src/code/target-thread.lisp

   1 ;;;; support for threads in the target machine
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; This software is derived from the CMU CL system, which was
   7 ;;;; written at Carnegie Mellon University and released into the
   8 ;;;; public domain. The software is in the public domain and is
   9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  10 ;;;; files for more information.
  11
  12 (in-package "SB!THREAD")
  13
  14 ;;; Of the WITH-PINNED-OBJECTS in this file, not every single one is
  15 ;;; necessary because threads are only supported with the conservative
  16 ;;; gencgc and numbers on the stack (returned by GET-LISP-OBJ-ADDRESS)
  17 ;;; are treated as references.
  18
  19 ;;; set the doc here because in early-thread FDOCUMENTATION is not
  20 ;;; available, yet
  21 #!+sb-doc
  22 (setf (fdocumentation '*current-thread* 'variable)
  23       "Bound in each thread to the thread itself.")
  24
  25 (defstruct (thread (:constructor %make-thread))
  26   #!+sb-doc
  27   "Thread type. Do not rely on threads being structs as it may change
  28 in future versions."
  29   name
  30   %alive-p
  31   os-thread
  32   interruptions
  33   (interruptions-lock (make-mutex :name "thread interruptions lock"))
  34   result
  35   (result-lock (make-mutex :name "thread result lock")))
  36
  37 #!+sb-doc
  38 (setf (fdocumentation 'thread-name 'function)
  39       "The name of the thread. Setfable.")
  40
  41 (def!method print-object ((thread thread) stream)
  42   (if (thread-name thread)
  43       (print-unreadable-object (thread stream :type t :identity t)
  44         (prin1 (thread-name thread) stream))
  45       (print-unreadable-object (thread stream :type t :identity t)
  46         ;; body is empty => there is only one space between type and
  47         ;; identity
  48         ))
  49   thread)
  50
  51 (defun thread-alive-p (thread)
  52   #!+sb-doc
  53   "Check if THREAD is running."
  54   (thread-%alive-p thread))
  55
  56 ;; A thread is eligible for gc iff it has finished and there are no
  57 ;; more references to it. This list is supposed to keep a reference to
  58 ;; all running threads.
  59 (defvar *all-threads* ())
  60 (defvar *all-threads-lock* (make-mutex :name "all threads lock"))
  61
  62 (defmacro with-all-threads-lock (&body body)
  63   `(call-with-system-mutex (lambda () ,@body) *all-threads-lock*))
  64
  65 (defun list-all-threads ()
  66   #!+sb-doc
  67   "Return a list of the live threads."
  68   (with-all-threads-lock
  69     (copy-list *all-threads*)))
  70
  71 (declaim (inline current-thread-sap))
  72 (defun current-thread-sap ()
  73   (sb!vm::current-thread-offset-sap sb!vm::thread-this-slot))
  74
  75 (declaim (inline current-thread-sap-id))
  76 (defun current-thread-sap-id ()
  77   (sap-int
  78    (sb!vm::current-thread-offset-sap sb!vm::thread-os-thread-slot)))
  79
  80 (defun init-initial-thread ()
  81   (/show0 "Entering INIT-INITIAL-THREAD")
  82   (let ((initial-thread (%make-thread :name "initial thread"
  83                                       :%alive-p t
  84                                       :os-thread (current-thread-sap-id))))
  85     (setq *current-thread* initial-thread)
  86     ;; Either *all-threads* is empty or it contains exactly one thread
  87     ;; in case we are in reinit since saving core with multiple
  88     ;; threads doesn't work.
  89     (setq *all-threads* (list initial-thread))))
  90
  91 ;;;;
  92
  93 #!+sb-thread
  94 (progn
  95   ;; FIXME it would be good to define what a thread id is or isn't
  96   ;; (our current assumption is that it's a fixnum).  It so happens
  97   ;; that on Linux it's a pid, but it might not be on posix thread
  98   ;; implementations.
