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

Class StateStoreDriver

java.lang.Object

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

All Implemented Interfaces:

StateStoreRecordOperations

Direct Known Subclasses:

StateStoreBaseImpl

@Public
@Evolving
public abstract class StateStoreDriver
extends java.lang.Object
implements StateStoreRecordOperations

Driver class for an implementation of a StateStoreService provider. Driver implementations will extend this class and implement some of the default methods.

Constructor Summary

Constructors

Constructor	Description
StateStoreDriver()

Method Summary

Modifier and Type	Method	Description
abstract void	close()	Close the State Store driver connection.
protected org.apache.hadoop.conf.Configuration	getConf()	Get the State Store configuration.
java.lang.String	getIdentifier()	Gets a unique identifier for the running task/process.
StateStoreMetrics	getMetrics()	Get the metrics for the State Store.
long	getTime()	Returns the current time synchronization from the underlying store.
boolean	init(org.apache.hadoop.conf.Configuration config, java.lang.String id, java.util.Collection<java.lang.Class<? extends BaseRecord>> records, StateStoreMetrics stateStoreMetrics)	Initialize the state store connection.
abstract boolean	initDriver()	Prepare the driver to access data storage.
abstract <T extends BaseRecord> boolean	initRecordStorage(java.lang.String className, java.lang.Class<T> clazz)	Initialize storage for a single record class.
abstract boolean	isDriverReady()	Check if the driver is currently running and the data store connection is valid.
void	verifyDriverReady()	Check if the driver is ready to be used and throw an exception otherwise.

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, get, getMultiple, put, putAll, remove, remove, removeAll

Constructor Detail

StateStoreDriver

public StateStoreDriver()

Method Detail

init

public boolean init(org.apache.hadoop.conf.Configuration config,
                    java.lang.String id,
                    java.util.Collection<java.lang.Class<? extends BaseRecord>> records,
                    StateStoreMetrics stateStoreMetrics)

Initialize the state store connection.

Parameters:

config - Configuration for the driver.

id - Identifier for the driver.

records - Records that are supported.

stateStoreMetrics - State store metrics.

Returns:

If initialized and ready, false if failed to initialize driver.

getConf

protected org.apache.hadoop.conf.Configuration getConf()

Get the State Store configuration.

Returns:

Configuration for the State Store.

getIdentifier

public java.lang.String getIdentifier()

Gets a unique identifier for the running task/process. Typically, the router address.

Returns:

Unique identifier for the running task.

getMetrics

public StateStoreMetrics getMetrics()

Get the metrics for the State Store.

Returns:

State Store metrics.

initDriver

public abstract boolean initDriver()

Prepare the driver to access data storage.

Returns:

True if the driver was successfully initialized. If false is returned, the state store will periodically attempt to re-initialize the driver and the router will remain in safe mode until the driver is initialized.

initRecordStorage

public abstract <T extends BaseRecord> boolean initRecordStorage(java.lang.String className,
                                                                 java.lang.Class<T> clazz)

Initialize storage for a single record class.

Type Parameters:

T - Type of the state store record.

Parameters:

className - String reference of the record class to initialize, used to construct paths and file names for the record. Determined by configuration settings for the specific driver.

clazz - Record type corresponding to the provided name.

Returns:

True if successful, false otherwise.

isDriverReady

public abstract boolean isDriverReady()

Check if the driver is currently running and the data store connection is valid.

Returns:

True if the driver is initialized and the data store is ready.

verifyDriverReady

public void verifyDriverReady()
                       throws StateStoreUnavailableException

Check if the driver is ready to be used and throw an exception otherwise.

Throws:

StateStoreUnavailableException - If the driver is not ready.

close

public abstract void close()
                    throws java.lang.Exception

Close the State Store driver connection.

Throws:

java.lang.Exception - if something goes wrong while closing the state store driver connection.

getTime

public long getTime()

Returns the current time synchronization from the underlying store. Override for stores that supply a current date. The data store driver is responsible for maintaining the official synchronization time/date for all distributed components.

Returns:

Current time stamp, used for all synchronization dates.