1 /*
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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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
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24 
25 package sun.jvm.hotspot.gc.z;
26 
27 import java.util.HashMap;
28 
29 import sun.jvm.hotspot.runtime.VM;
30 import sun.jvm.hotspot.utilities.BitMap;
31 import sun.jvm.hotspot.utilities.BitMapInterface;
32 
33 /** Discontiguous bitmap for ZGC. */
34 public class ZExternalBitMap implements BitMapInterface {
35     private ZPageTable pageTable;
36     private final long oopSize;
37 
38     private HashMap<ZPage, BitMap> pageToBitMap = new HashMap<ZPage, BitMap>();
39 
ZExternalBitMap(ZCollectedHeap collectedHeap)40     public ZExternalBitMap(ZCollectedHeap collectedHeap) {
41         pageTable = collectedHeap.heap().pageTable();
42         oopSize = VM.getVM().getOopSize();
43     }
44 
getPage(long zOffset)45     private ZPage getPage(long zOffset) {
46         if (zOffset > ZGlobals.ZAddressOffsetMask) {
47             throw new RuntimeException("Not a Z offset: " + zOffset);
48         }
49 
50         ZPage page = pageTable.get(ZUtils.longToAddress(zOffset));
51         if (page == null) {
52             throw new RuntimeException("Address not in pageTable: " + zOffset);
53         }
54         return page;
55     }
56 
getOrAddBitMap(ZPage page)57     private BitMap getOrAddBitMap(ZPage page) {
58         BitMap bitMap = pageToBitMap.get(page);
59         if (bitMap == null) {
60             long size = page.size();
61 
62             long maxNumObjects = size >>> page.object_alignment_shift();
63             if (maxNumObjects > Integer.MAX_VALUE) {
64                 throw new RuntimeException("int overflow");
65             }
66             int intMaxNumObjects = (int)maxNumObjects;
67 
68             bitMap = new BitMap(intMaxNumObjects);
69             pageToBitMap.put(page,  bitMap);
70         }
71 
72         return bitMap;
73     }
74 
pageLocalBitMapIndex(ZPage page, long zOffset)75     private int pageLocalBitMapIndex(ZPage page, long zOffset) {
76         long pageLocalZOffset = zOffset - page.start();
77         return (int)(pageLocalZOffset >>> page.object_alignment_shift());
78     }
79 
convertToZOffset(long offset)80     private long convertToZOffset(long offset) {
81         long addr = ZGlobals.ZAddressSpaceStart + oopSize * offset;
82         return addr & ZGlobals.ZAddressOffsetMask;
83     }
84 
85     @Override
at(long offset)86     public boolean at(long offset) {
87         long zOffset = convertToZOffset(offset);
88         ZPage page = getPage(zOffset);
89         BitMap bitMap = getOrAddBitMap(page);
90         int index = pageLocalBitMapIndex(page, zOffset);
91 
92         return bitMap.at(index);
93     }
94 
95     @Override
atPut(long offset, boolean value)96     public void atPut(long offset, boolean value) {
97         long zOffset = convertToZOffset(offset);
98         ZPage page = getPage(zOffset);
99         BitMap bitMap = getOrAddBitMap(page);
100         int index = pageLocalBitMapIndex(page, zOffset);
101 
102         bitMap.atPut(index, value);
103     }
104 
105     @Override
clear()106     public void clear() {
107         for (BitMap bitMap : pageToBitMap.values()) {
108             bitMap.clear();
109         }
110     }
111 }
112