1 /*
   2  * Copyright (c) 2017, 2018, Red Hat, Inc. 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_GC_EPSILON_EPSILONHEAP_HPP
  26 #define SHARE_GC_EPSILON_EPSILONHEAP_HPP
  27 
  28 #include "gc/shared/collectedHeap.hpp"
  29 #include "gc/shared/softRefPolicy.hpp"
  30 #include "gc/shared/space.hpp"
  31 #include "gc/epsilon/epsilonMonitoringSupport.hpp"
  32 #include "gc/epsilon/epsilonBarrierSet.hpp"
  33 #include "services/memoryManager.hpp"
  34 
  35 class EpsilonHeap : public CollectedHeap {
  36   friend class VMStructs;
  37 private:
  38   SoftRefPolicy _soft_ref_policy;
  39   EpsilonMonitoringSupport* _monitoring_support;
  40   MemoryPool* _pool;
  41   GCMemoryManager _memory_manager;
  42   ContiguousSpace* _space;
  43   VirtualSpace _virtual_space;
  44   size_t _max_tlab_size;
  45   size_t _step_counter_update;
  46   size_t _step_heap_print;
  47   int64_t _decay_time_ns;
  48   volatile size_t _last_counter_update;
  49   volatile size_t _last_heap_print;
  50 
  51 public:
  52   static EpsilonHeap* heap();
  53 
  54   EpsilonHeap() :
  55           _memory_manager("Epsilon Heap", ""),
  56           _space(NULL) {};
  57 
  58   virtual Name kind() const {
  59     return CollectedHeap::Epsilon;
  60   }
  61 
  62   virtual const char* name() const {
  63     return "Epsilon";
  64   }
  65 
  66   virtual SoftRefPolicy* soft_ref_policy() {
  67     return &_soft_ref_policy;
  68   }
  69 
  70   virtual jint initialize();
  71   virtual void post_initialize();
  72   virtual void initialize_serviceability();
  73 
  74   virtual GrowableArray<GCMemoryManager*> memory_managers();
  75   virtual GrowableArray<MemoryPool*> memory_pools();
  76 
  77   virtual size_t max_capacity() const { return _virtual_space.reserved_size();  }
  78   virtual size_t capacity()     const { return _virtual_space.committed_size(); }
  79   virtual size_t used()         const { return _space->used(); }
  80 
  81   virtual bool is_in(const void* p) const {
  82     return _space->is_in(p);
  83   }
  84 
  85   virtual bool is_maximal_no_gc() const {
  86     // No GC is going to happen. Return "we are at max", when we are about to fail.
  87     return used() == capacity();
  88   }
  89 
  90   // Allocation
  91   HeapWord* allocate_work(size_t size);
  92   virtual HeapWord* mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded);
  93   virtual HeapWord* allocate_new_tlab(size_t min_size,
  94                                       size_t requested_size,
  95                                       size_t* actual_size);
  96 
  97   // TLAB allocation
  98   virtual bool supports_tlab_allocation()           const { return true;           }
  99   virtual size_t tlab_capacity(Thread* thr)         const { return capacity();     }
 100   virtual size_t tlab_used(Thread* thr)             const { return used();         }
 101   virtual size_t max_tlab_size()                    const { return _max_tlab_size; }
 102   virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
 103 
 104   virtual void collect(GCCause::Cause cause);
 105   virtual void do_full_collection(bool clear_all_soft_refs);
 106 
 107   // Heap walking support
 108   virtual void object_iterate(ObjectClosure* cl);
 109 
 110   // Object pinning support: every object is implicitly pinned
 111   virtual bool supports_object_pinning() const           { return true; }
 112   virtual oop pin_object(JavaThread* thread, oop obj)    { return obj; }
 113   virtual void unpin_object(JavaThread* thread, oop obj) { }
 114 
 115   // No support for block parsing.
 116   HeapWord* block_start(const void* addr) const { return NULL;  }
 117   bool block_is_obj(const HeapWord* addr) const { return false; }
 118 
 119   // No GC threads
 120   virtual void gc_threads_do(ThreadClosure* tc) const {}
 121 
 122   // Runs the given AbstractGangTask with the current active workers
 123   // No workGang for EpsilonHeap, work serially with thread 0
 124   virtual void run_task(AbstractGangTask* task) { task->work(0); }
 125 
 126   // No nmethod handling
 127   virtual void register_nmethod(nmethod* nm) {}
 128   virtual void unregister_nmethod(nmethod* nm) {}
 129   virtual void flush_nmethod(nmethod* nm) {}
 130   virtual void verify_nmethod(nmethod* nm) {}
 131 
 132   // No heap verification
 133   virtual void prepare_for_verify() {}
 134   virtual void verify(VerifyOption option) {}
 135 
 136   MemRegion reserved_region() const { return _reserved; }
 137   bool is_in_reserved(const void* addr) const { return _reserved.contains(addr); }
 138 
 139   virtual void print_on(outputStream* st) const;
 140   virtual void print_tracing_info() const;
 141   virtual bool print_location(outputStream* st, void* addr) const;
 142 
 143 private:
 144   void print_heap_info(size_t used) const;
 145   void print_metaspace_info() const;
 146 
 147 };
 148 
 149 #endif // SHARE_GC_EPSILON_EPSILONHEAP_HPP
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