X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Ftarget-thread.lisp;h=c534ca01fb2e94e0b61973ecc1322602059ac56a;hb=ee222567ee95eaac8f6f4c877242dd116bfb8337;hp=dd25ecbbce9595f49501c954a98ded9342935dfe;hpb=df61d054712f14fda874034fde70a269a76c792b;p=sbcl.git diff --git a/src/code/target-thread.lisp b/src/code/target-thread.lisp index dd25ecb..c534ca0 100644 --- a/src/code/target-thread.lisp +++ b/src/code/target-thread.lisp @@ -1,5 +1,4 @@ -;;;; 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. @@ -12,45 +11,55 @@ (in-package "SB!THREAD") +;;; 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) +;;; are treated as references. + +;;; set the doc here because in early-thread FDOCUMENTATION is not +;;; available, yet +#!+sb-doc +(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 - %sap) + %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.") (def!method print-object ((thread thread) stream) - (if (thread-name thread) - (print-unreadable-object (thread stream :type t :identity t) - (prin1 (thread-name thread) stream)) - (print-unreadable-object (thread stream :type t :identity t) - ;; body is empty => there is only one space between type and - ;; identity - )) - thread) - -(defun thread-state (thread) - (let ((state - (sb!sys:sap-int - (sb!sys:sap-ref-sap (thread-%sap thread) - (* sb!vm::thread-state-slot - sb!vm::n-word-bytes))))) - (ecase state - (#.(sb!vm:fixnumize 0) :starting) - (#.(sb!vm:fixnumize 1) :running) - (#.(sb!vm:fixnumize 2) :suspended) - (#.(sb!vm:fixnumize 3) :dead)))) - -(defun %set-thread-state (thread state) - (setf (sb!sys:sap-ref-sap (thread-%sap thread) - (* sb!vm::thread-state-slot - sb!vm::n-word-bytes)) - (sb!sys:int-sap - (ecase state - (:starting #.(sb!vm:fixnumize 0)) - (:running #.(sb!vm:fixnumize 1)) - (:suspended #.(sb!vm:fixnumize 2)) - (:dead #.(sb!vm:fixnumize 3)))))) + (print-unreadable-object (thread stream :type t :identity t) + (let* ((cookie (list thread)) + (info (if (thread-alive-p thread) + :running + (multiple-value-list (join-thread thread :default cookie)))) + (state (if (eq :running info) + info + (if (eq cookie (car info)) + :aborted + :finished))) + (values (when (eq :finished state) info))) + (format stream "~@[~S ~]~:[~A~;~A~:[ no values~; values: ~:*~{~S~^, ~}~]~]" + (thread-name thread) + (eq :finished state) + state + values)))) (defun thread-alive-p (thread) - (not (eq :dead (thread-state thread)))) + #!+sb-doc + "Check if THREAD is running." + (thread-%alive-p thread)) ;; A thread is eligible for gc iff it has finished and there are no ;; more references to it. This list is supposed to keep a reference to @@ -58,24 +67,885 @@ (defvar *all-threads* ()) (defvar *all-threads-lock* (make-mutex :name "all threads lock")) +(defvar *default-alloc-signal* nil) + +(defmacro with-all-threads-lock (&body body) + `(with-system-mutex (*all-threads-lock*) + ,@body)) + (defun list-all-threads () - (with-mutex (*all-threads-lock*) + #!+sb-doc + "Return a list of the live threads." + (with-all-threads-lock (copy-list *all-threads*))) (declaim (inline current-thread-sap)) (defun current-thread-sap () (sb!vm::current-thread-offset-sap sb!vm::thread-this-slot)) -(declaim (inline current-thread-sap-id)) -(defun current-thread-sap-id () - (sb!sys:sap-int +(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))) (defun init-initial-thread () + (/show0 "Entering INIT-INITIAL-THREAD") (let ((initial-thread (%make-thread :name "initial thread" - :%sap (current-thread-sap)))) + :%alive-p t + :os-thread (current-thread-os-thread)))) (setq *current-thread* initial-thread) ;; Either *all-threads* is empty or it contains exactly one thread ;; in case we are in reinit since saving core with multiple ;; threads doesn't work. (setq *all-threads* (list initial-thread)))) + +;;;; + +#!+sb-thread +(progn + ;; 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. + (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)) + + (define-alien-routine "block_deferrable_signals" + void) + + #!