src/main/java/eu/svjatoslav/sixth/data/store/file/VacuumContext.java

   1 /*
   2  * Sixth Data. Author: Svjatoslav Agejenko.
   3  * This project is released under Creative Commons Zero (CC0) license.
   4  *
   5 */
   6
   7 package eu.svjatoslav.sixth.data.store.file;
   8
   9 public class VacuumContext {
  10     private final FileDataStore vacuumContext;
  11     private final int targetFragmentationPercent;
  12     long analyzedBytesCount = 0;
  13     long freeBytesCount = 0;
  14     long lastRecordStartAddress;
  15     long defragmentationStartAddress;
  16
  17     public VacuumContext(final FileDataStore fileDataStore,
  18                          final long currentFreeAddress, final int targetFragmentationPercent) {
  19
  20         vacuumContext = fileDataStore;
  21         lastRecordStartAddress = currentFreeAddress;
  22         defragmentationStartAddress = currentFreeAddress;
  23         this.targetFragmentationPercent = targetFragmentationPercent;
  24     }
  25
  26     public void analyzeEntry(final EntryRecord record) {
  27         final long bytesSinceLastEntry = lastRecordStartAddress
  28                 - record.location;
  29
  30         final long freeSpace = bytesSinceLastEntry - record.length;
  31         freeBytesCount += freeSpace;
  32         analyzedBytesCount += freeSpace;
  33
  34         checkDefragmentationPointer(record.location + record.length);
  35
  36         analyzedBytesCount += record.length;
  37         lastRecordStartAddress = record.location;
  38     }
  39
  40     public void analyzeStartOfDataArea() {
  41         freeBytesCount += lastRecordStartAddress
  42                 - vacuumContext.metaData.getEntriesStorageAreaStart();
  43
  44         checkDefragmentationPointer(vacuumContext.metaData
  45                 .getEntriesStorageAreaStart());
  46     }
  47
  48     public void checkDefragmentationPointer(
  49             final long defragmentationStartAddress) {
  50
  51         if (analyzedBytesCount == 0) {
  52             this.defragmentationStartAddress = defragmentationStartAddress;
  53             return;
  54         }
  55
  56         final int fragmentationPercentage = (int) ((100L * freeBytesCount) / analyzedBytesCount);
  57
  58         if (fragmentationPercentage >= targetFragmentationPercent)
  59             this.defragmentationStartAddress = defragmentationStartAddress;
  60     }
  61 }