  99   (define-alien-routine ("create_thread" %create-thread)
 100       unsigned-long (lisp-fun-address unsigned-long))
 101
 102   (define-alien-routine "signal_interrupt_thread"
 103       integer (os-thread unsigned-long))
 104
 105   (define-alien-routine "block_deferrable_signals"
 106       void)
 107
 108   #!+sb-lutex
 109   (progn
 110     (declaim (inline %lutex-init %lutex-wait %lutex-wake
 111                      %lutex-lock %lutex-unlock))
 112
 113     (define-alien-routine ("lutex_init" %lutex-init)
 114         int (lutex unsigned-long))
 115
 116     (define-alien-routine ("lutex_wait" %lutex-wait)
 117         int (queue-lutex unsigned-long) (mutex-lutex unsigned-long))
 118
 119     (define-alien-routine ("lutex_wake" %lutex-wake)
 120         int (lutex unsigned-long) (n int))
 121
 122     (define-alien-routine ("lutex_lock" %lutex-lock)
 123         int (lutex unsigned-long))
 124
 125     (define-alien-routine ("lutex_trylock" %lutex-trylock)
 126         int (lutex unsigned-long))
 127
 128     (define-alien-routine ("lutex_unlock" %lutex-unlock)
 129         int (lutex unsigned-long))
 130
 131     (define-alien-routine ("lutex_destroy" %lutex-destroy)
 132         int (lutex unsigned-long))
 133
 134     ;; FIXME: Defining a whole bunch of alien-type machinery just for
 135     ;; passing primitive lutex objects directly to foreign functions
 136     ;; doesn't seem like fun right now. So instead we just manually
 137     ;; pin the lutex, get its address, and let the callee untag it.
 138     (defmacro with-lutex-address ((name lutex) &body body)
 139       `(let ((,name ,lutex))
 140          (with-pinned-objects (,name)
 141            (let ((,name (get-lisp-obj-address ,name)))
 142              ,@body))))
 143
 144     (defun make-lutex ()
 145       (/show0 "Entering MAKE-LUTEX")
 146       ;; Suppress GC until the lutex has been properly registered with
 147       ;; the GC.
 148       (without-gcing
 149         (let ((lutex (sb!vm::%make-lutex)))
 150           (/show0 "LUTEX=..")
 151           (/hexstr lutex)
 152           (with-lutex-address (lutex lutex)
 153             (%lutex-init lutex))
 154           lutex))))
 155
 156   #!-sb-lutex
 157   (progn
 158     (declaim (inline futex-wait %futex-wait futex-wake))
 159
 160     (define-alien-routine ("futex_wait" %futex-wait)
 161         int (word unsigned-long) (old-value unsigned-long)
 162         (to-sec long) (to-usec unsigned-long))
 163
 164     (defun futex-wait (word old to-sec to-usec)
 165       (with-interrupts
 166         (%futex-wait word old to-sec to-usec)))
 167
 168     (define-alien-routine "futex_wake"
 169         int (word unsigned-long) (n unsigned-long))))
 170
 171 ;;; used by debug-int.lisp to access interrupt contexts
 172 #!-(or sb-fluid sb-thread) (declaim (inline sb!vm::current-thread-offset-sap))
 173 #!-sb-thread
 174 (defun sb!vm::current-thread-offset-sap (n)
 175   (declare (type (unsigned-byte 27) n))
 176   (sap-ref-sap (alien-sap (extern-alien "all_threads" (* t)))
 177                (* n sb!vm:n-word-bytes)))
 178
 179 #!+sb-thread
 180 (defun sb!vm::current-thread-offset-sap (n)
 181   (declare (type (unsigned-byte 27) n))
 182   (sb!vm::current-thread-offset-sap n))
 183
 184 (declaim (inline get-spinlock release-spinlock))
 185
 186 ;; Should always be called with interrupts disabled.
 187 (defun get-spinlock (spinlock)
 188   (declare (optimize (speed 3) (safety 0)))
 189   (let* ((new *current-thread*)
 190          (old (sb!ext:compare-and-swap (spinlock-value spinlock) nil new)))
 191     (when old
 192       (when (eq old new)
 193         (error "Recursive lock attempt on ~S." spinlock))
 194       #!+sb-thread
 195       (flet ((cas ()
 196                (unless (sb!ext:compare-and-swap (spinlock-value spinlock) nil new)
 197                  (return-from get-spinlock t))))
 198         (if (and (not *interrupts-enabled*) *allow-with-interrupts*)
 199             ;; If interrupts are enabled, but we are allowed to enabled them,
 200             ;; check for pending interrupts every once in a while.
 201             (loop
 202               (loop repeat 128 do (cas)) ; 128 is arbitrary here
 203               (sb!unix::%check-interrupts))
 204             (loop (cas)))))
 205     t))
 206
 207 (defun release-spinlock (spinlock)
 208   (declare (optimize (speed 3) (safety 0)))
 209   (setf (spinlock-value spinlock) nil)
 210   nil)
 211
 212 ;;;; mutexes
 213
 214 #!+sb-doc
 215 (setf (fdocumentation 'make-mutex 'function)
 216       "Create a mutex."