+sb-lutex + (progn + (declaim (inline %lutex-init %lutex-wait %lutex-wake + %lutex-lock %lutex-unlock)) + + (define-alien-routine ("lutex_init" %lutex-init) + int (lutex unsigned-long)) + + (define-alien-routine ("lutex_wait" %lutex-wait) + int (queue-lutex unsigned-long) (mutex-lutex unsigned-long)) + + (define-alien-routine ("lutex_wake" %lutex-wake) + int (lutex unsigned-long) (n int)) + + (define-alien-routine ("lutex_lock" %lutex-lock) + int (lutex unsigned-long)) + + (define-alien-routine ("lutex_trylock" %lutex-trylock) + int (lutex unsigned-long)) + + (define-alien-routine ("lutex_unlock" %lutex-unlock) + int (lutex unsigned-long)) + + (define-alien-routine ("lutex_destroy" %lutex-destroy) + int (lutex unsigned-long)) + + ;; FIXME: Defining a whole bunch of alien-type machinery just for + ;; passing primitive lutex objects directly to foreign functions + ;; doesn't seem like fun right now. So instead we just manually + ;; pin the lutex, get its address, and let the callee untag it. + (defmacro with-lutex-address ((name lutex) &body body) + `(let ((,name ,lutex)) + (with-pinned-objects (,name) + (let ((,name (get-lisp-obj-address ,name))) + ,@body)))) + + (defun make-lutex () + (/show0 "Entering MAKE-LUTEX") + ;; Suppress GC until the lutex has been properly registered with + ;; the GC. + (without-gcing + (let ((lutex (sb!vm::%make-lutex))) + (/show0 "LUTEX=..") + (/hexstr lutex) + (with-lutex-address (lutex lutex) + (%lutex-init lutex)) + lutex)))) + + #!-sb-lutex + (progn + (declaim (inline futex-wait %futex-wait futex-wake)) + + (define-alien-routine ("futex_wait" %futex-wait) + int (word unsigned-long) (old-value unsigned-long) + (to-sec long) (to-usec unsigned-long)) + + (defun futex-wait (word old to-sec to-usec) + (with-interrupts + (%futex-wait word old to-sec to-usec))) + + (define-alien-routine "futex_wake" + int (word unsigned-long) (n unsigned-long)))) + +;;; used by debug-int.lisp to access interrupt contexts +#!-(or 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)) + (sap-ref-sap (alien-sap (extern-alien "all_threads" (* t))) + (* n sb!vm:n-word-bytes))) + +#!+sb-thread +(defun sb!vm::current-thread-offset-sap (n) + (declare (type (unsigned-byte 27) n)) + (sb!vm::current-thread-offset-sap n)) + +(declaim (inline get-spinlock release-spinlock)) + +;; Should always be called with interrupts disabled. +(defun get-spinlock (spinlock) + (declare (optimize (speed 3) (safety 0))) + (let* ((new *current-thread*) + (old (sb!ext:compare-and-swap (spinlock-value spinlock) nil new))) + (when old + (when (eq old new) + (error "Recursive lock attempt on ~S." spinlock)) + #!+sb-thread + (flet ((cas () + (if (sb!ext:compare-and-swap (spinlock-value spinlock) nil new) + (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)) + (loop (cas))))) + t)) + +(defun release-spinlock (spinlock) + (declare (optimize (speed 3) (safety 0))) + (setf (spinlock-value spinlock) nil) + nil) + +;;;; mutexes + +#!+sb-doc +(setf (fdocumentation 'make-mutex 'function) + "Create a mutex." + (fdocumentation 'mutex-name 'function) + "The name of the mutex. Setfable.") + +#!+(and sb-thread (not sb-lutex)) +(progn + (define-structure-slot-addressor mutex-state-address + :structure mutex + :slot state) + ;; Important: current code assumes these are fixnums or other + ;; lisp objects that don't need pinning. + (defconstant +lock-free+ 0) + (defconstant +lock-taken+ 1) + (defconstant +lock-contested+ 2)) + +(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 +NEW-OWNER is NIL, it defaults to the current thread. If WAITP is +non-NIL and the mutex is in use, sleep until it is available. + +Note: using GET-MUTEX to assign a MUTEX to another thread then the +current one is not recommended, and liable to be deprecated. + +GET-MUTEX is not interrupt safe. The correct way to call it is: + + (WITHOUT-INTERRUPTS + ... + (ALLOW-WITH-INTERRUPTS (GET-MUTEX ...)) + ...) + +WITHOUT-INTERRUPTS is necessary to avoid an interrupt unwinding the +call while the mutex is in an inconsistent state while +ALLOW-WITH-INTERRUPTS allows the call to be interrupted from sleep. + +It is recommended that you use WITH-MUTEX instead of calling GET-MUTEX +directly." + (declare (type mutex mutex) (optimize (speed 3)) + #!