1 /*

     2  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_FREELIST_HPP

    26 #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_FREELIST_HPP

    27 

    28 #include "gc_implementation/shared/allocationStats.hpp"

    29 

    30 class CompactibleFreeListSpace;

    31 

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

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

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

    35 // are not part of FreeList.  The statistics are

    36 // used to make decisions about coalescing FreeChunk's when they

    37 // are swept during collection.

    38 //

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

    40 // for that implementation.

    41 

    42 class Mutex;

    43 class TreeList;

    44 

    45 class FreeList VALUE_OBJ_CLASS_SPEC {

    46   friend class CompactibleFreeListSpace;

    47   friend class VMStructs;

    48   friend class PrintTreeCensusClosure;

    49 

    50  protected:

    51   TreeList* _parent;

    52   TreeList* _left;

    53   TreeList* _right;

    54 

    55  private:

    56   FreeChunk*    _head;          // Head of list of free chunks

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

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

    59   ssize_t       _count;         // Number of entries in list

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

    61 

    62   AllocationStats _allocation_stats; // allocation-related statistics

    63 

    64 #ifdef ASSERT

    65   Mutex*        _protecting_lock;

    66 #endif

    67 

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

    69   void assert_proper_lock_protection_work() const PRODUCT_RETURN;

    70   void assert_proper_lock_protection() const {

    71 #ifdef ASSERT

    72     if (_protecting_lock != NULL)

    73       assert_proper_lock_protection_work();

    74 #endif

    75   }

    76 

    77   // Initialize the allocation statistics.

    78  protected:

    79   void init_statistics(bool split_birth = false);

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

    81   void increment_count()    {

    82     _count++;

    83   }

    84 

    85   void decrement_count() {

    86     _count--;

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

    88   }

    89 

    90  public:

    91   // Constructor

    92   // Construct a list without any entries.

    93   FreeList();

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

    95   FreeList(FreeChunk* fc);

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

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

    98   FreeList(HeapWord* addr, size_t size);

    99 

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

   101   void reset(size_t hint);

   102 

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

   104 #ifdef ASSERT

   105   void set_protecting_lock(Mutex* protecting_lock) {

   106     _protecting_lock = protecting_lock;

   107   }

   108 #endif

   109 

   110   // Accessors.

   111   FreeChunk* head() const {

   112     assert_proper_lock_protection();

   113     return _head;

   114   }

   115   void set_head(FreeChunk* v) {

   116     assert_proper_lock_protection();

   117     _head = v;

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

   119   }

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

   121   // values to NULL.

   122   void link_head(FreeChunk* v) {

   123     assert_proper_lock_protection();

   124     set_head(v);

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

   126     // this check can be avoided.

   127     if (v != NULL) {

   128       v->linkPrev(NULL);

   129     }

   130   }

   131 

   132   FreeChunk* tail() const {

   133     assert_proper_lock_protection();

   134     return _tail;

   135   }

   136   void set_tail(FreeChunk* v) {

   137     assert_proper_lock_protection();

   138     _tail = v;

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

   140   }

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

   142   // values to NULL.

   143   void link_tail(FreeChunk* v) {

   144     assert_proper_lock_protection();

   145     set_tail(v);

   146     if (v != NULL) {

   147       v->clearNext();

   148     }

   149   }

   150 

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

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

   153   // requires atomicity guarantees in sections of code.

   154   size_t size() const {

   155     return _size;

   156   }

   157   void set_size(size_t v) {

   158     assert_proper_lock_protection();

   159     _size = v;

   160   }

   161   ssize_t count() const {

   162     return _count;

   163   }

   164   size_t hint() const {

   165     return _hint;

   166   }

   167   void set_hint(size_t v) {

   168     assert_proper_lock_protection();

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

   170   }

   171 

   172   // Accessors for statistics

   173   AllocationStats* allocation_stats() {

   174     assert_proper_lock_protection();

   175     return &_allocation_stats;

   176   }

   177 

   178   ssize_t desired() const {

   179     return _allocation_stats.desired();

   180   }

   181   void set_desired(ssize_t v) {

   182     assert_proper_lock_protection();

   183     _allocation_stats.set_desired(v);

   184   }

   185   void compute_desired(float inter_sweep_current,

   186                        float inter_sweep_estimate,

   187                        float intra_sweep_estimate) {

   188     assert_proper_lock_protection();

   189     _allocation_stats.compute_desired(_count,

   190                                       inter_sweep_current,

   191                                       inter_sweep_estimate,

   192                                       intra_sweep_estimate);

   193   }

   194   ssize_t coalDesired() const {

   195     return _allocation_stats.coalDesired();

