com.netflix.hollow.core.index

Class HollowHashIndex

java.lang.Object

com.netflix.hollow.core.index.HollowHashIndex

All Implemented Interfaces:

HollowTypeStateListener

public class HollowHashIndex
extends java.lang.Object
implements HollowTypeStateListener

A HollowHashIndex is used for indexing non-primary-key data. This type of index can map multiple keys to a single matching record, and/or multiple records to a single key.

The field definitions in a hash key may be hierarchical (traverse multiple record types) via dot-notation. For example, the field definition actors.element.actorId may be used to traverse a child LIST or SET type record referenced by the field actors, each elements contained therein, and finally each actors actorId field.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	HollowHashIndex.HollowHashIndexState

Constructor Summary

Constructors

Constructor and Description
HollowHashIndex(HollowReadStateEngine stateEngine, java.lang.String type, java.lang.String selectField, java.lang.String... matchFields) Define a HollowHashIndex.

Method Summary

Modifier and Type	Method and Description
void	addedOrdinal(int ordinal) Called once for each record which is added to the registered type.
void	beginUpdate() Called immediately before a delta update is applied to the state engine
void	detachFromDeltaUpdates() Once called, this HollowHashIndex will no longer be kept up-to-date when deltas are applied to the indexed state engine.
void	endUpdate() Called immediately after a delta update is applied to the state engine.
HollowHashIndexResult	findMatches(java.lang.Object... query) Query the index.
java.lang.String[]	getMatchFields()
java.lang.String	getSelectField()
HollowReadStateEngine	getStateEngine()
java.lang.String	getType()
void	listenForDeltaUpdates() Once called, this HollowHashIndex will be kept up-to-date when deltas are applied to the indexed state engine.
void	removedOrdinal(int ordinal) Called once for each record which is removed from the registered type.

Methods inherited from class java.lang.Object

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

Constructor Detail

HollowHashIndex

public HollowHashIndex(HollowReadStateEngine stateEngine,
                       java.lang.String type,
                       java.lang.String selectField,
                       java.lang.String... matchFields)

Define a HollowHashIndex.

Parameters:

stateEngine - The state engine to index

type - The query starts with the specified type

selectField - The query will select records at this field (specify "" to select the specified type). The selectField may span collection elements and/or map keys or values, which can result in multiple matches per record of the specified start type.

matchFields - The query will match on the specified match fields. The match fields may span collection elements and/or map keys or values.

Method Detail

findMatches

public HollowHashIndexResult findMatches(java.lang.Object... query)

Query the index.

Parameters:

query - the query

Returns:

the hash index result to gather the matched ordinals. A null value indicated no matches were found.

listenForDeltaUpdates

public void listenForDeltaUpdates()

Once called, this HollowHashIndex will be kept up-to-date when deltas are applied to the indexed state engine.

This method should be called before any subsequent deltas occur after the index is created.

In order to prevent memory leaks, if this method is called and the index is no longer needed, call detachFromDeltaUpdates() before discarding the index.

detachFromDeltaUpdates

public void detachFromDeltaUpdates()

Once called, this HollowHashIndex will no longer be kept up-to-date when deltas are applied to the indexed state engine.

Call this method before discarding indexes which are currently listening for delta updates.

beginUpdate

public void beginUpdate()

Description copied from interface: HollowTypeStateListener

Called immediately before a delta update is applied to the state engine

Specified by:

beginUpdate in interface HollowTypeStateListener

addedOrdinal

public void addedOrdinal(int ordinal)

Description copied from interface: HollowTypeStateListener

Called once for each record which is added to the registered type.

Specified by:

addedOrdinal in interface HollowTypeStateListener

Parameters:

ordinal - the ordinal of an object that was added

removedOrdinal

public void removedOrdinal(int ordinal)

Description copied from interface: HollowTypeStateListener

Called once for each record which is removed from the registered type.

Specified by:

removedOrdinal in interface HollowTypeStateListener

Parameters:

ordinal - the ordinal of an object that was removed

endUpdate

public void endUpdate()

Description copied from interface: HollowTypeStateListener

Called immediately after a delta update is applied to the state engine.

Specified by:

endUpdate in interface HollowTypeStateListener

getStateEngine

public HollowReadStateEngine getStateEngine()

getType

public java.lang.String getType()

getSelectField

public java.lang.String getSelectField()

getMatchFields

public java.lang.String[] getMatchFields()