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

   1 /*
   2  * Sixth Data. Copyright ©2012-2019, Svjatoslav Agejenko, svjatoslav@svjatoslav.eu
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of version 3 of the GNU Lesser General Public License
   6  * or later as published by the Free Software Foundation.
   7  */
   8
   9 package eu.svjatoslav.sixth.data.store.file;
  10
  11 public class VacuumContext {
  12     private final FileDataStore vacuumContext;
  13     private final int targetFragmentationPercent;
  14     long analyzedBytesCount = 0;
  15     long freeBytesCount = 0;
  16     long lastRecordStartAddress;
  17     long defragmentationStartAddress;
  18
  19     public VacuumContext(final FileDataStore fileDataStore,
  20                          final long currentFreeAddress, final int targetFragmentationPercent) {
  21
  22         vacuumContext = fileDataStore;
  23         lastRecordStartAddress = currentFreeAddress;
  24         defragmentationStartAddress = currentFreeAddress;
  25         this.targetFragmentationPercent = targetFragmentationPercent;
  26     }
  27
  28     public void analyzeEntry(final EntryRecord record) {
  29         final long bytesSinceLastEntry = lastRecordStartAddress
  30                 - record.location;
  31
  32         final long freeSpace = bytesSinceLastEntry - record.length;
  33         freeBytesCount += freeSpace;
  34         analyzedBytesCount += freeSpace;
  35
  36         checkDefragmentationPointer(record.location + record.length);
  37
  38         analyzedBytesCount += record.length;
  39         lastRecordStartAddress = record.location;
  40     }
  41
  42     public void analyzeStartOfDataArea() {
  43         freeBytesCount += lastRecordStartAddress
  44                 - vacuumContext.metaData.getEntriesStorageAreaStart();
  45
  46         checkDefragmentationPointer(vacuumContext.metaData
  47                 .getEntriesStorageAreaStart());
  48     }
  49
  50     public void checkDefragmentationPointer(
  51             final long defragmentationStartAddress) {
  52
  53         if (analyzedBytesCount == 0) {
  54             this.defragmentationStartAddress = defragmentationStartAddress;
  55             return;
  56         }
  57
  58         final int fragmentationPercentage = (int) ((100L * freeBytesCount) / analyzedBytesCount);
  59
  60         if (fragmentationPercentage >= targetFragmentationPercent)
  61             this.defragmentationStartAddress = defragmentationStartAddress;
  62     }
  63 }