/*

 * Copyright (c) 2015, 2019, 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.

 *

 */

#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP

#define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP

#include "classfile/javaClasses.inline.hpp"

#include "gc/shared/markBitMap.inline.hpp"

#include "gc/shared/threadLocalAllocBuffer.inline.hpp"

#include "gc/shared/suspendibleThreadSet.hpp"

#include "gc/shenandoah/shenandoahAsserts.hpp"

#include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"

#include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"

#include "gc/shenandoah/shenandoahForwarding.inline.hpp"

#include "gc/shenandoah/shenandoahWorkGroup.hpp"

#include "gc/shenandoah/shenandoahHeap.hpp"

#include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"

#include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"

#include "gc/shenandoah/shenandoahControlThread.hpp"

#include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"

#include "gc/shenandoah/shenandoahThreadLocalData.hpp"

#include "oops/compressedOops.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.hpp"

#include "runtime/prefetch.inline.hpp"

#include "runtime/thread.hpp"

#include "utilities/copy.hpp"

#include "utilities/globalDefinitions.hpp"

inline ShenandoahHeapRegion* ShenandoahRegionIterator::next() {

  size_t new_index = Atomic::add((size_t) 1, &_index);

  // get_region() provides the bounds-check and returns NULL on OOB.

  return _heap->get_region(new_index - 1);

}

inline bool ShenandoahHeap::has_forwarded_objects() const {

  return _gc_state.is_set(HAS_FORWARDED);

}

inline WorkGang* ShenandoahHeap::workers() const {

  return _workers;

}

inline WorkGang* ShenandoahHeap::get_safepoint_workers() {

  return _safepoint_workers;

}

inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {

  uintptr_t region_start = ((uintptr_t) addr);

  uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();

  assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));

  return index;

}

inline ShenandoahHeapRegion* const ShenandoahHeap::heap_region_containing(const void* addr) const {

  size_t index = heap_region_index_containing(addr);

  ShenandoahHeapRegion* const result = get_region(index);

  assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));

  return result;

}

template <class T>

inline oop ShenandoahHeap::update_with_forwarded_not_null(T* p, oop obj) {

  if (in_collection_set(obj)) {

    shenandoah_assert_forwarded_except(p, obj, is_full_gc_in_progress() || cancelled_gc() || is_degenerated_gc_in_progress());

    obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);

    RawAccess<IS_NOT_NULL>::oop_store(p, obj);

  }

#ifdef ASSERT

  else {

    shenandoah_assert_not_forwarded(p, obj);

  }

#endif

  return obj;

}

template <class T>

inline oop ShenandoahHeap::maybe_update_with_forwarded(T* p) {

  T o = RawAccess<>::oop_load(p);

  if (!CompressedOops::is_null(o)) {

    oop obj = CompressedOops::decode_not_null(o);

    return maybe_update_with_forwarded_not_null(p, obj);

  } else {

    return NULL;

  }

}

template <class T>

inline oop ShenandoahHeap::evac_update_with_forwarded(T* p) {

  T o = RawAccess<>::oop_load(p);

  if (!CompressedOops::is_null(o)) {

    oop heap_oop = CompressedOops::decode_not_null(o);

    if (in_collection_set(heap_oop)) {

      oop forwarded_oop = ShenandoahBarrierSet::resolve_forwarded_not_null(heap_oop);

      if (forwarded_oop == heap_oop) {

        forwarded_oop = evacuate_object(heap_oop, Thread::current());

      }

      oop prev = cas_oop(forwarded_oop, p, heap_oop);

      if (prev == heap_oop) {

        return forwarded_oop;

      } else {

        return NULL;

      }

    }

    return heap_oop;

  } else {

    return NULL;

  }

}

inline oop ShenandoahHeap::cas_oop(oop n, oop* addr, oop c) {

  return (oop) Atomic::cmpxchg(n, addr, c);

}

inline oop ShenandoahHeap::cas_oop(oop n, narrowOop* addr, narrowOop c) {

  narrowOop val = CompressedOops::encode(n);

  return CompressedOops::decode((narrowOop) Atomic::cmpxchg(val, addr, c));

}

inline oop ShenandoahHeap::cas_oop(oop n, narrowOop* addr, oop c) {

  narrowOop cmp = CompressedOops::encode(c);

  narrowOop val = CompressedOops::encode(n);

  return CompressedOops::decode((narrowOop) Atomic::cmpxchg(val, addr, cmp));

