;;; set the doc here because in early-thread FDOCUMENTATION is not
;;; available, yet
#!+sb-doc
-(setf (sb!kernel:fdocumentation '*current-thread* 'variable)
+(setf (fdocumentation '*current-thread* 'variable)
"Bound in each thread to the thread itself.")
(defstruct (thread (:constructor %make-thread))
(result-lock (make-mutex :name "thread result lock")))
#!+sb-doc
-(setf (sb!kernel:fdocumentation 'thread-name 'function)
+(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)
+ (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
(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)
- #!-sb-thread
- `(locally ,@body)
- #!+sb-thread
- `(without-interrupts
- (with-mutex (*all-threads-lock*)
- ,@body)))
+ `(with-system-mutex (*all-threads-lock*)
+ ,@body))
(defun list-all-threads ()
#!+sb-doc
(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 ()
- (sap-int
- (sb!vm::current-thread-offset-sap sb!vm::thread-os-thread-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-sap-id))))
+ :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
+
+(define-alien-routine "kill_safely"
+ integer
+ (os-thread #!-alpha unsigned-long #!+alpha unsigned-int)
+ (signal int))
#!+sb-thread
(progn
(define-alien-routine ("create_thread" %create-thread)
unsigned-long (lisp-fun-address unsigned-long))
- (define-alien-routine "signal_interrupt_thread"
- integer (os-thread unsigned-long))
+ (declaim (inline %block-deferrable-signals))
+ (define-alien-routine ("block_deferrable_signals" %block-deferrable-signals)
+ void
+ (where sb!alien:unsigned-long)
+ (old sb!alien:unsigned-long))
- (define-alien-routine "block_deferrable_signals"
- void)
+ (defun block-deferrable-signals ()
+ (%block-deferrable-signals 0 0))
#!+sb-lutex
(progn
(declaim (inline %lutex-init %lutex-wait %lutex-wake
%lutex-lock %lutex-unlock))
- (sb!alien:define-alien-routine ("lutex_init" %lutex-init)
+ (define-alien-routine ("lutex_init" %lutex-init)
int (lutex unsigned-long))
- (sb!alien:define-alien-routine ("lutex_wait" %lutex-wait)
+ (define-alien-routine ("lutex_wait" %lutex-wait)
int (queue-lutex unsigned-long) (mutex-lutex unsigned-long))
- (sb!alien:define-alien-routine ("lutex_wake" %lutex-wake)
+ (define-alien-routine ("lutex_wake" %lutex-wake)
int (lutex unsigned-long) (n int))
- (sb!alien:define-alien-routine ("lutex_lock" %lutex-lock)
+ (define-alien-routine ("lutex_lock" %lutex-lock)
int (lutex unsigned-long))
- (sb!alien:define-alien-routine ("lutex_trylock" %lutex-trylock)
+ (define-alien-routine ("lutex_trylock" %lutex-trylock)
int (lutex unsigned-long))
- (sb!alien:define-alien-routine ("lutex_unlock" %lutex-unlock)
+ (define-alien-routine ("lutex_unlock" %lutex-unlock)
int (lutex unsigned-long))
- (sb!alien:define-alien-routine ("lutex_destroy" %lutex-destroy)
+ (define-alien-routine ("lutex_destroy" %lutex-destroy)
int (lutex unsigned-long))
;; FIXME: Defining a whole bunch of alien-type machinery just for
(defmacro with-lutex-address ((name lutex) &body body)
`(let ((,name ,lutex))
(with-pinned-objects (,name)
- (let ((,name (sb!kernel:get-lisp-obj-address ,name)))
+ (let ((,name (get-lisp-obj-address ,name)))
,@body))))
(defun make-lutex ()
#!-sb-lutex
(progn
- (declaim (inline futex-wait futex-wake))
+ (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))
- (sb!alien:define-alien-routine "futex_wait"
- int (word unsigned-long) (old-value unsigned-long))
+ (defun futex-wait (word old to-sec to-usec)
+ (with-interrupts
+ (%futex-wait word old to-sec to-usec)))
- (sb!alien:define-alien-routine "futex_wake"
+ (define-alien-routine "futex_wake"
int (word unsigned-long) (n unsigned-long))))
;;; used by debug-int.lisp to access interrupt contexts
(defun sb!vm::current-thread-offset-sap (n)
(declare (type (unsigned-byte 27) n))
(sb!vm::current-thread-offset-sap n))
+\f
-;;;; spinlocks
+;;;; Spinlocks
(declaim (inline get-spinlock release-spinlock))
-;;; The bare 2 here and below are offsets of the slots in the struct.
