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 /*

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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * 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

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 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP

 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP

 #include "memory/allocation.hpp"

 #include "memory/cardTableModRefBS.hpp"

 #include "runtime/thread.hpp"

 #include "utilities/globalDefinitions.hpp"

 // Forward decl

 class ConcurrentG1RefineThread;

 class G1RemSet;

 class ConcurrentG1Refine: public CHeapObj<mtGC> {

   ConcurrentG1RefineThread** _threads;

   int _n_threads;

   int _n_worker_threads;

  /*

   * The value of the update buffer queue length falls into one of 3 zones:

   * green, yellow, red. If the value is in [0, green) nothing is

   * done, the buffers are left unprocessed to enable the caching effect of the

   * dirtied cards. In the yellow zone [green, yellow) the concurrent refinement

   * threads are gradually activated. In [yellow, red) all threads are

   * running. If the length becomes red (max queue length) the mutators start

   * processing the buffers.

   *

   * There are some interesting cases (when G1UseAdaptiveConcRefinement

   * is turned off):

   * 1) green = yellow = red = 0. In this case the mutator will process all

   *    buffers. Except for those that are created by the deferred updates

   *    machinery during a collection.

   * 2) green = 0. Means no caching. Can be a good way to minimize the

   *    amount of time spent updating rsets during a collection.

   */

   int _green_zone;

   int _yellow_zone;

   int _red_zone;

   int _thread_threshold_step;

   // Reset the threshold step value based of the current zone boundaries.

   void reset_threshold_step();

   // The cache for card refinement.

   bool   _use_cache;

   bool   _def_use_cache;

   size_t _n_periods;    // Used as clearing epoch

   // An evicting cache of the number of times each card

   // is accessed. Reduces, but does not eliminate, the amount

   // of duplicated processing of dirty cards.

   enum SomePrivateConstants {

     epoch_bits           = 32,

     card_num_shift       = epoch_bits,

     epoch_mask           = AllBits,

     card_num_mask        = AllBits,

     // The initial cache size is approximately this fraction

     // of a maximal cache (i.e. the size needed for all cards

     // in the heap)

     InitialCacheFraction = 512

   };

   const static julong card_num_mask_in_place =

                         (julong) card_num_mask << card_num_shift;

   typedef struct {

     julong _value;      // |  card_num   |  epoch   |

   } CardEpochCacheEntry;

   julong make_epoch_entry(unsigned int card_num, unsigned int epoch) {

     assert(0 <= card_num && card_num < _max_cards, "Bounds");

     assert(0 <= epoch && epoch <= _n_periods, "must be");

     return ((julong) card_num << card_num_shift) | epoch;

   }

   unsigned int extract_epoch(julong v) {

     return (v & epoch_mask);

   }

   unsigned int extract_card_num(julong v) {

     return (v & card_num_mask_in_place) >> card_num_shift;

   }

   typedef struct {

     unsigned char _count;

     unsigned char _evict_count;

   } CardCountCacheEntry;

   CardCountCacheEntry* _card_counts;

   CardEpochCacheEntry* _card_epochs;

   // The current number of buckets in the card count cache

   size_t _n_card_counts;

   // The number of cards for the entire reserved heap

   size_t _max_cards;

   // The max number of buckets for the card counts and epochs caches.

   // This is the maximum that the counts and epochs will grow to.

   // It is specified as a fraction or percentage of _max_cards using

   // G1MaxHotCardCountSizePercent.

   size_t _max_n_card_counts;

   // Possible sizes of the cache: odd primes that roughly double in size.

   // (See jvmtiTagMap.cpp).

   enum {

     MAX_CC_CACHE_INDEX = 15    // maximum index into the cache size array.

   };

   static size_t _cc_cache_sizes[MAX_CC_CACHE_INDEX];

   // The index in _cc_cache_sizes corresponding to the size of

   // _card_counts.

   int _cache_size_index;

   bool _expand_card_counts;

   const jbyte* _ct_bot;

   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;

   // Needed to workaround 6817995

   CardTableModRefBS* _ct_bs;

   G1CollectedHeap*   _g1h;

   // Helper routine for expand_card_count_cache().

   // The arrays used to hold the card counts and the epochs must have

   // a 1:1 correspondence. Hence they are allocated and freed together.

   // Returns true if the allocations of both the counts and epochs

   // were successful; false otherwise.

   bool allocate_card_count_cache(size_t n,

                                  CardCountCacheEntry** counts,

                                  CardEpochCacheEntry** epochs);

   // Expands the arrays that hold the card counts and epochs

   // to the cache size at index. Returns true if the expansion/

   // allocation was successful; false otherwise.

   bool expand_card_count_cache(int index);

   // hash a given key (index of card_ptr) with the specified size

   static unsigned int hash(size_t key, size_t size) {

     return (unsigned int) (key % size);

   }

   // hash a given key (index of card_ptr)

   unsigned int hash(size_t key) {

     return hash(key, _n_card_counts);

   }

   unsigned int ptr_2_card_num(jbyte* card_ptr) {

     return (unsigned int) (card_ptr - _ct_bot);

   }

   jbyte* card_num_2_ptr(unsigned int card_num) {

     return (jbyte*) (_ct_bot + card_num);

   }

   // Returns the count of this card after incrementing it.

   jbyte* add_card_count(jbyte* card_ptr, int* count, bool* defer);

   // Returns true if this card is in a young region

   bool is_young_card(jbyte* card_ptr);

  public:

   ConcurrentG1Refine();

   ~ConcurrentG1Refine();

   void init(); // Accomplish some initialization that has to wait.

   void stop();

   void reinitialize_threads();

   // Iterate over the conc refine threads

   void threads_do(ThreadClosure *tc);

   // If this is the first entry for the slot, writes into the cache and

   // returns NULL.  If it causes an eviction, returns the evicted pointer.

   // Otherwise, its a cache hit, and returns NULL.

   jbyte* cache_insert(jbyte* card_ptr, bool* defer);

   // Process the cached entries.

   void clean_up_cache(int worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq);

   // Set up for parallel processing of the cards in the hot cache

   void clear_hot_cache_claimed_index() {

     _hot_cache_par_claimed_idx = 0;

   }

   // Discard entries in the hot cache.

   void clear_hot_cache() {

     _hot_cache_idx = 0; _n_hot = 0;

   }

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

   bool use_cache() { return _use_cache; }

   void set_use_cache(bool b) {

     if (b) _use_cache = _def_use_cache;

     else   _use_cache = false;

   }

   void clear_and_record_card_counts();

   static int thread_num();

   void print_worker_threads_on(outputStream* st) const;

   void set_green_zone(int x)  { _green_zone = x;  }

   void set_yellow_zone(int x) { _yellow_zone = x; }

   void set_red_zone(int x)    { _red_zone = x;    }

   int green_zone() const      { return _green_zone;  }

   int yellow_zone() const     { return _yellow_zone; }

   int red_zone() const        { return _red_zone;    }

   int total_thread_num() const  { return _n_threads;        }

   int worker_thread_num() const { return _n_worker_threads; }

   int thread_threshold_step() const { return _thread_threshold_step; }

 };

 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP