org.apache.hadoop.hbase.filter

Class FilterBase

java.lang.Object

org.apache.hadoop.hbase.filter.Filter

org.apache.hadoop.hbase.filter.FilterBase

Direct Known Subclasses:

AccessControlFilter, ColumnCountGetFilter, ColumnPaginationFilter, ColumnPrefixFilter, ColumnRangeFilter, ColumnValueFilter, CompareFilter, FilterList, FilterListBase, FirstKeyOnlyFilter, FuzzyRowFilter, InclusiveStopFilter, KeyOnlyFilter, MobReferenceOnlyFilter, MultipleColumnPrefixFilter, MultiRowRangeFilter, PageFilter, PrefixFilter, RandomRowFilter, SingleColumnValueFilter, SkipFilter, TimestampsFilter, VisibilityController.DeleteVersionVisibilityExpressionFilter, VisibilityLabelFilter, WhileMatchFilter

@InterfaceAudience.Private
public abstract class FilterBase
extends Filter

Abstract base class to help you implement new Filters. Common "ignore" or NOOP type methods can go here, helping to reduce boiler plate in an ever-expanding filter library. If you could instantiate FilterBase, it would end up being a "null" filter - that is one that never filters anything.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.hbase.filter.Filter

Filter.ReturnCode

Field Summary

Fields inherited from class org.apache.hadoop.hbase.filter.Filter

reversed

Constructor Summary

Constructors

Constructor and Description
FilterBase()

Method Summary

Modifier and Type	Method and Description
(package private) boolean	areSerializedFieldsEqual(Filter other) Default implementation so that writers of custom filters aren't forced to implement.
static Filter	createFilterFromArguments(ArrayList<byte[]> filterArguments) Given the filter's arguments it constructs the filter
boolean	filterAllRemaining() Filters that never filter all remaining can inherit this implementation that never stops the filter early.
boolean	filterRow() Filters that never filter by rows based on previously gathered state from Filter.filterCell(Cell) can inherit this implementation that never filters a row.
void	filterRowCells(List<Cell> ignored) Filters that never filter by modifying the returned List of Cells can inherit this implementation that does nothing.
boolean	filterRowKey(byte[] buffer, int offset, int length) Deprecated. As of release 2.0.0, this will be removed in HBase 3.0.0. Instead use filterRowKey(Cell)
boolean	filterRowKey(Cell cell) Filters a row based on the row key.
Cell	getNextCellHint(Cell currentCell) Filters that are not sure which key must be next seeked to, can inherit this implementation that, by default, returns a null Cell.
boolean	hasFilterRow() Fitlers that never filter by modifying the returned List of Cells can inherit this implementation that does nothing.
boolean	isFamilyEssential(byte[] name) By default, we require all scan's column families to be present.
void	reset() Filters that are purely stateless and do nothing in their reset() methods can inherit this null/empty implementation.
byte[]	toByteArray() Return length 0 byte array for Filters that don't require special serialization
String	toString() Return filter's info for debugging and logging purpose.
Cell	transformCell(Cell v) By default no transformation takes place Give the filter a chance to transform the passed KeyValue.

Methods inherited from class org.apache.hadoop.hbase.filter.Filter

filterCell, filterKeyValue, isReversed, parseFrom, setReversed

Methods inherited from class java.lang.Object

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

Constructor Detail

FilterBase

public FilterBase()

Method Detail

reset

public void reset()
           throws IOException

Filters that are purely stateless and do nothing in their reset() methods can inherit this null/empty implementation. Reset the state of the filter between rows. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Specified by:

reset in class Filter

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

filterRowKey

@Deprecated
public boolean filterRowKey(byte[] buffer,
                                        int offset,
                                        int length)
                                 throws IOException

Deprecated. As of release 2.0.0, this will be removed in HBase 3.0.0. Instead use filterRowKey(Cell)

Filters that do not filter by row key can inherit this implementation that never filters anything. (ie: returns false). Filters a row based on the row key. If this returns true, the entire row will be excluded. If false, each KeyValue in the row will be passed to Filter.filterCell(Cell) below. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Specified by:

filterRowKey in class Filter

Parameters:

buffer - buffer containing row key

offset - offset into buffer where row key starts

length - length of the row key

Returns:

true, remove entire row, false, include the row (maybe).

