--- /dev/null	2017-03-05 16:31:28.352698584 -0500
+++ new/src/share/vm/gc/shenandoah/shenandoahPhaser.hpp	2017-03-13 09:18:25.113584610 -0400
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2017, Red Hat, Inc. and/or its affiliates.
+ *
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAH_PHASER_HPP
+#define SHARE_VM_GC_SHENANDOAH_SHENANDOAH_PHASER_HPP
+
+#include "memory/allocation.hpp"
+
+/**
+ * This is an implementation of simplified java.util.concurrent.Phaser
+ */
+
+class ShenandoahPhaser : public CHeapObj<mtGC> {
+private:
+  enum {
+    MAX_PARTIES     = 0xffff,
+    MAX_PHASE       = 2147483647,
+    PARTIES_SHIFT   = 16,
+    PHASE_SHIFT     = 32,
+    ONE_ARRIVAL     = 1,
+    ONE_PARTY       = 1 << PARTIES_SHIFT,
+    ONE_DEREGISTER  = ONE_ARRIVAL|ONE_PARTY,
+    EMPTY           = 1
+  };
+
+  static const jlong PARTIES_MARK     = 0xffff0000L;
+  static const jlong UNARRIVED_MASK   = 0x0000ffffL;
+  static const jlong COUNTS_MARK      = 0xffffffffL;
+  static const jlong TERMINATION_BIT  = 1L << 63;
+  
+private:
+  volatile  jlong  _state;
+
+public:
+  ShenandoahPhaser(int parties = 1);
+
+  inline int register_party() { return do_register(1); }  
+
+  inline bool is_terminated() const { return _state < 0L; }
+
+  int arrive() { return do_arrive(ONE_ARRIVAL); }
+  int arriveAndAwaitAdvance();
+  int arriveAndDeregister() { return do_arrive(ONE_DEREGISTER); }
+ 
+  inline int  get_registered_parties() const {
+    return parties_of(_state);
+  }
+
+  inline int get_arrived_parties() const {
+    return arrived_of(_state);
+  }
+
+protected:
+  // Termination condition 
+  virtual bool onAdvance(int phase, int registeredParties) = 0;
+  
+  // barrier
+  virtual int  blockWaiters(int phase) = 0;
+  virtual void releaseWaiters(int phase) = 0;
+
+private:
+  int do_register(int registrations);
+  int do_arrive(int adjust);
+
+  inline int parties_of(jlong s) const { return (int)((unsigned jlong)s & PARTIES_MARK) >> PARTIES_SHIFT; }
+  inline int phase_of(jlong s)   const { return (int)(s >> PHASE_SHIFT); }
+  inline int arrived_of(jlong s) const {
+    int counts = (int)s;
+    return (counts == EMPTY) ? 0 :
+      (int)(((unsigned int)counts) >> PARTIES_SHIFT) - (counts & UNARRIVED_MASK);
+  }
+  inline int unarrived_of(jlong s) const {
+    int counts = (int)s;
+    return (counts == EMPTY) ? 0 : (counts & UNARRIVED_MASK);
+  }
+
+};
+
+#endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAH_PHASER_HPP
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