
+ (values (symbol-value symbol) t)
+ (if errorp
+ (error 'symbol-value-in-thread-error
+ :name symbol
+ :thread thread
+ :info (list :read :unbound-in-thread))
+ (values nil nil))))
+
+(defun (setf symbol-value-in-thread) (value symbol thread &optional (errorp t))
+ (declare (symbol symbol) (thread thread))
+ #!+sb-thread
+ (multiple-value-bind (res status) (%set-symbol-value-in-thread symbol thread value)
+ (if (eq :ok status)
+ (values res t)
+ (if errorp
+ (error 'symbol-value-in-thread-error
+ :name symbol
+ :thread thread
+ :info (list :write status))
+ (values nil nil))))
+ #!-sb-thread
+ (if (boundp symbol)
+ (values (setf (symbol-value symbol) value) t)
+ (if errorp
+ (error 'symbol-value-in-thread-error
+ :name symbol
+ :thread thread
+ :info (list :write :unbound-in-thread))
+ (values nil nil))))
(defun sb!vm::locked-symbol-global-value-add (symbol-name delta)
(sb!vm::locked-symbol-global-value-add symbol-name delta))
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