+;;;; support for threads in the target machine
+
+;;;; This software is part of the SBCL system. See the README file for
+;;;; more information.
+;;;;
+;;;; This software is derived from the CMU CL system, which was
+;;;; written at Carnegie Mellon University and released into the
+;;;; public domain. The software is in the public domain and is
+;;;; provided with absolutely no warranty. See the COPYING and CREDITS
+;;;; files for more information.
+
(in-package "SB!THREAD")
-(sb!alien::define-alien-routine ("create_thread" %create-thread)
- sb!alien:unsigned-long
- (lisp-fun-address sb!alien:unsigned-long))
-
-(defun make-thread (function)
- (let ((real-function (coerce function 'function)))
- (%create-thread
- (sb!kernel:get-lisp-obj-address
- (lambda ()
- ;; in time we'll move some of the binding presently done in C
- ;; here too
- (let ((sb!kernel::*restart-clusters* nil)
- (sb!impl::*descriptor-handlers* nil); serve-event
- (sb!impl::*available-buffers* nil)) ;for fd-stream
- ;; can't use handling-end-of-the-world, because that flushes
- ;; output streams, and we don't necessarily have any (or we
- ;; could be sharing them)
- (sb!sys:enable-interrupt sb!unix:sigint :ignore)
- (sb!unix:unix-exit
- (catch 'sb!impl::%end-of-the-world
- (with-simple-restart
- (destroy-thread
- (format nil "~~@<Destroy this thread (~A)~~@:>"
- (current-thread-id)))
- (funcall real-function))
- 0))))))))
-
-;;; Really, you don't want to use these: they'll get into trouble with
-;;; garbage collection. Use a lock or a waitqueue instead
-(defun suspend-thread (thread-id)
- (sb!unix:unix-kill thread-id sb!unix:sigstop))
-(defun resume-thread (thread-id)
- (sb!unix:unix-kill thread-id sb!unix:sigcont))
-;;; Note warning about cleanup forms
-(defun destroy-thread (thread-id)
- "Destroy the thread identified by THREAD-ID abruptly, without running cleanup forms"
- (sb!unix:unix-kill thread-id sb!unix:sigterm)
- ;; may have been stopped for some reason, so now wake it up to
- ;; deliver the TERM
- (sb!unix:unix-kill thread-id sb!unix:sigcont))
-
-
-;;; a moderate degree of care is expected for use of interrupt-thread,
-;;; due to its nature: if you interrupt a thread that was holding
-;;; important locks then do something that turns out to need those
-;;; locks, you probably won't like the effect. Used with thought
-;;; though, it's a good deal gentler than the last-resort functions above
+;;; 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.
-(defun interrupt-thread (thread function)
- "Interrupt THREAD and make it run FUNCTION. "
- (sb!unix::syscall* ("interrupt_thread"
- sb!alien:unsigned-long sb!alien:unsigned-long)
- thread
- thread (sb!kernel:get-lisp-obj-address
- (coerce function 'function))))
-(defun terminate-thread (thread-id)
- "Terminate the thread identified by THREAD-ID, by causing it to run
-SB-EXT:QUIT - the usual cleanup forms will be evaluated"
- (interrupt-thread thread-id 'sb!ext:quit))
+;;; 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
+ %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)
+ (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)
+ #!+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
+;; all running threads.
+(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 ()
+ #!+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-os-thread))
+(defun current-thread-os-thread ()
+ #!+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")
+ (let ((initial-thread (%make-thread :name "initial thread"
+ :%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))))
+\f
+
+;;;; Aliens, low level stuff
+
+#!+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))
-(declaim (inline current-thread-id))
-(defun current-thread-id ()
- (logand
- (sb!sys:sap-int
- (sb!vm::current-thread-offset-sap sb!vm::thread-pid-slot))
- ;; KLUDGE pids are 16 bit really. Avoid boxing the return value
- (1- (ash 1 16))))
+ ;; 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))))
-;;;; iterate over the in-memory threads
+ (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))))
-(defun mapcar-threads (function)
- "Call FUNCTION once for each known thread, giving it the thread structure as argument"
- (let ((function (coerce function 'function)))
- (loop for thread = (alien-sap (extern-alien "all_threads" (* t)))
- then (sb!sys:sap-ref-sap thread (* 4 sb!vm::thread-next-slot))
- until (sb!sys:sap= thread (sb!sys:int-sap 0))
- collect (funcall function thread))))
+ #!-sb-lutex
+ (progn
+ (declaim (inline futex-wait %futex-wait futex-wake))
-;;;; queues, locks
+ (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))
+\f
+
+;;;; Spinlocks
-;; spinlocks use 0 as "free" value: higher-level locks use NIL
(declaim (inline get-spinlock release-spinlock))
-(defun get-spinlock (lock offset new-value)
+;;; Should always be called with interrupts disabled.
+(defun get-spinlock (spinlock)
(declare (optimize (speed 3) (safety 0)))
- (loop until
- (eql (sb!vm::%instance-set-conditional lock offset 0 new-value) 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 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))
+ (loop (cas)))))
+ t))
-;; this should do nothing if we didn't own the lock, so safe to use in
-;; unwind-protect cleanups when lock acquisition failed for some reason
-(defun release-spinlock (lock offset our-value)
+(defun release-spinlock (spinlock)
(declare (optimize (speed 3) (safety 0)))
- (sb!vm::%instance-set-conditional lock offset our-value 0))
+ ;; On x86 and x86-64 we can get away with no memory barriers, (see
+ ;; Linux kernel mailing list "spin_unlock optimization(i386)"
+ ;; thread, summary at
+ ;; http://kt.iserv.nl/kernel-traffic/kt19991220_47.html#1.
+ ;;
+ ;; If the compiler may reorder this with other instructions, insert
+ ;; compiler barrier here.
+ ;;
+ ;; FIXME: this does not work on SMP Pentium Pro and OOSTORE systems,
+ ;; neither on most non-x86 architectures (but we don't have threads
+ ;; on those).
+ (setf (spinlock-value spinlock) nil))
+\f
+
+;;;; 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 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
+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 ...))
+ ...)
-(defmacro with-spinlock ((queue) &body body)
- (with-unique-names (pid)
- `(let ((,pid (current-thread-id)))
- (unwind-protect
- (progn
- (get-spinlock ,queue 2 ,pid)
- ,@body)
- (release-spinlock ,queue 2 ,pid)))))
+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*))
+ (let ((old (mutex-%owner mutex)))
+ (when (eq new-owner old)
+ (error "Recursive lock attempt ~S." mutex))
+ #!-sb-thread
+ (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
+ ;; 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
+ ;; This is a direct tranlation 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+)))
+ (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."))))))
-;;;; the higher-level locking operations are based on waitqueues
+(defun release-mutex (mutex)
+ #!+sb-doc
+ "Release MUTEX by setting it to NIL. Wake up threads waiting for
+this mutex.
-(defstruct waitqueue
- (name nil :type (or null simple-base-string))
- (lock 0)
+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."
+ (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))
+\f
+
+;;;; 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))
-(defstruct (mutex (:include waitqueue))
- (value nil))
-
-(sb!alien:define-alien-routine "block_sigcont" void)
-(sb!alien:define-alien-routine "unblock_sigcont_and_sleep" void)
-
-
-;;; this should only be called while holding the queue spinlock.
-;;; it releases the spinlock before sleeping
-(defun wait-on-queue (queue &optional lock)
- (let ((pid (current-thread-id)))
- (block-sigcont)
- (when lock (release-mutex lock))
- (sb!sys:without-interrupts
- (pushnew pid (waitqueue-data queue)))
- (setf (waitqueue-lock queue) 0)
- (unblock-sigcont-and-sleep)))
-
-;;; this should only be called while holding the queue spinlock. It doesn't
-;;; release it
-(defun dequeue (queue)
- (let ((pid (current-thread-id)))
- (sb!sys:without-interrupts
- (setf (waitqueue-data queue)
- (delete pid (waitqueue-data queue))))))
-
-;;; this should only be called while holding the queue spinlock.
-(defun signal-queue-head (queue)
- (let ((p (car (waitqueue-data queue))))
- (when p (sb!unix:unix-kill p sb!unix::sig-dequeue))))
-
-;;;; mutex
-
-(defun get-mutex (lock &optional new-value (wait-p t))
- (declare (type mutex lock)
- (optimize (speed 3)))
- (let ((pid (current-thread-id)))
- (unless new-value (setf new-value pid))
- (assert (not (eql new-value (mutex-value lock))))
- (get-spinlock lock 2 pid)
- (loop
- (unless
- ;; args are object slot-num old-value new-value
- (sb!vm::%instance-set-conditional lock 4 nil new-value)
- (dequeue lock)
- (setf (waitqueue-lock lock) 0)
- (return t))
- (unless wait-p
- (setf (waitqueue-lock lock) 0)
- (return nil))
- (wait-on-queue lock nil))))
-
-(defun release-mutex (lock &optional (new-value nil))
- (declare (type mutex lock))
- ;; we assume the lock is ours to release
- (with-spinlock (lock)
- (setf (mutex-value lock) new-value)
- (signal-queue-head lock)))
-
-
-(defmacro with-mutex ((mutex &key value (wait-p t)) &body body)
- (with-unique-names (got)
- `(let ((,got (get-mutex ,mutex ,value ,wait-p)))
- (when ,got
- (unwind-protect
- (progn ,@body)
- (release-mutex ,mutex))))))
-
-
-;;;; condition variables
-
-(defun condition-wait (queue lock)
- "Atomically release LOCK and enqueue ourselves on QUEUE. Another
+(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 LOCK and return to the caller."
