/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * 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

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 */

#include "precompiled.hpp"

#include "gc/parallel/mutableSpace.hpp"

#include "gc/shared/spaceDecorator.hpp"

#include "memory/iterator.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.hpp"

#include "runtime/safepoint.hpp"

#include "runtime/thread.hpp"

#include "utilities/align.hpp"

#include "utilities/macros.hpp"

MutableSpace::MutableSpace(size_t alignment): ImmutableSpace(), _top(NULL), _alignment(alignment) {

  assert(MutableSpace::alignment() % os::vm_page_size() == 0,

         "Space should be aligned");

  _mangler = new MutableSpaceMangler(this);

}

MutableSpace::~MutableSpace() {

  delete _mangler;

}

void MutableSpace::numa_setup_pages(MemRegion mr, bool clear_space) {

  if (!mr.is_empty()) {

    size_t page_size = UseLargePages ? alignment() : os::vm_page_size();

    HeapWord *start = align_up(mr.start(), page_size);

    HeapWord *end =   align_down(mr.end(), page_size);

    if (end > start) {

      size_t size = pointer_delta(end, start, sizeof(char));

      if (clear_space) {

        // Prefer page reallocation to migration.

        os::free_memory((char*)start, size, page_size);

      }

      os::numa_make_global((char*)start, size);

    }

  }

}

void MutableSpace::pretouch_pages(MemRegion mr) {

  os::pretouch_memory(mr.start(), mr.end());

}

void MutableSpace::initialize(MemRegion mr,

                              bool clear_space,

                              bool mangle_space,

                              bool setup_pages) {

  assert(Universe::on_page_boundary(mr.start()) && Universe::on_page_boundary(mr.end()),

         "invalid space boundaries");

  if (setup_pages && (UseNUMA || AlwaysPreTouch)) {

    // The space may move left and right or expand/shrink.

    // We'd like to enforce the desired page placement.

    MemRegion head, tail;

    if (last_setup_region().is_empty()) {

      // If it's the first initialization don't limit the amount of work.

      head = mr;

      tail = MemRegion(mr.end(), mr.end());

    } else {

      // Is there an intersection with the address space?

      MemRegion intersection = last_setup_region().intersection(mr);

      if (intersection.is_empty()) {

        intersection = MemRegion(mr.end(), mr.end());

      }

      // All the sizes below are in words.

      size_t head_size = 0, tail_size = 0;

      if (mr.start() <= intersection.start()) {

        head_size = pointer_delta(intersection.start(), mr.start());

      }

      if(intersection.end() <= mr.end()) {

        tail_size = pointer_delta(mr.end(), intersection.end());

      }

      // Limit the amount of page manipulation if necessary.

      if (NUMASpaceResizeRate > 0 && !AlwaysPreTouch) {

        const size_t change_size = head_size + tail_size;

        const float setup_rate_words = NUMASpaceResizeRate >> LogBytesPerWord;

        head_size = MIN2((size_t)(setup_rate_words * head_size / change_size),

                         head_size);

        tail_size = MIN2((size_t)(setup_rate_words * tail_size / change_size),

                         tail_size);

      }

      head = MemRegion(intersection.start() - head_size, intersection.start());

      tail = MemRegion(intersection.end(), intersection.end() + tail_size);

    }

    assert(mr.contains(head) && mr.contains(tail), "Sanity");

    if (UseNUMA) {

      numa_setup_pages(head, clear_space);

      numa_setup_pages(tail, clear_space);

    }

    if (AlwaysPreTouch) {

      pretouch_pages(head);

      pretouch_pages(tail);

    }

    // Remember where we stopped so that we can continue later.

    set_last_setup_region(MemRegion(head.start(), tail.end()));

  }

  set_bottom(mr.start());

  set_end(mr.end());

  if (clear_space) {

    clear(mangle_space);

  }

}

void MutableSpace::clear(bool mangle_space) {

  set_top(bottom());

  if (ZapUnusedHeapArea && mangle_space) {

    mangle_unused_area();

