1 /*
   2  * Copyright (c) 2016, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  23  */
  24 
  25 #ifndef SHARE_VM_GC_G1_G1CONCURRENTMARKOBJARRAYPROCESSOR_HPP
  26 #define SHARE_VM_GC_G1_G1CONCURRENTMARKOBJARRAYPROCESSOR_HPP
  27 
  28 #include "oops/oopsHierarchy.hpp"
  29 
  30 class G1CMTask;
  31 
  32 // Helper class to mark through large objArrays during marking in an efficient way.
  33 // Instead of pushing large object arrays, we push continuations onto the
  34 // mark stack. These continuations are identified by having their LSB set.
  35 // This allows incremental processing of large objects.
  36 class G1CMObjArrayProcessor {
  37 private:
  38   // Reference to the task for doing the actual work.
  39   G1CMTask* _task;
  40 
  41   // Push the continuation at the given address onto the mark stack.
  42   void push_array_slice(HeapWord* addr);
  43 
  44   // Process (apply the closure) on the given continuation of the given objArray.
  45   size_t process_array_slice(objArrayOop const obj, HeapWord* start_from, size_t remaining);
  46 public:
  47   static bool should_be_sliced(oop obj);
  48 
  49   G1CMObjArrayProcessor(G1CMTask* task) : _task(task) {
  50   }
  51 
  52   // Process the given continuation. Returns the number of words scanned.
  53   size_t process_slice(HeapWord* slice);
  54   // Start processing the given objArrayOop by scanning the header and pushing its
  55   // continuation.
  56   size_t process_obj(oop obj);
  57 };
  58 
  59 #endif /* SHARE_VM_GC_G1_G1CONCURRENTMARKOBJARRAYPROCESSOR_HPP */