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/zForwardingTable.inline.hpp"

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

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

    28 #include "utilities/debug.hpp"

    29 

    30 void ZForwardingTable::setup(size_t live_objects) {

    31   assert(is_null(), "Should be empty");

    32   assert(live_objects > 0, "Invalid size");

    33 

    34   // Allocate table for linear probing. The size of the table must be

    35   // a power of two to allow for quick and inexpensive indexing/masking.

    36   // The table is sized to have a load factor of 50%, i.e. sized to have

    37   // double the number of entries actuallly inserted.

    38   _size = ZUtils::round_up_power_of_2(live_objects * 2);

    39   _table = MallocArrayAllocator<ZForwardingTableEntry>::allocate(_size, mtGC);

    40 

    41   // Clear table

    42   memset(_table, ZForwardingTableEntry::empty(), _size * sizeof(ZForwardingTableEntry));

    43 }

    44 

    45 void ZForwardingTable::reset() {

    46   // Free table

    47   MallocArrayAllocator<ZForwardingTableEntry>::free(_table);

    48   _table = NULL;

    49   _size = 0;

    50 }

    51 

    52 void ZForwardingTable::verify(size_t object_max_count, size_t live_objects) const {

    53   size_t count = 0;

    54 

    55   for (size_t i = 0; i < _size; i++) {

    56     const ZForwardingTableEntry entry = _table[i];

    57     if (entry.is_empty()) {

    58       // Skip empty entries

    59       continue;

    60     }

    61 

    62     // Check from index

    63     guarantee(entry.from_index() < object_max_count, "Invalid from index");

    64 

    65     // Check for duplicates

    66     for (size_t j = i + 1; j < _size; j++) {

    67       const ZForwardingTableEntry other = _table[j];

    68       guarantee(entry.from_index() != other.from_index(), "Duplicate from");

    69       guarantee(entry.to_offset() != other.to_offset(), "Duplicate to");

    70     }

    71 

    72     count++;

    73   }

    74 

    75   // Check number of non-null entries

    76   guarantee(live_objects == count, "Count mismatch");

    77 }