1 /*

     2  * Copyright 2001-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 class HeapRegion;

    26 class HeapRegionClosure;

    27 

    28 class HeapRegionSeq: public CHeapObj {

    29 

    30   // _regions is kept sorted by start address order, and no two regions are

    31   // overlapping.

    32   GrowableArray<HeapRegion*> _regions;

    33 

    34   // The index in "_regions" at which to start the next allocation search.

    35   // (For efficiency only; private to obj_allocate after initialization.)

    36   int _alloc_search_start;

    37 

    38   // Attempts to allocate a block of the (assumed humongous) word_size,

    39   // starting at the region "ind".

    40   HeapWord* alloc_obj_from_region_index(int ind, size_t word_size);

    41 

    42   // Currently, we're choosing collection sets in a round-robin fashion,

    43   // starting here.

    44   int _next_rr_candidate;

    45 

    46   // The bottom address of the bottom-most region, or else NULL if there

    47   // are no regions in the sequence.

    48   char* _seq_bottom;

    49 

    50  public:

    51   // Initializes "this" to the empty sequence of regions.

    52   HeapRegionSeq();

    53 

    54   // Adds "hr" to "this" sequence.  Requires "hr" not to overlap with

    55   // any region already in "this".  (Will perform better if regions are

    56   // inserted in ascending address order.)

    57   void insert(HeapRegion* hr);

    58 

    59   // Given a HeapRegion*, returns its index within _regions,

    60   // or returns -1 if not found.

    61   int find(HeapRegion* hr);

    62 

    63   // Requires the index to be valid, and return the region at the index.

    64   HeapRegion* at(size_t i) { return _regions.at((int)i); }

    65 

    66   // Return the number of regions in the sequence.

    67   size_t length();

    68 

    69   // Returns the number of contiguous regions at the end of the sequence

    70   // that are available for allocation.

    71   size_t free_suffix();

    72 

    73   // Requires "word_size" to be humongous (in the technical sense).  If

    74   // possible, allocates a contiguous subsequence of the heap regions to

    75   // satisfy the allocation, and returns the address of the beginning of

    76   // that sequence, otherwise returns NULL.

    77   HeapWord* obj_allocate(size_t word_size);

    78 

    79   // Apply the "doHeapRegion" method of "blk" to all regions in "this",

    80   // in address order, terminating the iteration early

    81   // if the "doHeapRegion" method returns "true".

    82   void iterate(HeapRegionClosure* blk);

    83 

    84   // Apply the "doHeapRegion" method of "blk" to all regions in "this",

    85   // starting at "r" (or first region, if "r" is NULL), in a circular

    86   // manner, terminating the iteration early if the "doHeapRegion" method

    87   // returns "true".

    88   void iterate_from(HeapRegion* r, HeapRegionClosure* blk);

    89 

    90   // As above, but start from a given index in the sequence

    91   // instead of a given heap region.

    92   void iterate_from(int idx, HeapRegionClosure* blk);

    93 

    94   // Requires "shrink_bytes" to be a multiple of the page size and heap

    95   // region granularity.  Deletes as many "rightmost" completely free heap

    96   // regions from the sequence as comprise shrink_bytes bytes.  Returns the

    97   // MemRegion indicating the region those regions comprised, and sets

    98   // "num_regions_deleted" to the number of regions deleted.

    99   MemRegion shrink_by(size_t shrink_bytes, size_t& num_regions_deleted);

   100 

   101   // If "addr" falls within a region in the sequence, return that region,

   102   // or else NULL.

   103   HeapRegion* addr_to_region(const void* addr);

   104 

   105   void print();

   106 

   107   // Prints out runs of empty regions.  If the arg is "true" reserved

   108   // (popular regions are considered "empty".

   109   void print_empty_runs(bool reserved_are_empty);

   110 

   111 };