/*

 * Copyright (c) 2017, Red Hat, Inc. and/or its affiliates.

 *

 * 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.

 *

 */

#ifndef SHARE_VM_GC_EPSILON_COLLECTEDHEAP_HPP

#define SHARE_VM_GC_EPSILON_COLLECTEDHEAP_HPP

#include "gc/shared/collectedHeap.hpp"

#include "gc/shared/space.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 {

private:

  EpsilonCollectorPolicy* _policy;

  EpsilonMonitoringSupport* _monitoring_support;

  ContiguousSpace* _space;

  VirtualSpace _virtual_space;

  size_t _max_tlab_size;

  size_t _last_counter_update;

public:

  EpsilonHeap(EpsilonCollectorPolicy* p) : _policy(p) {};

  virtual Name kind() const {

    return CollectedHeap::EpsilonHeap;

  }

  virtual const char *name() const {

    return "Epsilon GC";

  }

  virtual jint initialize();

  static EpsilonHeap* heap();

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

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

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

  virtual bool is_maximal_no_gc() const {

    // No GC is going to happen, unless we are at capacity.

    // At which point we will fail anyway.

    return used() == capacity();

  }

  virtual bool is_in(const void *p) const { return _space->is_in(p); }

  virtual bool is_scavengable(oop obj) {

    // Epsilon does not move objects, no objects are scavengable.

    return false;

  }

  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 size);

  // TLAB allocations

  virtual bool supports_tlab_allocation()           const { return UseTLAB; }

  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 bool can_elide_tlab_store_barriers() const {

    // No store barriers for Epsilon, allow elision

    return true;

  }

  virtual bool can_elide_initializing_store_barrier(oop new_obj) {

    // No card marks for Epsilon, can elide them all.

    return true;

  }

  virtual bool card_mark_must_follow_store() const {

    // No card marks for Epsilon.

    return false;

  }

  virtual void collect(GCCause::Cause cause);

  virtual void do_full_collection(bool clear_all_soft_refs);

  virtual AdaptiveSizePolicy *size_policy() {

    // No such thing for Epsilon

    return NULL;

  }

  virtual CollectorPolicy *collector_policy() const {

    return _policy;

  }

  virtual void object_iterate(ObjectClosure *cl) {

    safe_object_iterate(cl);

  }

  virtual void safe_object_iterate(ObjectClosure *cl);

  virtual HeapWord* block_start(const void *addr) const {

    // Epsilon does not support block parsing.

    return NULL;

  }

  virtual size_t block_size(const HeapWord *addr) const {

    // Epsilon does not support block parsing.

    return 0;

  }

  virtual bool block_is_obj(const HeapWord *addr) const {

    // Epsilon does not support block parsing.

    return false;

  }

  virtual jlong millis_since_last_gc() {

    // Report time since the VM start

    return os::elapsed_counter() / NANOSECS_PER_MILLISEC;

  }

  virtual void prepare_for_verify() {

    // No heap verification.

  }

  virtual void print_gc_threads_on(outputStream *st) const {

    // No GC threads.

  }

  virtual void gc_threads_do(ThreadClosure *tc) const {

    // No GC threads.

  }

  virtual void print_on(outputStream *st) const;

  virtual void print_tracing_info() const;

  virtual void verify(VerifyOption option) {

    // No heap verification for Epsilon.

  }

};

#endif // SHARE_VM_GC_EPSILON_COLLECTEDHEAP_HPP