WriteAheadLog

org.mapdb.WriteAheadLog

```
public class WriteAheadLog
```
WAL shared between StoreWAL

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`I_BYTE_ARRAY`
`static int`	`I_COMMIT`
`static int`	`I_EOF`
`static int`	`I_LONG`
`static int`	`I_PREALLOCATE`
`static int`	`I_RECORD`
`static int`	`I_ROLLBACK`
`static int`	`I_SKIP_MANY`
`static int`	`I_SKIP_SINGLE`
`static int`	`I_TOMBSTONE`
`static long`	`MAX_FILE_RESERVE`
`static long`	`MAX_FILE_SIZE`
`static WriteAheadLog.WALReplay`	`NOREPLAY` does nothing
`static int`	`WAL_HEADER` 4 byte file header
`static long`	`WAL_SEAL`
`Volume`	`curVol`
`long`	`featureBitMap`
`boolean`	`fileDeleteAfterOpen`
`long`	`fileNum`
`long`	`fileOffset`
`java.util.concurrent.locks.ReentrantLock`	`fileOffsetLock`
`int`	`lastChecksum`
`long`	`lastChecksumOffset`
`int`	`pointerFileBites`
`long`	`pointerFileMask`
`int`	`pointerOffsetBites`
`long`	`pointerOffsetMask`
`int`	`pointerSizeBites`
`long`	`pointerSizeMask`
`java.util.List<org.mapdb.volume.Volume>`	`volumes`
`java.util.List<org.mapdb.volume.Volume>`	`walRec` record WALs, store recid-record pairs. Created during compaction when memory allocator is not available

Constructor Summary

Constructors
Constructor and Description

WriteAheadLog()

WriteAheadLog()

Constructors
Constructor and Description
`WriteAheadLog()`
`WriteAheadLog()`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`long`	`allocate()` Allocate space in WAL
`int`	`checksum()`
`void`	`close()`
`void`	`commit()`
`void`	`destroyWalFiles()`
`void`	`ensureFileReady()`
`boolean`	`fileLoad()`
`void`	`fileOffsetSet()`
`java.lang.Iterable<java.lang.String>`	`getAllFiles()`
`long`	`getNumberOfFiles()`
`java.lang.String`	`getWalFileName()`
`void`	`initFailedCloseFiles()`
`void`	`replayWAL()`
`void`	`rollback()`
`void`	`seal()`
`void`	`startNextFile()`
`void`	`sync()`
`DataInput2`	`walGetByteArray()` Retrieve `DataInput` from WAL. This data were written by `WriteAheadLog.walPutByteArray`
`byte[]`	`walGetByteArray2()` Retrieve `byte[]` from WAL. This data were written by `WriteAheadLog.walPutByteArray`
`byte[]`	`walGetRecord()`
`long`	`walPointer()`
`long`	`walPointerToFileNum()`
`long`	`walPointerToOffset()`
`int`	`walPointerToSize()`
`long`	`walPutByteArray()` Puts instruction into WAL. It should write part of `byte[]` at given offset. This value returns pointer to WAL, which can be used to retrieve data back with `WriteAheadLog.walGetByteArray`. Pointer is composed of file number, and offset in WAL file.
`void`	`walPutLong()` Put 8 byte long into WAL.
`void`	`walPutPreallocate()`
`long`	`walPutRecord()`
`void`	`walPutTombstone()`

