Add thread barrier abstraction.

diff --git a/src/runtime/runtime.pkg b/src/runtime/runtime.pkg
index 715eef5965bd49a010539190e785e9a3b7fe8c59..98107c5ac27465cfddf17bc8e8ab089f6c18da27 100644 (file)
--- a/src/runtime/runtime.pkg
+++ b/src/runtime/runtime.pkg
@@ -5058,6 +5058,14 @@ USA.
          thread-float-environment)
   (initialization (initialize-package!)))
 
+(define-package (runtime thread barrier)
+  (files "thread-barrier")
+  (parent (runtime thread))
+  (export ()
+         make-thread-barrier
+         thread-barrier-wait
+         thread-barrier?))
+
 (define-package (runtime thread condition-variable)
   (files "condvar")
   (parent (runtime thread))

diff --git a/src/runtime/thread-barrier.scm b/src/runtime/thread-barrier.scm
new file mode 100644 (file)
index 0000000..48a75d9
--- /dev/null
+++ b/src/runtime/thread-barrier.scm
@@ -0,0 +1,69 @@
+#| -*-Scheme-*-
+
+Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
+    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
+    2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014 Massachusetts
+    Institute of Technology
+
+This file is part of MIT/GNU Scheme.
+
+MIT/GNU Scheme is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or (at
+your option) any later version.
+
+MIT/GNU Scheme is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with MIT/GNU Scheme; if not, write to the Free Software
+Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
+USA.
+
+|#
+
+;;;; Thread barriers
+;;; package: (runtime thread barrier)
+
+(declare (usual-integrations))
+\f
+(define-structure (thread-barrier
+                  (constructor %make-thread-barrier (count current))
+                  (conc-name thread-barrier.))
+  (lock (make-thread-mutex) read-only #t)
+  (condvar (make-condition-variable) read-only #t)
+  (count #f read-only #t)
+  current
+  (generation 0))
+
+(define-guarantee thread-barrier "thread barrier")
+
+(define (make-thread-barrier count)
+  (guarantee-exact-positive-integer count 'MAKE-THREAD-BARRIER)
+  (%make-thread-barrier count count))
+
+(define (thread-barrier-wait barrier)
+  (guarantee-thread-barrier barrier 'THREAD-BARRIER-WAIT)
+  (let ((lock (thread-barrier.lock barrier))
+       (condvar (thread-barrier.condvar barrier)))
+    (with-thread-mutex-locked lock
+      (lambda ()
+       (let ((count (thread-barrier.count barrier))
+             (current (thread-barrier.current barrier))
+             (generation (thread-barrier.generation barrier)))
+         (assert (< 0 current))
+         (assert (<= current count))
+         (let ((next (- current 1)))
+           (if (zero? next)
+               (begin
+                 (set-thread-barrier.current! barrier count)
+                 (set-thread-barrier.generation! barrier (+ 1 generation))
+                 (condition-variable-broadcast! condvar)
+                 #t)
+               (begin
+                 (set-thread-barrier.current! barrier next)
+                 (do () ((< generation (thread-barrier.generation barrier)))
+                   (condition-variable-wait! condvar lock))
+                 #f))))))))
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