Package org.apache.hadoop.hbase.master
Class RegionPlacementMaintainer.RandomizedMatrix
java.lang.Object
org.apache.hadoop.hbase.master.RegionPlacementMaintainer.RandomizedMatrix
 Enclosing class:
 RegionPlacementMaintainer
Some algorithms for solving the assignment problem may traverse workers or jobs in linear order
which may result in skewing the assignments of the first jobs in the matrix toward the last
workers in the matrix if the costs are uniform. To avoid this kind of clumping, we can
randomize the rows and columns of the cost matrix in a reversible way, such that the solution
to the assignment problem can be interpreted in terms of the original untransformed cost
matrix. Rows and columns are transformed independently such that the elements contained in any
row of the input matrix are the same as the elements in the corresponding output matrix, and
each row has its elements transformed in the same way. Similarly for columns.

Field Summary
Modifier and TypeFieldDescriptionprivate final int[]
private final int
private final int[]
private final int[]
private final int
private final int[]

Constructor Summary
ConstructorDescriptionRandomizedMatrix
(int rows, int cols) Create a randomization scheme for a matrix of a given size. 
Method Summary
Modifier and TypeMethodDescriptionfloat[][]
invert
(float[][] matrix) Copy a given matrix into a new matrix, transforming each row index and each column index according to the inverse of the randomization scheme that was created at construction time.int[]
invertIndices
(int[] indices) Given an array where each elementindices[i]
represents the randomized column index corresponding to randomized row indexi
, create a new array with the corresponding inverted indices.float[][]
transform
(float[][] matrix) Copy a given matrix into a new matrix, transforming each row index and each column index according to the randomization scheme that was created at construction time.

Field Details

rows

cols

rowTransform

rowInverse

colTransform

colInverse


Constructor Details

RandomizedMatrix
Create a randomization scheme for a matrix of a given size. Parameters:
rows
 the number of rows in the matrixcols
 the number of columns in the matrix


Method Details

transform
Copy a given matrix into a new matrix, transforming each row index and each column index according to the randomization scheme that was created at construction time. Parameters:
matrix
 the cost matrix to transform Returns:
 a new matrix with row and column indices transformed

invert
Copy a given matrix into a new matrix, transforming each row index and each column index according to the inverse of the randomization scheme that was created at construction time. Parameters:
matrix
 the cost matrix to be inverted Returns:
 a new matrix with row and column indices inverted

invertIndices
Given an array where each elementindices[i]
represents the randomized column index corresponding to randomized row indexi
, create a new array with the corresponding inverted indices. Parameters:
indices
 an array of transformed indices to be inverted Returns:
 an array of inverted indices
