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 /*

  * Copyright (c) 2001, 2012, 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.

  *

  */

 #include "precompiled.hpp"

 #include "memory/freeBlockDictionary.hpp"

 #include "memory/freeList.hpp"

 #include "memory/metablock.hpp"

 #include "memory/metachunk.hpp"

 #include "memory/sharedHeap.hpp"

 #include "runtime/globals.hpp"

 #include "runtime/mutex.hpp"

 #include "runtime/vmThread.hpp"

 #ifndef SERIALGC

 #include "gc_implementation/concurrentMarkSweep/freeChunk.hpp"

 #endif // SERIALGC

 // 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>

 FreeList<Chunk>::FreeList(Chunk* fc) :

   _head(fc), _tail(fc)

 #ifdef ASSERT

   , _protecting_lock(NULL)

 #endif

 {

   _size         = fc->size();

   _count        = 1;

 }

 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;

 }

 #ifndef PRODUCT

 template <class Chunk>

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

   assert(protecting_lock() != NULL, "Don't call this directly");

   assert(ParallelGCThreads > 0, "Don't call this directly");

   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());

   }

 }

 template class FreeList<Metablock>;

 template class FreeList<Metachunk>;

 #ifndef SERIALGC

 template class FreeList<FreeChunk>;

 #endif // SERIALGC