 217       (fdocumentation 'mutex-name 'function)
 218       "The name of the mutex. Setfable."
 219       (fdocumentation 'mutex-value 'function)
 220       "The value of the mutex. NIL if the mutex is free. Setfable.")
 221
 222 #!+(and sb-thread (not sb-lutex))
 223 (define-structure-slot-addressor mutex-value-address
 224       :structure mutex
 225       :slot value)
 226
 227 (defun get-mutex (mutex &optional (new-value *current-thread*) (waitp t))
 228   #!+sb-doc
 229   "Acquire MUTEX, setting it to NEW-VALUE or some suitable default value if
 230 NIL. If WAITP is non-NIL and the mutex is in use, sleep until it is available."
 231   (declare (type mutex mutex) (optimize (speed 3)))
 232   (/show0 "Entering GET-MUTEX")
 233   (unless new-value
 234     (setq new-value *current-thread*))
 235   #!-sb-thread
 236   (let ((old (mutex-value mutex)))
 237     (when (and old waitp)
 238       (error "In unithread mode, mutex ~S was requested with WAITP ~S and ~
 239               new-value ~S, but has already been acquired (with value ~S)."
 240              mutex waitp new-value old))
 241     (setf (mutex-value mutex) new-value)
 242     t)
 243   #!+sb-thread
 244   (progn
 245     (when (eql new-value (mutex-value mutex))
 246       (warn "recursive lock attempt ~S~%" mutex)
 247       (format *debug-io* "Thread: ~A~%" *current-thread*)
 248       (sb!debug:backtrace most-positive-fixnum *debug-io*)
 249       (force-output *debug-io*))
 250     ;; FIXME: Lutexes do not currently support deadlines, as at least
 251     ;; on Darwin pthread_foo_timedbar functions are not supported:
 252     ;; this means that we probably need to use the Carbon multiprocessing
 253     ;; functions on Darwin.
 254     ;;
 255     ;; FIXME: This is definitely not interrupt safe: what happens if
 256     ;; we get hit (1) during the lutex calls (ok, they may be safe,
 257     ;; but has that been checked?) (2) after the lutex call, but
 258     ;; before setting the mutex value.
 259     #!+sb-lutex
 260     (when (zerop (with-lutex-address (lutex (mutex-lutex mutex))
 261                    (if waitp
 262                        (with-interrupts (%lutex-lock lutex))
 263                        (%lutex-trylock lutex))))
 264       (setf (mutex-value mutex) new-value))
 265     #!-sb-lutex
 266     (let (old)
 267       (when (and (setf old (sb!ext:compare-and-swap (mutex-value mutex) nil new-value))
 268                  waitp)
 269         (loop while old
 270               do (multiple-value-bind (to-sec to-usec) (decode-timeout nil)
 271                    (when (= 1 (with-pinned-objects (mutex old)
 272                                 (futex-wait (mutex-value-address mutex)
 273                                             (get-lisp-obj-address old)
 274                                             (or to-sec -1)
 275                                             (or to-usec 0))))
 276                      (signal-deadline)))
 277               (setf old (sb!ext:compare-and-swap (mutex-value mutex) nil new-value))))
 278       (not old))))
 279
 280 (defun release-mutex (mutex)
 281   #!+sb-doc
 282   "Release MUTEX by setting it to NIL. Wake up threads waiting for
 283 this mutex."
 284   (declare (type mutex mutex))
 285   (/show0 "Entering RELEASE-MUTEX")
 286   (setf (mutex-value mutex) nil)
 287   #!+sb-thread
 288   (progn
 289     #!+sb-lutex
 290     (with-lutex-address (lutex (mutex-lutex mutex))
 291       (%lutex-unlock lutex))
 292     #!-sb-lutex
 293     (futex-wake (mutex-value-address mutex) 1)))
 294
 295 ;;;; waitqueues/condition variables
 296
 297 (defstruct (waitqueue (:constructor %make-waitqueue))
 298   #!+sb-doc
 299   "Waitqueue type."
 300   (name nil :type (or null simple-string))
 301   #!+(and sb-lutex sb-thread)
 302   (lutex (make-lutex))
 303   #!-sb-lutex
 304   (data nil))
 305
 306 (defun make-waitqueue (&key name)
 307   #!+sb-doc
 308   "Create a waitqueue."
 309   (%make-waitqueue :name name))
 310
 311 #!+sb-doc
 312 (setf (fdocumentation 'waitqueue-name 'function)
 313       "The name of the waitqueue. Setfable.")
