1 (in-package "SB!THREAD")
3 (sb!alien::define-alien-routine ("create_thread" %create-thread)
5 (lisp-fun-address sb!alien:unsigned-long))
7 (defun make-thread (function)
8 (let ((real-function (coerce function 'function)))
10 (sb!kernel:get-lisp-obj-address
12 ;; in time we'll move some of the binding presently done in C
14 (let ((sb!kernel::*restart-clusters* nil)
15 (sb!impl::*descriptor-handlers* nil); serve-event
16 (sb!impl::*available-buffers* nil)) ;for fd-stream
17 ;; can't use handling-end-of-the-world, because that flushes
18 ;; output streams, and we don't necessarily have any (or we
19 ;; could be sharing them)
20 (sb!sys:enable-interrupt :sigint :ignore)
22 (catch 'sb!impl::%end-of-the-world
25 (format nil "~~@<Destroy this thread (~A)~~@:>"
27 (funcall real-function))
30 (defun destroy-thread (thread-id)
31 (sb!unix:unix-kill thread-id :sigterm)
32 ;; may have been stopped for some reason, so now wake it up to
34 (sb!unix:unix-kill thread-id :sigcont))
36 ;; Conventional wisdom says that it's a bad idea to use these unless
37 ;; you really need to. Use a lock or a waitqueue instead
38 (defun suspend-thread (thread-id)
39 (sb!unix:unix-kill thread-id :sigstop))
40 (defun resume-thread (thread-id)
41 (sb!unix:unix-kill thread-id :sigcont))
43 (defun current-thread-id ()
45 (sb!vm::current-thread-offset-sap sb!vm::thread-pid-slot)))
47 ;;;; iterate over the in-memory threads
49 (defun mapcar-threads (function)
50 "Call FUNCTION once for each known thread, giving it the thread structure as argument"
51 (let ((function (coerce function 'function)))
52 (loop for thread = (alien-sap (extern-alien "all_threads" (* t)))
53 then (sb!sys:sap-ref-sap thread (* 4 sb!vm::thread-next-slot))
54 until (sb!sys:sap= thread (sb!sys:int-sap 0))
55 collect (funcall function thread))))
59 ;; spinlocks use 0 as "free" value: higher-level locks use NIL
60 (defun get-spinlock (lock offset new-value)
61 (declare (optimize (speed 3) (safety 0)))
63 (eql (sb!vm::%instance-set-conditional lock offset 0 new-value) 0)))
65 (defmacro with-spinlock ((queue) &body body)
66 (with-unique-names (pid)
68 (let ((,pid (current-thread-id)))
69 (get-spinlock ,queue 2 ,pid)
71 (setf (waitqueue-lock ,queue) 0))))
73 ;;;; the higher-level locking operations are based on waitqueues
76 (name nil :type (or null simple-base-string))
80 (defstruct (mutex (:include waitqueue))
83 (sb!alien:define-alien-routine "block_sigcont" void)
84 (sb!alien:define-alien-routine "unblock_sigcont_and_sleep" void)
86 ;;; this should only be called while holding the queue spinlock.
87 ;;; it releases the spinlock before sleeping
88 (defun wait-on-queue (queue &optional lock)
89 (let ((pid (current-thread-id)))
90 ;; FIXME what should happen if we get interrupted when we've blocked
91 ;; the sigcont? For that matter, can we get interrupted?
93 (when lock (release-mutex lock))
94 (sb!sys:without-interrupts
95 (pushnew pid (waitqueue-data queue)))
96 (setf (waitqueue-lock queue) 0)
97 (unblock-sigcont-and-sleep)))
99 ;;; this should only be called while holding the queue spinlock. It doesn't
101 (defun dequeue (queue)
102 (let ((pid (current-thread-id)))
103 (sb!sys:without-interrupts
104 (setf (waitqueue-data queue)
105 (delete pid (waitqueue-data queue))))))
107 ;;; this should probably only be called while holding the queue spinlock.
