org.apache.hadoop.hbase.filter
Class FilterWrapper

java.lang.Object
  extended by org.apache.hadoop.hbase.filter.Filter
      extended by org.apache.hadoop.hbase.filter.FilterWrapper

@InterfaceAudience.Private
@InterfaceStability.Evolving
public class FilterWrapper
extends Filter

This is a Filter wrapper class which is used in the server side. Some filter related hooks can be defined in this wrapper. The only way to create a FilterWrapper instance is passing a client side Filter instance through Scan.getFilter().


Nested Class Summary
 
Nested classes/interfaces inherited from class org.apache.hadoop.hbase.filter.Filter
Filter.ReturnCode
 
Constructor Summary
FilterWrapper(Filter filter)
           
 
Method Summary
 boolean filterAllRemaining()
          If this returns true, the scan will terminate.
 Filter.ReturnCode filterKeyValue(KeyValue v)
          A way to filter based on the column family, column qualifier and/or the column value.
 boolean filterRow()
          Last chance to veto row based on previous Filter.filterKeyValue(KeyValue) calls.
 void filterRow(List<KeyValue> kvs)
          Chance to alter the list of keyvalues to be submitted.
 boolean filterRowKey(byte[] buffer, int offset, int length)
          Filters a row based on the row key.
 KeyValue getNextKeyHint(KeyValue currentKV)
          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.
 boolean hasFilterRow()
          Primarily used to check for conflicts with scans(such as scans that do not read a full row at a time).
 boolean isFamilyEssential(byte[] name)
          Check that given column family is essential for filter to check row.
static FilterWrapper parseFrom(byte[] pbBytes)
           
 void reset()
          Reset the state of the filter between rows.
 byte[] toByteArray()
          TODO: JAVADOC Concrete implementers can signal a failure condition in their code by throwing an IOException.
 KeyValue transform(KeyValue v)
          Give the filter a chance to transform the passed KeyValue.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

FilterWrapper

public FilterWrapper(Filter filter)
Method Detail

toByteArray

public byte[] toByteArray()
                   throws IOException
Description copied from class: Filter
TODO: JAVADOC Concrete implementers can signal a failure condition in their code by throwing an IOException.

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.

parseFrom

public static FilterWrapper parseFrom(byte[] pbBytes)
                               throws DeserializationException
Parameters:
pbBytes - A pb serialized FilterWrapper instance
Returns:
An instance of FilterWrapper made from bytes
Throws:
DeserializationException
See Also:
toByteArray()

reset

public void reset()
           throws IOException
Description copied from class: Filter
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.

filterAllRemaining

public boolean filterAllRemaining()
                           throws IOException
Description copied from class: Filter
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.

filterRow

public boolean filterRow()
                  throws IOException
Description copied from class: Filter
Last chance to veto row based on previous Filter.filterKeyValue(KeyValue) 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.

getNextKeyHint

public KeyValue getNextKeyHint(KeyValue currentKV)
                        throws IOException
Description copied from class: Filter
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:
getNextKeyHint 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.

filterRowKey

public boolean filterRowKey(byte[] buffer,
                            int offset,
                            int length)
                     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.filterKeyValue(KeyValue) 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.

filterKeyValue

public Filter.ReturnCode filterKeyValue(KeyValue v)
                                 throws IOException
Description copied from class: Filter
A way to filter based on the column family, column qualifier and/or the column value. Return code is described below. This allows filters to filter only certain number of columns, then terminate without matching ever column. If your filter returns ReturnCode.NEXT_ROW, it should return ReturnCode.NEXT_ROW until Filter.reset() is called just in case the caller calls for the next row. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Specified by:
filterKeyValue in class Filter
Parameters:
v - the KeyValue in question
Returns:
code as described below
Throws:
IOException - in case an I/O or an filter specific failure needs to be signaled.
See Also:
Filter.ReturnCode

transform

public KeyValue transform(KeyValue v)
                   throws IOException
Description copied from class: Filter
Give the filter a chance to transform the passed KeyValue. If the KeyValue is changed a new KeyValue object must be returned.

Specified by:
transform 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}.

hasFilterRow

public boolean hasFilterRow()
Description copied from class: Filter
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 filterRow(List) or filterRow().

filterRow

public void filterRow(List<KeyValue> kvs)
               throws IOException
Description copied from class: Filter
Chance to alter the list of keyvalues 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:
filterRow in class Filter
Parameters:
kvs - the list of keyvalues to be filtered
Throws:
IOException - in case an I/O or an filter specific failure needs to be signaled.

isFamilyEssential

public boolean isFamilyEssential(byte[] name)
                          throws IOException
Description copied from class: Filter
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.


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