(in-package "SB!THREAD")
+;;; 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
+
(sb!alien::define-alien-routine ("create_thread" %create-thread)
sb!alien:unsigned-long
(lisp-fun-address sb!alien:unsigned-long))
+(sb!alien::define-alien-routine "signal_thread_to_dequeue"
+ sb!alien:unsigned-int
+ (thread-pid sb!alien:unsigned-long))
+
+
(defun make-thread (function)
(let ((real-function (coerce function 'function)))
(%create-thread
;;;; the higher-level locking operations are based on waitqueues
+(declaim (inline waitqueue-data-address mutex-value-address))
+
(defstruct waitqueue
(name nil :type (or null simple-base-string))
(lock 0)
(data nil))
+;;; The bare 4 here and 5 below are offsets of the slots in the struct.
+;;; There ought to be some better way to get these numbers
+(defun waitqueue-data-address (lock)
+ (declare (optimize (speed 3)))
+ (sb!ext:truly-the
+ (unsigned-byte 32)
+ (+ (sb!kernel:get-lisp-obj-address lock)
+ (- (* 4 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag))))
+
(defstruct (mutex (:include waitqueue))
(value nil))
+(defun mutex-value-address (lock)
+ (declare (optimize (speed 3)))
+ (sb!ext:truly-the
+ (unsigned-byte 32)
+ (+ (sb!kernel:get-lisp-obj-address lock)
+ (- (* 5 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag))))
+
(sb!alien:define-alien-routine "block_sigcont" void)
(sb!alien:define-alien-routine "unblock_sigcont_and_sleep" void)
+#!+sb-futex
+(declaim (inline futex-wait futex-wake))
+#!+sb-futex
+(sb!alien:define-alien-routine
+ "futex_wait" int (word unsigned-long) (old-value unsigned-long))
+#!+sb-futex
+(sb!alien:define-alien-routine
+ "futex_wake" int (word unsigned-long) (n unsigned-long))
;;; this should only be called while holding the queue spinlock.
;;; it releases the spinlock before sleeping
;;; 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))))
+ (when p (signal-thread-to-dequeue p))))
;;;; mutex
+;;; i suspect there may be a race still in this: the futex version requires
+;;; the old mutex value before sleeping, so how do we get away without it
(defun get-mutex (lock &optional new-value (wait-p t))
- (declare (type mutex lock)
- (optimize (speed 3)))
+ (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))))
(return nil))
(wait-on-queue lock nil))))
+#!+sb-futex
+(defun get-mutex/futex (lock &optional new-value (wait-p t))
+ (declare (type mutex lock) (optimize (speed 3)))
+ (let ((pid (current-thread-id))
+ old)
+ (unless new-value (setf new-value pid))
+ (assert (not (eql new-value (mutex-value lock))))
+ (loop
+ (unless
+ (setf old (sb!vm::%instance-set-conditional lock 4 nil new-value))
+ (return t))
+ (unless wait-p (return nil))
+ (futex-wait (mutex-value-address lock)
+ (sb!kernel:get-lisp-obj-address old)))))
+
(defun release-mutex (lock &optional (new-value nil))
(declare (type mutex lock))
;; we assume the lock is ours to release
(setf (mutex-value lock) new-value)
(signal-queue-head lock)))
+#!+sb-futex
+(defun release-mutex/futex (lock)
+ (declare (type mutex lock))
+ (setf (mutex-value lock) nil)
+ (futex-wake (mutex-value-address lock) 1))
+
(defmacro with-mutex ((mutex &key value (wait-p t)) &body body)
(with-unique-names (got)
(dequeue queue))
(get-mutex lock value))))
+#!+sb-futex
+(defun condition-wait/futex (queue lock)
+ (assert lock)
+ (let ((value (mutex-value lock)))
+ (unwind-protect
+ (let ((me (current-thread-id)))
+ ;; XXX we should do something to ensure that the result of this setf
+ ;; is visible to all CPUs
+ (setf (waitqueue-data queue) me)
+ (release-mutex lock)
+ ;; Now we go to sleep using futex-wait. If anyone else
+ ;; manages to grab LOCK and call CONDITION-NOTIFY during
+ ;; this comment, it will change queue->data, and so
+ ;; futex-wait returns immediately instead of sleeping.