-sb-thread (ignore waitp)) + (unless new-owner + (setq new-owner *current-thread*)) + (when (eql new-owner (mutex-%owner mutex)) + (error "Recursive lock attempt ~S." mutex)) + #!+sb-thread + (progn + ;; FIXME: Lutexes do not currently support deadlines, as at least + ;; on Darwin pthread_foo_timedbar functions are not supported: + ;; this means that we probably need to use the Carbon multiprocessing + ;; functions on Darwin. + ;; + ;; FIXME: This is definitely not interrupt safe: what happens if + ;; we get hit (1) during the lutex calls (ok, they may be safe, + ;; but has that been checked?) (2) after the lutex call, but + ;; before setting the mutex owner. + #!+sb-lutex + (when (zerop (with-lutex-address (lutex (mutex-lutex mutex)) + (if waitp + (with-interrupts (%lutex-lock lutex)) + (%lutex-trylock lutex)))) + (setf (mutex-%owner mutex) new-owner) + t) + #!-sb-lutex + (let ((old (sb!ext:compare-and-swap (mutex-state mutex) + +lock-free+ + +lock-taken+))) + (unless (or (eql +lock-free+ old) (not waitp)) + (tagbody + :retry + (when (or (eql +lock-contested+ old) + (not (eql +lock-free+ + (sb!ext:compare-and-swap (mutex-state mutex) + +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)))) + (setf old (sb!ext:compare-and-swap (mutex-state mutex) + +lock-free+ + +lock-contested+)) + ;; Did we get it? + (unless (eql +lock-free+ old) + (go :retry)))) + (cond ((eql +lock-free+ old) + (let ((prev (sb!ext:compare-and-swap (mutex-%owner mutex) + nil new-owner))) + (when prev + (bug "Old owner in free mutex: ~S" prev)) + t)) + (waitp + (bug "Failed to acquire lock with WAITP.")))))) + +(defun release-mutex (mutex) + #!+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 is current thread is not the current owner of the +mutex." + (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)) + +;;;; waitqueues/condition variables + +(defstruct (waitqueue (:constructor %make-waitqueue)) + #!+sb-doc + "Waitqueue type." + (name nil :type (or null simple-string)) + #!+(and sb-lutex sb-thread) + (lutex (make-lutex)) + #!-sb-lutex + (data nil)) + +(defun make-waitqueue (&key name) + #!+sb-doc + "Create a waitqueue." + (%make-waitqueue :name name)) + +#!+sb-doc +(setf (fdocumentation 'waitqueue-name 'function) + "The name of the waitqueue. Setfable.") + +#!+(and sb-thread (not sb-lutex)) +(define-structure-slot-addressor waitqueue-data-address + :structure waitqueue + :slot data) + +(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 ((me *current-thread*)) + (assert (eq me (mutex-%owner mutex))) + (/show0 "CONDITION-WAITing") + #!+sb-lutex + ;; Need to disable interrupts so that we don't miss setting the owner on + ;; our way out. (pthread_cond_wait handles the actual re-acquisition.) + (without-interrupts + (unwind-protect + (progn + (setf (mutex-%owner mutex) nil) + (with-lutex-address (queue-lutex-address (waitqueue-lutex queue)) + (with-lutex-address (mutex-lutex-address (mutex-lutex mutex)) + (with-local-interrupts + (%lutex-wait queue-lutex-address mutex-lutex-address))))) + (setf (mutex-%owner mutex) me))) + #!-sb-lutex + ;; 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*)) + ;; FIXME: should we 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. 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) + (or to-sec -1) ;; our way if saying "no timeout" + (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))))) + +(defun condition-notify (queue &optional (n 1)) + #!+sb-doc + "Notify N threads waiting on QUEUE." + #!-sb-thread (declare (ignore queue n)) + #!-sb-thread (error "Not supported in unithread builds.") + #!+sb-thread + (declare (type (and fixnum (integer 1)) n)) + (/show0 "Entering CONDITION-NOTIFY") + #!+sb-thread + (progn + #!+sb-lutex + (with-lutex-address (lutex (waitqueue-lutex queue)) + (%lutex-wake lutex n)) + ;; 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 + #!-sb-lutex + (let ((me *current-thread*)) + (progn + (setf (waitqueue-data queue) me) + (with-pinned-objects (queue) + (futex-wake (waitqueue-data-address queue) n)))))) + +(defun condition-broadcast (queue) + #!