edu.rit.pj.reduction

Class SharedIntegerMatrix

java.lang.Object

edu.rit.pj.reduction.SharedIntegerMatrix

public class SharedIntegerMatrix
extends java.lang.Object

Class SharedIntegerMatrix provides a matrix reduction variable with elements of type int.

Class SharedIntegerMatrix is multiple thread safe. The methods use lock-free atomic compare-and-set.

Note: Class SharedIntegerMatrix is implemented using class java.util.concurrent.atomic.AtomicIntegerArray.

Constructor Summary

Constructors

Constructor and Description
SharedIntegerMatrix(int[][] matrix) Construct a new integer matrix reduction variable whose elements are copied from the given matrix.
SharedIntegerMatrix(int rows, int cols) Construct a new integer matrix reduction variable with the given number of rows and columns.

Method Summary

Modifier and Type	Method and Description
int	addAndGet(int r, int c, int value) Add the given value to this matrix reduction variable at the given row and column and return the new value.
int	cols() Returns the number of columns in this matrix reduction variable.
boolean	compareAndSet(int r, int c, int expect, int update) Atomically set this matrix reduction variable at the given row and column to the given updated value if the current value equals the expected value.
int	decrementAndGet(int r, int c) Subtract one from this matrix reduction variable at the given row and column and return the new value.
int	get(int r, int c) Returns this matrix reduction variable's current value at the given row and column.
int	getAndAdd(int r, int c, int value) Add the given value to this matrix reduction variable at the given row and column and return the previous value.
int	getAndDecrement(int r, int c) Subtract one from this matrix reduction variable at the given row and column and return the previous value.
int	getAndIncrement(int r, int c) Add one to this matrix reduction variable at the given row and column and return the previous value.
int	getAndSet(int r, int c, int value) Set this matrix reduction variable at the given row and column to the given value and return the previous value.
int	incrementAndGet(int r, int c) Add one to this matrix reduction variable at the given row and column and return the new value.
void	reduce(int[][] src, IntegerOp op) Combine this matrix reduction variable with the given matrix using the given operation.
void	reduce(int dstrow, int dstcol, int[][] src, int srcrow, int srccol, int rowlen, int collen, IntegerOp op) Combine a portion of this matrix reduction variable with a portion of the given matrix using the given operation.
int	reduce(int r, int c, int value, IntegerOp op) Combine this matrix reduction variable at the given row and column with the given value using the given operation.
int	rows() Returns the number of rows in this matrix reduction variable.
void	set(int r, int c, int value) Set this matrix reduction variable at the given row and column to the given value.
boolean	weakCompareAndSet(int r, int c, int expect, int update) Atomically set this matrix reduction variable at the given row and column to the given updated value if the current value equals the expected value.

Methods inherited from class java.lang.Object

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

Constructor Detail

SharedIntegerMatrix

public SharedIntegerMatrix(int rows,
                           int cols)

Construct a new integer matrix reduction variable with the given number of rows and columns. Each matrix element is initially 0.

Parameters:

rows - Number of rows.

cols - Number of columns.

Throws:

java.lang.NegativeArraySizeException - (unchecked exception) Thrown if rows < 0 or cols < 0.

SharedIntegerMatrix

public SharedIntegerMatrix(int[][] matrix)

Construct a new integer matrix reduction variable whose elements are copied from the given matrix. It is assumed that all rows of the matrix have the same number of columns.

Parameters:

matrix - Matrix to copy.

Throws:

java.lang.NullPointerException - (unchecked exception) Thrown if matrix is null or any row of matrix is null.

Method Detail

rows

public int rows()

Returns the number of rows in this matrix reduction variable.

Returns:

Rows.

cols

public int cols()

Returns the number of columns in this matrix reduction variable.

Returns:

Columns.

get

public int get(int r,
               int c)

Returns this matrix reduction variable's current value at the given row and column.

Parameters:

r - Row index.

c - Column index.

Returns:

Current value.

set

public void set(int r,
                int c,
                int value)

Set this matrix reduction variable at the given row and column to the given value.

Parameters:

r - Row index.

c - Column index.

value - New value.

getAndSet

public int getAndSet(int r,
                     int c,
                     int value)

Set this matrix reduction variable at the given row and column to the given value and return the previous value.

Parameters:

r - Row index.

c - Column index.

value - New value.

