--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/shared/suspendibleThreadSet.cpp	Fri Apr 11 12:29:24 2014 +0200
@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc_implementation/shared/suspendibleThreadSet.hpp"
+#include "runtime/mutexLocker.hpp"
+#include "runtime/thread.inline.hpp"
+
+uint   SuspendibleThreadSet::_nthreads          = 0;
+uint   SuspendibleThreadSet::_nthreads_stopped  = 0;
+bool   SuspendibleThreadSet::_suspend_all       = false;
+double SuspendibleThreadSet::_suspend_all_start = 0.0;
+
+void SuspendibleThreadSet::join() {
+  MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag);
+  while (_suspend_all) {
+    ml.wait(Mutex::_no_safepoint_check_flag);
+  }
+  _nthreads++;
+}
+
+void SuspendibleThreadSet::leave() {
+  MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag);
+  assert(_nthreads > 0, "Invalid");
+  _nthreads--;
+  if (_suspend_all) {
+    ml.notify_all();
+  }
+}
+
+void SuspendibleThreadSet::yield() {
+  if (_suspend_all) {
+    MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag);
+    if (_suspend_all) {
+      _nthreads_stopped++;
+      if (_nthreads_stopped == _nthreads) {
+        if (ConcGCYieldTimeout > 0) {
+          double now = os::elapsedTime();
+          guarantee((now - _suspend_all_start) * 1000.0 < (double)ConcGCYieldTimeout, "Long delay");
+        }
+      }
+      ml.notify_all();
+      while (_suspend_all) {
+        ml.wait(Mutex::_no_safepoint_check_flag);
+      }
+      assert(_nthreads_stopped > 0, "Invalid");
+      _nthreads_stopped--;
+      ml.notify_all();
+    }
+  }
+}
+
+void SuspendibleThreadSet::synchronize() {
+  assert(Thread::current()->is_VM_thread(), "Must be the VM thread");
+  if (ConcGCYieldTimeout > 0) {
+    _suspend_all_start = os::elapsedTime();
+  }
+  MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag);
+  assert(!_suspend_all, "Only one at a time");
+  _suspend_all = true;
+  while (_nthreads_stopped < _nthreads) {
+    ml.wait(Mutex::_no_safepoint_check_flag);
+  }
+}
+
+void SuspendibleThreadSet::desynchronize() {
+  assert(Thread::current()->is_VM_thread(), "Must be the VM thread");
+  MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag);
+  assert(_nthreads_stopped == _nthreads, "Invalid");
+  _suspend_all = false;
+  ml.notify_all();
+}