1 /*

     2  * Copyright (c) 2001, 2015, 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

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    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

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    24 

    25 #ifndef SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP

    26 #define SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP

    27 

    28 #include "gc/shared/barrierSet.hpp"

    29 #include "gc/shared/genRemSet.hpp"

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

    31 #include "memory/allocation.hpp"

    32 #include "utilities/macros.hpp"

    33 

    34 // This class (or more correctly, subtypes of this class)

    35 // are used to define global garbage collector attributes.

    36 // This includes initialization of generations and any other

    37 // shared resources they may need.

    38 //

    39 // In general, all flag adjustment and validation should be

    40 // done in initialize_flags(), which is called prior to

    41 // initialize_size_info().

    42 //

    43 // This class is not fully developed yet. As more collector(s)

    44 // are added, it is expected that we will come across further

    45 // behavior that requires global attention. The correct place

    46 // to deal with those issues is this class.

    47 

    48 // Forward declarations.

    49 class GenCollectorPolicy;

    50 class AdaptiveSizePolicy;

    51 #if INCLUDE_ALL_GCS

    52 class ConcurrentMarkSweepPolicy;

    53 class G1CollectorPolicy;

    54 #endif // INCLUDE_ALL_GCS

    55 

    56 class GCPolicyCounters;

    57 class MarkSweepPolicy;

    58 

    59 class CollectorPolicy : public CHeapObj<mtGC> {

    60  protected:

    61   GCPolicyCounters* _gc_policy_counters;

    62 

    63   virtual void initialize_alignments() = 0;

    64   virtual void initialize_flags();

    65   virtual void initialize_size_info();

    66 

    67   DEBUG_ONLY(virtual void assert_flags();)

    68   DEBUG_ONLY(virtual void assert_size_info();)

    69 

    70   size_t _initial_heap_byte_size;

    71   size_t _max_heap_byte_size;

    72   size_t _min_heap_byte_size;

    73 

    74   size_t _space_alignment;

    75   size_t _heap_alignment;

    76 

    77   // Needed to keep information if MaxHeapSize was set on the command line

    78   // when the flag value is aligned etc by ergonomics.

    79   bool _max_heap_size_cmdline;

    80 

    81   // The sizing of the heap is controlled by a sizing policy.

    82   AdaptiveSizePolicy* _size_policy;

    83 

    84   // Set to true when policy wants soft refs cleared.

    85   // Reset to false by gc after it clears all soft refs.

    86   bool _should_clear_all_soft_refs;

    87 

    88   // Set to true by the GC if the just-completed gc cleared all

    89   // softrefs.  This is set to true whenever a gc clears all softrefs, and

    90   // set to false each time gc returns to the mutator.  For example, in the

    91   // ParallelScavengeHeap case the latter would be done toward the end of

    92   // mem_allocate() where it returns op.result()

    93   bool _all_soft_refs_clear;

    94 

    95   CollectorPolicy();

    96 

    97  public:

    98   virtual void initialize_all() {

    99     initialize_alignments();

   100     initialize_flags();

   101     initialize_size_info();

   102   }

   103 

   104   // Return maximum heap alignment that may be imposed by the policy.

   105   static size_t compute_heap_alignment();

   106 

   107   size_t space_alignment()        { return _space_alignment; }

   108   size_t heap_alignment()         { return _heap_alignment; }

   109 

   110   size_t initial_heap_byte_size() { return _initial_heap_byte_size; }

   111   size_t max_heap_byte_size()     { return _max_heap_byte_size; }

   112   size_t min_heap_byte_size()     { return _min_heap_byte_size; }

   113 

   114   enum Name {

   115     CollectorPolicyKind,

   116     GenCollectorPolicyKind,

   117     ConcurrentMarkSweepPolicyKind,

   118     G1CollectorPolicyKind

   119   };

   120 

   121   AdaptiveSizePolicy* size_policy() { return _size_policy; }

   122   bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }

   123   void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }

   124   // Returns the current value of _should_clear_all_soft_refs.

