Package org.apache.druid.query.groupby.epinephelinae

Class BufferHashGrouper<KeyType>

java.lang.Object

org.apache.druid.query.groupby.epinephelinae.AbstractBufferHashGrouper<KeyType>

org.apache.druid.query.groupby.epinephelinae.BufferHashGrouper<KeyType>

All Implemented Interfaces:

Closeable, AutoCloseable, Grouper<KeyType>

public class BufferHashGrouper<KeyType>
extends AbstractBufferHashGrouper<KeyType>

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.druid.query.groupby.epinephelinae.Grouper

Grouper.BufferComparator, Grouper.Entry<T>, Grouper.KeySerde<T>, Grouper.KeySerdeFactory<T>

Field Summary

Fields inherited from class org.apache.druid.query.groupby.epinephelinae.AbstractBufferHashGrouper

aggregators, baseAggregatorOffset, bucketSize, bufferGrouperMaxSize, bufferSupplier, HASH_SIZE, hashTable, hashTableBuffer, initialBuckets, keySerde, keySize, log, maxLoadFactor

Constructor Summary

Constructors

Constructor	Description
BufferHashGrouper(com.google.common.base.Supplier<ByteBuffer> bufferSupplier, Grouper.KeySerde<KeyType> keySerde, AggregatorAdapters aggregators, int bufferGrouperMaxSize, float maxLoadFactor, int initialBuckets, boolean useDefaultSorting)

Method Summary

Modifier and Type	Method	Description
void	afterAggregateHook(int bucketOffset)	Called after a row is aggregated.
boolean	canSkipAggregate(int bucketOffset)	Called to check if it's possible to skip aggregation for a row.
ToIntFunction<KeyType>	hashFunction()
void	init()	Initialize the grouper.
boolean	isInitialized()	Check this grouper is initialized or not.
CloseableIterator<Grouper.Entry<KeyType>>	iterator(boolean sorted)	Iterate through entries.
void	newBucketHook(int bucketOffset)	Called when a new bucket is used for an entry in the hash table.
void	reset()	Reset the grouper to its initial state.

Methods inherited from class org.apache.druid.query.groupby.epinephelinae.AbstractBufferHashGrouper

aggregate, close, getBuckets, getGrowthCount, getMaxSize, getSize, populateBucketEntryForOffset

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.druid.query.groupby.epinephelinae.Grouper

aggregate

Constructor Detail

BufferHashGrouper

public BufferHashGrouper(com.google.common.base.Supplier<ByteBuffer> bufferSupplier,
                         Grouper.KeySerde<KeyType> keySerde,
                         AggregatorAdapters aggregators,
                         int bufferGrouperMaxSize,
                         float maxLoadFactor,
                         int initialBuckets,
                         boolean useDefaultSorting)

Method Detail

init

public void init()

Description copied from interface: Grouper

Initialize the grouper. This method needs to be called before calling Grouper.aggregate(Object) and Grouper.aggregate(Object, int).

isInitialized

public boolean isInitialized()

Description copied from interface: Grouper

Check this grouper is initialized or not.

Returns:

true if the grouper is already initialized, otherwise false.

hashFunction

public ToIntFunction<KeyType> hashFunction()

newBucketHook

public void newBucketHook(int bucketOffset)

Description copied from class: AbstractBufferHashGrouper

Called when a new bucket is used for an entry in the hash table. An implementing BufferHashGrouper class can use this to update its own state, e.g. tracking bucket offsets in a structure outside of the hash table.

Specified by:

newBucketHook in class AbstractBufferHashGrouper<KeyType>

Parameters:

bucketOffset - offset of the new bucket, within the buffer returned by hashTable.getTableBuffer()

canSkipAggregate

public boolean canSkipAggregate(int bucketOffset)

Description copied from class: AbstractBufferHashGrouper

Called to check if it's possible to skip aggregation for a row.

Specified by:

canSkipAggregate in class AbstractBufferHashGrouper<KeyType>

Parameters:

bucketOffset - Offset of the bucket containing this row's entry in the hash table, within the buffer returned by hashTable.getTableBuffer()

Returns:

true if aggregation can be skipped, false otherwise.

afterAggregateHook

public void afterAggregateHook(int bucketOffset)

Description copied from class: AbstractBufferHashGrouper

Called after a row is aggregated. An implementing BufferHashGrouper class can use this to update its own state, e.g. reading the new aggregated values for the row's key and acting on that information.

Specified by:

afterAggregateHook in class AbstractBufferHashGrouper<KeyType>

Parameters:

bucketOffset - Offset of the bucket containing the row that was aggregated, within the buffer returned by hashTable.getTableBuffer()

reset

public void reset()

Description copied from interface: Grouper

Reset the grouper to its initial state.

iterator

public CloseableIterator<Grouper.Entry<KeyType>> iterator(boolean sorted)

Description copied from interface: Grouper

Iterate through entries.

Some implementations allow writes even after this method is called. After you are done with the iterator returned by this method, you should either call Grouper.close() (if you are done with the Grouper) or Grouper.reset() (if you want to reuse it). Some implementations allow calling Grouper.iterator(boolean) again if you want another iterator. But, this method must not be called by multiple threads concurrently.

If "sorted" is true then the iterator will return sorted results. It will use KeyType's natural ordering on deserialized objects, and will use the Grouper.KeySerde.bufferComparator() on serialized objects. Woe be unto you if these comparators are not equivalent.

Callers must process and discard the returned Grouper.Entrys immediately because some implementations can reuse the key objects.

Parameters:

sorted - return sorted results

Returns:

entry iterator