/*

 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. 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 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_MEMORY_FREELIST_INLINE_HPP

#define SHARE_MEMORY_FREELIST_INLINE_HPP

#include "gc/shared/collectedHeap.hpp"

#include "memory/freeList.hpp"

#include "runtime/globals.hpp"

#include "runtime/mutex.hpp"

#include "runtime/vmThread.hpp"

#include "utilities/macros.hpp"

// Free list.  A FreeList is used to access a linked list of chunks

// of space in the heap.  The head and tail are maintained so that

// items can be (as in the current implementation) added at the

// at the tail of the list and removed from the head of the list to

// maintain a FIFO queue.

template <class Chunk>

FreeList<Chunk>::FreeList() :

  _head(NULL), _tail(NULL)

#ifdef ASSERT

  , _protecting_lock(NULL)

#endif

{

  _size         = 0;

  _count        = 0;

}

template <class Chunk>

void FreeList<Chunk>::link_head(Chunk* v) {

  assert_proper_lock_protection();

  set_head(v);

  // If this method is not used (just set the head instead),

  // this check can be avoided.

  if (v != NULL) {

    v->link_prev(NULL);

  }

}

template <class Chunk>

void FreeList<Chunk>::reset() {

  // Don't set the _size to 0 because this method is

  // used with a existing list that has a size but which has

  // been emptied.

  // Don't clear the _protecting_lock of an existing list.

  set_count(0);

  set_head(NULL);

  set_tail(NULL);

}

template <class Chunk>

void FreeList<Chunk>::initialize() {

#ifdef ASSERT

  // Needed early because it might be checked in other initializing code.

  set_protecting_lock(NULL);

#endif

  reset();

  set_size(0);

}

template <class Chunk_t>

Chunk_t* FreeList<Chunk_t>::get_chunk_at_head() {

  assert_proper_lock_protection();

  assert(head() == NULL || head()->prev() == NULL, "list invariant");

  assert(tail() == NULL || tail()->next() == NULL, "list invariant");

  Chunk_t* fc = head();

  if (fc != NULL) {

    Chunk_t* nextFC = fc->next();

    if (nextFC != NULL) {

      // The chunk fc being removed has a "next".  Set the "next" to the

      // "prev" of fc.

      nextFC->link_prev(NULL);

    } else { // removed tail of list

      link_tail(NULL);

    }

    link_head(nextFC);

    decrement_count();

  }

  assert(head() == NULL || head()->prev() == NULL, "list invariant");

  assert(tail() == NULL || tail()->next() == NULL, "list invariant");

  return fc;

}

template <class Chunk>

void FreeList<Chunk>::getFirstNChunksFromList(size_t n, FreeList<Chunk>* fl) {

  assert_proper_lock_protection();

  assert(fl->count() == 0, "Precondition");

  if (count() > 0) {

    int k = 1;

    fl->set_head(head()); n--;

    Chunk* tl = head();

    while (tl->next() != NULL && n > 0) {

      tl = tl->next(); n--; k++;

    }

    assert(tl != NULL, "Loop Inv.");

    // First, fix up the list we took from.

    Chunk* new_head = tl->next();

    set_head(new_head);

    set_count(count() - k);

    if (new_head == NULL) {

      set_tail(NULL);

    } else {

      new_head->link_prev(NULL);

    }

    // Now we can fix up the tail.

    tl->link_next(NULL);

    // And return the result.

    fl->set_tail(tl);

    fl->set_count(k);

  }

}

// Remove this chunk from the list

template <class Chunk>

void FreeList<Chunk>::remove_chunk(Chunk*fc) {

   assert_proper_lock_protection();

   assert(head() != NULL, "Remove from empty list");

   assert(fc != NULL, "Remove a NULL chunk");

   assert(size() == fc->size(), "Wrong list");

   assert(head() == NULL || head()->prev() == NULL, "list invariant");

   assert(tail() == NULL || tail()->next() == NULL, "list invariant");

   Chunk* prevFC = fc->prev();

   Chunk* nextFC = fc->next();

   if (nextFC != NULL) {

     // The chunk fc being removed has a "next".  Set the "next" to the

     // "prev" of fc.

     nextFC->link_prev(prevFC);

   } else { // removed tail of list

     link_tail(prevFC);

   }

   if (prevFC == NULL) { // removed head of list

     link_head(nextFC);

     assert(nextFC == NULL || nextFC->prev() == NULL,

       "Prev of head should be NULL");

   } else {

     prevFC->link_next(nextFC);

     assert(tail() != prevFC || prevFC->next() == NULL,

       "Next of tail should be NULL");

   }

   decrement_count();

   assert(((head() == NULL) + (tail() == NULL) + (count() == 0)) % 3 == 0,

          "H/T/C Inconsistency");

   // clear next and prev fields of fc, debug only

   NOT_PRODUCT(

     fc->link_prev(NULL);

     fc->link_next(NULL);

   )

   assert(fc->is_free(), "Should still be a free chunk");

   assert(head() == NULL || head()->prev() == NULL, "list invariant");

   assert(tail() == NULL || tail()->next() == NULL, "list invariant");

   assert(head() == NULL || head()->size() == size(), "wrong item on list");

   assert(tail() == NULL || tail()->size() == size(), "wrong item on list");

}

// Add this chunk at the head of the list.

