Package org.apfloat.spi

Class DataStorage

java.lang.Object

org.apfloat.spi.DataStorage

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

DiskDataStorage, DoubleMemoryDataStorage, FloatMemoryDataStorage, IntMemoryDataStorage, LongMemoryDataStorage

public abstract class DataStorage
extends Object
implements Serializable

Generic data storage class.

Initially when a data storage is created, it is mutable (it can be modified). After the contents have been properly set, the user should call setReadOnly() to set the storage to be immutable. After this the data storage can be safely shared between different users.

Access to DataStorage objects is generally not internally synchronized. Accessing multiple non-overlapping parts of the storage concurrently with the getArray(int,long,int), getArray(int,int,int,int) or getTransposedArray(int,int,int,int) method and with iterators over non-overlapping parts is permitted. Invoking other methods must generally be externally synchronized.

Version:

1.8.1

Author:

Mikko Tommila

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	DataStorage.AbstractIterator	Abstract base class for iterators iterating through this DataStorage.
static class	DataStorage.Iterator	Iterator for iterating through elements of the data storage.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	READ	Read access mode specifier.
static final int	READ_WRITE	Read-write access mode specifier.
static final int	WRITE	Write access mode specifier.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	DataStorage()	Default constructor.
protected	DataStorage(DataStorage dataStorage, long offset, long length)	Subsequence constructor.

Method Summary

Modifier and Type	Method	Description
final void	copyFrom(DataStorage dataStorage)	Copies all data from another data storage to this data storage.
final void	copyFrom(DataStorage dataStorage, long size)	Copies the specified number of elements from another data storage to this data storage.
final ArrayAccess	getArray(int mode, int startColumn, int columns, int rows)	Maps a block of data to a memory array when the data is treated as a matrix.
final ArrayAccess	getArray(int mode, long offset, int length)	Gets an array access to the data of this data storage when the data is treated as a linear block.
protected final long	getOffset()	Return the sub-sequence offset.
final long	getSize()	Return the size of the data storage, or the length of this sub-sequence if this data storage is a sub-sequence.
final ArrayAccess	getTransposedArray(int mode, int startColumn, int columns, int rows)	Maps a transposed block of data to a memory array when the data is treated as a matrix.
protected abstract void	implCopyFrom(DataStorage dataStorage, long size)	Copies the specified number of elements from another data storage to this data storage.
protected abstract ArrayAccess	implGetArray(int mode, int startColumn, int columns, int rows)	Maps a block of data to a memory array when the data is treated as a matrix.
protected abstract ArrayAccess	implGetArray(int mode, long offset, int length)	Gets an array access to the data of this data storage when it is treated as a linear block.
protected abstract long	implGetSize()	Return the size of the whole data storage, not including sub-sequence settings.
protected abstract ArrayAccess	implGetTransposedArray(int mode, int startColumn, int columns, int rows)	Maps a transposed block of data to a memory array when the data is treated as a matrix.
protected abstract void	implSetSize(long size)	Sets the size of the data storage.
protected abstract DataStorage	implSubsequence(long offset, long length)	Implementation of getting a subsequence of this data storage.
abstract boolean	isCached()	Is this object cached in memory.
final boolean	isReadOnly()	Returns the read-only state of this data storage.
final boolean	isSubsequenced()	Is this object a subsequence of some other object, or do subsequences of this object exist.
abstract DataStorage.Iterator	iterator(int mode, long startPosition, long endPosition)	Constructs a new iterator.
final void	setReadOnly()	Sets this data storage as read-only.
final void	setSize(long size)	Sets the size of the data storage.
final DataStorage	subsequence(long offset, long length)	Get a subsequence of this data storage.

Methods inherited from class java.lang.Object

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

Field Details

READ

public static final int READ

Read access mode specifier.

See Also:

• Constant Field Values

WRITE

public static final int WRITE

Write access mode specifier.

See Also:

• Constant Field Values

READ_WRITE

public static final int READ_WRITE

Read-write access mode specifier. For convenience, equivalent to READ | WRITE.

See Also:

• Constant Field Values

Constructor Details

DataStorage

protected DataStorage()

Default constructor. To be called by subclasses when creating a new empty DataStorage.

DataStorage

protected DataStorage(DataStorage dataStorage,
 long offset,
 long length)

Subsequence constructor. To be called by subclasses when creating a subsequence of an existing DataStorage.

Parameters:

dataStorage - The originating data storage.

offset - The subsequence starting position.

length - The subsequence length.

Method Details

subsequence

public final DataStorage subsequence(long offset,
 long length)
                              throws IllegalArgumentException,
ApfloatRuntimeException

Get a subsequence of this data storage.

Parameters:

offset - The subsequence starting position.

length - The subsequence length.

Returns:

Data storage that represents the specified part of this data storage.

Throws:

IllegalArgumentException - If the requested subsequence is out of range.

ApfloatRuntimeException

implSubsequence

protected abstract DataStorage implSubsequence(long offset,
 long length)
                                        throws ApfloatRuntimeException

Implementation of getting a subsequence of this data storage. The validity of the arguments of this method do not need to be checked.

Parameters:

offset - The subsequence starting position.

length - The subsequence length.

Returns:

Data storage that represents the specified part of this data storage.

Throws:

ApfloatRuntimeException

copyFrom

public final void copyFrom(DataStorage dataStorage)
                    throws IllegalArgumentException,
IllegalStateException,
ApfloatRuntimeException

Copies all data from another data storage to this data storage.

Parameters:

dataStorage - The data storage where the data should be copied from.

Throws:

IllegalArgumentException - If the origin data source has a size of zero.

IllegalStateException - If this data storage is read-only or has subsequences.

ApfloatRuntimeException

copyFrom

public final void copyFrom(DataStorage dataStorage,
 long size)
                    throws IllegalArgumentException,
IllegalStateException,
ApfloatRuntimeException

Copies the specified number of elements from another data storage to this data storage.

Parameters:

dataStorage - The data storage where the data should be copied from.

size - The number of elements to be copied.

Throws:

IllegalArgumentException - If the size is invalid or zero.

IllegalStateException - If this data storage is read-only or has subsequences.

ApfloatRuntimeException

implCopyFrom

protected abstract void implCopyFrom(DataStorage dataStorage,
 long size)
                              throws ApfloatRuntimeException

Copies the specified number of elements from another data storage to this data storage. The validity of the arguments of this method do not need to be checked.

Parameters:

dataStorage - The data storage where the data should be copied from.

size - The number of elements to be copied.

Throws:

ApfloatRuntimeException

getSize

public final long getSize()
                   throws ApfloatRuntimeException

Return the size of the data storage, or the length of this sub-sequence if this data storage is a sub-sequence.

Returns:

The size of the data storage.

Throws:

ApfloatRuntimeException

implGetSize

protected abstract long implGetSize()
                             throws ApfloatRuntimeException

Return the size of the whole data storage, not including sub-sequence settings.

Returns:

The size of the whole data storage, not including sub-sequence settings.

Throws:

ApfloatRuntimeException

setSize

public final void setSize(long size)
                   throws IllegalArgumentException,
IllegalStateException,
ApfloatRuntimeException

Sets the size of the data storage.

Parameters:

size - The size of the data storage.

Throws:

IllegalArgumentException - If the size is invalid or zero.

IllegalStateException - If this data storage is read-only or has subsequences.

ApfloatRuntimeException

implSetSize

protected abstract void implSetSize(long size)
                             throws ApfloatRuntimeException

Sets the size of the data storage. The validity of the arguments of this method do not need to be checked.

Parameters:

size - The size of the data storage.

Throws:

ApfloatRuntimeException

isReadOnly

public final boolean isReadOnly()

Returns the read-only state of this data storage.

Returns:

true if this data storage is read-only, otherwise false.

setReadOnly

public final void setReadOnly()
                       throws ApfloatRuntimeException

Sets this data storage as read-only. All existing sub-sequences (recursively) of this data storage are set to read-only as well.

Throws:

ApfloatRuntimeException

getArray

public final ArrayAccess getArray(int mode,
 long offset,
 int length)
                           throws IllegalArgumentException,
IllegalStateException,
ApfloatRuntimeException

Gets an array access to the data of this data storage when the data is treated as a linear block.

Parameters:

mode - Access mode for the array access: READ, WRITE or both.

offset - Starting position of the array access in the data storage.

length - Number of accessible elements in the array access.

Returns:

The array access.

Throws:

IllegalArgumentException - If the offset or length are out of bounds of the data storage.

IllegalStateException - If write access is requested for a read-only data storage.

ApfloatRuntimeException

implGetArray

protected abstract ArrayAccess implGetArray(int mode,
 long offset,
 int length)
                                     throws ApfloatRuntimeException

Gets an array access to the data of this data storage when it is treated as a linear block. The validity of the arguments of this method do not need to be checked.

Parameters:

mode - Access mode for the array access: READ, WRITE or both.

offset - Starting position of the array access in the data storage.

length - Number of accessible elements in the array access.

Returns:

The array access.