-;;; There ought to be some better way to get these numbers
+;;; Should always be called with interrupts disabled.
(defun get-spinlock (spinlock)
- (declare (optimize (speed 3) (safety 0))
- #!-sb-thread
- (ignore spinlock new-value))
- ;; %instance-set-conditional can test for 0 (which is a fixnum) and
- ;; store any value
- #!+sb-thread
- (loop until
- (eql (sb!vm::%instance-set-conditional spinlock 2 0 1) 0)))
+ (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 disabled, but we are allowed to
+ ;; enabled them, check for pending interrupts every once
+ ;; in a while. %CHECK-INTERRUPTS is taking shortcuts, make
+ ;; sure that deferrables are unblocked by doing an empty
+ ;; WITH-INTERRUPTS once.
+ (progn
+ (with-interrupts)
+ (loop
+ (loop repeat 128 do (cas)) ; 128 is arbitrary here
+ (sb!unix::%check-interrupts)))
+ (loop (cas)))))
+ t))
(defun release-spinlock (spinlock)
- (declare (optimize (speed 3) (safety 0))
- #!-sb-thread (ignore spinlock))
- ;; %instance-set-conditional cannot compare arbitrary objects
- ;; meaningfully, so
- ;; (sb!vm::%instance-set-conditional spinlock 2 our-value 0)
- ;; does not work for bignum thread ids.
- #!+sb-thread
- (sb!vm::%instance-set spinlock 2 0))
-
-(defmacro with-spinlock ((spinlock) &body body)
- (sb!int:with-unique-names (lock)
- `(let ((,lock ,spinlock))
- (get-spinlock ,lock)
- (unwind-protect
- (progn ,@body)
- (release-spinlock ,lock)))))
-
-;;;; mutexes
+ (declare (optimize (speed 3) (safety 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 (sb!kernel:fdocumentation 'make-mutex 'function)
+(setf (fdocumentation 'make-mutex 'function)
"Create a mutex."
- (sb!kernel:fdocumentation 'mutex-name 'function)
- "The name of the mutex. Setfable."
- (sb!kernel:fdocumentation 'mutex-value 'function)
- "The value of the mutex. NIL if the mutex is free. Setfable.")
+ (fdocumentation 'mutex-name 'function)
+ "The name of the mutex. Setfable.")
#!+(and sb-thread (not sb-lutex))
(progn
- (declaim (inline mutex-value-address))
- (defun mutex-value-address (mutex)
- (declare (optimize (speed 3)))
- (sb!ext:truly-the
- sb!vm:word
- (+ (sb!kernel:get-lisp-obj-address mutex)
- (- (* 3 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag)))))
-
-(defun get-mutex (mutex &optional (new-value *current-thread*) (wait-p t))
+ (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, setting it to NEW-VALUE or some suitable default
-value if NIL. If WAIT-P is non-NIL and the mutex is in use, sleep
-until it is available"
- (declare (type mutex mutex) (optimize (speed 3)))
- (/show0 "Entering GET-MUTEX")
- (unless new-value
- (setq new-value *current-thread*))
+ "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*))
+ (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
- (let ((old-value (mutex-value mutex)))
- (when (and old-value wait-p)
- (error "In unithread mode, mutex ~S was requested with WAIT-P ~S and ~
- new-value ~S, but has already been acquired (with value ~S)."