109 (defun signal-queue-head (queue)
110 (let ((p (car (waitqueue-data queue))))
111 (when p (sb!unix:unix-kill p :sigcont))))
115 (defun get-mutex (lock &optional new-value (wait-p t))
116 (declare (type mutex lock))
117 (let ((pid (current-thread-id)))
118 (unless new-value (setf new-value pid))
119 (assert (not (eql new-value (mutex-value lock))))
120 (get-spinlock lock 2 pid)
123 ;; args are object slot-num old-value new-value
124 (sb!vm::%instance-set-conditional lock 4 nil new-value)
126 (setf (waitqueue-lock lock) 0)
129 (setf (waitqueue-lock lock) 0)
131 (wait-on-queue lock nil))))
133 (defun release-mutex (lock &optional (new-value nil))
134 (declare (type mutex lock))
135 ;; we assume the lock is ours to release
136 (with-spinlock (lock)
137 (setf (mutex-value lock) new-value)
138 (signal-queue-head lock)))
141 (defmacro with-mutex ((mutex &key value (wait-p t)) &body body)
142 (with-unique-names (got)
143 `(let ((,got (get-mutex ,mutex ,value ,wait-p)))
147 (release-mutex ,mutex))))))
150 ;;;; condition variables
152 (defun condition-wait (queue lock)
153 "Atomically release LOCK and enqueue ourselves on QUEUE. Another
154 thread may subsequently notify us using CONDITION-NOTIFY, at which
155 time we reacquire LOCK and return to the caller."
158 (get-spinlock queue 2 (current-thread-id))
159 (wait-on-queue queue lock))
160 ;; If we are interrupted while waiting, we should do these things
161 ;; before returning. Ideally, in the case of an unhandled signal,
162 ;; we should do them before entering the debugger, but this is
163 ;; better than nothing.
164 (with-spinlock (queue)
168 (defun condition-notify (queue)
169 "Notify one of the processes waiting on QUEUE"
170 (signal-queue-head queue))
173 ;;;; multiple independent listeners
175 (defvar *session-lock* nil)
177 (defun make-listener-thread (tty-name)
178 (assert (probe-file tty-name))
179 ;; FIXME probably still need to do some tty stuff to get signals
180 ;; delivered correctly.
182 (let* ((in (sb!unix:unix-open (namestring tty-name) sb!unix:o_rdwr #o666))
183 (out (sb!unix:unix-dup in))
184 (err (sb!unix:unix-dup in)))
185 (labels ((thread-repl ()
186 (sb!unix::unix-setsid)
187 (let* ((*session-lock*
188 (make-mutex :name (format nil "lock for ~A" tty-name)))
190 (sb!sys:make-fd-stream in :input t :buffering :line))
192 (sb!sys:make-fd-stream out :output t :buffering :line))
194 (sb!sys:make-fd-stream err :output t :buffering :line))
196 (sb!sys:make-fd-stream err :input t :output t :buffering :line))
197 (sb!impl::*descriptor-handlers* nil))
198 (get-mutex *session-lock*)
199 (sb!sys:enable-interrupt :sigint #'sb!unix::sigint-handler)
201 (sb!impl::toplevel-repl nil)
202 (sb!int:flush-standard-output-streams)))))
203 (make-thread #'thread-repl))))
207 (defvar *background-threads-wait-for-debugger* t)
208 ;;; may be T, NIL, or a function called with a stream and thread id
209 ;;; as its two arguments, returning NIl or T
211 ;;; called from top of invoke-debugger
212 (defun debugger-wait-until-foreground-thread (stream)
213 "Returns T if thread had been running in background, NIL if it was
214 already the foreground thread, or transfers control to the first applicable
215 restart if *BACKGROUND-THREADS-WAIT-FOR-DEBUGGER* says to do that instead"
216 (let* ((wait-p *background-threads-wait-for-debugger*)
217 (*background-threads-wait-for-debugger* nil)
218 (lock *session-lock*))
219 (when (not (eql (mutex-value lock) (CURRENT-THREAD-ID)))
220 (when (functionp wait-p)
222 (funcall wait-p stream (CURRENT-THREAD-ID))))
223 (cond (wait-p (get-foreground))
224 (t (invoke-restart (car (compute-restarts))))))))
226 ;;; install this with (setf SB!INT:*REPL-PROMPT-FUN* #'thread-prompt-fun)
227 ;;; One day it will be default
228 (defun thread-repl-prompt-fun (out-stream)
229 (let ((lock *session-lock*))
231 (let ((stopped-threads (waitqueue-data lock)))
232 (when stopped-threads
