1 /*

     2  * Copyright (c) 2015, 2017, 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 #include "precompiled.hpp"

    25 #include "gc/z/zList.inline.hpp"

    26 #include "gc/z/zMemory.inline.hpp"

    27 #include "memory/allocation.inline.hpp"

    28 

    29 uintptr_t ZMemoryManager::alloc_from_front(size_t size) {

    30   ZListIterator<ZMemory> iter(&_freelist);

    31   for (ZMemory* area; iter.next(&area);) {

    32     if (area->size() >= size) {

    33       if (area->size() == size) {

    34         // Exact match, remove area

    35         const uintptr_t start = area->start();

    36         _freelist.remove(area);

    37         delete area;

    38         return start;

    39       } else {

    40         // Larger than requested, shrink area

    41         const uintptr_t start = area->start();

    42         area->shrink_from_front(size);

    43         return start;

    44       }

    45     }

    46   }

    47 

    48   // Out of memory

    49   return UINTPTR_MAX;

    50 }

    51 

    52 uintptr_t ZMemoryManager::alloc_from_back(size_t size) {

    53   ZListReverseIterator<ZMemory> iter(&_freelist);

    54   for (ZMemory* area; iter.next(&area);) {

    55     if (area->size() >= size) {

    56       if (area->size() == size) {

    57         // Exact match, remove area

    58         const uintptr_t start = area->start();

    59         _freelist.remove(area);

    60         delete area;

    61         return start;

    62       } else {

    63         // Larger than requested, shrink area

    64         area->shrink_from_back(size);

    65         return area->end();

    66       }

    67     }

    68   }

    69 

    70   // Out of memory

    71   return UINTPTR_MAX;

    72 }

    73 

    74 void ZMemoryManager::free(uintptr_t start, size_t size) {

    75   assert(start != UINTPTR_MAX, "Invalid address");

    76   const uintptr_t end = start + size;

    77 

    78   ZListIterator<ZMemory> iter(&_freelist);

    79   for (ZMemory* area; iter.next(&area);) {

    80     if (start < area->start()) {

    81       ZMemory* const prev = _freelist.prev(area);

    82       if (prev != NULL && start == prev->end()) {

    83         if (end == area->start()) {

    84           // Merge with prev and current area

    85           prev->grow_from_back(size + area->size());

    86           _freelist.remove(area);

    87           delete area;

    88         } else {

    89           // Merge with prev area

    90           prev->grow_from_back(size);

    91         }

    92       } else if (end == area->start()) {

    93         // Merge with current area

    94         area->grow_from_front(size);

    95       } else {

    96         // Insert new area before current area

    97         assert(end < area->start(), "Areas must not overlap");

    98         ZMemory* new_area = new ZMemory(start, size);

    99         _freelist.insert_before(area, new_area);

   100       }

   101 

   102       // Done

   103       return;

   104     }

   105   }

   106 

   107   // Insert last

   108   ZMemory* const last = _freelist.last();

   109   if (last != NULL && start == last->end()) {

   110     // Merge with last area

   111     last->grow_from_back(size);

   112   } else {

   113     // Insert new area last

   114     ZMemory* new_area = new ZMemory(start, size);

   115     _freelist.insert_last(new_area);

   116   }

   117 }