1 /*
   2  * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #ifndef SHARE_GC_EPSILON_EPSILONHEAP_HPP
  25 #define SHARE_GC_EPSILON_EPSILONHEAP_HPP
  26 
  27 #include "gc/shared/collectedHeap.hpp"
  28 #include "gc/shared/softRefPolicy.hpp"
  29 #include "gc/shared/space.hpp"
  30 #include "services/memoryManager.hpp"
  31 #include "gc/epsilon/epsilonCollectorPolicy.hpp"
  32 #include "gc/epsilon/epsilonMonitoringSupport.hpp"
  33 #include "gc/epsilon/epsilonBarrierSet.hpp"
  34 #include "gc/epsilon/epsilon_globals.hpp"
  35 
  36 class EpsilonHeap : public CollectedHeap {
  37   friend class VMStructs;
  38 private:
  39   EpsilonCollectorPolicy* _policy;
  40   SoftRefPolicy _soft_ref_policy;
  41   EpsilonMonitoringSupport* _monitoring_support;
  42   MemoryPool* _pool;
  43   GCMemoryManager _memory_manager;
  44   ContiguousSpace* _space;
  45   VirtualSpace _virtual_space;
  46   size_t _max_tlab_size;
  47   size_t _step_counter_update;
  48   size_t _step_heap_print;
  49   int64_t _decay_time_ns;
  50   volatile size_t _last_counter_update;
  51   volatile size_t _last_heap_print;
  52 
  53 public:
  54   static EpsilonHeap* heap();
  55 
  56   EpsilonHeap(EpsilonCollectorPolicy* p) :
  57           _policy(p),
  58           _memory_manager("Epsilon Heap", "") {};
  59 
  60   virtual Name kind() const {
  61     return CollectedHeap::Epsilon;
  62   }
  63 
  64   virtual const char* name() const {
  65     return "Epsilon";
  66   }
  67 
  68   virtual CollectorPolicy* collector_policy() const {
  69     return _policy;
  70   }
  71 
  72   virtual SoftRefPolicy* soft_ref_policy() {
  73     return &_soft_ref_policy;
  74   }
  75 
  76   virtual jint initialize();
  77   virtual void post_initialize();
  78   virtual void initialize_serviceability();
  79 
  80   virtual GrowableArray<GCMemoryManager*> memory_managers();
  81   virtual GrowableArray<MemoryPool*> memory_pools();
  82 
  83   virtual size_t max_capacity() const { return _virtual_space.reserved_size();  }
  84   virtual size_t capacity()     const { return _virtual_space.committed_size(); }
  85   virtual size_t used()         const { return _space->used(); }
  86 
  87   virtual bool is_in(const void* p) const {
  88     return _space->is_in(p);
  89   }
  90 
  91   virtual bool is_scavengable(oop obj) {
  92     // No GC is going to happen, therefore no objects ever move.
  93     return false;
  94   }
  95 
  96   virtual bool is_maximal_no_gc() const {
  97     // No GC is going to happen. Return "we are at max", when we are about to fail.
  98     return used() == capacity();
  99   }
 100 
 101   // Allocation
 102   HeapWord* allocate_work(size_t size);
 103   virtual HeapWord* mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded);
 104   virtual HeapWord* allocate_new_tlab(size_t min_size,
 105                                       size_t requested_size,
 106                                       size_t* actual_size);
 107 
 108   // TLAB allocation
 109   virtual bool supports_tlab_allocation()           const { return true;           }
 110   virtual size_t tlab_capacity(Thread* thr)         const { return capacity();     }
 111   virtual size_t tlab_used(Thread* thr)             const { return used();         }
 112   virtual size_t max_tlab_size()                    const { return _max_tlab_size; }
 113   virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
 114 
 115   virtual void collect(GCCause::Cause cause);
 116   virtual void do_full_collection(bool clear_all_soft_refs);
 117 
 118   // Heap walking support
 119   virtual void safe_object_iterate(ObjectClosure* cl);
 120   virtual void object_iterate(ObjectClosure* cl) {
 121     safe_object_iterate(cl);
 122   }
 123 
 124   // Object pinning support: every object is implicitly pinned
 125   virtual bool supports_object_pinning() const           { return true; }
 126   virtual oop pin_object(JavaThread* thread, oop obj)    { return obj; }
 127   virtual void unpin_object(JavaThread* thread, oop obj) { }
 128 
 129   // No support for block parsing.
 130   virtual HeapWord* block_start(const void* addr) const { return NULL;  }
 131   virtual size_t block_size(const HeapWord* addr) const { return 0;     }
 132   virtual bool block_is_obj(const HeapWord* addr) const { return false; }
 133 
 134   // No GC threads
 135   virtual void print_gc_threads_on(outputStream* st) const {}
 136   virtual void gc_threads_do(ThreadClosure* tc) const {}
 137 
 138   // No heap verification
 139   virtual void prepare_for_verify() {}
 140   virtual void verify(VerifyOption option) {}
 141 
 142   virtual jlong millis_since_last_gc() {
 143     // Report time since the VM start
 144     return os::elapsed_counter() / NANOSECS_PER_MILLISEC;
 145   }
 146 
 147   virtual void print_on(outputStream* st) const;
 148   virtual void print_tracing_info() const;
 149 
 150 };
 151 
 152 #endif // SHARE_GC_EPSILON_EPSILONHEAP_HPP