--- /dev/null	2013-05-02 12:20:43.000000000 -0700
+++ new/src/share/vm/gc_implementation/g1/g1HotCardCache.cpp	2013-05-02 12:20:42.810613953 -0700
@@ -0,0 +1,148 @@
+/*
+ * 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc_implementation/g1/dirtyCardQueue.hpp"
+#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
+#include "gc_implementation/g1/g1HotCardCache.hpp"
+#include "gc_implementation/g1/g1RemSet.hpp"
+#include "gc_implementation/g1/heapRegion.hpp"
+#include "runtime/atomic.hpp"
+
+G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):
+  _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {}
+  
+void G1HotCardCache::initialize() {
+  if (default_use_cache()) {
+    _use_cache = true;
+
+    _hot_cache_size = (1 << G1ConcRSLogCacheSize);
+    _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC);
+
+    _n_hot = 0;
+    _hot_cache_idx = 0;
+
+    // For refining the cards in the hot cache in parallel
+    int n_workers = (ParallelGCThreads > 0 ?
+                        _g1h->workers()->total_workers() : 1);
+    _hot_cache_par_chunk_size = MAX2(1, _hot_cache_size / n_workers);
+    _hot_cache_par_claimed_idx = 0;
+
+    _card_counts.initialize();
+  }
+}
+
+G1HotCardCache::~G1HotCardCache() {
+  if (default_use_cache()) {
+    assert(_hot_cache != NULL, "Logic");
+    FREE_C_HEAP_ARRAY(jbyte*, _hot_cache, mtGC);
+  }
+}
+
+jbyte* G1HotCardCache::insert(jbyte* card_ptr) {
+  uint count = _card_counts.add_card_count(card_ptr);
+  if (!_card_counts.is_hot(count)) {
+    // The card is not hot so do not store it in the cache;
+    // return it for immediate refining.
+    return card_ptr;
+  }
+
+  // Otherwise, the card is hot.
+  jbyte* res = NULL;
+  MutexLockerEx x(HotCardCache_lock, Mutex::_no_safepoint_check_flag);
+  if (_n_hot == _hot_cache_size) {
+    res = _hot_cache[_hot_cache_idx];
+    _n_hot--;
+  }
+
+  // Now _n_hot < _hot_cache_size, and we can insert at _hot_cache_idx.
+  _hot_cache[_hot_cache_idx] = card_ptr;
+  _hot_cache_idx++;
+
+  if (_hot_cache_idx == _hot_cache_size) {
+    // Wrap around
+    _hot_cache_idx = 0;
+  }
+  _n_hot++;
+
+  return res;
+}
+
+void G1HotCardCache::drain(int worker_i,
+                           G1RemSet* g1rs,
+                           DirtyCardQueue* into_cset_dcq) {
+  if (!default_use_cache()) {
+    assert(_hot_cache == NULL, "Logic");
+    return;
+  }
+
+  assert(_hot_cache != NULL, "Logic");
+  assert(!use_cache(), "cache should be disabled");
+  int start_idx;
+
+  while ((start_idx = _hot_cache_par_claimed_idx) < _n_hot) { // read once
+    int end_idx = start_idx + _hot_cache_par_chunk_size;
+
+    if (start_idx ==
+        Atomic::cmpxchg(end_idx, &_hot_cache_par_claimed_idx, start_idx)) {
+      // The current worker has successfully claimed the chunk [start_idx..end_idx)
+      end_idx = MIN2(end_idx, _n_hot);
+      for (int i = start_idx; i < end_idx; i++) {
+        jbyte* card_ptr = _hot_cache[i];
+        if (card_ptr != NULL) {
+          if (g1rs->refine_card(card_ptr, worker_i, true)) {
+            // The part of the heap spanned by the card contains references
+            // that point into the current collection set.
+            // We need to record the card pointer in the DirtyCardQueueSet
+            // that we use for such cards.
+            //
+            // The only time we care about recording cards that contain
+            // references that point into the collection set is during
+            // RSet updating while within an evacuation pause.
+            // In this case worker_i should be the id of a GC worker thread
+            assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
+            assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads),
+                   err_msg("incorrect worker id: "INT32_FORMAT, worker_i));
+
+            into_cset_dcq->enqueue(card_ptr);
+          }
+        }
+      }
+    }
+  }
+  // The existing entries in the hot card cache, which were just refined
+  // above, are discarded prior to re-enabling the cache near the end of the GC.
+}
+
+void G1HotCardCache::resize_card_counts(size_t heap_capacity) {
+  _card_counts.resize(heap_capacity);
+}
+
+void G1HotCardCache::reset_card_counts(HeapRegion* hr) {
+  _card_counts.clear_region(hr);
+}
+
+void G1HotCardCache::reset_card_counts() {
+  _card_counts.clear_all();
+}