}

template <class T>

inline oop ShenandoahHeap::maybe_update_with_forwarded_not_null(T* p, oop heap_oop) {

  shenandoah_assert_not_in_cset_loc_except(p, !is_in(p) || is_full_gc_in_progress() || is_degenerated_gc_in_progress());

  shenandoah_assert_correct(p, heap_oop);

  if (in_collection_set(heap_oop)) {

    oop forwarded_oop = ShenandoahBarrierSet::resolve_forwarded_not_null(heap_oop);

    if (forwarded_oop == heap_oop) {

      // E.g. during evacuation.

      return forwarded_oop;

    }

    shenandoah_assert_forwarded_except(p, heap_oop, is_full_gc_in_progress() || is_degenerated_gc_in_progress());

    shenandoah_assert_not_forwarded(p, forwarded_oop);

    shenandoah_assert_not_in_cset_except(p, forwarded_oop, cancelled_gc());

    // If this fails, another thread wrote to p before us, it will be logged in SATB and the

    // reference be updated later.

    oop witness = cas_oop(forwarded_oop, p, heap_oop);

    if (witness != heap_oop) {

      // CAS failed, someone had beat us to it. Normally, we would return the failure witness,

      // because that would be the proper write of to-space object, enforced by strong barriers.

      // However, there is a corner case with arraycopy. It can happen that a Java thread

      // beats us with an arraycopy, which first copies the array, which potentially contains

      // from-space refs, and only afterwards updates all from-space refs to to-space refs,

      // which leaves a short window where the new array elements can be from-space.

      // In this case, we can just resolve the result again. As we resolve, we need to consider

      // the contended write might have been NULL.

      oop result = ShenandoahBarrierSet::resolve_forwarded(witness);

      shenandoah_assert_not_forwarded_except(p, result, (result == NULL));

      shenandoah_assert_not_in_cset_except(p, result, (result == NULL) || cancelled_gc());

      return result;

    } else {

      // Success! We have updated with known to-space copy. We have already asserted it is sane.

      return forwarded_oop;

    }

  } else {

    shenandoah_assert_not_forwarded(p, heap_oop);

    return heap_oop;

  }

}

inline bool ShenandoahHeap::cancelled_gc() const {

  return _cancelled_gc.get() == CANCELLED;

}

inline bool ShenandoahHeap::check_cancelled_gc_and_yield(bool sts_active) {

  if (! (sts_active && ShenandoahSuspendibleWorkers)) {

    return cancelled_gc();

  }

  jbyte prev = _cancelled_gc.cmpxchg(NOT_CANCELLED, CANCELLABLE);

  if (prev == CANCELLABLE || prev == NOT_CANCELLED) {

    if (SuspendibleThreadSet::should_yield()) {

      SuspendibleThreadSet::yield();

    }

    // Back to CANCELLABLE. The thread that poked NOT_CANCELLED first gets

    // to restore to CANCELLABLE.

    if (prev == CANCELLABLE) {

      _cancelled_gc.set(CANCELLABLE);

    }

    return false;

  } else {

    return true;

  }

}

inline void ShenandoahHeap::clear_cancelled_gc() {

  _cancelled_gc.set(CANCELLABLE);

  _oom_evac_handler.clear();

}

inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {

  assert(UseTLAB, "TLABs should be enabled");

  PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);

  if (gclab == NULL) {

    assert(!thread->is_Java_thread() && !thread->is_Worker_thread(),

           "Performance: thread should have GCLAB: %s", thread->name());

    // No GCLABs in this thread, fallback to shared allocation

    return NULL;

  }

  HeapWord* obj = gclab->allocate(size);

  if (obj != NULL) {

    return obj;

  }

  // Otherwise...

  return allocate_from_gclab_slow(thread, size);

}

inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {

  if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) {

    // This thread went through the OOM during evac protocol and it is safe to return

    // the forward pointer. It must not attempt to evacuate any more.

    return ShenandoahBarrierSet::resolve_forwarded(p);

  }

  assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");

  size_t size = p->size();

  assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");

  bool alloc_from_gclab = true;

  HeapWord* copy = NULL;

#ifdef ASSERT

  if (ShenandoahOOMDuringEvacALot &&

      (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call

        copy = NULL;

  } else {

#endif

    if (UseTLAB) {

      copy = allocate_from_gclab(thread, size);