+sb-doc + "Notify all threads waiting on QUEUE." + (condition-notify queue + ;; On a 64-bit platform truncating M-P-F to an int results + ;; in -1, which wakes up only one thread. + (ldb (byte 29 0) + most-positive-fixnum))) + +;;;; semaphores + +(defstruct (semaphore (:constructor %make-semaphore (name %count))) + #!+sb-doc + "Semaphore type. The fact that a SEMAPHORE is a STRUCTURE-OBJECT +should be considered an implementation detail, and may change in the +future." + (name nil :type (or null simple-string)) + (%count 0 :type (integer 0)) + (waitcount 0 :type (integer 0)) + (mutex (make-mutex)) + (queue (make-waitqueue))) + +(setf (fdocumentation 'semaphore-name 'function) + "The name of the semaphore INSTANCE. Setfable.") + +(declaim (inline semaphore-count)) +(defun semaphore-count (instance) + "Returns the current count of the semaphore INSTANCE." + (semaphore-%count instance)) + +(defun make-semaphore (&key name (count 0)) + #!+sb-doc + "Create a semaphore with the supplied COUNT and NAME." + (%make-semaphore name count)) + +(defun wait-on-semaphore (semaphore) + #!+sb-doc + "Decrement the count of SEMAPHORE if the count would not be +negative. Else blocks until the semaphore can be decremented." + ;; A more direct implementation based directly on futexes should be + ;; possible. + ;; + ;; We need to disable interrupts so that we don't forget to decrement the + ;; waitcount (which would happen if an asynch interrupt should catch us on + ;; our way out from the loop.) + (with-system-mutex ((semaphore-mutex semaphore) :allow-with-interrupts t) + ;; Quick check: is it positive? If not, enter the wait loop. + (let ((count (semaphore-%count semaphore))) + (if (plusp count) + (setf (semaphore-%count semaphore) (1- count)) + (unwind-protect + (progn + (incf (semaphore-waitcount semaphore)) + (loop until (plusp (setf count (semaphore-%count semaphore))) + do (condition-wait (semaphore-queue semaphore) (semaphore-mutex semaphore))) + (setf (semaphore-%count semaphore) (1- count))) + (decf (semaphore-waitcount semaphore))))))) + +(defun signal-semaphore (semaphore &optional (n 1)) + #!+sb-doc + "Increment the count of SEMAPHORE by N. If there are threads waiting +on this semaphore, then N of them is woken up." + (declare (type (integer 1) n)) + ;; Need to disable interrupts so that we don't lose a wakeup after we have + ;; incremented the count. + (with-system-mutex ((semaphore-mutex semaphore)) + (let ((waitcount (semaphore-waitcount semaphore)) + (count (incf (semaphore-%count semaphore) n))) + (when (plusp waitcount) + (condition-notify (semaphore-queue semaphore) (min waitcount count)))))) + +;;;; 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. At the same time we need to allow interrupts while +;;; *waiting* for the session lock for things like GET-FOREGROUND +;;; to be interruptible. +;;; +;;; Take care: we sometimes need to obtain the session lock while holding +;;; on to *ALL-THREADS-LOCK*, so we must _never_ obtain it _after_ getting +;;; a session lock! (Deadlock risk.) +;;; +;;; FIXME: It would be good to have ordered locks to ensure invariants like +;;; the above. +(defmacro with-session-lock ((session) &body body) + `(with-system-mutex ((session-lock ,session) :allow-with-interrupts t) + ,@body)) + +(defun new-session () + (make-session :threads (list *current-thread*) + :interactive-threads (list *current-thread*))) + +(defun init-job-control () + (/show0 "Entering INIT-JOB-CONTROL") + (setf *session* (new-session)) + (/show0 "Exiting INIT-JOB-CONTROL")) + +(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) + (/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) + (setf (thread-os-thread thread) nil) + (setq *all-threads* (delete thread *all-threads*)) + (when *session* + (%delete-thread-from-session thread *session*))) + #!