1 package sun.jvm.hotspot.gc.z;
   2 
   3 import java.util.HashMap;
   4 
   5 import sun.jvm.hotspot.runtime.VM;
   6 import sun.jvm.hotspot.utilities.BitMap;
   7 import sun.jvm.hotspot.utilities.BitMapInterface;
   8 
   9 /** Discontiguous bitmap for ZGC. */
  10 public class ZExternalBitMap implements BitMapInterface {
  11     private ZPageTable pageTable;
  12     private final long oopSize;
  13 
  14     private HashMap<ZPage, BitMap> pageToBitMap = new HashMap<ZPage, BitMap>();
  15 
  16     public ZExternalBitMap(ZCollectedHeap collectedHeap) {
  17         pageTable = collectedHeap.heap().pageTable();
  18         oopSize = VM.getVM().getOopSize();
  19     }
  20 
  21     private ZPage getPage(long zOffset) {
  22         if (zOffset > ZGlobals.ZAddressOffsetMask) {
  23             throw new RuntimeException("Not a Z offset: " + zOffset);
  24         }
  25 
  26         ZPage page = pageTable.get(ZOop.to_address(zOffset));
  27         if (page == null) {
  28             throw new RuntimeException("Address not in pageTable: " + zOffset);
  29         }
  30         return page;
  31     }
  32 
  33     private BitMap getOrAddBitMap(ZPage page) {
  34         BitMap bitMap = pageToBitMap.get(page);
  35         if (bitMap == null) {
  36             long size = page.size();
  37 
  38             long maxNumObjects = size >>> page.object_alignment_shift();
  39             if (maxNumObjects > Integer.MAX_VALUE) {
  40                 throw new RuntimeException("int overflow");
  41             }
  42             int intMaxNumObjects = (int)maxNumObjects;
  43 
  44             bitMap = new BitMap(intMaxNumObjects);
  45             pageToBitMap.put(page,  bitMap);
  46         }
  47 
  48         return bitMap;
  49     }
  50 
  51     private int pageLocalBitMapIndex(ZPage page, long zOffset) {
  52         long pageLocalZOffset = zOffset - page.start();
  53         return (int)(pageLocalZOffset >>> page.object_alignment_shift());
  54     }
  55 
  56     private long convertToZOffset(long offset) {
  57         long addr = ZGlobals.ZAddressSpaceStart + oopSize * offset;
  58         return addr & ZGlobals.ZAddressOffsetMask;
  59     }
  60 
  61     @Override
  62     public boolean at(long offset) {
  63         long zOffset = convertToZOffset(offset);
  64         ZPage page = getPage(zOffset);
  65         BitMap bitMap = getOrAddBitMap(page);
  66         int index = pageLocalBitMapIndex(page, zOffset);
  67 
  68         return bitMap.at(index);
  69     }
  70 
  71     @Override
  72     public void atPut(long offset, boolean value) {
  73         long zOffset = convertToZOffset(offset);
  74         ZPage page = getPage(zOffset);
  75         BitMap bitMap = getOrAddBitMap(page);
  76         int index = pageLocalBitMapIndex(page, zOffset);
  77 
  78         bitMap.atPut(index, value);
  79     }
  80 
  81     @Override
  82     public void clear() {
  83         for (BitMap bitMap : pageToBitMap.values()) {
  84             bitMap.clear();
  85         }
  86     }
  87 }