   125   // _should_clear_all_soft_refs is set to false as a side effect.

   126   bool use_should_clear_all_soft_refs(bool v);

   127   bool all_soft_refs_clear() { return _all_soft_refs_clear; }

   128   void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }

   129 

   130   // Called by the GC after Soft Refs have been cleared to indicate

   131   // that the request in _should_clear_all_soft_refs has been fulfilled.

   132   void cleared_all_soft_refs();

   133 

   134   // Identification methods.

   135   virtual GenCollectorPolicy*           as_generation_policy()            { return NULL; }

   136   virtual MarkSweepPolicy*              as_mark_sweep_policy()            { return NULL; }

   137 #if INCLUDE_ALL_GCS

   138   virtual ConcurrentMarkSweepPolicy*    as_concurrent_mark_sweep_policy() { return NULL; }

   139   virtual G1CollectorPolicy*            as_g1_policy()                    { return NULL; }

   140 #endif // INCLUDE_ALL_GCS

   141   // Note that these are not virtual.

   142   bool is_generation_policy()            { return as_generation_policy() != NULL; }

   143   bool is_mark_sweep_policy()            { return as_mark_sweep_policy() != NULL; }

   144 #if INCLUDE_ALL_GCS

   145   bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }

   146   bool is_g1_policy()                    { return as_g1_policy() != NULL; }

   147 #else  // INCLUDE_ALL_GCS

   148   bool is_concurrent_mark_sweep_policy() { return false; }

   149   bool is_g1_policy()                    { return false; }

   150 #endif // INCLUDE_ALL_GCS

   151 

   152 

   153   virtual BarrierSet::Name barrier_set_name() = 0;

   154 

   155   virtual GenRemSet* create_rem_set(MemRegion reserved);

   156 

   157   // This method controls how a collector satisfies a request

   158   // for a block of memory.  "gc_time_limit_was_exceeded" will

   159   // be set to true if the adaptive size policy determine that

   160   // an excessive amount of time is being spent doing collections

   161   // and caused a NULL to be returned.  If a NULL is not returned,

   162   // "gc_time_limit_was_exceeded" has an undefined meaning.

   163   virtual HeapWord* mem_allocate_work(size_t size,

   164                                       bool is_tlab,

   165                                       bool* gc_overhead_limit_was_exceeded) = 0;

   166 

   167   // This method controls how a collector handles one or more

   168   // of its generations being fully allocated.

   169   virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;

   170   // This method controls how a collector handles a metadata allocation

   171   // failure.

   172   virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,

   173                                                        size_t size,

   174                                                        Metaspace::MetadataType mdtype);

   175 

   176   // Performance Counter support

   177   GCPolicyCounters* counters()     { return _gc_policy_counters; }

   178 

   179   // Create the jstat counters for the GC policy.  By default, policy's

   180   // don't have associated counters, and we complain if this is invoked.

   181   virtual void initialize_gc_policy_counters() {

   182     ShouldNotReachHere();

   183   }

   184 

   185   virtual CollectorPolicy::Name kind() {

   186     return CollectorPolicy::CollectorPolicyKind;

   187   }

   188 

   189   // Do any updates required to global flags that are due to heap initialization

   190   // changes

   191   virtual void post_heap_initialize() = 0;

   192 };

   193 

   194 class ClearedAllSoftRefs : public StackObj {

   195   bool _clear_all_soft_refs;

   196   CollectorPolicy* _collector_policy;

   197  public:

   198   ClearedAllSoftRefs(bool clear_all_soft_refs,

   199                      CollectorPolicy* collector_policy) :

   200     _clear_all_soft_refs(clear_all_soft_refs),

   201     _collector_policy(collector_policy) {}

   202 

   203   ~ClearedAllSoftRefs() {

   204     if (_clear_all_soft_refs) {

   205       _collector_policy->cleared_all_soft_refs();

   206     }

   207   }

   208 };

   209 

   210 class GenCollectorPolicy : public CollectorPolicy {

   211   friend class TestGenCollectorPolicy;

   212   friend class VMStructs;

   213  protected:

   214   size_t _min_young_size;

   215   size_t _initial_young_size;

   216   size_t _max_young_size;

   217   size_t _min_old_size;

   218   size_t _initial_old_size;

   219   size_t _max_old_size;

   220 

   221   // _gen_alignment and _space_alignment will have the same value most of the

   222   // time. When using large pages they can differ.