- (assert lock)
- (let ((value (mutex-value lock)))
- (unwind-protect
- (progn
- (get-spinlock queue 2 (current-thread-id))
- (wait-on-queue queue lock))
- ;; If we are interrupted while waiting, we should do these things
- ;; before returning. Ideally, in the case of an unhandled signal,
- ;; we should do them before entering the debugger, but this is
- ;; better than nothing.
- (with-spinlock (queue)
- (dequeue queue))
- (get-mutex lock value))))
-
-(defun condition-notify (queue)
- "Notify one of the processes waiting on QUEUE"
- (with-spinlock (queue) (signal-queue-head queue)))
-
-
-;;;; multiple independent listeners
-
-(defvar *session-lock* nil)
-
-(defun make-listener-thread (tty-name)
- (assert (probe-file tty-name))
- ;; FIXME probably still need to do some tty stuff to get signals
- ;; delivered correctly.
- ;; FIXME
- (let* ((in (sb!unix:unix-open (namestring tty-name) sb!unix:o_rdwr #o666))
- (out (sb!unix:unix-dup in))
- (err (sb!unix:unix-dup in)))
- (labels ((thread-repl ()
- (sb!unix::unix-setsid)
- (let* ((*session-lock*
- (make-mutex :name (format nil "lock for ~A" tty-name)))
- (sb!impl::*stdin*
- (sb!sys:make-fd-stream in :input t :buffering :line))
- (sb!impl::*stdout*
- (sb!sys:make-fd-stream out :output t :buffering :line))
- (sb!impl::*stderr*
- (sb!sys:make-fd-stream err :output t :buffering :line))
- (sb!impl::*tty*
- (sb!sys:make-fd-stream err :input t :output t :buffering :line))
- (sb!impl::*descriptor-handlers* nil))
- (get-mutex *session-lock*)
- (sb!sys:enable-interrupt sb!unix:sigint #'sb!unix::sigint-handler)
- (unwind-protect
- (sb!impl::toplevel-repl nil)
- (sb!int:flush-standard-output-streams)))))
- (make-thread #'thread-repl))))
-
-;;;; job control
+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*))
+ ;; 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)))))
+
+(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
+this call."
+ #!-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))))))
-(defvar *background-threads-wait-for-debugger* t)
-;;; may be T, NIL, or a function called with a stream and thread id
-;;; as its two arguments, returning NIl or T
+(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)))
+\f
+
+;;;; 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))))))
+\f
+
+;;;; 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")
+ ;; 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
-already the foreground thread, or transfers control to the first applicable
-restart if *BACKGROUND-THREADS-WAIT-FOR-DEBUGGER* says to do that instead"
- (let* ((wait-p *background-threads-wait-for-debugger*)
- (*background-threads-wait-for-debugger* nil)
- (lock *session-lock*))
- (when (not (eql (mutex-value lock) (CURRENT-THREAD-ID)))
- (when (functionp wait-p)
- (setf wait-p
- (funcall wait-p stream (CURRENT-THREAD-ID))))
- (cond (wait-p (get-foreground))
- (t (invoke-restart (car (compute-restarts))))))))
-
-;;; install this with
-;;; (setf SB-INT:*REPL-PROMPT-FUN* #'sb-thread::thread-repl-prompt-fun)
-;;; One day it will be default
-(defun thread-repl-prompt-fun (out-stream)
- (let ((lock *session-lock*))
- (get-foreground)
- (let ((stopped-threads (waitqueue-data lock)))
- (when stopped-threads
- (format out-stream "~{~&Thread ~A suspended~}~%" stopped-threads))
- (sb!impl::repl-prompt-fun out-stream))))
-
-(defun resume-stopped-thread (id)
- (let ((lock *session-lock*))
- (with-spinlock (lock)
- (setf (waitqueue-data lock)
- (cons id (delete id (waitqueue-data lock)))))
- (release-foreground)))
-
-(defstruct rwlock
- (name nil :type (or null simple-base-string))
- (value 0 :type fixnum)
- (max-readers nil :type (or fixnum null))
- (max-writers 1 :type fixnum))
-#+nil
-(macrolet
- ((make-rwlocking-function (lock-fn unlock-fn increment limit test)
- (let ((do-update '(when (eql old-value
- (sb!vm::%instance-set-conditional
- lock 2 old-value new-value))
- (return (values t old-value))))
- (vars `((timeout (and timeout (+ (get-internal-real-time) timeout)))
- old-value
- new-value
- (limit ,limit))))
- (labels ((do-setfs (v) `(setf old-value (rwlock-value lock)
- new-value (,v old-value ,increment))))
- `(progn
- (defun ,lock-fn (lock timeout)
- (declare (type rwlock lock))
- (let ,vars
