public class RandomAccessStorageModule extends Object implements IStorageModule
RandomAccessFile
,
which will immediately write all changes in the data to hard-disk.
This class is not thread-safe.
RandomAccessFile
Modifier and Type | Field and Description |
---|---|
protected long |
sizeInBlocks
The size of the medium in blocks.
|
VIRTUAL_BLOCK_SIZE
Constructor and Description |
---|
RandomAccessStorageModule(long sizeInBlocks,
File file)
Creates a new
RandomAccessStorageModule backed by the specified file. |
Modifier and Type | Method and Description |
---|---|
int |
checkBounds(long logicalBlockAddress,
int transferLengthInBlocks)
This method can be used for checking if a (series of) I/O operations will result in an
IOException due to
trying to access blocks outside the medium's boundaries. |
void |
close()
Closes the backing
RandomAccessFile . |
long |
getSizeInBlocks()
Returns the storage space size in bytes divided by the block size in bytes (rounded down).
|
static IStorageModule |
open(File file,
long storageLength,
boolean create,
Class<? extends IStorageModule> kind)
This is the build method for creating instances of
RandomAccessStorageModule . |
void |
read(byte[] bytes,
long storageIndex)
Copies bytes from storage to the passed byte array.
|
static boolean |
recursiveDelete(File pFile)
Deleting a storage recursive.
|
void |
write(byte[] bytes,
long storageIndex)
Saves part of the passed byte array's content.
|
protected final long sizeInBlocks
IStorageModule.VIRTUAL_BLOCK_SIZE
public RandomAccessStorageModule(long sizeInBlocks, File file) throws FileNotFoundException
RandomAccessStorageModule
backed by the specified file. If no such file exists, a
FileNotFoundException
will be thrown.sizeInBlocks
- blocksize for this modulefile
- the path to the file serving as storage mediumFileNotFoundException
- if the specified file does not existpublic void read(byte[] bytes, long storageIndex) throws IOException
read
in interface IStorageModule
bytes
- the array into which the data will be copied will be filled with data from storagestorageIndex
- the position of the first byte to be copiedIOException
public void write(byte[] bytes, long storageIndex) throws IOException
write
in interface IStorageModule
bytes
- the source of the data to be storedstorageIndex
- byte offset in the storage areaIOException
public final long getSizeInBlocks()
getSizeInBlocks
in interface IStorageModule
public final int checkBounds(long logicalBlockAddress, int transferLengthInBlocks)
IOException
due to
trying to access blocks outside the medium's boundaries.
The SCSI standard requires checking for these boundary violations right after receiving a read or write command, so that an appropriate error message can be returned to the initiator. Therefore this method must be called prior to each read or write sequence.
The values returned by this method and their meaning with regard to the interval [0, IStorageModule.getSizeInBlocks()
-
1] are shown in the following table:
Return Value | Meaning |
---|---|
0 | no boundaries are violated |
1 | the logicalBlockAddress parameter lies outside of the interval |
2 | the interval [logicalBlockAddress, logicalBlockAddress + transferLengthInBlocks] lies outside of the interval, or transferLengthInBlocks is negative |
Note that the parameters of this method are referring to blocks, not to byte indices.
checkBounds
in interface IStorageModule
logicalBlockAddress
- the index of the first block of data to be read or writtentransferLengthInBlocks
- the total number of consecutive blocks about to be read or writtenpublic final void close() throws IOException
RandomAccessFile
.close
in interface IStorageModule
IOException
- if an I/O Error occurspublic static final IStorageModule open(File file, long storageLength, boolean create, Class<? extends IStorageModule> kind) throws IOException
RandomAccessStorageModule
. If there is no file to be
found at the specified filePath
, then a FileNotFoundException
will be thrown.file
- a path leading to the file serving as storage mediumstorageLength
- length of storage (if not already existing)create
- should the storage be createdRandomAccessStorageModule
IOException
public static boolean recursiveDelete(File pFile)
pFile
- which should be deleted included descendantsCopyright © 2013 University of Konstanz, Distributed Systems Group. All Rights Reserved.