   223   size_t _gen_alignment;

   224 

   225   GenerationSpec* _young_gen_spec;

   226   GenerationSpec* _old_gen_spec;

   227 

   228   // Return true if an allocation should be attempted in the older generation

   229   // if it fails in the younger generation.  Return false, otherwise.

   230   virtual bool should_try_older_generation_allocation(size_t word_size) const;

   231 

   232   void initialize_flags();

   233   void initialize_size_info();

   234 

   235   DEBUG_ONLY(void assert_flags();)

   236   DEBUG_ONLY(void assert_size_info();)

   237 

   238   // Try to allocate space by expanding the heap.

   239   virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);

   240 

   241   // Compute max heap alignment.

   242   size_t compute_max_alignment();

   243 

   244   // Scale the base_size by NewRatio according to

   245   //     result = base_size / (NewRatio + 1)

   246   // and align by min_alignment()

   247   size_t scale_by_NewRatio_aligned(size_t base_size);

   248 

   249   // Bound the value by the given maximum minus the min_alignment.

   250   size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);

   251 

   252  public:

   253   GenCollectorPolicy();

   254 

   255   // Accessors

   256   size_t min_young_size()     { return _min_young_size; }

   257   size_t initial_young_size() { return _initial_young_size; }

   258   size_t max_young_size()     { return _max_young_size; }

   259   size_t gen_alignment()      { return _gen_alignment; }

   260   size_t min_old_size()       { return _min_old_size; }

   261   size_t initial_old_size()   { return _initial_old_size; }

   262   size_t max_old_size()       { return _max_old_size; }

   263 

   264   int number_of_generations() { return 2; }

   265 

   266   GenerationSpec* young_gen_spec() const {

   267     assert(_young_gen_spec != NULL, "_young_gen_spec should have been initialized");

   268     return _young_gen_spec;

   269   }

   270 

   271   GenerationSpec* old_gen_spec() const {

   272     assert(_old_gen_spec != NULL, "_old_gen_spec should have been initialized");

   273     return _old_gen_spec;

   274   }

   275 

   276   virtual GenCollectorPolicy* as_generation_policy() { return this; }

   277 

   278   virtual void initialize_generations() { };

   279 

   280   virtual void initialize_all() {

   281     CollectorPolicy::initialize_all();

   282     initialize_generations();

   283   }

   284 

   285   size_t young_gen_size_lower_bound();

   286 

   287   HeapWord* mem_allocate_work(size_t size,

   288                               bool is_tlab,

   289                               bool* gc_overhead_limit_was_exceeded);

   290 

   291   HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);

   292 

   293   // Adaptive size policy

   294   virtual void initialize_size_policy(size_t init_eden_size,

   295                                       size_t init_promo_size,

   296                                       size_t init_survivor_size);

   297 

   298   virtual void post_heap_initialize() {

   299     assert(_max_young_size == MaxNewSize, "Should be taken care of by initialize_size_info");

   300   }

   301 

   302   BarrierSet::Name barrier_set_name()  { return BarrierSet::CardTableModRef; }

   303 

   304   virtual CollectorPolicy::Name kind() {

   305     return CollectorPolicy::GenCollectorPolicyKind;

   306   }

   307 };

   308 

   309 class MarkSweepPolicy : public GenCollectorPolicy {

   310  protected:

   311   void initialize_alignments();

   312   void initialize_generations();

   313 

   314  public:

   315   MarkSweepPolicy() {}

   316 

   317   MarkSweepPolicy* as_mark_sweep_policy() { return this; }

   318 

   319   void initialize_gc_policy_counters();

   320 };

   321 

   322 #endif // SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP