X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Ftarget-thread.lisp;h=a73ec31051e28554eab99bacc5fab0002c0772e8;hb=d442c23da9851beac541b8bddfc2c0837cb87309;hp=091ed8d7be5026e44058e5a273a569c4c3f54380;hpb=b71ea3ac652d67b53d415378ed27da80cc90806f;p=sbcl.git diff --git a/src/code/target-thread.lisp b/src/code/target-thread.lisp index 091ed8d..a73ec31 100644 --- a/src/code/target-thread.lisp +++ b/src/code/target-thread.lisp @@ -11,6 +11,87 @@ (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) @@ -35,8 +116,10 @@ in future versions." (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) @@ -60,7 +143,9 @@ in future versions." (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 @@ -77,7 +162,9 @@ in future versions." (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*))) @@ -87,8 +174,10 @@ in future versions." (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") @@ -104,6 +193,11 @@ in future versions." ;;;; 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 @@ -113,11 +207,14 @@ in future versions." (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 @@ -214,11 +311,16 @@ in future versions." (thread-yield) (return-from get-spinlock t)))) (if (and (not *interrupts-enabled*) *allow-with-interrupts*) - ;; If interrupts are enabled, 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)) + ;; If interrupts are disabled, but we are allowed to + ;; enabled them, check for pending interrupts every once + ;; 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)) @@ -257,6 +359,15 @@ in future versions." (defconstant +lock-taken+ 1) (defconstant +lock-contested+ 2)) +(defun mutex-owner (mutex) + "Current owner of the mutex, NIL if the mutex is free. Naturally, +this is racy by design (another thread may acquire the mutex after +this function returns), it is intended for informative purposes. For +testing whether the current thread is holding a mutex see +HOLDING-MUTEX-P." + ;; Make sure to get the current value. + (sb!ext:compare-and-swap (mutex-%owner mutex) nil nil)) + (defun get-mutex (mutex &optional (new-owner *current-thread*) (waitp t)) #!+sb-doc "Acquire MUTEX for NEW-OWNER, which must be a thread or NIL. If @@ -287,9 +398,10 @@ directly." (when (eq new-owner old) (error "Recursive lock attempt ~S." mutex)) #!-sb-thread - (if old - (error "Strange deadlock on ~S in an unithreaded build?" mutex) - (setf (mutex-%owner mutex) new-owner))) + (when old + (error "Strange deadlock on ~S in an unithreaded build?" mutex))) + #!-sb-thread + (setf (mutex-%owner mutex) new-owner) #!+sb-thread (progn ;; FIXME: Lutexes do not currently support deadlines, as at least @@ -309,6 +421,8 @@ directly." (setf (mutex-%owner mutex) new-owner) t) #!-sb-lutex + ;; 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+))) @@ -321,13 +435,16 @@ directly." +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+)) @@ -343,7 +460,7 @@ directly." (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. @@ -351,29 +468,43 @@ this mutex. RELEASE-MUTEX is not interrupt safe: interrupts should be disabled around calls to it. -Signals a WARNING is 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 - (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))) ;;;; Waitqueues/condition variables @@ -430,39 +561,53 @@ time we reacquire MUTEX and return to the caller." ;; 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) (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 if 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 + ((1) (signal-deadline)) + ;; 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.") @@ -617,9 +762,6 @@ on this semaphore, then N of them is woken up." #!+sb-thread (defun handle-thread-exit (thread) (/show0 "HANDLING THREAD EXIT") - ;; We're going down, can't handle interrupts sanely anymore. GC - ;; remains enabled. - (block-deferrable-signals) ;; Lisp-side cleanup (with-all-threads-lock (setf (thread-%alive-p thread) nil) @@ -760,6 +902,9 @@ around and can be retrieved by JOIN-THREAD." ;; of Allegro's *cl-default-special-bindings*, as that is at ;; least accessible to users to secure their own libraries. ;; --njf, 2006-07-15 + ;; + ;; As it is, this lambda must not cons until we are ready + ;; to run GC. Be very careful. (let* ((*current-thread* thread) (*restart-clusters* nil) (*handler-clusters* (sb!kernel::initial-handler-clusters)) @@ -794,117 +939,121 @@ around and can be retrieved by JOIN-THREAD." (format nil "~~@" *current-thread*)) - (unwind-protect - (progn - ;; 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) - (setf (thread-result thread) - (cons t - (multiple-value-list - (funcall real-function))))) - (handle-thread-exit thread))))))) + (without-interrupts + (unwind-protect + (with-local-interrupts + ;; Now that most things have a chance + ;; to work properly without messing up + ;; other threads, it's time to enable + ;; signals. + (sb!unix::unblock-deferrable-signals) + (setf (thread-result thread) + (cons t + (multiple-value-list + (funcall real-function)))) + ;; Try to block deferrables. An + ;; interrupt may unwind it, but for a + ;; normal exit it prevents interrupt + ;; loss. + (block-deferrable-signals)) + ;; We're going down, can't handle interrupts + ;; sanely anymore. GC remains enabled. + (block-deferrable-signals) + ;; We don't want to run interrupts in a dead + ;; thread when we leave WITHOUT-INTERRUPTS. + ;; This potentially causes important + ;; interupts to be lost: SIGINT comes to + ;; mind. + (setq *interrupt-pending* nil) + (handle-thread-exit thread)))))))) (values)))) + ;; If the starting thread is stopped for gc before it signals the + ;; semaphore then we'd be stuck. + (assert (not *gc-inhibit*)) ;; Keep INITIAL-FUNCTION pinned until the child thread is - ;; initialized properly. - (with-pinned-objects (initial-function) - (let ((os-thread - (%create-thread - (get-lisp-obj-address initial-function)))) - (when (zerop os-thread) - (error "Can't create a new thread")) - (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.") + ;; initialized properly. Wrap the whole thing in + ;; WITHOUT-INTERRUPTS because we pass INITIAL-FUNCTION to another + ;; thread. + (without-interrupts + (with-pinned-objects (initial-function) + (let ((os-thread + (%create-thread + (get-lisp-obj-address initial-function)))) + (when (zerop os-thread) + (error "Can't create a new thread")) + (wait-on-semaphore setup-sem) + thread))))) (defun join-thread (thread &key (default nil defaultp)) #!+sb-doc "Suspend current thread until THREAD exits. Returns the result values of the thread function. If the thread does not exit normally, return DEFAULT if given or else signal JOIN-THREAD-ERROR." - (with-mutex ((thread-result-lock thread)) + (with-system-mutex ((thread-result-lock thread) :allow-with-interrupts t) (cond ((car (thread-result thread)) - (values-list (cdr (thread-result thread)))) + (return-from join-thread + (values-list (cdr (thread-result thread))))) (defaultp - default) - (t - (error 'join-thread-error :thread thread))))) + (return-from join-thread default)))) + (error 'join-thread-error :thread 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)) - #!+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*))))) - (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 @@ -938,43 +1087,112 @@ SB-EXT:QUIT - the usual cleanup forms will be evaluated" 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))