1 /*

     2  * Copyright (c) 2002, 2016, 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_PARALLEL_PSSCAVENGE_HPP

    26 #define SHARE_VM_GC_PARALLEL_PSSCAVENGE_HPP

    27 

    28 #include "gc/parallel/cardTableExtension.hpp"

    29 #include "gc/parallel/psVirtualspace.hpp"

    30 #include "gc/shared/collectorCounters.hpp"

    31 #include "gc/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 CollectorCounters*   _counters;             // collector performance counters

    83 

    84   static void clean_up_failed_promotion();

    85 

    86   static bool should_attempt_scavenge();

    87 

    88   static HeapWord* to_space_top_before_gc() { return _to_space_top_before_gc; }

    89   static inline void save_to_space_top_before_gc();

    90 

    91   // Private accessors

    92   static CardTableExtension* const card_table()       { assert(_card_table != NULL, "Sanity"); return _card_table; }

    93   static const ParallelScavengeTracer* gc_tracer() { return &_gc_tracer; }

    94 

    95  public:

    96   // Accessors

    97   static uint             tenuring_threshold()  { return _tenuring_threshold; }

    98   static elapsedTimer*    accumulated_time()    { return &_accumulated_time; }

    99   static int              consecutive_skipped_scavenges()

   100     { return _consecutive_skipped_scavenges; }

   101 

   102   // Performance Counters

   103   static CollectorCounters* counters()           { return _counters; }

   104 

   105   // Used by scavenge_contents && psMarkSweep

   106   static ReferenceProcessor* const reference_processor() {

   107     assert(_ref_processor != NULL, "Sanity");

   108     return _ref_processor;

   109   }

   110   // Used to add tasks

   111   static GCTaskManager* const gc_task_manager();

   112   // The promotion managers tell us if they encountered overflow

   113   static void set_survivor_overflow(bool state) {

   114     _survivor_overflow = state;

   115   }

   116   // Adaptive size policy support.  When the young generation/old generation

   117   // boundary moves, _young_generation_boundary must be reset

   118   static void set_young_generation_boundary(HeapWord* v);

   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   template <class T> static inline bool should_scavenge(T* p);

   129 

   130   // These call should_scavenge() above and, if it returns true, also check that

   131   // the object was not newly copied into to_space.  The version with the bool

   132   // argument is a convenience wrapper that fetches the to_space pointer from

   133   // the heap and calls the other version (if the arg is true).

   134   template <class T> static inline bool should_scavenge(T* p, MutableSpace* to_space);

   135   template <class T> static inline bool should_scavenge(T* p, bool check_to_space);

   136 

   137   static void copy_and_push_safe_barrier_from_klass(PSPromotionManager* pm, oop* p);

   138 

   139   // Is an object in the young generation

   140   // This assumes that the 'o' is in the heap,

   141   // so it only checks one side of the complete predicate.

   142 

   143   inline static bool is_obj_in_young(oop o) {

   144     return (HeapWord*)o >= _young_generation_boundary;

   145   }

   146 

   147   inline static bool is_obj_in_young(narrowOop o) {

   148     return (uintptr_t)o >= _young_generation_boundary_compressed;

   149   }

   150 

   151   inline static bool is_obj_in_young(HeapWord* o) {

   152     return o >= _young_generation_boundary;

   153   }

   154 };

   155 

   156 #endif // SHARE_VM_GC_PARALLEL_PSSCAVENGE_HPP