Package org.apache.hadoop.hdfs.server.federation.store.driver.impl

Class StateStoreBaseImpl

java.lang.Object

org.apache.hadoop.hdfs.server.federation.store.driver.StateStoreDriver

org.apache.hadoop.hdfs.server.federation.store.driver.impl.StateStoreBaseImpl

All Implemented Interfaces:

StateStoreRecordOperations

Direct Known Subclasses:

StateStoreSerializableImpl

@Public
@Evolving
public abstract class StateStoreBaseImpl
extends StateStoreDriver

Base implementation of a State Store driver. It contains default implementations for the optional functions. These implementations use an uncached read/write all algorithm for all changes. In most cases it is recommended to override the optional functions.

Drivers may optionally override additional routines for performance optimization, such as custom get/put/remove queries, depending on the capabilities of the data store.

Constructor Summary

Constructors

Constructor	Description
StateStoreBaseImpl()

Method Summary

Modifier and Type	Method	Description
<T extends BaseRecord> T	get(java.lang.Class<T> clazz, Query<T> query)	Get a single record from the store that matches the query.
<T extends BaseRecord> java.util.List<T>	getMultiple(java.lang.Class<T> clazz, Query<T> query)	Get multiple records from the store that match a query.
<T extends BaseRecord> boolean	put(T record, boolean allowUpdate, boolean errorIfExists)	Creates a single record.
<T extends BaseRecord> boolean	remove(T record)	Remove a single record.

Methods inherited from class org.apache.hadoop.hdfs.server.federation.store.driver.StateStoreDriver

close, getConf, getIdentifier, getMetrics, getTime, init, initDriver, initRecordStorage, isDriverReady, verifyDriverReady

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.hdfs.server.federation.store.driver.StateStoreRecordOperations

get, putAll, remove, removeAll

Constructor Detail

StateStoreBaseImpl

public StateStoreBaseImpl()

Method Detail

get

public <T extends BaseRecord> T get(java.lang.Class<T> clazz,
                                    Query<T> query)
                             throws java.io.IOException

Description copied from interface: StateStoreRecordOperations

Get a single record from the store that matches the query.

Type Parameters:

T - Record class of the records.

Parameters:

clazz - Class of record to fetch.

query - Query to filter results.

Returns:

A single record matching the query. Null if there are no matching records.

Throws:

java.io.IOException - If multiple records match or if the data store cannot be queried.

getMultiple

public <T extends BaseRecord> java.util.List<T> getMultiple(java.lang.Class<T> clazz,
                                                            Query<T> query)
                                                     throws java.io.IOException

Description copied from interface: StateStoreRecordOperations

Get multiple records from the store that match a query. This method assumes the underlying driver does not support filtering. If the driver supports filtering it should overwrite this method.

Type Parameters:

T - Record class of the records.

Parameters:

clazz - Class of record to fetch.

query - Query to filter results.

Returns:

Records of type class that match the query or empty list if none are found.

Throws:

java.io.IOException - Throws exception if unable to query the data store.

put

public <T extends BaseRecord> boolean put(T record,
                                          boolean allowUpdate,
                                          boolean errorIfExists)
                                   throws java.io.IOException

Description copied from interface: StateStoreRecordOperations

Creates a single record. Optionally updates an existing record with same primary key.

Type Parameters:

T - Record class of the records.

Parameters:

record - The record to insert or update.

allowUpdate - True if update of exiting record is allowed.

errorIfExists - True if an error should be returned when inserting an existing record. Only used if allowUpdate = false.

Returns:

True if the operation was successful.

Throws:

java.io.IOException - Throws exception if unable to query the data store.

remove

public <T extends BaseRecord> boolean remove(T record)
                                      throws java.io.IOException

Description copied from interface: StateStoreRecordOperations

Remove a single record.

Type Parameters:

T - Record class of the records.

Parameters:

record - Record to be removed.

Returns:

true If the record was successfully removed. False if the record could not be removed or not stored.

Throws:

java.io.IOException - Throws exception if unable to query the data store.