--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_implementation/shared/concurrentGCThread.hpp	Thu Jun 05 15:57:56 2008 -0700
@@ -0,0 +1,167 @@
+/*
+ * Copyright 2001-2005 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+class VoidClosure;
+
+// A SuspendibleThreadSet is (obviously) a set of threads that can be
+// suspended.  A thread can join and later leave the set, and periodically
+// yield.  If some thread (not in the set) requests, via suspend_all, that
+// the threads be suspended, then the requesting thread is blocked until
+// all the threads in the set have yielded or left the set.  (Threads may
+// not enter the set when an attempted suspension is in progress.)  The
+// suspending thread later calls resume_all, allowing the suspended threads
+// to continue.
+
+class SuspendibleThreadSet {
+  Monitor* _m;
+  int      _async;
+  bool     _async_stop;
+  int      _async_stopped;
+  bool     _initialized;
+  double   _suspend_all_start;
+
+  void initialize_work();
+
+ public:
+  SuspendibleThreadSet() : _initialized(false) {}
+
+  // Add the current thread to the set.  May block if a suspension
+  // is in progress.
+  void join();
+  // Removes the current thread from the set.
+  void leave();
+  // Returns "true" iff an suspension is in progress.
+  bool should_yield() { return _async_stop; }
+  // Suspends the current thread if a suspension is in progress (for
+  // the duration of the suspension.)
+  void yield(const char* id);
+  // Return when all threads in the set are suspended.
+  void suspend_all();
+  // Allow suspended threads to resume.
+  void resume_all();
+  // Redundant initializations okay.
+  void initialize() {
+    // Double-check dirty read idiom.
+    if (!_initialized) initialize_work();
+  }
+};
+
+
+class ConcurrentGCThread: public NamedThread {
+  friend class VMStructs;
+
+protected:
+  static bool _should_terminate;
+  static bool _has_terminated;
+
+  enum CGC_flag_type {
+    CGC_nil           = 0x0,
+    CGC_dont_suspend  = 0x1,
+    CGC_CGC_safepoint = 0x2,
+    CGC_VM_safepoint  = 0x4
+  };
+
+  static int _CGC_flag;
+
+  static bool CGC_flag_is_set(int b)       { return (_CGC_flag & b) != 0; }
+  static int set_CGC_flag(int b)           { return _CGC_flag |= b; }
+  static int reset_CGC_flag(int b)         { return _CGC_flag &= ~b; }
+
+  void stopWorldAndDo(VoidClosure* op);
+
+  // All instances share this one set.
+  static SuspendibleThreadSet _sts;
+
+  // Create and start the thread (setting it's priority high.)
+  void create_and_start();
+
+  // Do initialization steps in the thread: record stack base and size,
+  // init thread local storage, set JNI handle block.
+  void initialize_in_thread();
+
+  // Wait until Universe::is_fully_initialized();
+  void wait_for_universe_init();
+
+  // Record that the current thread is terminating, and will do more
+  // concurrent work.
+  void terminate();
+
+public:
+  // Constructor
+
+  ConcurrentGCThread();
+  ~ConcurrentGCThread() {} // Exists to call NamedThread destructor.
+
+  // Tester
+  bool is_ConcurrentGC_thread() const          { return true;       }
+
+  static void safepoint_synchronize();
+  static void safepoint_desynchronize();
+
+  // All overridings should probably do _sts::yield, but we allow
+  // overriding for distinguished debugging messages.  Default is to do
+  // nothing.
+  virtual void yield() {}
+
+  bool should_yield() { return _sts.should_yield(); }
+
+  // they are prefixed by sts since there are already yield() and
+  // should_yield() (non-static) methods in this class and it was an
+  // easy way to differentiate them.
+  static void stsYield(const char* id);
+  static bool stsShouldYield();
+  static void stsJoin();
+  static void stsLeave();
+
+};
+
+// The SurrogateLockerThread is used by concurrent GC threads for
+// manipulating Java monitors, in particular, currently for
+// manipulating the pending_list_lock. XXX
+class SurrogateLockerThread: public JavaThread {
+  friend class VMStructs;
+ public:
+  enum SLT_msg_type {
+    empty = 0,           // no message
+    acquirePLL,          // acquire pending list lock
+    releaseAndNotifyPLL  // notify and release pending list lock
+  };
+ private:
+  // the following are shared with the CMSThread
+  SLT_msg_type  _buffer;  // communication buffer
+  Monitor       _monitor; // monitor controlling buffer
+  BasicLock     _basicLock; // used for PLL locking
+
+ public:
+  static SurrogateLockerThread* make(TRAPS);
+
+  SurrogateLockerThread();
+
+  bool is_hidden_from_external_view() const     { return true; }
+
+  void loop(); // main method
+
+  void manipulatePLL(SLT_msg_type msg);
+
+};