+sb-lutex + (without-gcing + (/show0 "FREEING MUTEX LUTEX") + (with-lutex-address (lutex (mutex-lutex (thread-interruptions-lock thread))) + (%lutex-destroy lutex)))) + +(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 + (/show0 "Looping in GET-FOREGROUND") + (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*) + (when (rest (session-interactive-threads *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* + (make-fd-stream in :input t :buffering :line + :dual-channel-p t)) + (sb!impl::*stdout* + (make-fd-stream out :output t :buffering :line + :dual-channel-p t)) + (sb!impl::*stderr* + (make-fd-stream err :output t :buffering :line + :dual-channel-p t)) + (sb!impl::*tty* + (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. The return values of FUNCTION are kept +around and can be retrieved by JOIN-THREAD." + #!-sb-thread (declare (ignore function name)) + #!-sb-thread (error "Not supported in unithread builds.") + #!+sb-thread + (let* ((thread (%make-thread :name name)) + (setup-sem (make-semaphore :name "Thread setup semaphore")) + (real-function (coerce function 'function)) + (initial-function + (lambda () + ;; In time we'll move some of the binding presently done in C + ;; here too. + ;; + ;; KLUDGE: Here we have a magic list of variables that are + ;; not thread-safe for one reason or another. As people + ;; report problems with the thread safety of certain + ;; variables, (e.g. "*print-case* in multiple threads + ;; broken", sbcl-devel 2006-07-14), we add a few more + ;; bindings here. The Right Thing is probably some variant + ;; of Allegro's *cl-default-special-bindings*, as that is at + ;; least accessible to users to secure their own libraries. + ;; --njf, 2006-07-15 + (let* ((*current-thread* thread) + (*restart-clusters* nil) + (*handler-clusters* (sb!kernel::initial-handler-clusters)) + (*condition-restarts* nil) + (sb!impl::*deadline* nil) + (sb!impl::*step-out* nil) + ;; 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 + (setf sb!vm:*alloc-signal* *default-alloc-signal*) + (setf (thread-os-thread thread) (current-thread-os-thread)) + (with-mutex ((thread-result-lock thread)) + (with-all-threads-lock + (push thread *all-threads*)) + (with-session-lock (*session*) + (push thread (session-threads *session*))) + (setf (thread-%alive-p thread) t) + (signal-semaphore setup-sem) + ;; 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) + (catch 'sb!impl::toplevel-catcher + (catch 'sb!impl::%end-of-the-world + (with-simple-restart + (terminate-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))))))) + (values)))) + ;; 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.") + +(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)) + (cond ((car (thread-result thread)) + (values-list (cdr (thread-result thread)))) + (defaultp + default) + (t + (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. +(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. +(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 + (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))))))) + +(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)) + +(define-alien-routine "thread_yield" int) + +#!+sb-doc +(setf (fdocumentation 'thread-yield 'function) + "Yield the processor to other threads.") + +;;; internal use only. If you think you need to use these, 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 +(progn + (defun %thread-sap (thread) + (let ((thread-sap (alien-sap (extern-alien "all_threads" (* t)))) + (target (thread-os-thread thread))) + (loop + (when (sap= thread-sap (int-sap 0)) (return nil)) + (let ((os-thread (sap-ref-word thread-sap + (* sb!vm:n-word-bytes + sb!vm::thread-os-thread-slot)))) + (when (= os-thread target) (return thread-sap)) + (setf thread-sap + (sap-ref-sap thread-sap (* sb!vm:n-word-bytes + 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))) + + (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)))) + +(defun sb!vm::locked-symbol-global-value-add (symbol-name delta) + (sb!vm::locked-symbol-global-value-add symbol-name delta)) + +;;; Stepping + +(defun thread-stepping () + (make-lisp-obj + (sap-ref-word (current-thread-sap) + (* sb!vm::thread-stepping-slot sb!vm:n-word-bytes)))) + +(defun (setf thread-stepping) (value) + (setf (sap-ref-word (current-thread-sap) + (* sb!vm::thread-stepping-slot sb!vm:n-word-bytes)) + (get-lisp-obj-address value)))