- mutex wait-p new-value old-value))
- (setf (mutex-value mutex) new-value)
- t)
+ (setf (mutex-%owner mutex) new-owner)
#!+sb-thread
(progn
- (when (eql new-value (mutex-value mutex))
- (warn "recursive lock attempt ~S~%" mutex)
- (format *debug-io* "Thread: ~A~%" *current-thread*)
- (sb!debug:backtrace most-positive-fixnum *debug-io*)
- (force-output *debug-io*))
+ ;; 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 wait-p
- (%lutex-lock lutex)
+ (if waitp
+ (with-interrupts (%lutex-lock lutex))
(%lutex-trylock lutex))))
- (setf (mutex-value mutex) new-value))
+ (setf (mutex-%owner mutex) new-owner)
+ t)
#!-sb-lutex
- (let (old)
- (loop
- (unless
- (setf old (sb!vm::%instance-set-conditional mutex 2 nil
- new-value))
- (return t))
- (unless wait-p (return nil))
- (with-pinned-objects (mutex old)
- (futex-wait (mutex-value-address mutex)
- (sb!kernel:get-lisp-obj-address old)))))))
-
-(defun release-mutex (mutex)
+ ;; This is a direct translation of the Mutex 2 algorithm from
+ ;; "Futexes are Tricky" by Ulrich Drepper.
+ (let ((old (sb!ext:compare-and-swap (mutex-state mutex)
+ +lock-free+
+ +lock-taken+)))
+ (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.
+ (loop
+ (multiple-value-bind (to-sec to-usec) (decode-timeout nil)
+ (case (with-pinned-objects (mutex)
+ (futex-wait (mutex-state-address mutex)
+ (get-lisp-obj-address +lock-contested+)
+ (or to-sec -1)
+ (or to-usec 0)))
+ ((1) (signal-deadline))
+ ((2))
+ (otherwise (return))))))
+ (setf old (sb!ext:compare-and-swap (mutex-state mutex)
+ +lock-free+
+ +lock-contested+))
+ ;; 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 &key (if-not-owner :punt))
#!+sb-doc
"Release MUTEX by setting it to NIL. Wake up threads waiting for
-this mutex."
- (declare (type mutex mutex))
- (/show0 "Entering RELEASE-MUTEX")
- (setf (mutex-value mutex) nil)
- #!+sb-thread
- (progn
- #!+sb-lutex
- (with-lutex-address (lutex (mutex-lutex mutex))
- (%lutex-unlock lutex))
- #!-sb-lutex
- (futex-wake (mutex-value-address mutex) 1)))
+this mutex.
+
+RELEASE-MUTEX is not interrupt safe: interrupts should be disabled
+around calls to it.
-;;;; waitqueues/condition variables
+If the current thread is not the owner of the mutex then it silently
+returns without doing anything (if IF-NOT-OWNER is :PUNT), signals a
+WARNING (if IF-NOT-OWNER is :WARN), or releases the mutex anyway (if
+IF-NOT-OWNER is :FORCE)."
+ (declare (type mutex mutex))
+ ;; Order matters: set owner to NIL before releasing state.
