Handles converting buffers to and from disk.
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#include <CubeIoHandler.h>
Inherited by Isis::CubeBsqHandler, and Isis::CubeTileHandler.
Classes |
class | BufferToChunkWriter |
| This class is designed to handle write() asynchronously.
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Detailed Description
Handles converting buffers to and from disk.
This class handles converting buffers to and from disk. This class holds the cube chunks in memory and is capable of reading and writing them. It asks the caching algorithms to recommend cube chunks to not keep in memory. Children need to call setChunkSizes() in their constructor.
This class handles all of the virtual band conversions. This class also guarantees that unwritten cube data ends up read and written as NULLs. The default caching algorithm is a RegionalCachingAlgorithm.
- Author
- 2011-??-?? Jai Rideout and Steven Lambright
Constructor & Destructor Documentation
Isis::CubeIoHandler::CubeIoHandler |
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QFile * |
dataFile, |
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const QList< int > * |
virtualBandList, |
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const Pvl & |
label, |
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bool |
alreadyOnDisk |
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) |
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Isis::CubeIoHandler::~CubeIoHandler |
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virtual |
Cleans up all allocated memory.
Child destructors must call clearCache() because we can no longer do IO by the time this destructor is called.
References ASSERT.
Member Function Documentation
This will add the given caching algorithm to the list of attempted caching algorithms.
The algorithms are tried in the opposite order that they were added - the first algorithm added is the last algorithm tried.
This method takes ownership of algorithm.
- Parameters
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algorithm | The caching algorithm to add to the Cube for I/O |
int Isis::CubeIoHandler::bandCount |
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const |
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protected |
- Returns
- the number of physical bands in the cube.
void Isis::CubeIoHandler::clearCache |
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bool |
blockForWriteCache = true | ) |
const |
Free all cube chunks (cached cube data) from memory and write them to disk.
Child destructors need to call this method.
This method should only be called otherwise when lots of cubes are in memory and the many caches cause problems with system RAM limitations.
- Parameters
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blockForWriteCache | This should be true unless this method is called from the write thread. |
Referenced by Isis::CubeBsqHandler::~CubeBsqHandler(), and Isis::CubeTileHandler::~CubeTileHandler().
QMutex * Isis::CubeIoHandler::dataFileMutex |
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Get the mutex that this IO handler is using around I/Os on the given data file.
A lock should be acquired before doing any reads/writes on the data file externally.
- Returns
- A mutex that can guarantee exclusive access to the data file
int Isis::CubeIoHandler::getBandCountInChunk |
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const |
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protected |
- Returns
- the number of bands per chunk for this cube.
BigInt Isis::CubeIoHandler::getBytesPerChunk |
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const |
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protected |
- Returns
- the byte size of each chunk in the cube. Currently they must be constant size, but this is planned to be changed at some point in time.
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Number of bytes in a cube chunk
References Isis::SizeOf().
int Isis::CubeIoHandler::getChunkCountInBandDimension |
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const |
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protected |
- Returns
- the total number of chunks in the band (Z) dimension. This is always enough to contain every band in the cube.
int Isis::CubeIoHandler::getChunkCountInLineDimension |
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const |
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protected |
- Returns
- the total number of chunks in the line (Y) dimension. This is always enough to contain every line in the cube.
int Isis::CubeIoHandler::getChunkCountInSampleDimension |
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const |
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protected |
- Returns
- the total number of chunks in the sample (X) dimension. This is always enough to contain every sample in the cube.
int Isis::CubeIoHandler::getChunkIndex |
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const RawCubeChunk & |
chunk | ) |
const |
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protected |
Given a chunk, what's its index in the file.
Chunks are ordered from left to right, then top to bottom, then front to back (BSQ). The first chunk is at the top left of band 1 and is index 0, for example. In other words, this is going from the value of m_rawData to the key.
Chunks which sit outside of the cube entirely must not be passed into this method; the results will be wrong.
- Returns
- The chunk's index into the file
References Isis::RawCubeChunk::getStartBand(), Isis::RawCubeChunk::getStartLine(), and Isis::RawCubeChunk::getStartSample().
QFile * Isis::CubeIoHandler::getDataFile |
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protected |
BigInt Isis::CubeIoHandler::getDataSize |
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const |
- Returns
- the number of bytes that the cube DNs will take up. This includes padding caused by the cube chunks not aligning with the cube dimensions.
BigInt Isis::CubeIoHandler::getDataStartByte |
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const |
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protected |
- Returns
- the byte offset to the beginning of the cube data.
int Isis::CubeIoHandler::getLineCountInChunk |
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const |
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protected |
int Isis::CubeIoHandler::getSampleCountInChunk |
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const |
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protected |
int Isis::CubeIoHandler::lineCount |
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const |
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protected |
PixelType Isis::CubeIoHandler::pixelType |
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const |
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protected |
void Isis::CubeIoHandler::read |
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Buffer & |
bufferToFill | ) |
const |
virtual void Isis::CubeIoHandler::readRaw |
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RawCubeChunk & |
chunkToFill | ) |
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protectedpure virtual |
int Isis::CubeIoHandler::sampleCount |
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const |
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protected |
void Isis::CubeIoHandler::setChunkSizes |
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int |
numSamples, |
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int |
numLines, |
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int |
numBands |
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) |
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protected |
This should be called once from the child constructor.
This determines the chunk sizes used for the cube and often should remain constant for a particular cube (BSQ, for example, doesn't need it to be constant but Tile does). These being large can cause excessive use of disk space that stores no cube data. These being large can also drastically increase the amount of RAM consumed.
- Parameters
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numSamples | The chunk size in the sample dimension |
numLines | The chunk size in the line dimension |
numBands | The chunk size in the band dimension |
References _FILEINFO_.
Referenced by Isis::CubeBsqHandler::CubeBsqHandler(), and Isis::CubeTileHandler::CubeTileHandler().
void Isis::CubeIoHandler::setVirtualBands |
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const QList< int > * |
virtualBandList | ) |
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This changes the virtual band list.
- Parameters
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virtualBandList | A list where the indices are the vbands and the values are the physical bands. The values are 1-based. This can be specified as NULL, in which case the vbands are the physical bands. The virtual band list is copied (the pointer provided isn't remembered). |
void Isis::CubeIoHandler::updateLabels |
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Pvl & |
labels | ) |
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virtual |
Children should probably implement this method.
This is called to allow the IO Handling algorithm to change the labels to include things like TileSamples/TileLines for example.
- Parameters
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labels | The PVL cube label to be updated to reflect information that the child IO handlers need to properly re-read the cube. |
Reimplemented in Isis::CubeBsqHandler, and Isis::CubeTileHandler.
void Isis::CubeIoHandler::write |
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const Buffer & |
bufferToWrite | ) |
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Write buffer data into the cube data on disk.
This could do no IO if the cube chunks required are already in memory and our caching algorithms say to not free any of the cube chunks afterwards.
- Parameters
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bufferToWrite | The buffer to get cube data from. |
virtual void Isis::CubeIoHandler::writeRaw |
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const RawCubeChunk & |
chunkToWrite | ) |
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protectedpure virtual |
The documentation for this class was generated from the following files: