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.
  22  *
  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   // 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 HeapWord*            _young_generation_boundary;
  80   // Used to optimize compressed oops young gen boundary checking.
  81   static uintptr_t            _young_generation_boundary_compressed;
  82   static Stack<markOop, mtGC> _preserved_mark_stack; // List of marks to be restored after failed promotion
  83   static Stack<oop, mtGC>     _preserved_oop_stack;  // List of oops that need their mark restored.
  84   static CollectorCounters*   _counters;             // collector performance counters
  85 
  86   static void clean_up_failed_promotion();
  87 
  88   static bool should_attempt_scavenge();
  89 
  90   static HeapWord* to_space_top_before_gc() { return _to_space_top_before_gc; }
  91   static inline void save_to_space_top_before_gc();
  92 
  93   // Private accessors
  94   static CardTableExtension* const card_table()       { assert(_card_table != NULL, "Sanity"); return _card_table; }
  95   static const ParallelScavengeTracer* gc_tracer() { return &_gc_tracer; }
  96 
  97  public:
  98   // Accessors
  99   static uint             tenuring_threshold()  { return _tenuring_threshold; }
 100   static elapsedTimer*    accumulated_time()    { return &_accumulated_time; }
 101   static int              consecutive_skipped_scavenges()
 102     { return _consecutive_skipped_scavenges; }
 103 
 104   // Performance Counters
 105   static CollectorCounters* counters()           { return _counters; }
 106 
 107   // Used by scavenge_contents && psMarkSweep
 108   static ReferenceProcessor* const reference_processor() {
 109     assert(_ref_processor != NULL, "Sanity");
 110     return _ref_processor;
 111   }
 112   // Used to add tasks
 113   static GCTaskManager* const gc_task_manager();
 114   // The promotion managers tell us if they encountered overflow
 115   static void set_survivor_overflow(bool state) {
 116     _survivor_overflow = state;
 117   }
 118   // Adaptive size policy support.  When the young generation/old generation
 119   // boundary moves, _young_generation_boundary must be reset
 120   static void set_young_generation_boundary(HeapWord* v) {
 121     _young_generation_boundary = v;
 122     if (UseCompressedOops) {
 123       _young_generation_boundary_compressed = (uintptr_t)oopDesc::encode_heap_oop((oop)v);
 124     }
 125   }
 126 
 127   // Called by parallelScavengeHeap to init the tenuring threshold
 128   static void initialize();
 129 
 130   // Scavenge entry point.  This may invoke a full gc; return true if so.
 131   static bool invoke();
 132   // Return true if a collection was done; false otherwise.
 133   static bool invoke_no_policy();
 134 
 135   // If an attempt to promote fails, this method is invoked
 136   static void oop_promotion_failed(oop obj, markOop obj_mark);
 137 
 138   template <class T> static inline bool should_scavenge(T* p);
 139 
 140   // These call should_scavenge() above and, if it returns true, also check that
 141   // the object was not newly copied into to_space.  The version with the bool
 142   // argument is a convenience wrapper that fetches the to_space pointer from
 143   // the heap and calls the other version (if the arg is true).
 144   template <class T> static inline bool should_scavenge(T* p, MutableSpace* to_space);
 145   template <class T> static inline bool should_scavenge(T* p, bool check_to_space);
 146 
 147   static void copy_and_push_safe_barrier_from_klass(PSPromotionManager* pm, oop* p);
 148 
 149   // Is an object in the young generation
 150   // This assumes that the 'o' is in the heap,
 151   // so it only checks one side of the complete predicate.
 152 
 153   inline static bool is_obj_in_young(oop o) {
 154     return (HeapWord*)o >= _young_generation_boundary;
 155   }
 156 
 157   inline static bool is_obj_in_young(narrowOop o) {
 158     return (uintptr_t)o >= _young_generation_boundary_compressed;
 159   }
 160 
 161   inline static bool is_obj_in_young(HeapWord* o) {
 162     return o >= _young_generation_boundary;
 163   }
 164 };
 165 
 166 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSSCAVENGE_HPP