edu.unh.sdb.datasource
Class ThreadedBlockCacheDataSource

java.lang.Object
  edu.unh.sdb.datasource.DataCollection
      edu.unh.sdb.datasource.DataSource
          edu.unh.sdb.datasource.CacheDataSource
              edu.unh.sdb.datasource.BlockCacheDataSource
                  edu.unh.sdb.datasource.ThreadedBlockCacheDataSource

All Implemented Interfaces:

Indexable

public class ThreadedBlockCacheDataSource
extends BlockCacheDataSource

The ThreadedBlockCacheDataSource provides cache service for an underlying datasource. CacheDataSources are typically created by the CacheMaker class, which tunes the size of the cache blocks to a particular iteration and underlying datasource. As its name implies, the ThreadedBlockCacheDataSource uses an IO thread to read cache blocks from disk before they are actually needed by the user. To accomplish this, this class actually creates two cache blocks. One is being accessed by the user, and the other is being preloaded. This scheme is especially effective if the user is doing substantial computation, so that the IO thread has time to completely read its block before it is needed. The IO thread is triggered whenever the lower bounds of a user query crosses into a new cache block. When this happens, it is assumed that the user is done with the old block, so new data can be loaded into it. Notice that if a subblock query straddles two cache blocks, the I/O thread will not be triggered, because the lower bounds of the query block are still within the old block. When a query is received, it will be satisfied from the two cache blocks if possible. Otherwise, the query is satisfied directly from the datasource, and the cache blocks remain unchanged.

Field Summary

protected AxisOrdering

iteratorOrdering

Fields inherited from class edu.unh.sdb.datasource.DataSource

fdlDescriptor, isActivated, name, wsName

Fields inherited from class edu.unh.sdb.datasource.DataCollection

attributeOrder, axisOrdering, axisWeights, bounds, dataOrder, dimensionality, numAttributes, pointOrder, recordDesc

Constructor Summary

ThreadedBlockCacheDataSource(java.lang.String name, DataSource ds, IndexSpaceID blockDimensions, AxisOrdering iteratorOrdering)
Create a ThreadedBlockCacheDataSource with a single CacheBlock connected to the DataSource argument.

ThreadedBlockCacheDataSource(java.lang.String name, DataSource ds, ISBounds iterationSpace, IndexSpaceID blockDimensions, AxisOrdering iteratorOrdering)
Create a ThreadedBlockCacheDataSource with a single CacheBlock connected to the DataSource argument.

Method Summary

void	activate() Calls activate() for the underlying datasource, and creates the actual cache, which allocates memory for the CacheBlock.
void	deactivate() Calls super.deactivate() for the underlying datasource, and waits for any lingering IO threads to terminate.
protected void	halt() Any lingering IO threads will have terminated after this method completes.
static void	main(java.lang.String[] args) For debugging.

Methods inherited from class edu.unh.sdb.datasource.BlockCacheDataSource

getCacheBlockBounds, getCacheBlockBounds, getCacheBlockBounds, getCacheBlockBoundsIterator, getCacheBlockBoundsIterator, getCacheBlockDimensions, getCacheMemoryUsage

Methods inherited from class edu.unh.sdb.datasource.CacheDataSource

datum, datum, datum, getIterationSpace, getSource, subblock, subblock

Methods inherited from class edu.unh.sdb.datasource.DataSource

checkActivated, clearCache, copyBestID, create, create, create, createRemote, createRemote, createRemoteClient, createRemoteClient, createRemoteDataSource, createRemoteDataSource, createRemoteDataSourceUDP, createRemoteUDP, createRemoteUDP, dumpData, equals, getName, getValues, isActivated, toString, toString

Methods inherited from class edu.unh.sdb.datasource.DataCollection

byteSize, computeOffset, computeOffset, copyBounds, createDataBlock, createDataBlock, createDataBlock, createDatum, createDatum, createDatum, createDatum, createDatum, createDatum, datum, datum, datum, datum, dim, getAxisOrdering, getAxisWeight, getAxisWeights, getBounds, getByte, getBytes, getBytes, getBytes, getBytes, getBytes, getBytes, getBytesByAttribute, getBytesByAttribute, getBytesByPoint, getBytesByPoint, getDataOrder, getDimensionsArray, getDouble, getDoubles, getDoubles, getDoubles, getDoubles, getDoubles, getDoubles, getDoublesByAttribute, getDoublesByAttribute, getDoublesByPoint, getDoublesByPoint, getFloat, getFloats, getFloats, getFloats, getFloats, getFloats, getFloats, getFloatsByAttribute, getFloatsByAttribute, getFloatsByPoint, getFloatsByPoint, getInt, getInts, getInts, getInts, getInts, getInts, getInts, getIntsByAttribute, getIntsByAttribute, getIntsByPoint, getIntsByPoint, getLowerBoundsArray, getNumAttributes, getRecordDescriptor, getShort, getShorts, getShorts, getShorts, getShorts, getShorts, getShorts, getShortsByAttribute, getShortsByAttribute, getShortsByPoint, getShortsByPoint, getStorageType, getValues, getValuesByAttribute, getValuesByPoint, longVolume, setAxisOrdering, setBounds, setRecordDescriptor, size, subblock, subblock, subblock, subblock, subblock, subblock, subblock, subblock, subblock, subblock, useBytesOnly, volume

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

iteratorOrdering

protected AxisOrdering iteratorOrdering

Constructor Detail

ThreadedBlockCacheDataSource

public ThreadedBlockCacheDataSource(java.lang.String name,
                                    DataSource ds,
                                    ISBounds iterationSpace,
                                    IndexSpaceID blockDimensions,
                                    AxisOrdering iteratorOrdering)

Create a ThreadedBlockCacheDataSource with a single CacheBlock connected to the DataSource argument. The CacheBlock dimensions are specified by the last argument. The memory for the cache itself is not allocated until this datasource is activated.

ThreadedBlockCacheDataSource

public ThreadedBlockCacheDataSource(java.lang.String name,
                                    DataSource ds,
                                    IndexSpaceID blockDimensions,
                                    AxisOrdering iteratorOrdering)

Create a ThreadedBlockCacheDataSource with a single CacheBlock connected to the DataSource argument. The CacheBlock dimensions are specified by the last argument. The memory for the cache itself is not allocated until this datasource is activated.

Method Detail

activate

public void activate()

Calls activate() for the underlying datasource, and creates the actual cache, which allocates memory for the CacheBlock.

Overrides:

activate in class BlockCacheDataSource

deactivate

public void deactivate()

Calls super.deactivate() for the underlying datasource, and waits for any lingering IO threads to terminate.

Overrides:

deactivate in class CacheDataSource

halt

protected void halt()

Any lingering IO threads will have terminated after this method completes.

main

public static void main(java.lang.String[] args)

For debugging. Runs basic tests on the ThreadedBlockCacheDataSource class.