    }

    if (copy == NULL) {

      ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size);

      copy = allocate_memory(req);

      alloc_from_gclab = false;

    }

#ifdef ASSERT

  }

#endif

  if (copy == NULL) {

    control_thread()->handle_alloc_failure_evac(size);

    _oom_evac_handler.handle_out_of_memory_during_evacuation();

    return ShenandoahBarrierSet::resolve_forwarded(p);

  }

  // Copy the object:

  Copy::aligned_disjoint_words((HeapWord*) p, copy, size);

  // Try to install the new forwarding pointer.

  oop copy_val = oop(copy);

  oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);

  if (result == copy_val) {

    // Successfully evacuated. Our copy is now the public one!

    shenandoah_assert_correct(NULL, copy_val);

    return copy_val;

  }  else {

    // Failed to evacuate. We need to deal with the object that is left behind. Since this

    // new allocation is certainly after TAMS, it will be considered live in the next cycle.

    // But if it happens to contain references to evacuated regions, those references would

    // not get updated for this stale copy during this cycle, and we will crash while scanning

    // it the next cycle.

    //

    // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next

    // object will overwrite this stale copy, or the filler object on LAB retirement will

    // do this. For non-GCLAB allocations, we have no way to retract the allocation, and

    // have to explicitly overwrite the copy with the filler object. With that overwrite,

    // we have to keep the fwdptr initialized and pointing to our (stale) copy.

    if (alloc_from_gclab) {

      ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);

    } else {

      fill_with_object(copy, size);

      shenandoah_assert_correct(NULL, copy_val);

    }

    shenandoah_assert_correct(NULL, result);

    return result;

  }

}

template<bool RESOLVE>

inline bool ShenandoahHeap::requires_marking(const void* entry) const {

  oop obj = oop(entry);

  if (RESOLVE) {

    obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);

  }

  return !_marking_context->is_marked(obj);

}

template <class T>

inline bool ShenandoahHeap::in_collection_set(T p) const {

  HeapWord* obj = (HeapWord*) p;

  assert(collection_set() != NULL, "Sanity");

  assert(is_in(obj), "should be in heap");

  return collection_set()->is_in(obj);

}

inline bool ShenandoahHeap::is_stable() const {

  return _gc_state.is_clear();

}

inline bool ShenandoahHeap::is_idle() const {

  return _gc_state.is_unset(MARKING | EVACUATION | UPDATEREFS | TRAVERSAL);

}

inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {

  return _gc_state.is_set(MARKING);

}

inline bool ShenandoahHeap::is_concurrent_traversal_in_progress() const {

  return _gc_state.is_set(TRAVERSAL);

}

inline bool ShenandoahHeap::is_evacuation_in_progress() const {

  return _gc_state.is_set(EVACUATION);

}

inline bool ShenandoahHeap::is_gc_in_progress_mask(uint mask) const {

  return _gc_state.is_set(mask);

}

inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {

  return _degenerated_gc_in_progress.is_set();

}

inline bool ShenandoahHeap::is_full_gc_in_progress() const {

  return _full_gc_in_progress.is_set();

}

inline bool ShenandoahHeap::is_full_gc_move_in_progress() const {

  return _full_gc_move_in_progress.is_set();

}

inline bool ShenandoahHeap::is_update_refs_in_progress() const {

  return _gc_state.is_set(UPDATEREFS);

}

template<class T>

inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {

  marked_object_iterate(region, cl, region->top());

}

template<class T>

inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {

  assert(! region->is_humongous_continuation(), "no humongous continuation regions here");

  ShenandoahMarkingContext* const ctx = complete_marking_context();

  assert(ctx->is_complete(), "sanity");

  MarkBitMap* mark_bit_map = ctx->mark_bit_map();

  HeapWord* tams = ctx->top_at_mark_start(region);

  size_t skip_bitmap_delta = 1;

  HeapWord* start = region->bottom();

  HeapWord* end = MIN2(tams, region->end());

  // Step 1. Scan below the TAMS based on bitmap data.

  HeapWord* limit_bitmap = MIN2(limit, tams);

  // Try to scan the initial candidate. If the candidate is above the TAMS, it would

  // fail the subsequent "< limit_bitmap" checks, and fall through to Step 2.