 314
 315 #!+(and sb-thread (not sb-lutex))
 316 (define-structure-slot-addressor waitqueue-data-address
 317     :structure waitqueue
 318     :slot data)
 319
 320 (defun condition-wait (queue mutex)
 321   #!+sb-doc
 322   "Atomically release MUTEX and enqueue ourselves on QUEUE.  Another
 323 thread may subsequently notify us using CONDITION-NOTIFY, at which
 324 time we reacquire MUTEX and return to the caller."
 325   #!-sb-thread (declare (ignore queue))
 326   (assert mutex)
 327   #!-sb-thread (error "Not supported in unithread builds.")
 328   #!+sb-thread
 329   (let ((value (mutex-value mutex)))
 330     (/show0 "CONDITION-WAITing")
 331     #!+sb-lutex
 332     (progn
 333       ;; FIXME: This doesn't look interrupt safe!
 334       (setf (mutex-value mutex) nil)
 335       (with-lutex-address (queue-lutex-address (waitqueue-lutex queue))
 336         (with-lutex-address (mutex-lutex-address (mutex-lutex mutex))
 337           (%lutex-wait queue-lutex-address mutex-lutex-address)))
 338       (setf (mutex-value mutex) value))
 339     #!-sb-lutex
 340     (unwind-protect
 341          (let ((me *current-thread*))
 342            ;; FIXME: should we do something to ensure that the result
 343            ;; of this setf is visible to all CPUs?
 344            (setf (waitqueue-data queue) me)
 345            (release-mutex mutex)
 346            ;; Now we go to sleep using futex-wait.  If anyone else
 347            ;; manages to grab MUTEX and call CONDITION-NOTIFY during
 348            ;; this comment, it will change queue->data, and so
 349            ;; futex-wait returns immediately instead of sleeping.
 350            ;; Ergo, no lost wakeup. We may get spurious wakeups,
 351            ;; but that's ok.
 352            (multiple-value-bind (to-sec to-usec) (decode-timeout nil)
 353              (when (= 1 (with-pinned-objects (queue me)
 354                           (futex-wait (waitqueue-data-address queue)
 355                                       (get-lisp-obj-address me)
 356                                       (or to-sec -1) ;; our way if saying "no timeout"
 357                                       (or to-usec 0))))
 358                (signal-deadline))))
 359       ;; If we are interrupted while waiting, we should do these things
 360       ;; before returning.  Ideally, in the case of an unhandled signal,
 361       ;; we should do them before entering the debugger, but this is
 362       ;; better than nothing.
 363       (get-mutex mutex value))))
 364
 365 (defun condition-notify (queue &optional (n 1))
 366   #!+sb-doc
 367   "Notify N threads waiting on QUEUE."
 368   #!-sb-thread (declare (ignore queue n))
 369   #!-sb-thread (error "Not supported in unithread builds.")
 370   #!+sb-thread
 371   (declare (type (and fixnum (integer 1)) n))
 372   (/show0 "Entering CONDITION-NOTIFY")
 373   #!+sb-thread
 374   (progn
 375     #!+sb-lutex
 376     (with-lutex-address (lutex (waitqueue-lutex queue))
 377       (%lutex-wake lutex n))
 378     ;; no problem if >1 thread notifies during the comment in
 379     ;; condition-wait: as long as the value in queue-data isn't the
 380     ;; waiting thread's id, it matters not what it is
 381     ;; XXX we should do something to ensure that the result of this setf
 382     ;; is visible to all CPUs
 383     #!-sb-lutex
 384     (let ((me *current-thread*))
 385       (progn
 386         (setf (waitqueue-data queue) me)
 387         (with-pinned-objects (queue)
 388           (futex-wake (waitqueue-data-address queue) n))))))
 389
 390 (defun condition-broadcast (queue)
 391   #!+sb-doc
 392   "Notify all threads waiting on QUEUE."
 393   (condition-notify queue
 394                     ;; On a 64-bit platform truncating M-P-F to an int results
 395                     ;; in -1, which wakes up only one thread.
 396                     (ldb (byte 29 0)
 397                          most-positive-fixnum)))
 398
 399 ;;;; semaphores
 400
 401 (defstruct (semaphore (:constructor %make-semaphore))
 402   #!+sb-doc
 403   "Semaphore type."
 404   (name nil :type (or null simple-string))
 405   (count 0 :type (integer 0))
 406   (mutex (make-mutex))
 407   (queue (make-waitqueue)))
 408
 409 (defun make-semaphore (&key name (count 0))
 410   #!+sb-doc
 411   "Create a semaphore with the supplied COUNT."
