X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Ftarget-thread.lisp;h=a73ec31051e28554eab99bacc5fab0002c0772e8;hb=95591ed483dbb8c0846c129953acac1554f28809;hp=7cf305df8e5f38d27e95bd10efd00b5a84934218;hpb=a08efdfc11a98f4c7531cf67e0d4fdf5f274681f;p=sbcl.git diff --git a/src/code/target-thread.lisp b/src/code/target-thread.lisp index 7cf305d..a73ec31 100644 --- a/src/code/target-thread.lisp +++ b/src/code/target-thread.lisp @@ -37,14 +37,16 @@ read by the function THREAD-ERROR-THREAD.")) (cell-error-name condition) (thread-error-thread condition) (ecase problem - (:unbound "the symbol is unbound in thread.") - (:dead "the thread has exited.")))))) + (:unbound-in-thread "the symbol is unbound in thread.") + (:no-tls-value "the symbol has no thread-local value.") + (:thread-dead "the thread has exited.") + (:invalid-tls-value "the thread-local value is not valid.")))))) #!+sb-doc (:documentation - "Signalled when SYMBOL-VALUE-IN-THREAD or its SETF version fails due to the -symbol being unbound in target thread, or the target thread having exited. The -offending symbol can be accessed using CELL-ERROR-NAME, and the offending -thread using THREAD-ERROR-THREAD.")) + "Signalled when SYMBOL-VALUE-IN-THREAD or its SETF version fails due to eg. +the symbol not having a thread-local value, or the target thread having +exited. The offending symbol can be accessed using CELL-ERROR-NAME, and the +offending thread using THREAD-ERROR-THREAD.")) (define-condition join-thread-error (thread-error) () (:report (lambda (c s) @@ -1085,17 +1087,40 @@ SB-EXT:QUIT - the usual cleanup forms will be evaluated" sb!vm::thread-next-slot))))))) (defun %symbol-value-in-thread (symbol thread) - ;; Prevent the thread from dying completely while we look for the TLS - ;; area... + ;; Prevent the thread 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) - (values nil :unbound) - (values (make-lisp-obj tl-val) :bound))) - (values nil :dead)))) + (loop + (if (thread-alive-p thread) + (let* ((epoch sb!kernel::*gc-epoch*) + (offset (* sb!vm:n-word-bytes + (sb!vm::symbol-tls-index symbol))) + (tl-val (sap-ref-word (%thread-sap thread) offset))) + (cond ((zerop offset) + (return (values nil :no-tls-value))) + ((or (eql tl-val sb!vm:no-tls-value-marker-widetag) + (eql tl-val sb!vm:unbound-marker-widetag)) + (return (values nil :unbound-in-thread))) + (t + (multiple-value-bind (obj ok) (make-lisp-obj tl-val nil) + ;; The value we constructed may be invalid if a GC has + ;; occurred. That is harmless, though, since OBJ is + ;; either in a register or on stack, and we are + ;; conservative on both on GENCGC -- so a bogus object + ;; is safe here as long as we don't return it. If we + ;; ever port threads to a non-conservative GC we must + ;; pin the TL-VAL address before constructing OBJ, or + ;; make WITH-ALL-THREADS-LOCK imply WITHOUT-GCING. + ;; + ;; The reason we don't just rely on TL-VAL pinning the + ;; object is that the call to MAKE-LISP-OBJ may cause + ;; bignum allocation, at which point TL-VAL might not + ;; be alive anymore -- hence the epoch check. + (when (eq epoch sb!kernel::*gc-epoch*) + (if ok + (return (values obj :ok)) + (return (values obj :invalid-tls-value)))))))) + (return (values nil :thread-dead)))))) (defun %set-symbol-value-in-thread (symbol thread value) (with-pinned-objects (value) @@ -1103,17 +1128,15 @@ SB-EXT:QUIT - the usual cleanup forms will be evaluated" ;; 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))) - (cond ((eql tl-val sb!vm::no-tls-value-marker-widetag) - (values nil :unbound)) + (let ((offset (* sb!vm:n-word-bytes + (sb!vm::symbol-tls-index symbol)))) + (cond ((zerop offset) + (values nil :no-tls-value)) (t - (setf (sap-ref-word sap offset) + (setf (sap-ref-word (%thread-sap thread) offset) (get-lisp-obj-address value)) - (values value :bound)))) - (values nil :dead)))))) + (values value :ok)))) + (values nil :thread-dead)))))) (defun symbol-value-in-thread (symbol thread &optional (errorp t)) "Return the local value of SYMBOL in THREAD, and a secondary value of T @@ -1127,11 +1150,11 @@ NIL, and a secondary value of NIL. Can also be used with SETF to change the thread-local value of SYMBOL. SYMBOL-VALUE-IN-THREAD is primarily intended as a debugging tool, and not as a -mechanism form inter-thread communication." +mechanism for inter-thread communication." (declare (symbol symbol) (thread thread)) #!+sb-thread (multiple-value-bind (res status) (%symbol-value-in-thread symbol thread) - (if (eq :bound status) + (if (eq :ok status) (values res t) (if errorp (error 'symbol-value-in-thread-error @@ -1146,14 +1169,14 @@ mechanism form inter-thread communication." (error 'symbol-value-in-thread-error :name symbol :thread thread - :info (list :read :unbound)) + :info (list :read :unbound-in-thread)) (values nil nil)))) (defun (setf symbol-value-in-thread) (value symbol thread &optional (errorp t)) (declare (symbol symbol) (thread thread)) #!+sb-thread (multiple-value-bind (res status) (%set-symbol-value-in-thread symbol thread value) - (if (eq :bound status) + (if (eq :ok status) (values res t) (if errorp (error 'symbol-value-in-thread-error @@ -1168,7 +1191,7 @@ mechanism form inter-thread communication." (error 'symbol-value-in-thread-error :name symbol :thread thread - :info (list :write :unbound)) + :info (list :write :unbound-in-thread)) (values nil nil)))) (defun sb!vm::locked-symbol-global-value-add (symbol-name delta)