/*

 * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "gc/shared/collectedHeap.hpp"

#include "gc/shared/softRefPolicy.hpp"

#include "gc/shared/space.hpp"

#include "services/memoryManager.hpp"

#include "gc/epsilon/epsilonCollectorPolicy.hpp"

#include "gc/epsilon/epsilonMonitoringSupport.hpp"

#include "gc/epsilon/epsilonBarrierSet.hpp"

#include "gc/epsilon/epsilon_globals.hpp"

class EpsilonHeap : public CollectedHeap {

  friend class VMStructs;

private:

  EpsilonCollectorPolicy* _policy;

  SoftRefPolicy _soft_ref_policy;

  EpsilonMonitoringSupport* _monitoring_support;

  MemoryPool* _pool;

  GCMemoryManager _memory_manager;

  ContiguousSpace* _space;

  VirtualSpace _virtual_space;

  size_t _max_tlab_size;

  size_t _step_counter_update;

  size_t _step_heap_print;

  int64_t _decay_time_ns;

  volatile size_t _last_counter_update;

  volatile size_t _last_heap_print;

public:

  static EpsilonHeap* heap();

  EpsilonHeap(EpsilonCollectorPolicy* p) :

          _policy(p),

          _memory_manager("Epsilon Heap", "") {};

  virtual Name kind() const {

    return CollectedHeap::Epsilon;

  }

  virtual const char* name() const {

    return "Epsilon";

  }

  virtual CollectorPolicy* collector_policy() const {

    return _policy;

  }

  virtual SoftRefPolicy* soft_ref_policy() {

    return &_soft_ref_policy;

  }

  virtual jint initialize();

  virtual void post_initialize();

  virtual void initialize_serviceability();

  virtual GrowableArray<GCMemoryManager*> memory_managers();

  virtual GrowableArray<MemoryPool*> memory_pools();

  virtual size_t max_capacity() const { return _virtual_space.reserved_size();  }

  virtual size_t capacity()     const { return _virtual_space.committed_size(); }

  virtual size_t used()         const { return _space->used(); }

  virtual bool is_in(const void* p) const {

    return _space->is_in(p);

  }

  virtual bool is_scavengable(oop obj) {

    // No GC is going to happen, therefore no objects ever move.

    return false;

  }

  virtual bool is_maximal_no_gc() const {

    // No GC is going to happen. Return "we are at max", when we are about to fail.

    return used() == capacity();

  }

  // Allocation

  HeapWord* allocate_work(size_t size);

  virtual HeapWord* mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded);

  virtual HeapWord* allocate_new_tlab(size_t min_size,

                                      size_t requested_size,

                                      size_t* actual_size);

  // TLAB allocation

  virtual bool supports_tlab_allocation()           const { return true;           }

  virtual size_t tlab_capacity(Thread* thr)         const { return capacity();     }

  virtual size_t tlab_used(Thread* thr)             const { return used();         }

  virtual size_t max_tlab_size()                    const { return _max_tlab_size; }

  virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;

  virtual void collect(GCCause::Cause cause);

  virtual void do_full_collection(bool clear_all_soft_refs);

  // Heap walking support

  virtual void safe_object_iterate(ObjectClosure* cl);

  virtual void object_iterate(ObjectClosure* cl) {

    safe_object_iterate(cl);

  }

  // Object pinning support: every object is implicitly pinned

  virtual bool supports_object_pinning() const           { return true; }

  virtual oop pin_object(JavaThread* thread, oop obj)    { return obj; }

  virtual void unpin_object(JavaThread* thread, oop obj) { }

  // No support for block parsing.

  virtual HeapWord* block_start(const void* addr) const { return NULL;  }

  virtual size_t block_size(const HeapWord* addr) const { return 0;     }

  virtual bool block_is_obj(const HeapWord* addr) const { return false; }

  // No GC threads

  virtual void print_gc_threads_on(outputStream* st) const {}

  virtual void gc_threads_do(ThreadClosure* tc) const {}

  // No heap verification

  virtual void prepare_for_verify() {}

  virtual void verify(VerifyOption option) {}

  virtual jlong millis_since_last_gc() {

    // Report time since the VM start

    return os::elapsed_counter() / NANOSECS_PER_MILLISEC;

  }

  virtual void print_on(outputStream* st) const;

  virtual void print_tracing_info() const;

};