 412   (%make-semaphore :name name :count count))
 413
 414 (setf (fdocumentation 'semaphore-name 'function)
 415       "The name of the semaphore. Setfable.")
 416
 417 (defun wait-on-semaphore (sem)
 418   #!+sb-doc
 419   "Decrement the count of SEM if the count would not be negative. Else
 420 block until the semaphore can be decremented."
 421   ;; a more direct implementation based directly on futexes should be
 422   ;; possible
 423   (with-mutex ((semaphore-mutex sem))
 424     (loop until (> (semaphore-count sem) 0)
 425           do (condition-wait (semaphore-queue sem) (semaphore-mutex sem))
 426           finally (decf (semaphore-count sem)))))
 427
 428 (defun signal-semaphore (sem &optional (n 1))
 429   #!+sb-doc
 430   "Increment the count of SEM by N. If there are threads waiting on
 431 this semaphore, then N of them is woken up."
 432   (declare (type (and fixnum (integer 1)) n))
 433   (with-mutex ((semaphore-mutex sem))
 434     (when (= n (incf (semaphore-count sem) n))
 435       (condition-notify (semaphore-queue sem) n))))
 436
 437 ;;;; job control, independent listeners
 438
 439 (defstruct session
 440   (lock (make-mutex :name "session lock"))
 441   (threads nil)
 442   (interactive-threads nil)
 443   (interactive-threads-queue (make-waitqueue)))
 444
 445 (defvar *session* nil)
 446
 447 ;;; the debugger itself tries to acquire the session lock, don't let
 448 ;;; funny situations (like getting a sigint while holding the session
 449 ;;; lock) occur
 450 (defmacro with-session-lock ((session) &body body)
 451   `(call-with-system-mutex (lambda () ,@body) (session-lock ,session)))
 452
 453 (defun new-session ()
 454   (make-session :threads (list *current-thread*)
 455                 :interactive-threads (list *current-thread*)))
 456
 457 (defun init-job-control ()
 458   (/show0 "Entering INIT-JOB-CONTROL")
 459   (setf *session* (new-session))
 460   (/show0 "Exiting INIT-JOB-CONTROL"))
 461
 462 (defun %delete-thread-from-session (thread session)
 463   (with-session-lock (session)
 464     (setf (session-threads session)
 465           (delete thread (session-threads session))
 466           (session-interactive-threads session)
 467           (delete thread (session-interactive-threads session)))))
 468
 469 (defun call-with-new-session (fn)
 470   (%delete-thread-from-session *current-thread* *session*)
 471   (let ((*session* (new-session)))
 472     (funcall fn)))
 473
 474 (defmacro with-new-session (args &body forms)
 475   (declare (ignore args))               ;for extensibility
 476   (sb!int:with-unique-names (fb-name)
 477     `(labels ((,fb-name () ,@forms))
 478       (call-with-new-session (function ,fb-name)))))
 479
 480 ;;; Remove thread from its session, if it has one.
 481 #!+sb-thread
 482 (defun handle-thread-exit (thread)
 483   (/show0 "HANDLING THREAD EXIT")
 484   ;; We're going down, can't handle interrupts sanely anymore.
 485   ;; GC remains enabled.
 486   (block-deferrable-signals)
 487   ;; Lisp-side cleanup
 488   (with-all-threads-lock
 489     (setf (thread-%alive-p thread) nil)
 490     (setf (thread-os-thread thread) nil)
 491     (setq *all-threads* (delete thread *all-threads*))
 492     (when *session*
 493       (%delete-thread-from-session thread *session*)))
 494   #!+sb-lutex
 495   (without-gcing
 496     (/show0 "FREEING MUTEX LUTEX")
 497     (with-lutex-address (lutex (mutex-lutex (thread-interruptions-lock thread)))
 498       (%lutex-destroy lutex))))
 499
 500 (defun terminate-session ()
 501   #!+sb-doc
 502   "Kill all threads in session except for this one.  Does nothing if current
 503 thread is not the foreground thread."
 504   ;; FIXME: threads created in other threads may escape termination
 505   (let ((to-kill
 506          (with-session-lock (*session*)
 507            (and (eq *current-thread*
 508                     (car (session-interactive-threads *session*)))
 509                 (session-threads *session*)))))
 510     ;; do the kill after dropping the mutex; unwind forms in dying
 511     ;; threads may want to do session things
 512     (dolist (thread to-kill)
 513       (unless (eq thread *current-thread*)
 514         ;; terminate the thread but don't be surprised if it has
 515         ;; exited in the meantime
 516         (handler-case (terminate-thread thread)
 517           (interrupt-thread-error ()))))))
 518
 519 ;;; called from top of invoke-debugger
 520 (defun debugger-wait-until-foreground-thread (stream)
 521   "Returns T if thread had been running in background, NIL if it was
 522 interactive."
