8048949: Requeue queue implementation

Summary: devirtualize flush and move calls
Reviewed-by: brutisso, tschatzl, mschoene
Contributed-by: kim.barrett@oracle.com

src/share/vm/gc_implementation/g1/dirtyCardQueue.hpp

 /*
- * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 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
@@ -47,6 +47,13 @@ public:
     // active field set to true.
     PtrQueue(qset_, perm, true /* active */) { }
 
+  // Flush before destroying; queue may be used to capture pending work while
+  // doing something else, with auto-flush on completion.
+  ~DirtyCardQueue() { if (!is_permanent()) flush(); }
+
+  // Process queue entries and release resources.
+  void flush() { flush_impl(); }
+
   // Apply the closure to all elements, and reset the index to make the
   // buffer empty.  If a closure application returns "false", return
   // "false" immediately, halting the iteration.  If "consume" is true,

src/share/vm/gc_implementation/g1/ptrQueue.cpp

 /*
- * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 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
@@ -31,11 +31,15 @@
 #include "runtime/thread.inline.hpp"
 
 PtrQueue::PtrQueue(PtrQueueSet* qset, bool perm, bool active) :
-  _qset(qset), _buf(NULL), _index(0), _active(active),
+  _qset(qset), _buf(NULL), _index(0), _sz(0), _active(active),
   _perm(perm), _lock(NULL)
 {}
 
-void PtrQueue::flush() {
+PtrQueue::~PtrQueue() {
+  assert(_perm || (_buf == NULL), "queue must be flushed before delete");
+}
+
+void PtrQueue::flush_impl() {
   if (!_perm && _buf != NULL) {
     if (_index == _sz) {
       // No work to do.

src/share/vm/gc_implementation/g1/ptrQueue.hpp

 /*
- * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 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
@@ -65,15 +65,18 @@ protected:
   Mutex* _lock;
 
   PtrQueueSet* qset() { return _qset; }
+  bool is_permanent() const { return _perm; }
+
+  // Process queue entries and release resources, if not permanent.
+  void flush_impl();
 
 public:
   // Initialize this queue to contain a null buffer, and be part of the
   // given PtrQueueSet.
   PtrQueue(PtrQueueSet* qset, bool perm = false, bool active = false);
-  // Release any contained resources.
-  virtual void flush();
-  // Calls flush() when destroyed.
-  ~PtrQueue() { flush(); }
+
+  // Requires queue flushed or permanent.
+  ~PtrQueue();
 
   // Associate a lock with a ptr queue.
   void set_lock(Mutex* lock) { _lock = lock; }

src/share/vm/gc_implementation/g1/satbQueue.cpp

@@ -39,7 +39,7 @@ void ObjPtrQueue::flush() {
   // first before we flush it, otherwise we might end up with an
   // enqueued buffer with refs into the CSet which breaks our invariants.
   filter();
-  PtrQueue::flush();
+  flush_impl();
 }
 
 // This method removes entries from an SATB buffer that will not be

src/share/vm/gc_implementation/g1/satbQueue.hpp

 /*
- * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 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
@@ -58,9 +58,8 @@ public:
     // field to true. This is done in JavaThread::initialize_queues().
     PtrQueue(qset, perm, false /* active */) { }
 
-  // Overrides PtrQueue::flush() so that it can filter the buffer
-  // before it is flushed.
-  virtual void flush();
+  // Process queue entries and free resources.
+  void flush();
 
   // Overrides PtrQueue::should_enqueue_buffer(). See the method's
   // definition for more information.