(in-package "SB!IMPL")
-(defmacro atomic-incf/symbol (symbol-name &optional (delta 1))
- #!-sb-thread
- `(incf ,symbol-name ,delta)
- #!+sb-thread
- `(locally
- (declare (optimize (safety 0) (speed 3)))
- (sb!vm::locked-symbol-global-value-add ',symbol-name ,delta)))
+;;;; these are initialized in cold init
-(defvar *gc-inhibit*) ; initialized in cold init
+(defvar *in-without-gcing*)
+(defvar *gc-inhibit*)
;;; When the dynamic usage increases beyond this amount, the system
;;; notes that a garbage collection needs to occur by setting
;;; *GC-PENDING* to T. It starts out as NIL meaning nobody has figured
;;; out what it should be yet.
-(defvar *gc-pending* nil)
+(defvar *gc-pending*)
#!+sb-thread
-(defvar *stop-for-gc-pending* nil)
+(defvar *stop-for-gc-pending*)
(defmacro without-gcing (&body body)
#!+sb-doc
- "Executes the forms in the body without doing a garbage
-collection. It inhibits both automatically and explicitly triggered
-gcs. Finally, upon leaving the BODY if gc is not inhibited it runs the
-pending gc. Similarly, if gc is triggered in another thread then it
-waits until gc is enabled in this thread."
- `(unwind-protect
- (let ((*gc-inhibit* t))
- ,@body)
- ;; the test is racy, but it can err only on the overeager side
- (when (and (not *gc-inhibit*)
- (or #!+sb-thread *stop-for-gc-pending*
- *gc-pending*))
- (sb!unix::receive-pending-interrupt))))
-
+ "Executes the forms in the body without doing a garbage collection. It
+inhibits both automatically and explicitly triggered collections. Finally,
+upon leaving the BODY if gc is not inhibited it runs the pending gc.
+Similarly, if gc is triggered in another thread then it waits until gc is
+enabled in this thread.
+
+Implies SB-SYS:WITHOUT-INTERRUPTS for BODY, and causes any nested
+SB-SYS:WITH-INTERRUPTS to signal a warning during execution of the BODY.
+
+Should be used with great care, and not at all in multithreaded application
+code: Any locks that are ever acquired while GC is inhibited need to be always
+held with GC inhibited to prevent deadlocks: if T1 holds the lock and is
+stopped for GC while T2 is waiting for the lock inside WITHOUT-GCING the
+system will be deadlocked. Since SBCL does not currently document its internal
+locks, application code can never be certain that this invariant is
+maintained."
+ (with-unique-names (without-gcing-body)
+ `(flet ((,without-gcing-body ()
+ ,@body))
+ (if *gc-inhibit*
+ (,without-gcing-body)
+ ;; We need to disable interrupts before disabling GC, so
+ ;; that signal handlers using locks don't accidentally try
+ ;; to grab them with GC inhibited.
+ (let ((*in-without-gcing* t))
+ (unwind-protect
+ (let* ((*allow-with-interrupts* nil)
+ (*interrupts-enabled* nil)
+ (*gc-inhibit* t))
+ (,without-gcing-body))
+ ;; This is not racy becuase maybe_defer_handler
+ ;; defers signals if *GC-INHIBIT* is NIL but there
+ ;; is a pending gc or stop-for-gc.
+ (when (or *interrupt-pending*
+ *gc-pending*
+ #!+sb-thread *stop-for-gc-pending*)
+ (sb!unix::receive-pending-interrupt))))))))
\f
;;; EOF-OR-LOSE is a useful macro that handles EOF.
(defmacro eof-or-lose (stream eof-error-p eof-value)
;;; This macro sets up some local vars for use by the
;;; FAST-READ-CHAR macro within the enclosed lexical scope. The stream
;;; is assumed to be a ANSI-STREAM.
+;;;
+;;; KLUDGE: Some functions (e.g. ANSI-STREAM-READ-LINE) use these variables
+;;; directly, instead of indirecting through FAST-READ-CHAR.
(defmacro prepare-for-fast-read-char (stream &body forms)
`(let* ((%frc-stream% ,stream)
(%frc-method% (ansi-stream-in %frc-stream%))
`(setf (ansi-stream-in-index %frc-stream%) %frc-index%))
;;; a macro with the same calling convention as READ-CHAR, to be used
-;;; within the scope of a PREPARE-FOR-FAST-READ-CHAR
+;;; within the scope of a PREPARE-FOR-FAST-READ-CHAR.
(defmacro fast-read-char (&optional (eof-error-p t) (eof-value ()))
`(cond
- ((not %frc-buffer%)
- (funcall %frc-method% %frc-stream% ,eof-error-p ,eof-value))
- ((= %frc-index% +ansi-stream-in-buffer-length+)
- (prog1 (fast-read-char-refill %frc-stream% ,eof-error-p ,eof-value)
- (setq %frc-index% (ansi-stream-in-index %frc-stream%))))
- (t
- (prog1 (aref %frc-buffer% %frc-index%)
- (incf %frc-index%)))))
+ ((not %frc-buffer%)
+ (funcall %frc-method% %frc-stream% ,eof-error-p ,eof-value))
+ ((= %frc-index% +ansi-stream-in-buffer-length+)
+ (multiple-value-bind (eof-p index-or-value)
+ (fast-read-char-refill %frc-stream% ,eof-error-p ,eof-value)
+ (if eof-p
+ index-or-value
+ (progn
+ (setq %frc-index% (1+ index-or-value))
+ (aref %frc-buffer% index-or-value)))))
+ (t
+ (prog1 (aref %frc-buffer% %frc-index%)
+ (incf %frc-index%)))))
;;;; And these for the fasloader...
projects / sbcl.git / blobdiff