  HeapWord* cb = mark_bit_map->get_next_marked_addr(start, end);

  intx dist = ShenandoahMarkScanPrefetch;

  if (dist > 0) {

    // Batched scan that prefetches the oop data, anticipating the access to

    // either header, oop field, or forwarding pointer. Not that we cannot

    // touch anything in oop, while it still being prefetched to get enough

    // time for prefetch to work. This is why we try to scan the bitmap linearly,

    // disregarding the object size. However, since we know forwarding pointer

    // preceeds the object, we can skip over it. Once we cannot trust the bitmap,

    // there is no point for prefetching the oop contents, as oop->size() will

    // touch it prematurely.

    // No variable-length arrays in standard C++, have enough slots to fit

    // the prefetch distance.

    static const int SLOT_COUNT = 256;

    guarantee(dist <= SLOT_COUNT, "adjust slot count");

    HeapWord* slots[SLOT_COUNT];

    int avail;

    do {

      avail = 0;

      for (int c = 0; (c < dist) && (cb < limit_bitmap); c++) {

        Prefetch::read(cb, oopDesc::mark_offset_in_bytes());

        slots[avail++] = cb;

        cb += skip_bitmap_delta;

        if (cb < limit_bitmap) {

          cb = mark_bit_map->get_next_marked_addr(cb, limit_bitmap);

        }

      }

      for (int c = 0; c < avail; c++) {

        assert (slots[c] < tams,  "only objects below TAMS here: "  PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(tams));

        assert (slots[c] < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(limit));

        oop obj = oop(slots[c]);

        assert(oopDesc::is_oop(obj), "sanity");

        assert(ctx->is_marked(obj), "object expected to be marked");

        cl->do_object(obj);

      }

    } while (avail > 0);

  } else {

    while (cb < limit_bitmap) {

      assert (cb < tams,  "only objects below TAMS here: "  PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(tams));

      assert (cb < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(limit));

      oop obj = oop(cb);

      assert(oopDesc::is_oop(obj), "sanity");

      assert(ctx->is_marked(obj), "object expected to be marked");

      cl->do_object(obj);

      cb += skip_bitmap_delta;

      if (cb < limit_bitmap) {

        cb = mark_bit_map->get_next_marked_addr(cb, limit_bitmap);

      }

    }

  }

  // Step 2. Accurate size-based traversal, happens past the TAMS.

  // This restarts the scan at TAMS, which makes sure we traverse all objects,

  // regardless of what happened at Step 1.

  HeapWord* cs = tams;

  while (cs < limit) {

    assert (cs >= tams, "only objects past TAMS here: "   PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(tams));

    assert (cs < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(limit));

    oop obj = oop(cs);

    assert(oopDesc::is_oop(obj), "sanity");

    assert(ctx->is_marked(obj), "object expected to be marked");

    int size = obj->size();

    cl->do_object(obj);

    cs += size;

  }

}

template <class T>

class ShenandoahObjectToOopClosure : public ObjectClosure {

  T* _cl;

public:

  ShenandoahObjectToOopClosure(T* cl) : _cl(cl) {}

  void do_object(oop obj) {

    obj->oop_iterate(_cl);

  }

};

template <class T>

class ShenandoahObjectToOopBoundedClosure : public ObjectClosure {

  T* _cl;

  MemRegion _bounds;

public:

  ShenandoahObjectToOopBoundedClosure(T* cl, HeapWord* bottom, HeapWord* top) :

    _cl(cl), _bounds(bottom, top) {}

  void do_object(oop obj) {

    obj->oop_iterate(_cl, _bounds);

  }

};

template<class T>

inline void ShenandoahHeap::marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* top) {

  if (region->is_humongous()) {

    HeapWord* bottom = region->bottom();

    if (top > bottom) {

      region = region->humongous_start_region();

      ShenandoahObjectToOopBoundedClosure<T> objs(cl, bottom, top);

      marked_object_iterate(region, &objs);

    }

  } else {

    ShenandoahObjectToOopClosure<T> objs(cl);

    marked_object_iterate(region, &objs, top);

  }

}

inline ShenandoahHeapRegion* const ShenandoahHeap::get_region(size_t region_idx) const {

  if (region_idx < _num_regions) {

    return _regions[region_idx];

  } else {

    return NULL;

  }

}

inline void ShenandoahHeap::mark_complete_marking_context() {

  _marking_context->mark_complete();

}

inline void ShenandoahHeap::mark_incomplete_marking_context() {

  _marking_context->mark_incomplete();

}