Class CompoundTupleIter

  extended by org.eigenbase.runtime.CompoundTupleIter
All Implemented Interfaces:
TupleIter, ClosableAllocation

public class CompoundTupleIter
extends Object
implements TupleIter

CompoundTupleIter creates an iterator out of several iterators.

CompoundTupleIter is serial: it yields all the elements of its first input Iterator, then all those of its second input, etc. When all inputs are exhausted, it is done. (Cf CompoundParallelTupleIter.)

$Id: //open/dev/farrago/src/org/eigenbase/runtime/ $
Stephan Zuercher

Nested Class Summary
static class CompoundTupleIter.Test
Nested classes/interfaces inherited from interface org.eigenbase.runtime.TupleIter
TupleIter.NoDataReason, TupleIter.TimeoutException
Field Summary
private  int i
private  TupleIter iterator
private  TupleIter[] iterators
private static Logger tracer
Fields inherited from interface org.eigenbase.runtime.TupleIter
Constructor Summary
CompoundTupleIter(TupleIter[] iterators)
Method Summary
 void closeAllocation()
          Closes this object.
 Object fetchNext()
          Returns the next element in the iteration.
private  void initIterator()
 void restart()
          Restarts this iterator, so that a subsequent call to TupleIter.fetchNext() returns the first element in the collection being iterated.
 boolean setTimeout(long timeout, boolean asUnderflow)
          Sets a timeout for TupleIter.fetchNext(); (optional operation).
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail


private static final Logger tracer


private TupleIter iterator


private TupleIter[] iterators


private int i
Constructor Detail


public CompoundTupleIter(TupleIter[] iterators)
Method Detail


private void initIterator()


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


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


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


public void closeAllocation()
Description copied from interface: ClosableAllocation
Closes this object.

Specified by:
closeAllocation in interface ClosableAllocation