 523   (declare (ignore stream))
 524   #!-sb-thread nil
 525   #!+sb-thread
 526   (prog1
 527       (with-session-lock (*session*)
 528         (not (member *current-thread*
 529                      (session-interactive-threads *session*))))
 530     (get-foreground)))
 531
 532 (defun get-foreground ()
 533   #!-sb-thread t
 534   #!+sb-thread
 535   (let ((was-foreground t))
 536     (loop
 537      (/show0 "Looping in GET-FOREGROUND")
 538      (with-session-lock (*session*)
 539        (let ((int-t (session-interactive-threads *session*)))
 540          (when (eq (car int-t) *current-thread*)
 541            (unless was-foreground
 542              (format *query-io* "Resuming thread ~A~%" *current-thread*))
 543            (return-from get-foreground t))
 544          (setf was-foreground nil)
 545          (unless (member *current-thread* int-t)
 546            (setf (cdr (last int-t))
 547                  (list *current-thread*)))
 548          (condition-wait
 549           (session-interactive-threads-queue *session*)
 550           (session-lock *session*)))))))
 551
 552 (defun release-foreground (&optional next)
 553   #!+sb-doc
 554   "Background this thread.  If NEXT is supplied, arrange for it to
 555 have the foreground next."
 556   #!-sb-thread (declare (ignore next))
 557   #!-sb-thread nil
 558   #!+sb-thread
 559   (with-session-lock (*session*)
 560     (when (rest (session-interactive-threads *session*))
 561       (setf (session-interactive-threads *session*)
 562             (delete *current-thread* (session-interactive-threads *session*))))
 563     (when next
 564       (setf (session-interactive-threads *session*)
 565             (list* next
 566                    (delete next (session-interactive-threads *session*)))))
 567     (condition-broadcast (session-interactive-threads-queue *session*))))
 568
 569 (defun foreground-thread ()
 570   (car (session-interactive-threads *session*)))
 571
 572 (defun make-listener-thread (tty-name)
 573   (assert (probe-file tty-name))
 574   (let* ((in (sb!unix:unix-open (namestring tty-name) sb!unix:o_rdwr #o666))
 575          (out (sb!unix:unix-dup in))
 576          (err (sb!unix:unix-dup in)))
 577     (labels ((thread-repl ()
 578                (sb!unix::unix-setsid)
 579                (let* ((sb!impl::*stdin*
 580                        (make-fd-stream in :input t :buffering :line
 581                                        :dual-channel-p t))
 582                       (sb!impl::*stdout*
 583                        (make-fd-stream out :output t :buffering :line
 584                                               :dual-channel-p t))
 585                       (sb!impl::*stderr*
 586                        (make-fd-stream err :output t :buffering :line
 587                                               :dual-channel-p t))
 588                       (sb!impl::*tty*
 589                        (make-fd-stream err :input t :output t
 590                                               :buffering :line
 591                                               :dual-channel-p t))
 592                       (sb!impl::*descriptor-handlers* nil))
 593                  (with-new-session ()
 594                    (unwind-protect
 595                         (sb!impl::toplevel-repl nil)
 596                      (sb!int:flush-standard-output-streams))))))
 597       (make-thread #'thread-repl))))
 598
 599 ;;;; the beef
 600
 601 (defun make-thread (function &key name)
 602   #!+sb-doc
 603   "Create a new thread of NAME that runs FUNCTION. When the function
 604 returns the thread exits. The return values of FUNCTION are kept
 605 around and can be retrieved by JOIN-THREAD."
 606   #!-sb-thread (declare (ignore function name))
 607   #!-sb-thread (error "Not supported in unithread builds.")
 608   #!+sb-thread
 609   (let* ((thread (%make-thread :name name))
 610          (setup-sem (make-semaphore :name "Thread setup semaphore"))
 611          (real-function (coerce function 'function))
 612          (initial-function
 613           (lambda ()
 614             ;; In time we'll move some of the binding presently done in C
 615             ;; here too.
 616             ;;
 617             ;; KLUDGE: Here we have a magic list of variables that are
 618             ;; not thread-safe for one reason or another.  As people
 619             ;; report problems with the thread safety of certain
 620             ;; variables, (e.g. "*print-case* in multiple threads
 621             ;; broken", sbcl-devel 2006-07-14), we add a few more
 622             ;; bindings here.  The Right Thing is probably some variant
 623             ;; of Allegro's *cl-default-special-bindings*, as that is at
 624             ;; least accessible to users to secure their own libraries.
