net.sf.farrago.runtime
Class FennelTupleIter

java.lang.Object
  org.eigenbase.runtime.AbstractTupleIter
      net.sf.farrago.runtime.FennelAbstractTupleIter
          net.sf.farrago.runtime.FennelTupleIter

All Implemented Interfaces:

TupleIter, ClosableAllocation

public class FennelTupleIter
extends FennelAbstractTupleIter

FennelTupleIter implements the TupleIter interfaces by reading tuples from a Fennel ExecStream.

FennelTupleIter only deals with raw byte buffers; it delegates to a FennelTupleReader object the responsibility to unmarshal individual fields.

FennelTupleIter's implementation of populateBuffer() blocks.

Version:

$Id: //open/dev/farrago/src/net/sf/farrago/runtime/FennelTupleIter.java#7 $

Author:

John V. Sichi, Stephan Zuercher

Nested Class Summary

Nested classes/interfaces inherited from interface org.eigenbase.runtime.TupleIter

TupleIter.NoDataReason, TupleIter.TimeoutException

Field Summary

private FennelStreamGraph	streamGraph
private FennelStreamHandle	streamHandle

Fields inherited from class net.sf.farrago.runtime.FennelAbstractTupleIter

bufferAsArray, byteBuffer, tupleReader

Fields inherited from interface org.eigenbase.runtime.TupleIter

EMPTY_ITERATOR

Constructor Summary

FennelTupleIter(FennelTupleReader tupleReader, FennelStreamGraph streamGraph, FennelStreamHandle streamHandle, int bufferSize)
Creates a new FennelTupleIter object.

Method Summary

void	closeAllocation() Closes this object.
protected int	populateBuffer() Blocking implementation of populateBuffer().
void	restart() Restarts this iterator, so that a subsequent call to TupleIter.fetchNext() returns the first element in the collection being iterated.

Methods inherited from class net.sf.farrago.runtime.FennelAbstractTupleIter

fetchNext, getStatus, requestData, traceNext

Methods inherited from class org.eigenbase.runtime.AbstractTupleIter

setTimeout

Methods inherited from class java.lang.Object

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

Field Detail

streamGraph

private final FennelStreamGraph streamGraph

streamHandle

private final FennelStreamHandle streamHandle

Constructor Detail

FennelTupleIter

public FennelTupleIter(FennelTupleReader tupleReader,
                       FennelStreamGraph streamGraph,
                       FennelStreamHandle streamHandle,
                       int bufferSize)

Creates a new FennelTupleIter object.

Parameters:

tupleReader - FennelTupleReader to use to interpret Fennel data

streamGraph - underlying FennelStreamGraph

streamHandle - handle to underlying Fennel ExecStream that this TupleIter reads from

bufferSize - number of bytes in buffer used for fetching from Fennel

Method Detail

restart

public void restart()

Description copied from interface: TupleIter

Restarts this iterator, so that a subsequent call to TupleIter.fetchNext() returns the first element in the collection being iterated.

Specified by:

restart in interface TupleIter

Overrides:

restart in class FennelAbstractTupleIter

closeAllocation

public void closeAllocation()

Description copied from interface: ClosableAllocation

Closes this object.

populateBuffer

protected int populateBuffer()

Blocking implementation of populateBuffer().

Specified by:

populateBuffer in class FennelAbstractTupleIter

Returns:

number of bytes read into FennelAbstractTupleIter.byteBuffer or 0 for end of stream.