Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 2001-2006 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.

  *

  */

 class CompactibleFreeListSpace;

 // A class for maintaining a free list of FreeChunk'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 FreeChunk's when they

 // are swept during collection.

 //

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

 // for that implementation.

 class Mutex;

 class FreeList VALUE_OBJ_CLASS_SPEC {

   friend class CompactibleFreeListSpace;

   FreeChunk*    _head;          // List of free chunks

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

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

   ssize_t       _count;         // Number of entries in list

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

   AllocationStats _allocation_stats;            // statistics for smart allocation

 #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();

   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(FreeChunk* fc);

   // Construct a list which will have a FreeChunk at address "addr" and

   // of size "size" as the first (and lone) entry in the list.

   FreeList(HeapWord* addr, size_t size);

   // 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.

   FreeChunk* head() const {

     assert_proper_lock_protection();

     return _head;

   }

   void set_head(FreeChunk* 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(FreeChunk* 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->linkPrev(NULL);

     }

   }

   FreeChunk* tail() const {

     assert_proper_lock_protection();

     return _tail;

   }

   void set_tail(FreeChunk* 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(FreeChunk* v) {

     assert_proper_lock_protection();

     set_tail(v);

     if (v != NULL) {

       v->clearNext();

     }

   }

   // 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 compute_desired(float inter_sweep_current,

                        float inter_sweep_estimate) {

     assert_proper_lock_protection();

     _allocation_stats.compute_desired(_count,

                                       inter_sweep_current,

                                       inter_sweep_estimate);

   }

   ssize_t coalDesired() const {

     return _allocation_stats.coalDesired();

   }

   void set_coalDesired(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_coalDesired(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 bfrSurp() const {

     return _allocation_stats.bfrSurp();

   }

   void set_bfrSurp(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_bfrSurp(v);

   }

   ssize_t prevSweep() const {

     return _allocation_stats.prevSweep();

   }

   void set_prevSweep(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_prevSweep(v);

   }

   ssize_t beforeSweep() const {

     return _allocation_stats.beforeSweep();

   }

   void set_beforeSweep(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_beforeSweep(v);

   }

   ssize_t coalBirths() const {

     return _allocation_stats.coalBirths();

   }

   void set_coalBirths(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_coalBirths(v);

   }

   void increment_coalBirths() {

     assert_proper_lock_protection();

     _allocation_stats.increment_coalBirths();

   }

   ssize_t coalDeaths() const {

     return _allocation_stats.coalDeaths();

   }

   void set_coalDeaths(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_coalDeaths(v);

   }

   void increment_coalDeaths() {

     assert_proper_lock_protection();

     _allocation_stats.increment_coalDeaths();

   }

   ssize_t splitBirths() const {

     return _allocation_stats.splitBirths();

   }

   void set_splitBirths(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_splitBirths(v);

   }

   void increment_splitBirths() {

     assert_proper_lock_protection();

     _allocation_stats.increment_splitBirths();

   }

   ssize_t splitDeaths() const {

     return _allocation_stats.splitDeaths();

   }

   void set_splitDeaths(ssize_t v) {

     assert_proper_lock_protection();

     _allocation_stats.set_splitDeaths(v);

   }

   void increment_splitDeaths() {

     assert_proper_lock_protection();

     _allocation_stats.increment_splitDeaths();

   }

   NOT_PRODUCT(

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

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

     // collection.

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

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

     void increment_returnedBytes_by(size_t v) {

       _allocation_stats.set_returnedBytes(_allocation_stats.returnedBytes() + v);

     }

   )

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

   // the list is empty.

   FreeChunk* getChunkAtHead();

   // 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* fl);

   // Unlink this chunk from it's free list

   void removeChunk(FreeChunk* fc);

   // Add this chunk to this free list.

   void returnChunkAtHead(FreeChunk* fc);

   void returnChunkAtTail(FreeChunk* fc);

   // Similar to returnChunk* but also records some diagnostic

   // information.

   void returnChunkAtHead(FreeChunk* fc, bool record_return);

   void returnChunkAtTail(FreeChunk* 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* fl);

   // Verify that the chunk is in the list.

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

   bool verifyChunkInFreeLists(FreeChunk* fc) const;

 };