- (loop
- ,(do-setfs '+)
- (when ,test
- ,do-update)
- (when (sleep-a-bit timeout) (return nil)) ;expired
- )))
- ;; unlock doesn't need timeout or test-in-range
- (defun ,unlock-fn (lock)
- (declare (type rwlock lock))
- (declare (ignorable limit))
- (let ,(cdr vars)
- (loop
- ,(do-setfs '-)
- ,do-update))))))))
-
- (make-rwlocking-function %lock-for-reading %unlock-for-reading 1
- (rwlock-max-readers lock)
- (and (>= old-value 0)
- (or (null limit) (<= new-value limit))))
- (make-rwlocking-function %lock-for-writing %unlock-for-writing -1
- (- (rwlock-max-writers lock))
- (and (<= old-value 0)
- (>= new-value limit))))
-#+nil
-(defun get-rwlock (lock direction &optional timeout)
- (ecase direction
- (:read (%lock-for-reading lock timeout))
- (:write (%lock-for-writing lock timeout))))
-#+nil
-(defun free-rwlock (lock direction)
- (ecase direction
- (:read (%unlock-for-reading lock))
- (:write (%unlock-for-writing lock))))
-
-;;;; beyond this point all is commented.
-
-;;; Lock-Wait-With-Timeout -- Internal
-;;;
-;;; Wait with a timeout for the lock to be free and acquire it for the
-;;; *current-process*.
-;;;
-#+nil
-(defun lock-wait-with-timeout (lock whostate timeout)
- (declare (type lock lock))
- (process-wait-with-timeout
- whostate timeout
- #'(lambda ()
- (declare (optimize (speed 3)))
- #-i486
- (unless (lock-process lock)
- (setf (lock-process lock) *current-process*))
- #+i486
- (null (kernel:%instance-set-conditional
- lock 2 nil *current-process*)))))
-
-;;; With-Lock-Held -- Public
-;;;
-#+nil
-(defmacro with-lock-held ((lock &optional (whostate "Lock Wait")
- &key (wait t) timeout)
- &body body)
- "Execute the body with the lock held. If the lock is held by another
- process then the current process waits until the lock is released or
- an optional timeout is reached. The optional wait timeout is a time in
- seconds acceptable to process-wait-with-timeout. The results of the
- body are return upon success and NIL is return if the timeout is
- reached. When the wait key is NIL and the lock is held by another
- process then NIL is return immediately without processing the body."
- (let ((have-lock (gensym)))
- `(let ((,have-lock (eq (lock-process ,lock) *current-process*)))
- (unwind-protect
- ,(cond ((and timeout wait)
- `(progn
- (when (and (error-check-lock-p ,lock) ,have-lock)
- (error "Dead lock"))
- (when (or ,have-lock
- #+i486 (null (kernel:%instance-set-conditional
- ,lock 2 nil *current-process*))
- #-i486 (seize-lock ,lock)
- (if ,timeout
- (lock-wait-with-timeout
- ,lock ,whostate ,timeout)
- (lock-wait ,lock ,whostate)))
- ,@body)))
- (wait
- `(progn
- (when (and (error-check-lock-p ,lock) ,have-lock)
- (error "Dead lock"))
- (unless (or ,have-lock
- #+i486 (null (kernel:%instance-set-conditional
- ,lock 2 nil *current-process*))
- #-i486 (seize-lock ,lock))
- (lock-wait ,lock ,whostate))
- ,@body))
- (t
- `(when (or (and (recursive-lock-p ,lock) ,have-lock)
- #+i486 (null (kernel:%instance-set-conditional
- ,lock 2 nil *current-process*))
- #-i486 (seize-lock ,lock))
- ,@body)))
- (unless ,have-lock
- #+i486 (kernel:%instance-set-conditional
- ,lock 2 *current-process* nil)
- #-i486 (when (eq (lock-process ,lock) *current-process*)
- (setf (lock-process ,lock) nil)))))))
+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))))
+\f
+
+;;;; 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
+ ;;
+ ;; 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))
+ (*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
+ "~~@<Terminate this thread (~A)~~@:>"
+ *current-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. 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)))))
+
+(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-system-mutex ((thread-result-lock thread) :allow-with-interrupts t)
+ (cond ((car (thread-result thread))
+ (return-from join-thread
+ (values-list (cdr (thread-result thread)))))
+ (defaultp
+ (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.
+(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.
+(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))
+\f
+;;;; 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)))
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