   196   }

   197   void set_coalDesired(ssize_t v) {

   198     assert_proper_lock_protection();

   199     _allocation_stats.set_coalDesired(v);

   200   }

   201 

   202   ssize_t surplus() const {

   203     return _allocation_stats.surplus();

   204   }

   205   void set_surplus(ssize_t v) {

   206     assert_proper_lock_protection();

   207     _allocation_stats.set_surplus(v);

   208   }

   209   void increment_surplus() {

   210     assert_proper_lock_protection();

   211     _allocation_stats.increment_surplus();

   212   }

   213   void decrement_surplus() {

   214     assert_proper_lock_protection();

   215     _allocation_stats.decrement_surplus();

   216   }

   217 

   218   ssize_t bfrSurp() const {

   219     return _allocation_stats.bfrSurp();

   220   }

   221   void set_bfrSurp(ssize_t v) {

   222     assert_proper_lock_protection();

   223     _allocation_stats.set_bfrSurp(v);

   224   }

   225   ssize_t prevSweep() const {

   226     return _allocation_stats.prevSweep();

   227   }

   228   void set_prevSweep(ssize_t v) {

   229     assert_proper_lock_protection();

   230     _allocation_stats.set_prevSweep(v);

   231   }

   232   ssize_t beforeSweep() const {

   233     return _allocation_stats.beforeSweep();

   234   }

   235   void set_beforeSweep(ssize_t v) {

   236     assert_proper_lock_protection();

   237     _allocation_stats.set_beforeSweep(v);

   238   }

   239 

   240   ssize_t coalBirths() const {

   241     return _allocation_stats.coalBirths();

   242   }

   243   void set_coalBirths(ssize_t v) {

   244     assert_proper_lock_protection();

   245     _allocation_stats.set_coalBirths(v);

   246   }

   247   void increment_coalBirths() {

   248     assert_proper_lock_protection();

   249     _allocation_stats.increment_coalBirths();

   250   }

   251 

   252   ssize_t coalDeaths() const {

   253     return _allocation_stats.coalDeaths();

   254   }

   255   void set_coalDeaths(ssize_t v) {

   256     assert_proper_lock_protection();

   257     _allocation_stats.set_coalDeaths(v);

   258   }

   259   void increment_coalDeaths() {

   260     assert_proper_lock_protection();

   261     _allocation_stats.increment_coalDeaths();

   262   }

   263 

   264   ssize_t splitBirths() const {

   265     return _allocation_stats.splitBirths();

   266   }

   267   void set_splitBirths(ssize_t v) {

   268     assert_proper_lock_protection();

   269     _allocation_stats.set_splitBirths(v);

   270   }

   271   void increment_splitBirths() {

   272     assert_proper_lock_protection();

   273     _allocation_stats.increment_splitBirths();

   274   }

   275 

   276   ssize_t splitDeaths() const {

   277     return _allocation_stats.splitDeaths();

   278   }

   279   void set_splitDeaths(ssize_t v) {

   280     assert_proper_lock_protection();

   281     _allocation_stats.set_splitDeaths(v);

   282   }

   283   void increment_splitDeaths() {

   284     assert_proper_lock_protection();

   285     _allocation_stats.increment_splitDeaths();

   286   }

   287 

   288   NOT_PRODUCT(

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

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

   291     // collection.

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

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

   294     void increment_returnedBytes_by(size_t v) {

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

   296     }

   297   )

   298 

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

   300   // the list is empty.

   301   FreeChunk* getChunkAtHead();

   302 

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

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

   305   void getFirstNChunksFromList(size_t n, FreeList* fl);

   306 

   307   // Unlink this chunk from it's free list

   308   void removeChunk(FreeChunk* fc);

   309 

   310   // Add this chunk to this free list.

   311   void returnChunkAtHead(FreeChunk* fc);

   312   void returnChunkAtTail(FreeChunk* fc);

   313 

   314   // Similar to returnChunk* but also records some diagnostic

   315   // information.

   316   void returnChunkAtHead(FreeChunk* fc, bool record_return);

   317   void returnChunkAtTail(FreeChunk* fc, bool record_return);

   318 

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

   320   // to the front of "this" list.

   321   void prepend(FreeList* fl);

   322 

   323   // Verify that the chunk is in the list.

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

   325   bool verifyChunkInFreeLists(FreeChunk* fc) const;

   326 

   327   // Stats verification

   328   void verify_stats() const PRODUCT_RETURN;

   329 

   330   // Printing support

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

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

   333 };

   334 

   335 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_FREELIST_HPP