233 (format out-stream "~{~&Thread ~A suspended~}~%" stopped-threads))
234 (sb!impl::repl-prompt-fun out-stream))))
236 (defun resume-stopped-thread (id)
237 (let ((pid (current-thread-id))
238 (lock *session-lock*))
239 (with-spinlock (lock)
240 (setf (waitqueue-data lock)
241 (cons id (delete id (waitqueue-data lock)))))
242 (release-foreground)))
245 (name nil :type (or null simple-base-string))
246 (value 0 :type fixnum)
247 (max-readers nil :type (or fixnum null))
248 (max-writers 1 :type fixnum))
251 ((make-rwlocking-function (lock-fn unlock-fn increment limit test)
252 (let ((do-update '(when (eql old-value
253 (sb!vm::%instance-set-conditional
254 lock 2 old-value new-value))
255 (return (values t old-value))))
256 (vars `((timeout (and timeout (+ (get-internal-real-time) timeout)))
260 (labels ((do-setfs (v) `(setf old-value (rwlock-value lock)
261 new-value (,v old-value ,increment))))
263 (defun ,lock-fn (lock timeout)
264 (declare (type rwlock lock))
270 (when (sleep-a-bit timeout) (return nil)) ;expired
272 ;; unlock doesn't need timeout or test-in-range
273 (defun ,unlock-fn (lock)
274 (declare (type rwlock lock))
275 (declare (ignorable limit))
281 (make-rwlocking-function %lock-for-reading %unlock-for-reading 1
282 (rwlock-max-readers lock)
283 (and (>= old-value 0)
284 (or (null limit) (<= new-value limit))))
285 (make-rwlocking-function %lock-for-writing %unlock-for-writing -1
286 (- (rwlock-max-writers lock))
287 (and (<= old-value 0)
288 (>= new-value limit))))
290 (defun get-rwlock (lock direction &optional timeout)
292 (:read (%lock-for-reading lock timeout))
293 (:write (%lock-for-writing lock timeout))))
295 (defun free-rwlock (lock direction)
297 (:read (%unlock-for-reading lock))
298 (:write (%unlock-for-writing lock))))
300 ;;;; beyond this point all is commented.
302 ;;; Lock-Wait-With-Timeout -- Internal
304 ;;; Wait with a timeout for the lock to be free and acquire it for the
305 ;;; *current-process*.
308 (defun lock-wait-with-timeout (lock whostate timeout)
309 (declare (type lock lock))
310 (process-wait-with-timeout
313 (declare (optimize (speed 3)))
315 (unless (lock-process lock)
316 (setf (lock-process lock) *current-process*))
318 (null (kernel:%instance-set-conditional
319 lock 2 nil *current-process*)))))
321 ;;; With-Lock-Held -- Public
324 (defmacro with-lock-held ((lock &optional (whostate "Lock Wait")
325 &key (wait t) timeout)
327 "Execute the body with the lock held. If the lock is held by another
328 process then the current process waits until the lock is released or
329 an optional timeout is reached. The optional wait timeout is a time in
330 seconds acceptable to process-wait-with-timeout. The results of the
331 body are return upon success and NIL is return if the timeout is
332 reached. When the wait key is NIL and the lock is held by another
333 process then NIL is return immediately without processing the body."
334 (let ((have-lock (gensym)))
335 `(let ((,have-lock (eq (lock-process ,lock) *current-process*)))
337 ,(cond ((and timeout wait)
339 (when (and (error-check-lock-p ,lock) ,have-lock)
342 #+i486 (null (kernel:%instance-set-conditional
343 ,lock 2 nil *current-process*))
344 #-i486 (seize-lock ,lock)
346 (lock-wait-with-timeout
347 ,lock ,whostate ,timeout)
348 (lock-wait ,lock ,whostate)))
352 (when (and (error-check-lock-p ,lock) ,have-lock)
354 (unless (or ,have-lock
355 #+i486 (null (kernel:%instance-set-conditional
356 ,lock 2 nil *current-process*))
357 #-i486 (seize-lock ,lock))
358 (lock-wait ,lock ,whostate))
361 `(when (or (and (recursive-lock-p ,lock) ,have-lock)
362 #+i486 (null (kernel:%instance-set-conditional
363 ,lock 2 nil *current-process*))
364 #-i486 (seize-lock ,lock))
367 #+i486 (kernel:%instance-set-conditional
368 ,lock 2 *current-process* nil)
369 #-i486 (when (eq (lock-process ,lock) *current-process*)
370 (setf (lock-process ,lock) nil)))))))