org.apache.lens.server.api.driver

Class AbstractLensDriver

java.lang.Object

org.apache.lens.server.api.driver.AbstractLensDriver

All Implemented Interfaces:

Externalizable, Serializable, LensDriver

Direct Known Subclasses:

ESDriver, HiveDriver, JDBCDriver

public abstract class AbstractLensDriver
extends Object
implements LensDriver

Abstract class for Lens Driver Implementations. Provides default implementations and some utility methods for drivers

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AbstractLensDriver()

Method Summary

Methods

Modifier and Type	Method and Description
void	configure(org.apache.hadoop.conf.Configuration conf, String driverType, String driverName) Configure driver with Configuration passed.
Priority	decidePriority(AbstractQueryContext queryContext) decide priority based on query's cost.
LensResultSet	fetchResultSet(QueryContext ctx) Default implementation for fetchResultSet for all drivers.
String	getFullyQualifiedName() Driver's fully qualified name ( Example hive/hive1, jdbc/mysql1)
DriverQueryHook	getQueryHook()
String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.lens.server.api.driver.LensDriver

cancelQuery, close, closePreparedQuery, closeQuery, closeResultSet, estimate, execute, executeAsync, explain, explainAndPrepare, getConf, getQueryConstraints, getWaitingQuerySelectionPolicies, prepare, registerDriverEventListener, registerForCompletionNotification, updateStatus

Methods inherited from interface java.io.Externalizable

readExternal, writeExternal

Constructor Detail

AbstractLensDriver

public AbstractLensDriver()

Method Detail

configure

public void configure(org.apache.hadoop.conf.Configuration conf,
             String driverType,
             String driverName)
               throws LensException

Description copied from interface: LensDriver

Configure driver with Configuration passed.

Specified by:

configure in interface LensDriver

Parameters:

conf - The configuration object

driverType - Type of the driver (Example: hive, jdbc, el)

driverName - Name of this driver

Throws:

LensException - the lens exception

fetchResultSet

public LensResultSet fetchResultSet(QueryContext ctx)
                             throws LensException

Default implementation for fetchResultSet for all drivers. Should hold good in most cases. Note : If a driver is sticking to this default implementation, it should override createResultSet(QueryContext)

Specified by:

fetchResultSet in interface LensDriver

Parameters:

ctx - The query context

Returns:

returns the result set

Throws:

LensException - the lens exception

decidePriority

public Priority decidePriority(AbstractQueryContext queryContext)

Description copied from interface: LensDriver

decide priority based on query's cost. The cost should be already computed by estimate call, but it's not guaranteed to be pre-computed. It's up to the driver to do an on-demand computation of cost.

Specified by:

decidePriority in interface LensDriver

See Also:

that handles this on-demand computation.

getQueryHook

public DriverQueryHook getQueryHook()

Specified by:

getQueryHook in interface LensDriver

Returns:

the DriverQueryHook implementation for the driver.

See Also:

for more details.

toString

public String toString()

Overrides:

toString in class Object

getFullyQualifiedName

@Generated(value="lombok")
public String getFullyQualifiedName()

Driver's fully qualified name ( Example hive/hive1, jdbc/mysql1)

Specified by:

getFullyQualifiedName in interface LensDriver

Returns:

fully qualified name of this driver. This should be unique for each driver instance. This name can be used for referring to the driver while logging, persisting and restoring driver details,etc. (Examples: hive/hive1, jdbc/mysql1 )