1 /*
   2  * Copyright (c) 2002, 2013, 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
  21  * questions.
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  23  */
  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSSCAVENGE_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSSCAVENGE_HPP
  27 
  28 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp"
  29 #include "gc_implementation/parallelScavenge/psVirtualspace.hpp"
  30 #include "gc_implementation/shared/collectorCounters.hpp"
  31 #include "gc_implementation/shared/gcTrace.hpp"
  32 #include "memory/allocation.hpp"
  33 #include "oops/oop.hpp"
  34 #include "utilities/stack.hpp"
  35 
  36 class GCTaskManager;
  37 class GCTaskQueue;
  38 class OopStack;
  39 class ReferenceProcessor;
  40 class ParallelScavengeHeap;
  41 class ParallelScavengeTracer;
  42 class PSIsAliveClosure;
  43 class PSRefProcTaskExecutor;
  44 class STWGCTimer;
  45 
  46 class PSScavenge: AllStatic {
  47   friend class PSIsAliveClosure;
  48   friend class PSKeepAliveClosure;
  49   friend class PSPromotionManager;
  50 
  51  enum ScavengeSkippedCause {
  52    not_skipped = 0,
  53    to_space_not_empty,
  54    promoted_too_large,
  55    full_follows_scavenge
  56  };
  57 
  58   // Saved value of to_space->top(), used to prevent objects in to_space from
  59   // being rescanned.
  60   static HeapWord* _to_space_top_before_gc;
  61 
  62   // Number of consecutive attempts to scavenge that were skipped
  63   static int                _consecutive_skipped_scavenges;
  64 
  65 
  66  protected:
  67   // Flags/counters
  68   static ReferenceProcessor* _ref_processor;        // Reference processor for scavenging.
  69   static PSIsAliveClosure    _is_alive_closure;     // Closure used for reference processing
  70   static CardTableExtension* _card_table;           // We cache the card table for fast access.
  71   static bool                _survivor_overflow;    // Overflow this collection
  72   static uint                _tenuring_threshold;   // tenuring threshold for next scavenge
  73   static elapsedTimer        _accumulated_time;     // total time spent on scavenge
  74   static STWGCTimer          _gc_timer;             // GC time book keeper
  75   static ParallelScavengeTracer _gc_tracer;         // GC tracing
  76   static HeapWord*           _young_generation_boundary; // The lowest address possible for the young_gen.
  77                                                          // This is used to decide if an oop should be scavenged,
  78                                                          // cards should be marked, etc.
  79   static Stack<markOop, mtGC> _preserved_mark_stack; // List of marks to be restored after failed promotion
  80   static Stack<oop, mtGC>     _preserved_oop_stack;  // List of oops that need their mark restored.
  81   static CollectorCounters*      _counters;          // collector performance counters
  82 
  83   static void clean_up_failed_promotion();
  84 
  85   static bool should_attempt_scavenge();
  86 
  87   static HeapWord* to_space_top_before_gc() { return _to_space_top_before_gc; }
  88   static inline void save_to_space_top_before_gc();
  89 
  90   // Private accessors
  91   static CardTableExtension* const card_table()       { assert(_card_table != NULL, "Sanity"); return _card_table; }
  92 
  93  public:
  94   // Accessors
  95   static uint             tenuring_threshold()  { return _tenuring_threshold; }
  96   static elapsedTimer*    accumulated_time()    { return &_accumulated_time; }
  97   static int              consecutive_skipped_scavenges()
  98     { return _consecutive_skipped_scavenges; }
  99 
 100   // Performance Counters
 101   static CollectorCounters* counters()           { return _counters; }
 102 
 103   // Used by scavenge_contents && psMarkSweep
 104   static ReferenceProcessor* const reference_processor() {
 105     assert(_ref_processor != NULL, "Sanity");
 106     return _ref_processor;
 107   }
 108   // Used to add tasks
 109   static GCTaskManager* const gc_task_manager();
 110   // The promotion managers tell us if they encountered overflow
 111   static void set_survivor_overflow(bool state) {
 112     _survivor_overflow = state;
 113   }
 114   // Adaptive size policy support.  When the young generation/old generation
 115   // boundary moves, _young_generation_boundary must be reset
 116   static void set_young_generation_boundary(HeapWord* v) {
 117     _young_generation_boundary = v;
 118   }
 119 
 120   // Called by parallelScavengeHeap to init the tenuring threshold
 121   static void initialize();
 122 
 123   // Scavenge entry point.  This may invoke a full gc; return true if so.
 124   static bool invoke();
 125   // Return true if a collection was done; false otherwise.
 126   static bool invoke_no_policy();
 127 
 128   // If an attempt to promote fails, this method is invoked
 129   static void oop_promotion_failed(oop obj, markOop obj_mark);
 130 
 131   template <class T> static inline bool should_scavenge(T* p);
 132 
 133   // These call should_scavenge() above and, if it returns true, also check that
 134   // the object was not newly copied into to_space.  The version with the bool
 135   // argument is a convenience wrapper that fetches the to_space pointer from
 136   // the heap and calls the other version (if the arg is true).
 137   template <class T> static inline bool should_scavenge(T* p, MutableSpace* to_space);
 138   template <class T> static inline bool should_scavenge(T* p, bool check_to_space);
 139 
 140   template <class T, bool promote_immediately>
 141     inline static void copy_and_push_safe_barrier(PSPromotionManager* pm, T* p);
 142 
 143   static void copy_and_push_safe_barrier_from_klass(PSPromotionManager* pm, oop* p);
 144 
 145   // Is an object in the young generation
 146   // This assumes that the HeapWord argument is in the heap,
 147   // so it only checks one side of the complete predicate.
 148   inline static bool is_obj_in_young(HeapWord* o) {
 149     const bool result = (o >= _young_generation_boundary);
 150     return result;
 151   }
 152 };
 153 
 154 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSSCAVENGE_HPP