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1
21 package com.db4o.inside.freespace;
22
23 import com.db4o.*;
24
25 public abstract class FreespaceManager {
26
27 final YapFile _file;
28
29 public static final byte FM_DEFAULT = 0;
30 public static final byte FM_LEGACY_RAM = 1;
31 public static final byte FM_RAM = 2;
32 public static final byte FM_IX = 3;
33 public static final byte FM_DEBUG = 4;
34
35 private static final int INTS_IN_SLOT = 12;
36
37 public FreespaceManager(YapFile file){
38 _file = file;
39 }
40
41 public static byte checkType(byte systemType){
42 if(systemType == FM_DEFAULT){
43 return FM_RAM;
44 }
45 return systemType;
46 }
47
48 public static FreespaceManager createNew(YapFile file){
49 return createNew(file, file.systemData().freespaceSystem());
50 }
51
52 public abstract void onNew(YapFile file);
53
54 public static FreespaceManager createNew(YapFile file, byte systemType){
55 systemType = checkType(systemType);
56 switch(systemType){
57 case FM_IX:
58 return new FreespaceManagerIx(file);
59 default:
60 return new FreespaceManagerRam(file);
61
62 }
63 }
64
65 public static int initSlot(YapFile file){
66 int address = file.getSlot(slotLength());
67 slotEntryToZeroes(file, address);
68 return address;
69 }
70
71 static void slotEntryToZeroes(YapFile file, int address){
72 YapWriter writer = new YapWriter(file.getSystemTransaction(), address, slotLength());
73 for (int i = 0; i < INTS_IN_SLOT; i++) {
74 writer.writeInt(0);
75 }
76 if (Debug.xbytes) {
77 writer.setID(YapConst.IGNORE_ID); }
79 writer.writeEncrypt();
80 }
81
82
83 final static int slotLength(){
84 return YapConst.INT_LENGTH * INTS_IN_SLOT;
85 }
86
87 public abstract void beginCommit();
88
89 final int blockSize(){
90 return _file.blockSize();
91 }
92
93 public abstract void debug();
94
95 final int discardLimit(){
96 return _file.configImpl().discardFreeSpace();
97 }
98
99 public abstract void endCommit();
100
101 public abstract int entryCount();
102
103 public abstract void free(int a_address, int a_length);
104
105 public abstract int freeSize();
106
107 public abstract void freeSelf();
108
109 public abstract int getSlot(int length);
110
111 public abstract void migrate(FreespaceManager newFM);
112
113 public abstract void read(int freeSlotsID);
114
115 public abstract void start(int slotAddress);
116
117 public abstract byte systemType();
118
119 public abstract int write(boolean shuttingDown);
120
121 public boolean requiresMigration(byte configuredSystem, byte readSystem) {
122 return (configuredSystem != 0 || readSystem == FM_LEGACY_RAM ) && (systemType() != configuredSystem);
123 }
124
125 public static void migrate(FreespaceManager oldFM, FreespaceManager newFM) {
126 oldFM.migrate(newFM);
127 oldFM.freeSelf();
128 newFM.beginCommit();
129 newFM.endCommit();
130 }
131
132 }
133 |
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