  }

}

#ifndef PRODUCT

void MutableSpace::check_mangled_unused_area(HeapWord* limit) {

  mangler()->check_mangled_unused_area(limit);

}

void MutableSpace::check_mangled_unused_area_complete() {

  mangler()->check_mangled_unused_area_complete();

}

// Mangle only the unused space that has not previously

// been mangled and that has not been allocated since being

// mangled.

void MutableSpace::mangle_unused_area() {

  mangler()->mangle_unused_area();

}

void MutableSpace::mangle_unused_area_complete() {

  mangler()->mangle_unused_area_complete();

}

void MutableSpace::mangle_region(MemRegion mr) {

  SpaceMangler::mangle_region(mr);

}

void MutableSpace::set_top_for_allocations(HeapWord* v) {

  mangler()->set_top_for_allocations(v);

}

void MutableSpace::set_top_for_allocations() {

  mangler()->set_top_for_allocations(top());

}

#endif

// This version requires locking. */

HeapWord* MutableSpace::allocate(size_t size) {

  assert(Heap_lock->owned_by_self() ||

         (SafepointSynchronize::is_at_safepoint() &&

          Thread::current()->is_VM_thread()),

         "not locked");

  HeapWord* obj = top();

  if (pointer_delta(end(), obj) >= size) {

    HeapWord* new_top = obj + size;

    set_top(new_top);

    assert(is_object_aligned(obj) && is_object_aligned(new_top),

           "checking alignment");

    return obj;

  } else {

    return NULL;

  }

}

// This version is lock-free.

HeapWord* MutableSpace::cas_allocate(size_t size) {

  do {

    HeapWord* obj = top();

    if (pointer_delta(end(), obj) >= size) {

      HeapWord* new_top = obj + size;

      HeapWord* result = Atomic::cmpxchg(new_top, top_addr(), obj);

      // result can be one of two:

      //  the old top value: the exchange succeeded

      //  otherwise: the new value of the top is returned.

      if (result != obj) {

        continue; // another thread beat us to the allocation, try again

      }

      assert(is_object_aligned(obj) && is_object_aligned(new_top),

             "checking alignment");

      return obj;

    } else {

      return NULL;

    }

  } while (true);

}

// Try to deallocate previous allocation. Returns true upon success.

bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) {

  HeapWord* expected_top = obj + size;

  return Atomic::cmpxchg(obj, top_addr(), expected_top) == expected_top;

}

void MutableSpace::oop_iterate(OopIterateClosure* cl) {

  HeapWord* obj_addr = bottom();

  HeapWord* t = top();

  // Could call objects iterate, but this is easier.

  while (obj_addr < t) {

    obj_addr += oop(obj_addr)->oop_iterate_size(cl);

  }

}

void MutableSpace::object_iterate(ObjectClosure* cl) {

  HeapWord* p = bottom();

  while (p < top()) {

    cl->do_object(oop(p));

    p += oop(p)->size();

  }

}

void MutableSpace::print_short() const { print_short_on(tty); }

void MutableSpace::print_short_on( outputStream* st) const {

  st->print(" space " SIZE_FORMAT "K, %d%% used", capacity_in_bytes() / K,

            (int) ((double) used_in_bytes() * 100 / capacity_in_bytes()));

}

void MutableSpace::print() const { print_on(tty); }

void MutableSpace::print_on(outputStream* st) const {

  MutableSpace::print_short_on(st);

  st->print_cr(" [" INTPTR_FORMAT "," INTPTR_FORMAT "," INTPTR_FORMAT ")",

                 p2i(bottom()), p2i(top()), p2i(end()));

}

void MutableSpace::verify() {

  HeapWord* p = bottom();

  HeapWord* t = top();

  HeapWord* prev_p = NULL;

  while (p < t) {

    prev_p = p;

    p += oop(p)->size();

  }

  guarantee(p == top(), "end of last object must match end of space");

}