+ (let* ((self *current-thread*)
+ (old-owner (sb!ext:compare-and-swap (mutex-%owner mutex) self nil)))
+ (unless (eql self old-owner)
+ (ecase if-not-owner
+ ((:punt) (return-from release-mutex nil))
+ ((:warn)
+ (warn "Releasing ~S, owned by another thread: ~S" mutex old-owner))
+ ((:force))))
+ #!+sb-thread
+ (when old-owner
+ (setf (mutex-%owner mutex) nil)
+ #!+sb-lutex
+ (with-lutex-address (lutex (mutex-lutex mutex))
+ (%lutex-unlock lutex))
+ #!-sb-lutex
+ ;; FIXME: once ATOMIC-INCF supports struct slots with word sized
+ ;; unsigned-byte type this can be used:
+ ;;
+ ;; (let ((old (sb!ext:atomic-incf (mutex-state mutex) -1)))
+ ;; (unless (eql old +lock-free+)
+ ;; (setf (mutex-state mutex) +lock-free+)
+ ;; (with-pinned-objects (mutex)
+ ;; (futex-wake (mutex-state-address mutex) 1))))
+ (let ((old (sb!ext:compare-and-swap (mutex-state mutex)
+ +lock-taken+ +lock-free+)))
+ (when (eql old +lock-contested+)
+ (sb!ext:compare-and-swap (mutex-state mutex)
+ +lock-contested+ +lock-free+)
+ (with-pinned-objects (mutex)
+ (futex-wake (mutex-state-address mutex) 1))))
+ nil)))
+\f
+
+;;;; Waitqueues/condition variables
(defstruct (waitqueue (:constructor %make-waitqueue))
#!+sb-doc
(%make-waitqueue :name name))
#!+sb-doc
-(setf (sb!kernel:fdocumentation 'waitqueue-name 'function)
+(setf (fdocumentation 'waitqueue-name 'function)
"The name of the waitqueue. Setfable.")
#!+(and sb-thread (not sb-lutex))
-(progn
- (declaim (inline waitqueue-data-address))
- (defun waitqueue-data-address (waitqueue)
- (declare (optimize (speed 3)))
- (sb!ext:truly-the
- sb!vm:word
- (+ (sb!kernel:get-lisp-obj-address waitqueue)
- (- (* 3 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag)))))
+(define-structure-slot-addressor waitqueue-data-address
+ :structure waitqueue
+ :slot data)
(defun condition-wait (queue mutex)
#!+sb-doc
(assert mutex)
#!-sb-thread (error "Not supported in unithread builds.")
#!+sb-thread
- (let ((value (mutex-value mutex)))
+ (let ((me *current-thread*))
+ (assert (eq me (mutex-%owner mutex)))
(/show0 "CONDITION-WAITing")
#!+sb-lutex
- (progn
- (setf (mutex-value mutex) nil)
- (with-lutex-address (queue-lutex-address (waitqueue-lutex queue))
- (with-lutex-address (mutex-lutex-address (mutex-lutex mutex))
- (%lutex-wait queue-lutex-address mutex-lutex-address)))
- (setf (mutex-value mutex) value))
+ ;; 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
- (unwind-protect
- (let ((me *current-thread*))
- ;; 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 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
- (with-pinned-objects (queue me)
- (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 mutex value))))
+ ;; Need to disable interrupts so that we don't miss grabbing the
+ ;; mutex on our way out.
+ (without-interrupts
+ (let ((me nil))
+ ;; This setf becomes visible to other CPUS due to the usual
+ ;; memory barrier semantics of lock acquire/release. This must
+ ;; not be moved into the loop else wakeups may be lost upon
+ ;; continuing after a deadline or EINTR.
+ (setf (waitqueue-data queue) me)
+ (loop
+ (multiple-value-bind (to-sec to-usec) (decode-timeout nil)
+ (case (unwind-protect
+ (with-pinned-objects (queue me)
+ ;; RELEASE-MUTEX is purposefully as close to
+ ;; FUTEX-WAIT as possible to reduce the size
+ ;; of the window where WAITQUEUE-DATA may be
+ ;; set by a notifier.
+ (release-mutex mutex)
+ ;; Now we go to sleep using futex-wait. If
+ ;; anyone else manages to grab MUTEX and call
+ ;; CONDITION-NOTIFY during this comment, it
+ ;; will change queue->data, and so futex-wait
+ ;; returns immediately instead of sleeping.
+ ;; Ergo, no lost wakeup. We may get spurious
+ ;; wakeups, but that's ok.
+ (allow-with-interrupts
+ (futex-wait (waitqueue-data-address queue)
+ (get-lisp-obj-address me)
+ ;; our way if saying "no
+ ;; timeout":
+ (or to-sec -1)
+ (or to-usec 0))))
+ ;; If we are interrupted while waiting, we should
+ ;; do these things before returning. Ideally, in
+ ;; the case of an unhandled signal, we should do
+ ;; them before entering the debugger, but this is
+ ;; better than nothing.