 625             ;;   --njf, 2006-07-15
 626             (let ((*current-thread* thread)
 627                   (*restart-clusters* nil)
 628                   (*handler-clusters* nil)
 629                   (*condition-restarts* nil)
 630                   (sb!impl::*step-out* nil)
 631                   ;; internal printer variables
 632                   (sb!impl::*previous-case* nil)
 633                   (sb!impl::*previous-readtable-case* nil)
 634                   (sb!impl::*merge-sort-temp-vector* (vector)) ; keep these small!
 635                   (sb!impl::*zap-array-data-temp* (vector))    ;
 636                   (sb!impl::*internal-symbol-output-fun* nil)
 637                   (sb!impl::*descriptor-handlers* nil)) ; serve-event
 638               (setf (thread-os-thread thread) (current-thread-sap-id))
 639               (with-mutex ((thread-result-lock thread))
 640                 (with-all-threads-lock
 641                   (push thread *all-threads*))
 642                 (with-session-lock (*session*)
 643                   (push thread (session-threads *session*)))
 644                 (setf (thread-%alive-p thread) t)
 645                 (signal-semaphore setup-sem)
 646                 ;; can't use handling-end-of-the-world, because that flushes
 647                 ;; output streams, and we don't necessarily have any (or we
 648                 ;; could be sharing them)
 649                 (catch 'sb!impl::toplevel-catcher
 650                   (catch 'sb!impl::%end-of-the-world
 651                     (with-simple-restart
 652                         (terminate-thread
 653                          (format nil
 654                                  "~~@<Terminate this thread (~A)~~@:>"
 655                                  *current-thread*))
 656                       (unwind-protect
 657                            (progn
 658                              ;; now that most things have a chance to
 659                              ;; work properly without messing up other
 660                              ;; threads, it's time to enable signals
 661                              (sb!unix::reset-signal-mask)
 662                              (setf (thread-result thread)
 663                                    (cons t
 664                                          (multiple-value-list
 665                                           (funcall real-function)))))
 666                         (handle-thread-exit thread)))))))
 667             (values))))
 668     ;; Keep INITIAL-FUNCTION pinned until the child thread is
 669     ;; initialized properly.
 670     (with-pinned-objects (initial-function)
 671       (let ((os-thread
 672              (%create-thread
 673               (get-lisp-obj-address initial-function))))
 674         (when (zerop os-thread)
 675           (error "Can't create a new thread"))
 676         (wait-on-semaphore setup-sem)
 677         thread))))
 678
 679 (define-condition join-thread-error (error)
 680   ((thread :reader join-thread-error-thread :initarg :thread))
 681   #!+sb-doc
 682   (:documentation "Joining thread failed.")
 683   (:report (lambda (c s)
 684              (format s "Joining thread failed: thread ~A ~
 685                         has not returned normally."
 686                      (join-thread-error-thread c)))))
 687
 688 #!+sb-doc
 689 (setf (fdocumentation 'join-thread-error-thread 'function)
 690       "The thread that we failed to join.")
 691
 692 (defun join-thread (thread &key (default nil defaultp))
 693   #!+sb-doc
 694   "Suspend current thread until THREAD exits. Returns the result
 695 values of the thread function. If the thread does not exit normally,
 696 return DEFAULT if given or else signal JOIN-THREAD-ERROR."
 697   (with-mutex ((thread-result-lock thread))
 698     (cond ((car (thread-result thread))
 699            (values-list (cdr (thread-result thread))))
 700           (defaultp
 701            default)
 702           (t
 703            (error 'join-thread-error :thread thread)))))
 704
 705 (defun destroy-thread (thread)
 706   #!+sb-doc
 707   "Deprecated. Same as TERMINATE-THREAD."
 708   (terminate-thread thread))
 709
 710 (define-condition interrupt-thread-error (error)
 711   ((thread :reader interrupt-thread-error-thread :initarg :thread))
 712   #!+sb-doc
 713   (:documentation "Interrupting thread failed.")
 714   (:report (lambda (c s)
 715              (format s "Interrupt thread failed: thread ~A has exited."
 716                      (interrupt-thread-error-thread c)))))
 717
 718 #!+sb-doc
 719 (setf (fdocumentation 'interrupt-thread-error-thread 'function)
 720       "The thread that was not interrupted.")
