/*

 * Copyright 2001-2008 Sun Microsystems, Inc.  All Rights Reserved.

 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

# include "incls/_precompiled.incl"

# include "incls/_mutableSpace.cpp.incl"

MutableSpace::MutableSpace(): ImmutableSpace(), _top(NULL) {

  _mangler = new MutableSpaceMangler(this);

}

MutableSpace::~MutableSpace() {

  delete _mangler;

}

void MutableSpace::initialize(MemRegion mr,

                              bool clear_space,

                              bool mangle_space) {

  HeapWord* bottom = mr.start();

  HeapWord* end    = mr.end();

  assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),

         "invalid space boundaries");

  set_bottom(bottom);

  set_end(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((intptr_t)obj) && is_object_aligned((intptr_t)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 = (HeapWord*)Atomic::cmpxchg_ptr(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((intptr_t)obj) && is_object_aligned((intptr_t)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 (HeapWord*)Atomic::cmpxchg_ptr(obj, top_addr(), expected_top) == expected_top;

}

void MutableSpace::oop_iterate(OopClosure* 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(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 ")",

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

}

void MutableSpace::verify(bool allow_dirty) {

  HeapWord* p = bottom();

  HeapWord* t = top();

  HeapWord* prev_p = NULL;

  while (p < t) {

    oop(p)->verify();

    prev_p = p;

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

  }

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

}