Returns:

Previous value.

compareAndSet

public boolean compareAndSet(int r,
                             int c,
                             int expect,
                             int update)

Atomically set this matrix reduction variable at the given row and column to the given updated value if the current value equals the expected value.

Parameters:

r - Row index.

c - Column index.

expect - Expected value.

update - Updated value.

Returns:

True if the update happened, false otherwise.

weakCompareAndSet

public boolean weakCompareAndSet(int r,
                                 int c,
                                 int expect,
                                 int update)

Atomically set this matrix reduction variable at the given row and column to the given updated value if the current value equals the expected value. May fail spuriously.

Parameters:

r - Row index.

c - Column index.

expect - Expected value.

update - Updated value.

Returns:

True if the update happened, false otherwise.

getAndIncrement

public int getAndIncrement(int r,
                           int c)

Add one to this matrix reduction variable at the given row and column and return the previous value.

Parameters:

r - Row index.

c - Column index.

Returns:

Previous value.

getAndDecrement

public int getAndDecrement(int r,
                           int c)

Subtract one from this matrix reduction variable at the given row and column and return the previous value.

Parameters:

r - Row index.

c - Column index.

Returns:

Previous value.

getAndAdd

public int getAndAdd(int r,
                     int c,
                     int value)

Add the given value to this matrix reduction variable at the given row and column and return the previous value.

Parameters:

r - Row index.

c - Column index.

value - Value to add.

Returns:

Previous value.

incrementAndGet

public int incrementAndGet(int r,
                           int c)

Add one to this matrix reduction variable at the given row and column and return the new value.

Parameters:

r - Row index.

c - Column index.

Returns:

New value.

decrementAndGet

public int decrementAndGet(int r,
                           int c)

Subtract one from this matrix reduction variable at the given row and column and return the new value.

Parameters:

r - Row index.

c - Column index.

Returns:

New value.

addAndGet

public int addAndGet(int r,
                     int c,
                     int value)

Add the given value to this matrix reduction variable at the given row and column and return the new value.

Parameters:

r - Row index.

c - Column index.

value - Value to add.

Returns:

New value.

reduce

public int reduce(int r,
                  int c,
                  int value,
                  IntegerOp op)

Combine this matrix reduction variable at the given row and column with the given value using the given operation. (This matrix [r,c]) is set to (this matrix [r,c]) op (value), then (this matrix [r,c]) is returned.

Parameters:

r - Row index.

c - Column index.

value - Value.

op - Binary operation.

Returns:

(This matrix [r,c]) op (value).

reduce

public void reduce(int[][] src,
                   IntegerOp op)

Combine this matrix reduction variable with the given matrix using the given operation. For every row r and column c in this matrix, (this matrix [r,c]) is set to (this matrix [r,c]) op (src[r,c]).

The reduce() method is multiple thread safe on a per-element basis. Each individual matrix element is updated atomically, but the matrix as a whole is not updated atomically.

Parameters:

src - Source matrix.

op - Binary operation.

Throws:

java.lang.NullPointerException - (unchecked exception) Thrown if src is null. Thrown if op is null.

java.lang.IndexOutOfBoundsException - (unchecked exception) Thrown if any matrix index would be out of bounds.

reduce

public void reduce(int dstrow,
                   int dstcol,
                   int[][] src,
                   int srcrow,
                   int srccol,
                   int rowlen,
                   int collen,
                   IntegerOp op)

Combine a portion of this matrix reduction variable with a portion of the given matrix using the given operation. For each row index r from 0 to rowlen-1 inclusive, and for each column index c from 0 to collen-1 inclusive, (this matrix [dstrow+r,dstcol+c]) is set to (this matrix [dstrow+r,dstcol+c]) op (src[srcrow+r,srccol+c]).

The reduce() method is multiple thread safe on a per-element basis. Each individual matrix element is updated atomically, but the matrix as a whole is not updated atomically.

Parameters:

dstrow - Row index of first element to update in this matrix.

dstcol - Column index of first element to update in this matrix.

src - Source matrix.

srcrow - Row index of first element to update from in the source matrix.

srccol - Column index of first element to update from in the source matrix.

rowlen - Number of rows to update.

collen - Number of columns to update.

op - Binary operation.

Throws:

java.lang.NullPointerException - (unchecked exception) Thrown if src is null. Thrown if op is null.

java.lang.IndexOutOfBoundsException - (unchecked exception) Thrown if rowlen < 0. Thrown if collen < 0. Thrown if any matrix index would be out of bounds.