alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (g1HotCardCache.hpp)

This example Java source code file (g1HotCardCache.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

cheapobj, current, dirtycardqueue, g1cardcounts, g1collectedheap, g1concrslogcachesize, g1hotcardcache, g1remset, heapregion, share_vm_gc_implementation_g1_g1hotcardcache_hpp, should, vmthread

The g1HotCardCache.hpp Java example source code

/*
 * Copyright (c) 2013, 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.
 *
 */

#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP

#include "gc_implementation/g1/g1_globals.hpp"
#include "gc_implementation/g1/g1CardCounts.hpp"
#include "memory/allocation.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/thread.inline.hpp"
#include "utilities/globalDefinitions.hpp"

class DirtyCardQueue;
class G1CollectedHeap;
class G1RemSet;
class HeapRegion;

// An evicting cache of cards that have been logged by the G1 post
// write barrier. Placing a card in the cache delays the refinement
// of the card until the card is evicted, or the cache is drained
// during the next evacuation pause.
//
// The first thing the G1 post write barrier does is to check whether
// the card containing the updated pointer is already dirty and, if
// so, skips the remaining code in the barrier.
//
// Delaying the refinement of a card will make the card fail the
// first is_dirty check in the write barrier, skipping the remainder
// of the write barrier.
//
// This can significantly reduce the overhead of the write barrier
// code, increasing throughput.

class G1HotCardCache: public CHeapObj<mtGC> {
  G1CollectedHeap*   _g1h;

  // The card cache table
  jbyte**      _hot_cache;

  int          _hot_cache_size;
  int          _n_hot;
  int          _hot_cache_idx;

  int          _hot_cache_par_chunk_size;
  volatile int _hot_cache_par_claimed_idx;

  bool         _use_cache;

  G1CardCounts _card_counts;

  bool default_use_cache() const {
    return (G1ConcRSLogCacheSize > 0);
  }

 public:
  G1HotCardCache(G1CollectedHeap* g1h);
  ~G1HotCardCache();

  void initialize();

  bool use_cache() { return _use_cache; }

  void set_use_cache(bool b) {
    _use_cache = (b ? default_use_cache() : false);
  }

  // Returns the card to be refined or NULL.
  //
  // Increments the count for given the card. if the card is not 'hot',
  // it is returned for immediate refining. Otherwise the card is
  // added to the hot card cache.
  // If there is enough room in the hot card cache for the card we're
  // adding, NULL is returned and no further action in needed.
  // If we evict a card from the cache to make room for the new card,
  // the evicted card is then returned for refinement.
  jbyte* insert(jbyte* card_ptr);

  // Refine the cards that have delayed as a result of
  // being in the cache.
  void drain(int worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq);

  // Set up for parallel processing of the cards in the hot cache
  void reset_hot_cache_claimed_index() {
    _hot_cache_par_claimed_idx = 0;
  }

  // Resets the hot card cache and discards the entries.
  void reset_hot_cache() {
    assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
    assert(Thread::current()->is_VM_thread(), "Current thread should be the VMthread");
    _hot_cache_idx = 0; _n_hot = 0;
  }

  bool hot_cache_is_empty() { return _n_hot == 0; }

  // Resizes the card counts table to match the given capacity
  void resize_card_counts(size_t heap_capacity);

  // Zeros the values in the card counts table for entire committed heap
  void reset_card_counts();

  // Zeros the values in the card counts table for the given region
  void reset_card_counts(HeapRegion* hr);
};

#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP

Other Java examples (source code examples)

Here is a short list of links related to this Java g1HotCardCache.hpp source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.