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 /*

  * Copyright (c) 2001, 2010, 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.

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  */

 #ifndef SHARE_VM_MEMORY_FREELIST_HPP

 #define SHARE_VM_MEMORY_FREELIST_HPP

 #include "gc_implementation/shared/allocationStats.hpp"

 class CompactibleFreeListSpace;

 // A class for maintaining a free list of Chunk's.  The FreeList

 // maintains a the structure of the list (head, tail, etc.) plus

 // statistics for allocations from the list.  The links between items

 // are not part of FreeList.  The statistics are

 // used to make decisions about coalescing Chunk's when they

 // are swept during collection.

 //

 // See the corresponding .cpp file for a description of the specifics

 // for that implementation.

 class Mutex;

 template <class Chunk> class TreeList;

 template <class Chunk> class PrintTreeCensusClosure;

 template <class Chunk>

 class FreeList VALUE_OBJ_CLASS_SPEC {

   friend class CompactibleFreeListSpace;

   friend class VMStructs;

   friend class PrintTreeCensusClosure<Chunk>;

  private:

   Chunk*        _head;          // Head of list of free chunks

   Chunk*        _tail;          // Tail of list of free chunks

   size_t        _size;          // Size in Heap words of each chunk

   ssize_t       _count;         // Number of entries in list

   size_t        _hint;          // next larger size list with a positive surplus

   AllocationStats _allocation_stats; // allocation-related statistics

 #ifdef ASSERT

   Mutex*        _protecting_lock;

 #endif

   // Asserts false if the protecting lock (if any) is not held.

   void assert_proper_lock_protection_work() const PRODUCT_RETURN;

   void assert_proper_lock_protection() const {

 #ifdef ASSERT

     if (_protecting_lock != NULL)

       assert_proper_lock_protection_work();

 #endif

   }

   // Initialize the allocation statistics.

  protected:

   void init_statistics(bool split_birth = false);

   void set_count(ssize_t v) { _count = v;}

   void increment_count()    {

     _count++;

   }

   void decrement_count() {

     _count--;

     assert(_count >= 0, "Count should not be negative");

   }

  public:

   // Constructor

   // Construct a list without any entries.

   FreeList();

   // Construct a list with "fc" as the first (and lone) entry in the list.

   FreeList(Chunk* fc);

   // Reset the head, tail, hint, and count of a free list.

   void reset(size_t hint);

   // Declare the current free list to be protected by the given lock.

 #ifdef ASSERT

   void set_protecting_lock(Mutex* protecting_lock) {

     _protecting_lock = protecting_lock;

   }

 #endif

   // Accessors.

   Chunk* head() const {

     assert_proper_lock_protection();

     return _head;

   }

   void set_head(Chunk* v) {

     assert_proper_lock_protection();

     _head = v;

     assert(!_head || _head->size() == _size, "bad chunk size");

   }

   // Set the head of the list and set the prev field of non-null

   // values to NULL.

   void 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);

     }

   }

   Chunk* tail() const {

     assert_proper_lock_protection();

     return _tail;

   }

   void set_tail(Chunk* v) {

     assert_proper_lock_protection();

     _tail = v;

     assert(!_tail || _tail->size() == _size, "bad chunk size");

   }

   // Set the tail of the list and set the next field of non-null

   // values to NULL.

   void link_tail(Chunk* v) {

     assert_proper_lock_protection();

     set_tail(v);

     if (v != NULL) {

       v->clear_next();

     }

   }

   // No locking checks in read-accessors: lock-free reads (only) are benign.

   // Readers are expected to have the lock if they are doing work that

   // requires atomicity guarantees in sections of code.

   size_t size() const {

     return _size;

   }

   void set_size(size_t v) {

     assert_proper_lock_protection();

     _size = v;

   }

   ssize_t count() const {

     return _count;

   }

   size_t hint() const {

     return _hint;

   }

   void set_hint(size_t v) {

     assert_proper_lock_protection();

     assert(v == 0 || _size < v, "Bad hint"); _hint = v;

   }

   // Accessors for statistics

   AllocationStats* allocation_stats() {

     assert_proper_lock_protection();

     return &_allocation_stats;

   }

   ssize_t desired() const {

     return _allocation_stats.desired();