template <class Chunk>

void FreeList<Chunk>::return_chunk_at_head(Chunk* chunk, bool record_return) {

  assert_proper_lock_protection();

  assert(chunk != NULL, "insert a NULL chunk");

  assert(size() == chunk->size(), "Wrong size");

  assert(head() == NULL || head()->prev() == NULL, "list invariant");

  assert(tail() == NULL || tail()->next() == NULL, "list invariant");

  Chunk* oldHead = head();

  assert(chunk != oldHead, "double insertion");

  chunk->link_after(oldHead);

  link_head(chunk);

  if (oldHead == NULL) { // only chunk in list

    assert(tail() == NULL, "inconsistent FreeList");

    link_tail(chunk);

  }

  increment_count(); // of # of chunks in list

  assert(head() == NULL || head()->prev() == NULL, "list invariant");

  assert(tail() == NULL || tail()->next() == NULL, "list invariant");

  assert(head() == NULL || head()->size() == size(), "wrong item on list");

  assert(tail() == NULL || tail()->size() == size(), "wrong item on list");

}

template <class Chunk>

void FreeList<Chunk>::return_chunk_at_head(Chunk* chunk) {

  assert_proper_lock_protection();

  return_chunk_at_head(chunk, true);

}

// Add this chunk at the tail of the list.

template <class Chunk>

void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk, bool record_return) {

  assert_proper_lock_protection();

  assert(head() == NULL || head()->prev() == NULL, "list invariant");

  assert(tail() == NULL || tail()->next() == NULL, "list invariant");

  assert(chunk != NULL, "insert a NULL chunk");

  assert(size() == chunk->size(), "wrong size");

  Chunk* oldTail = tail();

  assert(chunk != oldTail, "double insertion");

  if (oldTail != NULL) {

    oldTail->link_after(chunk);

  } else { // only chunk in list

    assert(head() == NULL, "inconsistent FreeList");

    link_head(chunk);

  }

  link_tail(chunk);

  increment_count();  // of # of chunks in list

  assert(head() == NULL || head()->prev() == NULL, "list invariant");

  assert(tail() == NULL || tail()->next() == NULL, "list invariant");

  assert(head() == NULL || head()->size() == size(), "wrong item on list");

  assert(tail() == NULL || tail()->size() == size(), "wrong item on list");

}

template <class Chunk>

void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk) {

  return_chunk_at_tail(chunk, true);

}

template <class Chunk>

void FreeList<Chunk>::prepend(FreeList<Chunk>* fl) {

  assert_proper_lock_protection();

  if (fl->count() > 0) {

    if (count() == 0) {

      set_head(fl->head());

      set_tail(fl->tail());

      set_count(fl->count());

    } else {

      // Both are non-empty.

      Chunk* fl_tail = fl->tail();

      Chunk* this_head = head();

      assert(fl_tail->next() == NULL, "Well-formedness of fl");

      fl_tail->link_next(this_head);

      this_head->link_prev(fl_tail);

      set_head(fl->head());

      set_count(count() + fl->count());

    }

    fl->set_head(NULL);

    fl->set_tail(NULL);

    fl->set_count(0);

  }

}

// verify_chunk_in_free_lists() is used to verify that an item is in this free list.

// It is used as a debugging aid.

template <class Chunk>

bool FreeList<Chunk>::verify_chunk_in_free_list(Chunk* fc) const {

  // This is an internal consistency check, not part of the check that the

  // chunk is in the free lists.

  guarantee(fc->size() == size(), "Wrong list is being searched");

  Chunk* curFC = head();

  while (curFC) {

    // This is an internal consistency check.

    guarantee(size() == curFC->size(), "Chunk is in wrong list.");

    if (fc == curFC) {

      return true;

    }

    curFC = curFC->next();

  }

  return false;

}

#ifdef ASSERT

template <class Chunk>

void FreeList<Chunk>::assert_proper_lock_protection_work() const {

  // Nothing to do if the list has no assigned protecting lock

  if (protecting_lock() == NULL) {

    return;

  }

  Thread* thr = Thread::current();

  if (thr->is_VM_thread() || thr->is_ConcurrentGC_thread()) {

    // assert that we are holding the freelist lock

  } else if (thr->is_GC_task_thread()) {

    assert(protecting_lock()->owned_by_self(), "FreeList RACE DETECTED");

  } else if (thr->is_Java_thread()) {

    assert(!SafepointSynchronize::is_at_safepoint(), "Should not be executing");

  } else {

    ShouldNotReachHere();  // unaccounted thread type?

  }

}

#endif

// Print the "label line" for free list stats.

template <class Chunk>

void FreeList<Chunk>::print_labels_on(outputStream* st, const char* c) {

  st->print("%16s\t", c);

  st->print("%14s\t"    "%14s\t"    "%14s\t"    "%14s\t"    "%14s\t"

            "%14s\t"    "%14s\t"    "%14s\t"    "%14s\t"    "%14s\t"    "\n",

            "bfrsurp", "surplus", "desired", "prvSwep", "bfrSwep",

            "count",   "cBirths", "cDeaths", "sBirths", "sDeaths");

}

// Print the AllocationStats for the given free list. If the second argument

// to the call is a non-null string, it is printed in the first column;

// otherwise, if the argument is null (the default), then the size of the

// (free list) block is printed in the first column.

template <class Chunk_t>

void FreeList<Chunk_t>::print_on(outputStream* st, const char* c) const {

  if (c != NULL) {

    st->print("%16s", c);

  } else {

    st->print(SIZE_FORMAT_W(16), size());

  }

}

#endif // SHARE_MEMORY_FREELIST_INLINE_HPP