Field Detail

WAL_HEADER
```
public static int WAL_HEADER
```
4 byte file header

WAL_SEAL
```
public static long WAL_SEAL
```

I_EOF
```
public static int I_EOF
```

I_LONG
```
public static int I_LONG
```

I_BYTE_ARRAY
```
public static int I_BYTE_ARRAY
```

I_SKIP_MANY
```
public static int I_SKIP_MANY
```

I_SKIP_SINGLE
```
public static int I_SKIP_SINGLE
```

I_RECORD
```
public static int I_RECORD
```

I_TOMBSTONE
```
public static int I_TOMBSTONE
```

I_PREALLOCATE
```
public static int I_PREALLOCATE
```

I_COMMIT
```
public static int I_COMMIT
```

I_ROLLBACK
```
public static int I_ROLLBACK
```

MAX_FILE_SIZE
```
public static long MAX_FILE_SIZE
```

MAX_FILE_RESERVE
```
public static long MAX_FILE_RESERVE
```

featureBitMap
```
public long featureBitMap
```

pointerOffsetBites
```
public int pointerOffsetBites
```

pointerOffsetMask
```
public long pointerOffsetMask
```

pointerSizeBites
```
public int pointerSizeBites
```

pointerSizeMask
```
public long pointerSizeMask
```

pointerFileBites
```
public int pointerFileBites
```

pointerFileMask
```
public long pointerFileMask
```

fileDeleteAfterOpen
```
public boolean fileDeleteAfterOpen
```

lastChecksum
```
public int lastChecksum
```

lastChecksumOffset
```
public long lastChecksumOffset
```

NOREPLAY

public static WriteAheadLog.WALReplay NOREPLAY

does nothing

fileOffset
```
public long fileOffset
```

fileOffsetLock

public java.util.concurrent.locks.ReentrantLock fileOffsetLock

volumes

public java.util.List<org.mapdb.volume.Volume> volumes

walRec
```
public java.util.List<org.mapdb.volume.Volume> walRec
```
record WALs, store recid-record pairs. Created during compaction when memory allocator is not available

curVol
```
public Volume curVol
```

fileNum
```
public long fileNum
```

Constructor Detail

WriteAheadLog
```
public WriteAheadLog()
```

WriteAheadLog
```
public WriteAheadLog()
```

Method Detail
- initFailedCloseFiles
```
public void initFailedCloseFiles()
```
- close
```
public void close()
```
- seal
```
public void seal()
```
- startNextFile
```
public void startNextFile()
```
- rollback
```
public void rollback()
```
- commit
```
public void commit()
```
- checksum
```
public int checksum()
```
- fileLoad
```
public boolean fileLoad()
```
- sync
```
public void sync()
```
- getAllFiles
```
public java.lang.Iterable<java.lang.String> getAllFiles()
```
- allocate
```
public long allocate()
```
  Allocate space in WAL
- fileOffsetSet
```
public void fileOffsetSet()
```
- replayWAL
```
public void replayWAL()
```
- destroyWalFiles
```
public void destroyWalFiles()
```
- getWalFileName
```
public java.lang.String getWalFileName()
```
- getNumberOfFiles
```
public long getNumberOfFiles()
```
- walGetByteArray
```
public DataInput2 walGetByteArray()
```
  Retrieve DataInput from WAL. This data were written by WriteAheadLog.walPutByteArray
  
  See Also:
  
  WriteAheadLog.walPutByteArray
- walGetByteArray2
```
public byte[] walGetByteArray2()
```
  Retrieve byte[] from WAL. This data were written by WriteAheadLog.walPutByteArray
  
  See Also:
  
  WriteAheadLog.walPutByteArray
- walPointerToOffset
```
public long walPointerToOffset()
```
- walPointerToFileNum
```
public long walPointerToFileNum()
```
- walPointerToSize
```
public int walPointerToSize()
```
- walGetRecord
```
public byte[] walGetRecord()
```
- walPutByteArray
```
public long walPutByteArray()
```
  Puts instruction into WAL. It should write part of byte[] at given offset. This value returns pointer to WAL, which can be used to retrieve data back with WriteAheadLog.walGetByteArray. Pointer is composed of file number, and offset in WAL file.
  
  See Also:
  
  WriteAheadLog.walGetByteArray
- walPointer
```
public long walPointer()
```
- walPutRecord
```
public long walPutRecord()
```
- walPutLong
```
public void walPutLong()
```
  Put 8 byte long into WAL.
- ensureFileReady
```
public void ensureFileReady()
```
- walPutTombstone
```
public void walPutTombstone()
```
- walPutPreallocate
```
public void walPutPreallocate()
```

Class WriteAheadLog

Field Summary

Constructor Summary

Method Summary

Field Detail

WAL_HEADER

WAL_SEAL

I_EOF

I_LONG

I_BYTE_ARRAY

I_SKIP_MANY

I_SKIP_SINGLE

I_RECORD

I_TOMBSTONE

I_PREALLOCATE

I_COMMIT

I_ROLLBACK

MAX_FILE_SIZE

MAX_FILE_RESERVE

featureBitMap

pointerOffsetBites

pointerOffsetMask

pointerSizeBites

pointerSizeMask

pointerFileBites

pointerFileMask

fileDeleteAfterOpen

lastChecksum

lastChecksumOffset

NOREPLAY

fileOffset

fileOffsetLock

volumes

walRec

curVol

fileNum

Constructor Detail

WriteAheadLog

WriteAheadLog

Method Detail

initFailedCloseFiles

close

seal

startNextFile

rollback

commit

checksum

fileLoad

sync

getAllFiles

allocate

fileOffsetSet

replayWAL

destroyWalFiles

getWalFileName

getNumberOfFiles

walGetByteArray

walGetByteArray2

walPointerToOffset

walPointerToFileNum

walPointerToSize

walGetRecord

walPutByteArray

walPointer

walPutRecord

walPutLong

ensureFileReady

walPutTombstone

walPutPreallocate