Throws:

ApfloatRuntimeException

getArray

public final ArrayAccess getArray(int mode,
 int startColumn,
 int columns,
 int rows)
                           throws IllegalArgumentException,
IllegalStateException,
ApfloatRuntimeException

Maps a block of data to a memory array when the data is treated as a matrix. The matrix size is n₁ x n₂. The following picture illustrates the block being accessed (in gray):

Matrix

← startColumn →	← columns →	↑ n1 ↓
← n2 →

Parameters:

mode - Whether the array is prepared for reading, writing or both. The value should be READ, WRITE or a combination of these.

startColumn - The starting column where data is read.

columns - The number of columns of data to read.

rows - The number of rows of data to read. This should be equivalent to n₁, number of rows in the matrix.

Returns:

Access to an array of size columns x rows containing the data.

Throws:

IllegalArgumentException - If the requested area is out of bounds of the data storage.

IllegalStateException - If write access is requested for a read-only data storage.

ApfloatRuntimeException

Since:

1.7.0

implGetArray

protected abstract ArrayAccess implGetArray(int mode,
 int startColumn,
 int columns,
 int rows)
                                     throws ApfloatRuntimeException

Maps a block of data to a memory array when the data is treated as a matrix. The validity of the arguments of this method do not need to be checked.

Parameters:

mode - Whether the array is prepared for reading, writing or both. The value should be READ, WRITE or a combination of these.

startColumn - The starting column where data is read.

columns - The number of columns of data to read.

rows - The number of rows of data to read. This should be equivalent to n₁, number of rows in the matrix.

Returns:

Access to an array of size columns x rows containing the data.

Throws:

ApfloatRuntimeException

Since:

1.7.0

getTransposedArray

public final ArrayAccess getTransposedArray(int mode,
 int startColumn,
 int columns,
 int rows)
                                     throws IllegalArgumentException,
IllegalStateException,
ApfloatRuntimeException

Maps a transposed block of data to a memory array when the data is treated as a matrix. The matrix size is n₁ x n₂. The accessed block is illustrated in gray in the following picture. The argument columns is the value b:

Matrix

← startColumn →	A	↑ n1 ↓
	B
	C
	D
	← b →
← n2 →

The data is read from an n₁ x b area of the matrix, in blocks of b elements, to a b x n₁ memory array as follows:

Read matrix section

A	↑ b ↓
B
C
D
← n1 →

Each b x b block is transposed, to form the final b x n₁ array in memory, where the columns are located linearly:

Transposed matrix section

A	B	C	D	↑ b ↓
← n1 →

Parameters:

mode - Whether the array is prepared for reading, writing or both. The value should be READ, WRITE or a combination of these.

startColumn - The starting column where data is read.

columns - The number of columns of data to read.

rows - The number of rows of data to read. This should be equivalent to n₁, number of rows in the matrix.

Returns:

Access to an array of size columns x rows containing the transposed data.

Throws:

IllegalArgumentException - If the requested area is out of bounds of the data storage.

IllegalStateException - If write access is requested for a read-only data storage.

ApfloatRuntimeException

implGetTransposedArray

protected abstract ArrayAccess implGetTransposedArray(int mode,
 int startColumn,
 int columns,
 int rows)
                                               throws ApfloatRuntimeException

Maps a transposed block of data to a memory array when the data is treated as a matrix. The validity of the arguments of this method do not need to be checked.

Parameters:

mode - Whether the array is prepared for reading, writing or both. The value should be READ, WRITE or a combination of these.

startColumn - The starting column where data is read.

columns - The number of columns of data to read.

rows - The number of rows of data to read. This should be equivalent to n₁, number of rows in the matrix.

Returns:

Access to an array of size columns x rows containing the transposed data.

Throws:

ApfloatRuntimeException

iterator

public abstract DataStorage.Iterator iterator(int mode,
 long startPosition,
 long endPosition)
                                       throws IllegalArgumentException,
IllegalStateException,
ApfloatRuntimeException

Constructs a new iterator. Elements can be iterated either in forward or in reverse order, depending on if startPosition is less than or greater than endPosition, correspondingly.

Parameters:

mode - Access mode for iterator: READ, WRITE or both.

startPosition - Starting position of iterator in the data set. For reverse access, the first element in the iterator is startPosition - 1.

endPosition - End position of iterator in the data set. For forward access, the last accessible element in the iterator is endPosition - 1.

Returns:

An iterator.

Throws:

IllegalArgumentException - If the requested area is out of bounds of the data storage.

IllegalStateException - If write access is requested for a read-only data storage.

ApfloatRuntimeException

isSubsequenced

public final boolean isSubsequenced()

Is this object a subsequence of some other object, or do subsequences of this object exist.

Returns:

true if this object is a subsequence of some other object, or if subsequences of this object exist, false otherwise.

isCached

public abstract boolean isCached()

Is this object cached in memory.

Returns:

true if this object is cached in memory, false if not.

Since:

1.7.0

getOffset

protected final long getOffset()

Return the sub-sequence offset.

Returns:

Absolute offset of the sub-sequence within the (top-level) base data storage.