+ (allow-with-interrupts (get-mutex mutex)))
+ ;; ETIMEDOUT
+ ((1) (signal-deadline))
+ ;; EINTR
+ ((2))
+ ;; EWOULDBLOCK, -1 here, is the possible spurious wakeup
+ ;; case. 0 is the normal wakeup.
+ (otherwise (return)))))))))
(defun condition-notify (queue &optional (n 1))
#!+sb-doc
- "Notify N threads waiting on QUEUE."
+ "Notify N threads waiting on QUEUE. The same mutex that is used in
+the corresponding CONDITION-WAIT must be held by this thread during
+this call."
#!-sb-thread (declare (ignore queue n))
#!-sb-thread (error "Not supported in unithread builds.")
#!+sb-thread
#!+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.
+ ;; 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
+;;;; Semaphores
-(defstruct (semaphore (:constructor %make-semaphore))
+(defstruct (semaphore (:constructor %make-semaphore (name %count)))
#!+sb-doc
- "Semaphore type."
+ "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))
+ (%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."
- (%make-semaphore :name name :count count))
+ "Create a semaphore with the supplied COUNT and NAME."
+ (%make-semaphore name count))
-(setf (sb!kernel:fdocumentation 'semaphore-name 'function)
- "The name of the semaphore. Setfable.")
-
-(defun wait-on-semaphore (sem)
+(defun wait-on-semaphore (semaphore)
#!+sb-doc
- "Decrement the count of SEM if the count would not be negative. Else
-block until the semaphore can be decremented."
- ;; a more direct implementation based directly on futexes should be
- ;; possible
- (with-mutex ((semaphore-mutex sem))
- (loop until (> (semaphore-count sem) 0)
- do (condition-wait (semaphore-queue sem) (semaphore-mutex sem))
- finally (decf (semaphore-count sem)))))
-
-(defun signal-semaphore (sem &optional (n 1))
+ "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 SEM by N. If there are threads waiting on
-this semaphore, then N of them is woken up."
- (declare (type (and fixnum (integer 1)) n))
- (with-mutex ((semaphore-mutex sem))
- (when (= n (incf (semaphore-count sem) n))
- (condition-notify (semaphore-queue sem) n))))
-
-;;;; job control, independent listeners
+ "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"))
(defvar *session* nil)
-;;; the debugger itself tries to acquire the session lock, don't let
+;;; The debugger itself tries to acquire the session lock, don't let
;;; funny situations (like getting a sigint while holding the session
-;;; lock) occur
+;;; 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)
- #!-sb-thread (declare (ignore session))
- #!-sb-thread
- `(locally ,@body)
- #!+sb-thread
- `(without-interrupts
- (with-mutex ((session-lock ,session))
- ,@body)))
+ `(with-system-mutex ((session-lock ,session) :allow-with-interrupts t)
+ ,@body))
(defun new-session ()
(make-session :threads (list *current-thread*)
#!+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)
(when *session*
(%delete-thread-from-session thread *session*)))
#!+sb-lutex
- (when (thread-interruptions-lock thread)
+ (without-gcing
(/show0 "FREEING MUTEX LUTEX")
(with-lutex-address (lutex (mutex-lutex (thread-interruptions-lock thread)))
(%lutex-destroy lutex))))
(sb!impl::toplevel-repl nil)
(sb!int:flush-standard-output-streams))))))
(make-thread #'thread-repl))))
+\f
-;;;; the beef
+;;;; The beef
(defun make-thread (function &key name)
#!+sb-doc
;; 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)
- (sb!kernel::*restart-clusters* nil)
- (sb!kernel::*handler-clusters* nil)
- (sb!kernel::*condition-restarts* nil)
- (sb!impl::*step-out* nil)
- ;; internal printer variables
- (sb!impl::*previous-case* nil)
- (sb!impl::*previous-readtable-case* nil)
- (sb!impl::*merge-sort-temp-vector* (vector)) ; keep these small!
- (sb!impl::*zap-array-data-temp* (vector)) ;
- (sb!impl::*internal-symbol-output-fun* nil)
- (sb!impl::*descriptor-handlers* nil)) ; serve-event
- (setf (thread-os-thread thread) (current-thread-sap-id))
+ ;;
+ ;; 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*))
(format nil
"~~@<Terminate this thread (~A)~~@:>"
*current-thread*))
- (unwind-protect
- (progn
- ;; now that most things have a chance to
- ;; work properly without messing up other
- ;; threads, it's time to enable signals
- (sb!unix::reset-signal-mask)
- (setf (thread-result thread)
- (cons t
- (multiple-value-list
- (funcall real-function)))))
- (handle-thread-exit thread)))))))
+ (without-interrupts
+ (unwind-protect
+ (with-local-interrupts
+ ;; Now that most things have a chance
+ ;; to work properly without messing up
+ ;; other threads, it's time to enable
+ ;; signals.
+ (sb!unix::unblock-deferrable-signals)
+ (setf (thread-result thread)
+ (cons t
+ (multiple-value-list
+ (funcall real-function))))
+ ;; Try to block deferrables. An
+ ;; interrupt may unwind it, but for a
+ ;; normal exit it prevents interrupt
+ ;; loss.
+ (block-deferrable-signals))
+ ;; We're going down, can't handle interrupts
+ ;; sanely anymore. GC remains enabled.
+ (block-deferrable-signals)
+ ;; We don't want to run interrupts in a dead
+ ;; thread when we leave WITHOUT-INTERRUPTS.
+ ;; This potentially causes important
+ ;; interupts to be lost: SIGINT comes to
+ ;; mind.
+ (setq *interrupt-pending* nil)
+ (handle-thread-exit thread))))))))
(values))))
+ ;; If the starting thread is stopped for gc before it signals the
+ ;; semaphore then we'd be stuck.
+ (assert (not *gc-inhibit*))
;; Keep INITIAL-FUNCTION pinned until the child thread is
- ;; initialized properly.
- (with-pinned-objects (initial-function)
- (let ((os-thread
- (%create-thread
- (sb!kernel:get-lisp-obj-address initial-function))))
- (when (zerop os-thread)
- (error "Can't create a new thread"))
- (wait-on-semaphore setup-sem)
- thread))))
+ ;; 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))
(join-thread-error-thread c)))))
#!+sb-doc
-(setf (sb!kernel:fdocumentation 'join-thread-error-thread 'function)
+(setf (fdocumentation 'join-thread-error-thread 'function)
"The thread that we failed to join.")
-(defun join-thread (thread &key (errorp t) default)
+(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 or signal JOIN-THREAD-ERROR depending on ERRORP."
- (with-mutex ((thread-result-lock thread))
+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))
- (values-list (cdr (thread-result thread))))
- (errorp
- (error 'join-thread-error :thread thread))
- (t
- default))))
+ (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
(interrupt-thread-error-thread c)))))
#!+sb-doc
-(setf (sb!kernel:fdocumentation 'interrupt-thread-error-thread 'function)
+(setf (fdocumentation 'interrupt-thread-error-thread 'function)
"The thread that was not interrupted.")
(defmacro with-interruptions-lock ((thread) &body body)
- `(without-interrupts
- (with-mutex ((thread-interruptions-lock ,thread))
- ,@body)))
+ `(with-system-mutex ((thread-interruptions-lock ,thread))
+ ,@body))
-;; Called from the signal handler.
+;;; Called from the signal handler.
+#!-win32
(defun run-interruption ()
- (in-interruption ()
- (loop
- (let ((interruption (with-interruptions-lock (*current-thread*)
- (pop (thread-interruptions *current-thread*)))))
- (if interruption
- (with-interrupts
- (funcall interruption))
- (return))))))
-
-;; The order of interrupt execution is peculiar. If thread A
-;; interrupts thread B with I1, I2 and B for some reason receives I1
-;; when FUN2 is already on the list, then it is FUN2 that gets to run
-;; first. But when FUN2 is run SIG_INTERRUPT_THREAD is enabled again
-;; and I2 hits pretty soon in FUN2 and run FUN1. This is of course
-;; just one scenario, and the order of thread interrupt execution is
-;; undefined.
+ (let ((interruption (with-interruptions-lock (*current-thread*)
+ (pop (thread-interruptions *current-thread*)))))
+ ;; If there is more to do, then resignal and let the normal
+ ;; interrupt deferral mechanism take care of the rest. From the
+ ;; OS's point of view the signal we are in the handler for is no
+ ;; longer pending, so the signal will not be lost.
+ (when (thread-interruptions *current-thread*)
+ (kill-safely (thread-os-thread *current-thread*) sb!unix:sigpipe))
+ (when interruption
+ (funcall interruption))))
+
(defun interrupt-thread (thread function)
#!+sb-doc
"Interrupt the live THREAD and make it run FUNCTION. A moderate
degree of care is expected for use of INTERRUPT-THREAD, due to its
nature: if you interrupt a thread that was holding important locks
then do something that turns out to need those locks, you probably
-won't like the effect."
- #!-sb-thread (declare (ignore thread))
- ;; not quite perfect, because it does not take WITHOUT-INTERRUPTS
- ;; into account
- #!-sb-thread
- (funcall function)
- #!+sb-thread
- (if (eq thread *current-thread*)
- (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)))))))
+won't like the effect. FUNCTION runs with interrupts disabled, but
+WITH-INTERRUPTS is allowed in it. Keep in mind that many things may
+enable interrupts (GET-MUTEX when contended, for instance) so the
+first thing to do is usually a WITH-INTERRUPTS or a
+WITHOUT-INTERRUPTS. Within a thread interrupts are queued, they are
+run in same the order they were sent."
+ #!+win32
+ (declare (ignore thread))
+ #!+win32
+ (with-interrupt-bindings
+ (with-interrupts (funcall function)))
+ #!-win32
+ (let ((os-thread (thread-os-thread thread)))
+ (cond ((not os-thread)
+ (error 'interrupt-thread-error :thread thread))
+ (t
+ (with-interruptions-lock (thread)
+ ;; Append to the end of the interruptions queue. It's
+ ;; O(N), but it does not hurt to slow interruptors down a
+ ;; bit when the queue gets long.
+ (setf (thread-interruptions thread)
+ (append (thread-interruptions thread)
+ (list (lambda ()
+ (without-interrupts
+ (allow-with-interrupts
+ (funcall function))))))))
+ (when (minusp (kill-safely os-thread sb!unix:sigpipe))
+ (error 'interrupt-thread-error :thread thread))))))
(defun terminate-thread (thread)
#!+sb-doc
SB-EXT:QUIT - the usual cleanup forms will be evaluated"
(interrupt-thread thread 'sb!ext:quit))
-;;; internal use only. If you think you need to use this, either you
+(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
-(defun thread-sap-for-id (id)
- (let ((thread-sap (alien-sap (extern-alien "all_threads" (* t)))))
- (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 id) (return thread-sap))
- (setf thread-sap
- (sap-ref-sap thread-sap (* sb!vm:n-word-bytes
- sb!vm::thread-next-slot)))))))
-
-#!+sb-thread
-(defun symbol-value-in-thread (symbol thread-sap)
- (let* ((index (sb!vm::symbol-tls-index symbol))
- (tl-val (sap-ref-word thread-sap
- (* sb!vm:n-word-bytes index))))
- (if (eql tl-val sb!vm::no-tls-value-marker-widetag)
- (sb!vm::symbol-global-value symbol)
- (sb!kernel:make-lisp-obj tl-val))))
+(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
+;;;; Stepping
(defun thread-stepping ()
- (sb!kernel:make-lisp-obj
+ (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))
- (sb!kernel:get-lisp-obj-address value)))
+ (get-lisp-obj-address value)))
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