org.apache.drill.exec.physical.impl.scan.v3.lifecycle

Class BaseTestScanLifecycle.BaseMockBatchReader

java.lang.Object

org.apache.drill.exec.physical.impl.scan.v3.lifecycle.BaseTestScanLifecycle.BaseMockBatchReader

All Implemented Interfaces:

ManagedReader

Direct Known Subclasses:

BaseTestScanLifecycle.MockEarlySchemaReader, BaseTestScanLifecycle.MockLateSchemaReader, BaseTestScanLifecycle.NoDataReader

Enclosing class:

BaseTestScanLifecycle

protected abstract static class BaseTestScanLifecycle.BaseMockBatchReader
extends Object
implements ManagedReader

Base class for the "mock" readers used in this test. The mock readers follow the normal (enhanced) reader API, but instead of actually reading from a data source, they just generate data with a known schema. They also expose internal state such as identifying which methods were actually called.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.drill.exec.physical.impl.scan.v3.ManagedReader

ManagedReader.EarlyEofException

Field Summary

Fields

Modifier and Type	Field and Description
protected int	batchCount
protected int	batchLimit
protected int	startIndex
protected ResultSetLoader	tableLoader

Constructor Summary

Constructors

Constructor and Description
BaseMockBatchReader(int batchLimit)

Method Summary

Modifier and Type	Method and Description
void	close() Release resources.
protected void	makeBatch()
boolean	next() Read the next batch.

Methods inherited from class java.lang.Object

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

Field Detail

startIndex

protected int startIndex

batchCount

protected int batchCount

batchLimit

protected int batchLimit

tableLoader

protected ResultSetLoader tableLoader

Constructor Detail

BaseMockBatchReader

public BaseMockBatchReader(int batchLimit)

Method Detail

makeBatch

protected void makeBatch()

next

public boolean next()

Description copied from interface: ManagedReader

Read the next batch. Reading continues until either EOF, or until the mutator indicates that the batch is full. The batch is considered valid if it is non-empty. Returning true with an empty batch is valid, and is helpful on the very first batch (returning schema only.) An empty batch with a false return code indicates EOF and the batch will be discarded. A non-empty batch along with a false return result indicates a final, valid batch, but that EOF was reached and no more data is available.

This somewhat complex protocol avoids the need to allocate a final batch just to find out that no more data is available; it allows EOF to be returned along with the final batch.

Specified by:

next in interface ManagedReader

Returns:

true if more data may be available (and so next() should be called again, false to indicate that EOF was reached

close

public void close()

Description copied from interface: ManagedReader

Release resources. Called just after a failure, when the scanner is cancelled, or after next() returns EOF. Release all resources and close files. Guaranteed to be called if open() returns normally; will not be called if open() throws an exception.

Specified by:

close in interface ManagedReader