0.8.7.46:

[sbcl.git] / src / code / gc.lisp

diff --git a/src/code/gc.lisp b/src/code/gc.lisp
index f3daccc..10f4bce 100644 (file)
--- a/src/code/gc.lisp
+++ b/src/code/gc.lisp
@@ -143,19 +143,14 @@ and submit it as a patch."
 (defvar *before-gc-hooks* nil ; actually initialized in cold init
   #!+sb-doc
   "A list of functions that are called before garbage collection occurs.
-  The functions should take no arguments.")
+  The functions are run with interrupts disabled and all other threads
+  paused.  They should take no arguments.")
 
 (defvar *after-gc-hooks* nil ; actually initialized in cold init
   #!+sb-doc
   "A list of functions that are called after garbage collection occurs.
-  The functions should take no arguments.")
-
-(defvar *gc-notify-stream* nil ; (actually initialized in cold init)
-  #!+sb-doc
-  "When non-NIL, this must be a STREAM; and the functions bound to
-  *GC-NOTIFY-BEFORE* and *GC-NOTIFY-AFTER* are called with the
-  STREAM value before and after a garbage collection occurs
-  respectively.")
+  The functions are run with interrupts disabled and all other threads
+  paused.  They should take no arguments.")
 
 (defvar *gc-run-time* 0
   #!+sb-doc
@@ -191,9 +186,6 @@ and submit it as a patch."
 (declaim (type (or index null) *gc-trigger*))
 (defvar *gc-trigger* nil)
 
-;;; When >0, inhibits garbage collection.
-(defvar *gc-inhibit*) ; initialized in cold init
-
 ;;; When T, indicates that a GC should have happened but did not due to 
 ;;; *GC-INHIBIT*. 
 (defvar *need-to-collect-garbage* nil) ; initialized in cold init
@@ -204,9 +196,14 @@ and submit it as a patch."
   (#!+gencgc last-gen #!-gencgc ignore sb!alien:int))
 
 #!+sb-thread
-(def-c-var-frob gc-thread-pid "gc_thread_pid")
+(progn
+  (sb!alien:define-alien-routine gc-stop-the-world sb!alien:void)
+  (sb!alien:define-alien-routine gc-start-the-world sb!alien:void))
+#!-sb-thread
+(progn
+  (defun gc-stop-the-world ())
+  (defun gc-start-the-world ()))
 
-       
 \f
 ;;;; SUB-GC
 
@@ -220,7 +217,8 @@ and submit it as a patch."
 
 ;;; SUB-GC does a garbage collection.  This is called from three places:
 ;;; (1) The C runtime will call here when it detects that we've consed 
-;;;     enough to exceed the gc trigger threshold
+;;;     enough to exceed the gc trigger threshold.  This is done in
+;;;     alloc() for gencgc or interrupt_maybe_gc() for cheneygc
 ;;; (2) The user may request a collection using GC, below
 ;;; (3) At the end of a WITHOUT-GCING section, we are called if
 ;;;     *NEED-TO-COLLECT-GARBAGE* is true
@@ -232,40 +230,27 @@ and submit it as a patch."
 
 ;;; For GENCGC all generations < GEN will be GC'ed.
 
-#!+sb-thread
-(defun sub-gc (&key (gen 0) &aux (pre-gc-dynamic-usage (dynamic-usage)))
-  (setf *need-to-collect-garbage* t)
-  (when (zerop *gc-inhibit*)
-    (setf (sb!alien:extern-alien "maybe_gc_pending" (sb!alien:unsigned 32))
-         (1+ gen))
-    (if (zerop (sb!alien:extern-alien "stop_the_world" (sb!alien:unsigned 32)))
-       (sb!unix:unix-kill (gc-thread-pid) :SIGALRM))
-    (loop
-     (when (zerop
-           (sb!alien:extern-alien "maybe_gc_pending" (sb!alien:unsigned 32)))
-       (return nil)))
-    (incf *n-bytes-freed-or-purified*
-         (max 0 (- pre-gc-dynamic-usage (dynamic-usage))))
-    (setf *need-to-collect-garbage* nil)
-    (scrub-control-stack))
-  (values))
+(defvar *already-in-gc* 
+  (sb!thread:make-mutex :name "GC lock") "ID of thread running SUB-GC")
 
-#!-sb-thread
-(defvar *already-in-gc* nil "System is running SUB-GC")
-#!-sb-thread
 (defun sub-gc (&key (gen 0) &aux (pre-gc-dynamic-usage (dynamic-usage)))
-  (when *already-in-gc* (return-from sub-gc nil))
-  (setf *need-to-collect-garbage* t)
-  (when (zerop *gc-inhibit*)
-    (let ((*already-in-gc* t))
-      (without-interrupts (collect-garbage gen))
-      (incf *n-bytes-freed-or-purified*
-           (max 0 (- pre-gc-dynamic-usage (dynamic-usage))))
-      (setf *need-to-collect-garbage* nil))
-    (scrub-control-stack))
-  (values))
-       
-
+  (let ((me (sb!thread:current-thread-id)))
+    (when (eql (sb!thread::mutex-value *already-in-gc*) me) 
+      (return-from sub-gc nil))
+    (setf *need-to-collect-garbage* t)
+    (when (zerop *gc-inhibit*)
+      (loop
+       (sb!thread:with-mutex (*already-in-gc*)
+        (unless *need-to-collect-garbage* (return-from sub-gc nil))
+        (without-interrupts
+         (gc-stop-the-world)
+         (collect-garbage gen)
+         (incf *n-bytes-freed-or-purified*
+               (max 0 (- pre-gc-dynamic-usage (dynamic-usage))))
+         (scrub-control-stack)
+         (setf *need-to-collect-garbage* nil)
+         (dolist (h *after-gc-hooks*) (carefully-funcall h))
+         (gc-start-the-world)))))))
 
 ;;; This is the user-advertised garbage collection function.
 (defun gc (&key (gen 0) (full nil) &allow-other-keys)