   }

   void set_desired(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_desired(v);

   }

   void compute_desired(float inter_sweep_current,

                        float inter_sweep_estimate,

                        float intra_sweep_estimate) {

     assert_proper_lock_protection();

     _allocation_stats.compute_desired(_count,

                                       inter_sweep_current,

                                       inter_sweep_estimate,

                                       intra_sweep_estimate);

   }

   ssize_t coal_desired() const {

     return _allocation_stats.coal_desired();

   }

   void set_coal_desired(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_coal_desired(v);

   }

   ssize_t surplus() const {

     return _allocation_stats.surplus();

   }

   void set_surplus(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_surplus(v);

   }

   void increment_surplus() {

     assert_proper_lock_protection();

     _allocation_stats.increment_surplus();

   }

   void decrement_surplus() {

     assert_proper_lock_protection();

     _allocation_stats.decrement_surplus();

   }

   ssize_t bfr_surp() const {

     return _allocation_stats.bfr_surp();

   }

   void set_bfr_surp(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_bfr_surp(v);

   }

   ssize_t prev_sweep() const {

     return _allocation_stats.prev_sweep();

   }

   void set_prev_sweep(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_prev_sweep(v);

   }

   ssize_t before_sweep() const {

     return _allocation_stats.before_sweep();

   }

   void set_before_sweep(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_before_sweep(v);

   }

   ssize_t coal_births() const {

     return _allocation_stats.coal_births();

   }

   void set_coal_births(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_coal_births(v);

   }

   void increment_coal_births() {

     assert_proper_lock_protection();

     _allocation_stats.increment_coal_births();

   }

   ssize_t coal_deaths() const {

     return _allocation_stats.coal_deaths();

   }

   void set_coal_deaths(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_coal_deaths(v);

   }

   void increment_coal_deaths() {

     assert_proper_lock_protection();

     _allocation_stats.increment_coal_deaths();

   }

   ssize_t split_births() const {

     return _allocation_stats.split_births();

   }

   void set_split_births(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_split_births(v);

   }

   void increment_split_births() {

     assert_proper_lock_protection();

     _allocation_stats.increment_split_births();

   }

   ssize_t split_deaths() const {

     return _allocation_stats.split_deaths();

   }

   void set_split_deaths(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_split_deaths(v);

   }

   void increment_split_deaths() {

     assert_proper_lock_protection();

     _allocation_stats.increment_split_deaths();

   }

   NOT_PRODUCT(

     // For debugging.  The "_returned_bytes" in all the lists are summed

     // and compared with the total number of bytes swept during a

     // collection.

     size_t returned_bytes() const { return _allocation_stats.returned_bytes(); }

     void set_returned_bytes(size_t v) { _allocation_stats.set_returned_bytes(v); }

     void increment_returned_bytes_by(size_t v) {

       _allocation_stats.set_returned_bytes(_allocation_stats.returned_bytes() + v);

     }

   )

   // Unlink head of list and return it.  Returns NULL if

   // the list is empty.

   Chunk* get_chunk_at_head();

   // Remove the first "n" or "count", whichever is smaller, chunks from the

   // list, setting "fl", which is required to be empty, to point to them.

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

   // Unlink this chunk from it's free list

   void remove_chunk(Chunk* fc);

   // Add this chunk to this free list.

   void return_chunk_at_head(Chunk* fc);

   void return_chunk_at_tail(Chunk* fc);

   // Similar to returnChunk* but also records some diagnostic

   // information.

   void return_chunk_at_head(Chunk* fc, bool record_return);

   void return_chunk_at_tail(Chunk* fc, bool record_return);

   // Prepend "fl" (whose size is required to be the same as that of "this")

   // to the front of "this" list.

   void prepend(FreeList<Chunk>* fl);

   // Verify that the chunk is in the list.

   // found.  Return NULL if "fc" is not found.

   bool verify_chunk_in_free_list(Chunk* fc) const;

   // Stats verification

   void verify_stats() const PRODUCT_RETURN;

   // Printing support

   static void print_labels_on(outputStream* st, const char* c);

   void print_on(outputStream* st, const char* c = NULL) const;

 };

 #endif // SHARE_VM_MEMORY_FREELIST_HPP