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

filterRowKey

public boolean filterRowKey(Cell cell)
                     throws IOException

Description copied from class: Filter

Filters a row based on the row key. If this returns true, the entire row will be excluded. If false, each KeyValue in the row will be passed to Filter.filterCell(Cell) below. If Filter.filterAllRemaining() returns true, then Filter.filterRowKey(Cell) should also return true. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Specified by:

filterRowKey in class Filter

Parameters:

cell - The first cell coming in the new row

Returns:

true, remove entire row, false, include the row (maybe).

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

filterAllRemaining

public boolean filterAllRemaining()
                           throws IOException

Filters that never filter all remaining can inherit this implementation that never stops the filter early. If this returns true, the scan will terminate. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Specified by:

filterAllRemaining in class Filter

Returns:

true to end scan, false to continue.

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

transformCell

public Cell transformCell(Cell v)
                   throws IOException

By default no transformation takes place Give the filter a chance to transform the passed KeyValue. If the Cell is changed a new Cell object must be returned.

Specified by:

transformCell in class Filter

Parameters:

v - the KeyValue in question

Returns:

the changed KeyValue

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

See Also:

The transformed KeyValue is what is eventually returned to the client. Most filters will return the passed KeyValue unchanged., for an example of a transformation. Concrete implementers can signal a failure condition in their code by throwing an {@link IOException}.

filterRowCells

public void filterRowCells(List<Cell> ignored)
                    throws IOException

Filters that never filter by modifying the returned List of Cells can inherit this implementation that does nothing. Chance to alter the list of Cells to be submitted. Modifications to the list will carry on Concrete implementers can signal a failure condition in their code by throwing an IOException.

Specified by:

filterRowCells in class Filter

Parameters:

ignored - the list of Cells to be filtered

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

hasFilterRow

public boolean hasFilterRow()

Fitlers that never filter by modifying the returned List of Cells can inherit this implementation that does nothing. Primarily used to check for conflicts with scans(such as scans that do not read a full row at a time).

Specified by:

hasFilterRow in class Filter

Returns:

True if this filter actively uses filterRowCells(List) or filterRow().

filterRow

public boolean filterRow()
                  throws IOException

Filters that never filter by rows based on previously gathered state from Filter.filterCell(Cell) can inherit this implementation that never filters a row. Last chance to veto row based on previous Filter.filterCell(Cell) calls. The filter needs to retain state then return a particular value for this call if they wish to exclude a row if a certain column is missing (for example). Concrete implementers can signal a failure condition in their code by throwing an IOException.

Specified by:

filterRow in class Filter

Returns:

true to exclude row, false to include row.

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

getNextCellHint

public Cell getNextCellHint(Cell currentCell)
                     throws IOException

Filters that are not sure which key must be next seeked to, can inherit this implementation that, by default, returns a null Cell. If the filter returns the match code SEEK_NEXT_USING_HINT, then it should also tell which is the next key it must seek to. After receiving the match code SEEK_NEXT_USING_HINT, the QueryMatcher would call this function to find out which key it must next seek to. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Specified by:

getNextCellHint in class Filter

Returns:

KeyValue which must be next seeked. return null if the filter is not sure which key to seek to next.

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

isFamilyEssential

public boolean isFamilyEssential(byte[] name)
                          throws IOException

By default, we require all scan's column families to be present. Our subclasses may be more precise. Check that given column family is essential for filter to check row. Most filters always return true here. But some could have more sophisticated logic which could significantly reduce scanning process by not even touching columns until we are 100% sure that it's data is needed in result. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Specified by:

isFamilyEssential in class Filter

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

createFilterFromArguments

public static Filter createFilterFromArguments(ArrayList<byte[]> filterArguments)

Given the filter's arguments it constructs the filter

Parameters:

filterArguments - the filter's arguments

Returns:

constructed filter object

toString

public String toString()

Return filter's info for debugging and logging purpose.

Overrides:

toString in class Object

toByteArray

public byte[] toByteArray()
                   throws IOException

Return length 0 byte array for Filters that don't require special serialization

Specified by:

toByteArray in class Filter

Returns:

The filter serialized using pb

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

areSerializedFieldsEqual

boolean areSerializedFieldsEqual(Filter other)

Default implementation so that writers of custom filters aren't forced to implement.

Specified by:

areSerializedFieldsEqual in class Filter

Parameters:

other -

Returns:

true if and only if the fields of the filter that are serialized are equal to the corresponding fields in other. Used for testing.