public interface IStorageModule
All index and length parameters used by the read and write methods are referring to bytes, unlike the values sent in
CommandDescriptorBlock
s.
Modifier and Type | Field and Description |
---|---|
static int |
VIRTUAL_BLOCK_SIZE
A fictitious block size.
|
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()
Closing the storage.
|
long |
getSizeInBlocks()
Returns the storage space size in bytes divided by the block size in bytes (rounded down).
|
void |
read(byte[] bytes,
long storageIndex)
Copies bytes from storage to the passed byte array.
|
void |
write(byte[] bytes,
long storageIndex)
Saves part of the passed byte array's content.
|
static final int VIRTUAL_BLOCK_SIZE
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, 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.
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 writtenlong getSizeInBlocks()
void read(byte[] bytes, long storageIndex) throws IOException
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
void write(byte[] bytes, long storageIndex) throws IOException
bytes
- the source of the data to be storedstorageIndex
- byte offset in the storage areaIOException
void close() throws IOException
IOException
- to be closedCopyright © 2013 University of Konstanz, Distributed Systems Group. All Rights Reserved.