+ ;; Ergo, no lost wakeup
+ (futex-wait (waitqueue-data-address queue)
+ (sb!kernel:get-lisp-obj-address me)))
+ ;; If we are interrupted while waiting, we should do these things
+ ;; before returning. Ideally, in the case of an unhandled signal,
+ ;; we should do them before entering the debugger, but this is
+ ;; better than nothing.
+ (get-mutex lock value))))
+
+
(defun condition-notify (queue)
"Notify one of the processes waiting on QUEUE"
(with-spinlock (queue) (signal-queue-head queue)))
+#!+sb-futex
+(defun condition-notify/futex (queue)
+ "Notify one of the processes waiting on QUEUE."
+ (let ((me (current-thread-id)))
+ ;; no problem if >1 thread notifies during the comment in
+ ;; condition-wait: as long as the value in queue-data isn't the
+ ;; waiting thread's id, it matters not what it is
+ ;; XXX we should do something to ensure that the result of this setf
+ ;; is visible to all CPUs
+ (setf (waitqueue-data queue) me)
+ (futex-wake (waitqueue-data-address queue) 1)))
+
+#!+sb-futex
+(defun condition-broadcast/futex (queue)
+ (let ((me (current-thread-id)))
+ (setf (waitqueue-data queue) me)
+ (futex-wake (waitqueue-data-address queue) (ash 1 30))))
+
+(defun condition-broadcast (queue)
+ "Notify all of the processes waiting on QUEUE."
+ (with-spinlock (queue)
+ (map nil #'signal-thread-to-dequeue (waitqueue-data queue))))
+
+;;; Futexes may be available at compile time but not runtime, so we
+;;; default to not using them unless os_init says they're available
+(defun maybe-install-futex-functions ()
+ #!+sb-futex
+ (unless (zerop (extern-alien "linux_supports_futex" int))
+ (setf (fdefinition 'get-mutex) #'get-mutex/futex
+ (fdefinition 'release-mutex) #'release-mutex/futex
+ (fdefinition 'condition-wait) #'condition-wait/futex
+ (fdefinition 'condition-broadcast) #'condition-broadcast/futex
+ (fdefinition 'condition-notify) #'condition-notify/futex)
+ t))
;;;; multiple independent listeners
;;;; job control
-(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
+
+(defvar *interactive-threads-lock*
+ (make-mutex :name "*interactive-threads* lock"))
+(defvar *interactive-threads* nil)
+(defvar *interactive-threads-queue*
+ (make-waitqueue :name "All threads that need the terminal. First ID on this list is running, the others are waiting"))
+
+(defun init-job-control ()
+ (with-mutex (*interactive-threads-lock*)
+ (setf *interactive-threads* (list (current-thread-id)))
+ (return-from init-job-control t)))
;;; 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."
+ (prog1
+ (with-mutex (*interactive-threads-lock*)
+ (not (member (current-thread-id) *interactive-threads*)))
+ (get-foreground)))
+(defun thread-repl-prompt-fun (out-stream)
+ (get-foreground)
+ (let ((stopped-threads (cdr *interactive-threads*)))
+ (when stopped-threads
+ (format out-stream "~{~&Thread ~A suspended~}~%" stopped-threads))
+ (sb!impl::repl-prompt-fun out-stream)))
+
+(defun get-foreground ()
+ (loop
+ (with-mutex (*interactive-threads-lock*)
+ (let ((tid (current-thread-id)))
+ (when (eql (car *interactive-threads*) tid)
+ (sb!sys:enable-interrupt sb!unix:sigint #'sb!unix::sigint-handler)
+ (return-from get-foreground t))
+ (unless (member tid *interactive-threads*)
+ (setf (cdr (last *interactive-threads*)) (list tid)))
+ (condition-wait
+ *interactive-threads-queue* *interactive-threads-lock* )))))
+
+(defun release-foreground (&optional next)
+ "Background this thread. If NEXT is supplied, arrange for it to have the foreground next"
+ (with-mutex (*interactive-threads-lock*)
+ (let ((tid (current-thread-id)))
+ (setf *interactive-threads* (delete tid *interactive-threads*))
+ (sb!sys:enable-interrupt sb!unix:sigint :ignore)
+ (when next (setf *interactive-threads*
+ (list* next (delete next *interactive-threads*))))
+ (condition-broadcast *interactive-threads-queue*))))
\ No newline at end of file
projects / sbcl.git / blobdiff