Package org.apache.druid.query.rowsandcols

Class ArrayListRowsAndColumns<RowType>

java.lang.Object

org.apache.druid.query.rowsandcols.ArrayListRowsAndColumns<RowType>

Type Parameters:

RowType -

All Implemented Interfaces:

RowsAndColumns, AppendableRowsAndColumns

public class ArrayListRowsAndColumns<RowType>
extends Object
implements AppendableRowsAndColumns

ArrayListRowsAndColumns is a RowsAndColumns implementation that believes it has all of its data on-heap.

It is an AppendableRowsAndColumns and, as with all RowsAndColumns, it is not thread-safe for multiple writes. Under certain circumstances, concurrent reads from multiple threads can be correct, but the code has to be follow a very strict ordering of code that ensures that reads only happen after writes and once a value is read, it will never be overwritten.

Additionally, this object implements various of the semantic interfaces directly to provide some degree of processing and memory optimization.

Constructor Summary

Constructors

Constructor	Description
ArrayListRowsAndColumns(ArrayList<RowType> rows, RowAdapter<RowType> rowAdapter, RowSignature rowSignature)

Method Summary

Modifier and Type	Method	Description
void	addColumn(String name, Column column)	Mutates the RowsAndColumns by appending the requested Column.
<T> T	as(Class<T> clazz)	Asks the RowsAndColumns to return itself as a concrete implementation of a specific interface.
Column	findColumn(String name)	Finds a column by name.
Collection<String>	getColumnNames()	The set of column names available from the RowsAndColumns
int	numRows()	The number of rows in the RowsAndColumns object
void	sort(ArrayList<ColumnWithDirection> ordering)

Methods inherited from class java.lang.Object

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

Constructor Detail

ArrayListRowsAndColumns

public ArrayListRowsAndColumns(ArrayList<RowType> rows,
                               RowAdapter<RowType> rowAdapter,
                               RowSignature rowSignature)

Method Detail

getColumnNames

public Collection<String> getColumnNames()

Description copied from interface: RowsAndColumns

The set of column names available from the RowsAndColumns

Specified by:

getColumnNames in interface RowsAndColumns

Returns:

The set of column names available from the RowsAndColumns

numRows

public int numRows()

Description copied from interface: RowsAndColumns

The number of rows in the RowsAndColumns object

Specified by:

numRows in interface RowsAndColumns

Returns:

the integer number of rows

findColumn

@Nullable
public Column findColumn(String name)

Description copied from interface: RowsAndColumns

Finds a column by name. null is returned if the column is not found. The RowsAndColumns object should not attempt to default not-found columns to pretend as if they exist, instead the user of the RowsAndColumns object should decide the correct semantic interpretation of a column that does not exist. It is expected that most locations will choose to believe that the column does exist and is always null, but there are often optimizations that can effect this same assumption without doing a lot of extra work if the calling code knows that it does not exist.

Specified by:

findColumn in interface RowsAndColumns

Parameters:

name - the name of the column to find

Returns:

the Column, if found. null if not found.

as

@Nullable
public <T> T as(Class<T> clazz)

Description copied from interface: RowsAndColumns

Asks the RowsAndColumns to return itself as a concrete implementation of a specific interface. The interface asked for will tend to be a semantically-meaningful interface. This method allows the calling code to interrogate the RowsAndColumns object about whether it can offer a meaningful optimization of the semantic interface. If a RowsAndColumns cannot do anything specifically optimal for the interface requested, it should return null instead of trying to come up with its own default implementation.

Specified by:

as in interface RowsAndColumns

Type Parameters:

T - The interface that the calling code wants a concrete implementation of

Parameters:

clazz - A class object representing the interface that the calling code wants a concrete implementation of

Returns:

A concrete implementation of the interface, or null if there is no meaningful optimization to be had through a local implementation of the interface.

addColumn

public void addColumn(String name,
                      Column column)

Description copied from interface: AppendableRowsAndColumns

Mutates the RowsAndColumns by appending the requested Column.

Specified by:

addColumn in interface AppendableRowsAndColumns

Parameters:

name - the name of the new column

column - the Column object representing the new column

sort

public void sort(ArrayList<ColumnWithDirection> ordering)