net.sf.farrago.runtime
Class FarragoJavaUdxIterator

java.lang.Object
  org.eigenbase.runtime.QueueIterator
      org.eigenbase.runtime.ThreadIterator
          net.sf.farrago.runtime.FarragoJavaUdxIterator

All Implemented Interfaces:

Runnable, Iterator, Iterable, RestartableIterator, TupleIter, ClosableAllocation

public abstract class FarragoJavaUdxIterator
extends ThreadIterator
implements RestartableIterator, TupleIter

FarragoJavaUdxIterator provides runtime support for a call to a Java UDX. It supports both the blocking interface Iterator and the non-blocking TupleIter.

Version:

$Id: //open/dev/farrago/src/net/sf/farrago/runtime/FarragoJavaUdxIterator.java#23 $

Author:

John V. Sichi

Nested Class Summary

class

FarragoJavaUdxIterator.PreparedStatementInvocationHandler

Nested classes/interfaces inherited from class org.eigenbase.runtime.QueueIterator

QueueIterator.TimeoutException

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

TupleIter.NoDataReason, TupleIter.TimeoutException

Field Summary

private long	defaultTimeout
private int	iRow
private CountDownLatch	latch
private ParameterMetaData	parameterMetaData
private static int	QUEUE_ARRAY_SIZE
private List<TupleIter>	restartableInputs
private PreparedStatement	resultInserter
private FarragoSyntheticObject[]	rowObjs
protected FarragoSessionRuntimeContext	runtimeContext
private boolean	stopThread
private boolean	timeoutAsUnderflow
protected static Logger	tracer

Fields inherited from class org.eigenbase.runtime.QueueIterator

hasNext, next, queue, throwable

Fields inherited from interface org.eigenbase.runtime.TupleIter

EMPTY_ITERATOR

Constructor Summary

protected

FarragoJavaUdxIterator(FarragoSessionRuntimeContext runtimeContext, Class rowClass, RelDataType rowType)

Method Summary

protected void	addRestartableInput(TupleIter inputIter) Called by generated code to add an input cursor's iterator so that it can be restarted as needed.
private void	checkCancel()
void	closeAllocation() Closes this object.
protected void	doWork() The implementation should call QueueIterator.put(java.lang.Object) with each row.
protected abstract void	executeUdx() Calls specific UDX to produce result set.
Object	fetchNext() Returns the next element in the iteration.
FarragoSyntheticObject	getCurrentRow()
PreparedStatement	getResultInserter()
boolean	hasNext()
boolean	hasNext(long timeout) As QueueIterator.hasNext, but throws QueueIterator.TimeoutException if no row is available within the timeout.
void	restart() Restarts this iterator, so that a subsequent call to next() returns the first element in the collection being iterated.
boolean	setTimeout(long timeout, boolean asUnderflow) Sets a timeout for TupleIter.fetchNext(); (optional operation).
private void	startWithLatch()
private void	stopWithLatch()

Methods inherited from class org.eigenbase.runtime.ThreadIterator

iterator, onEndOfQueue, run, start

Methods inherited from class org.eigenbase.runtime.QueueIterator

checkTermination, done, next, next, offer, put, remove, reset

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

next, remove

Field Detail

QUEUE_ARRAY_SIZE

private static final int QUEUE_ARRAY_SIZE

See Also:

Constant Field Values

tracer

protected static final Logger tracer

rowObjs

private final FarragoSyntheticObject[] rowObjs

resultInserter

private final PreparedStatement resultInserter

runtimeContext

protected final FarragoSessionRuntimeContext runtimeContext

iRow

private int iRow

defaultTimeout

private long defaultTimeout

timeoutAsUnderflow

private boolean timeoutAsUnderflow

stopThread

private boolean stopThread

latch

private CountDownLatch latch

parameterMetaData

private final ParameterMetaData parameterMetaData

restartableInputs

private List<TupleIter> restartableInputs

Constructor Detail

FarragoJavaUdxIterator

protected FarragoJavaUdxIterator(FarragoSessionRuntimeContext runtimeContext,
                                 Class rowClass,
                                 RelDataType rowType)

Method Detail

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator

Overrides:

hasNext in class QueueIterator

hasNext

public boolean hasNext(long timeout)
                throws QueueIterator.TimeoutException

Description copied from class: QueueIterator

As QueueIterator.hasNext, but throws QueueIterator.TimeoutException if no row is available within the timeout.

Overrides:

hasNext in class QueueIterator

Parameters:

timeout - Milliseconds to wait; less than or equal to zero means don't wait

Throws:

QueueIterator.TimeoutException

setTimeout

public boolean setTimeout(long timeout,
                          boolean asUnderflow)

Description copied from interface: TupleIter

Sets a timeout for TupleIter.fetchNext(); (optional operation). Not all implementing classes support a timeout. For those that do, this method provides a common interface, For those that do not, the adapter TimeoutQueueTupleIter puts a timeout queue on top.

Specified by:

setTimeout in interface TupleIter

Parameters:

timeout - in milliseconds. 0 means poll, infinity means block.

asUnderflow - true means indicate timeout by returning TupleIter.NoDataReason.UNDERFLOW; false means throw TupleIter.TimeoutException on a timeout.

Returns:

true if the timeout was set, false if the implementing class does not support a timeout.

fetchNext

public Object fetchNext()

Description copied from interface: TupleIter

Returns the next element in the iteration. If there is no next value, it returns a value from the TupleIter.NoDataReason enumeration indicating why no data was returned.

If this method returns TupleIter.NoDataReason.END_OF_DATA, no further data will be returned by this iterator unless TupleIter.restart() is called.

If this method returns TupleIter.NoDataReason.UNDERFLOW, no data is currently available, but may be come available in the future. It is possible for consecutive calls to return UNDERFLOW and then END_OF_DATA.

The object returned by this method may be re-used for each subsequent call to fetchNext(). In other words, callers must either make certain that the returned value is no longer needed or is copied before any subsequent calls to fetchNext().

Specified by:

fetchNext in interface TupleIter

Returns:

the next element in the iteration, or an instance of TupleIter.NoDataReason.

addRestartableInput

protected void addRestartableInput(TupleIter inputIter)

Called by generated code to add an input cursor's iterator so that it can be restarted as needed.

Parameters:

inputIter - input cursor's iterator

doWork

protected void doWork()

Description copied from class: ThreadIterator

The implementation should call QueueIterator.put(java.lang.Object) with each row.

Specified by:

doWork in class ThreadIterator

getResultInserter

public PreparedStatement getResultInserter()

getCurrentRow

public FarragoSyntheticObject getCurrentRow()

restart

public void restart()

Description copied from interface: RestartableIterator

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

Specified by:

restart in interface RestartableIterator

Specified by:

restart in interface TupleIter

closeAllocation

public void closeAllocation()

Description copied from interface: ClosableAllocation

Closes this object.

Specified by:

closeAllocation in interface ClosableAllocation

stopWithLatch

private void stopWithLatch()

startWithLatch

private void startWithLatch()

checkCancel

private void checkCancel()

executeUdx

protected abstract void executeUdx()

Calls specific UDX to produce result set. Subclass implementation is typically code-generated.