6711316: Open source the Garbage-First garbage collector

First mercurial integration of the code for the Garbage-First garbage collector.

Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr

hotspot/src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp

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+/*
+ * Copyright 2001-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// Forward decl
+class ConcurrentG1RefineThread;
+class G1RemSet;
+
+// What to do after a yield:
+enum PostYieldAction {
+  PYA_continue,  // Continue the traversal
+  PYA_restart,   // Restart
+  PYA_cancel     // It's been completed by somebody else: cancel.
+};
+
+class ConcurrentG1Refine {
+  ConcurrentG1RefineThread* _cg1rThread;
+
+  volatile jint _pya;
+  PostYieldAction _last_pya;
+
+  static bool _enabled;  // Protected by G1ConcRefine_mon.
+  unsigned _traversals;
+
+  // Number of cards processed during last refinement traversal.
+  unsigned _first_traversal;
+  unsigned _last_cards_during;
+
+  // The cache for card refinement.
+  bool     _use_cache;
+  bool     _def_use_cache;
+  size_t _n_periods;
+  size_t _total_cards;
+  size_t _total_travs;
+
+  unsigned char*  _card_counts;
+  unsigned _n_card_counts;
+  const jbyte* _ct_bot;
+  unsigned* _cur_card_count_histo;
+  unsigned* _cum_card_count_histo;
+  jbyte**  _hot_cache;
+  int      _hot_cache_size;
+  int      _n_hot;
+  int      _hot_cache_idx;
+
+  // Returns the count of this card after incrementing it.
+  int add_card_count(jbyte* card_ptr);
+
+  void print_card_count_histo_range(unsigned* histo, int from, int to,
+                                    float& cum_card_pct,
+                                    float& cum_travs_pct);
+ public:
+  ConcurrentG1Refine();
+  ~ConcurrentG1Refine();
+
+  void init(); // Accomplish some initialization that has to wait.
+
+  // Enabled Conc refinement, waking up thread if necessary.
+  void enable();
+
+  // Returns the number of traversals performed since this refiner was enabled.
+  unsigned disable();
+
+  // Requires G1ConcRefine_mon to be held.
+  bool enabled() { return _enabled; }
+
+  // Returns only when G1 concurrent refinement has been enabled.
+  void wait_for_ConcurrentG1Refine_enabled();
+
+  // Do one concurrent refinement pass over the card table.  Returns "true"
+  // if heuristics determine that another pass should be done immediately.
+  bool refine();
+
+  // Indicate that an in-progress refinement pass should start over.
+  void set_pya_restart();
+  // Indicate that an in-progress refinement pass should quit.
+  void set_pya_cancel();
+
+  // Get the appropriate post-yield action.  Also sets last_pya.
+  PostYieldAction get_pya();
+
+  // The last PYA read by "get_pya".
+  PostYieldAction get_last_pya();
+
+  bool do_traversal();
+
+  ConcurrentG1RefineThread* cg1rThread() { return _cg1rThread; }
+
+  // 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);
+
+  // Process the cached entries.
+  void clean_up_cache(int worker_i, G1RemSet* g1rs);
+
+  // 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();
+  void print_final_card_counts();
+};