 721
 722 (defmacro with-interruptions-lock ((thread) &body body)
 723   `(call-with-system-mutex (lambda () ,@body) (thread-interruptions-lock ,thread)))
 724
 725 ;; Called from the signal handler in C.
 726 (defun run-interruption ()
 727   (in-interruption ()
 728     (loop
 729        (let ((interruption (with-interruptions-lock (*current-thread*)
 730                              (pop (thread-interruptions *current-thread*)))))
 731          (if interruption
 732              (with-interrupts
 733                (funcall interruption))
 734              (return))))))
 735
 736 ;; The order of interrupt execution is peculiar. If thread A
 737 ;; interrupts thread B with I1, I2 and B for some reason receives I1
 738 ;; when FUN2 is already on the list, then it is FUN2 that gets to run
 739 ;; first. But when FUN2 is run SIG_INTERRUPT_THREAD is enabled again
 740 ;; and I2 hits pretty soon in FUN2 and run FUN1. This is of course
 741 ;; just one scenario, and the order of thread interrupt execution is
 742 ;; undefined.
 743 (defun interrupt-thread (thread function)
 744   #!+sb-doc
 745   "Interrupt the live THREAD and make it run FUNCTION. A moderate
 746 degree of care is expected for use of INTERRUPT-THREAD, due to its
 747 nature: if you interrupt a thread that was holding important locks
 748 then do something that turns out to need those locks, you probably
 749 won't like the effect."
 750   #!-sb-thread (declare (ignore thread))
 751   #!-sb-thread
 752   (with-interrupt-bindings
 753     (with-interrupts (funcall function)))
 754   #!+sb-thread
 755   (if (eq thread *current-thread*)
 756       (with-interrupt-bindings
 757         (with-interrupts (funcall function)))
 758       (let ((os-thread (thread-os-thread thread)))
 759         (cond ((not os-thread)
 760                (error 'interrupt-thread-error :thread thread))
 761               (t
 762                (with-interruptions-lock (thread)
 763                  (push function (thread-interruptions thread)))
 764                (when (minusp (signal-interrupt-thread os-thread))
 765                  (error 'interrupt-thread-error :thread thread)))))))
 766
 767 (defun terminate-thread (thread)
 768   #!+sb-doc
 769   "Terminate the thread identified by THREAD, by causing it to run
 770 SB-EXT:QUIT - the usual cleanup forms will be evaluated"
 771   (interrupt-thread thread 'sb!ext:quit))
 772
 773 ;;; internal use only.  If you think you need to use this, either you
 774 ;;; are an SBCL developer, are doing something that you should discuss
 775 ;;; with an SBCL developer first, or are doing something that you
 776 ;;; should probably discuss with a professional psychiatrist first
 777 #!+sb-thread
 778 (defun thread-sap-for-id (id)
 779   (let ((thread-sap (alien-sap (extern-alien "all_threads" (* t)))))
 780     (loop
 781      (when (sap= thread-sap (int-sap 0)) (return nil))
 782      (let ((os-thread (sap-ref-word thread-sap
 783                                     (* sb!vm:n-word-bytes
 784                                        sb!vm::thread-os-thread-slot))))
 785        (when (= os-thread id) (return thread-sap))
 786        (setf thread-sap
 787              (sap-ref-sap thread-sap (* sb!vm:n-word-bytes
 788                                         sb!vm::thread-next-slot)))))))
 789
 790 #!+sb-thread
 791 (defun symbol-value-in-thread (symbol thread-sap)
 792   (let* ((index (sb!vm::symbol-tls-index symbol))
 793          (tl-val (sap-ref-word thread-sap
 794                                (* sb!vm:n-word-bytes index))))
 795     (if (eql tl-val sb!vm::no-tls-value-marker-widetag)
 796         (sb!vm::symbol-global-value symbol)
 797         (make-lisp-obj tl-val))))
 798
 799 (defun sb!vm::locked-symbol-global-value-add (symbol-name delta)
 800   (sb!vm::locked-symbol-global-value-add symbol-name delta))
 801
 802 ;;; Stepping
 803
 804 (defun thread-stepping ()
 805   (make-lisp-obj
 806    (sap-ref-word (current-thread-sap)
 807                  (* sb!vm::thread-stepping-slot sb!vm:n-word-bytes))))
 808
 809 (defun (setf thread-stepping) (value)
 810   (setf (sap-ref-word (current-thread-sap)
 811                       (* sb!vm::thread-stepping-slot sb!vm:n-word-bytes))
 812         (get-lisp-obj-address value)))