io.druid.java.util.common.guava

Class SequenceWrapper

java.lang.Object

io.druid.java.util.common.guava.SequenceWrapper

public abstract class SequenceWrapper
extends Object

See Also:

Sequences.wrap(Sequence, SequenceWrapper)

Constructor Summary

Constructors

Constructor and Description
SequenceWrapper()

Method Summary

Modifier and Type	Method and Description
void	after(boolean isDone, Throwable thrown) Executed after sequence processing, i.
void	before() Executed before sequence processing, i.
<RetType> RetType	wrap(com.google.common.base.Supplier<RetType> sequenceProcessing) Wraps any bits of the wrapped sequence processing: Sequence.accumulate(OutType, io.druid.java.util.common.guava.Accumulator<OutType, T>) or Sequence.toYielder(OutType, io.druid.java.util.common.guava.YieldingAccumulator<OutType, T>) and Yielder.next(Object) on the wrapped yielder.

Methods inherited from class java.lang.Object

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

Constructor Detail

SequenceWrapper

public SequenceWrapper()

Method Detail

before

public void before()

Executed before sequence processing, i. e. before Sequence.accumulate(OutType, io.druid.java.util.common.guava.Accumulator<OutType, T>) or Sequence.toYielder(OutType, io.druid.java.util.common.guava.YieldingAccumulator<OutType, T>) on the wrapped sequence. Default implementation does nothing.

wrap

public <RetType> RetType wrap(com.google.common.base.Supplier<RetType> sequenceProcessing)
                       throws Exception

Wraps any bits of the wrapped sequence processing: Sequence.accumulate(OutType, io.druid.java.util.common.guava.Accumulator<OutType, T>) or Sequence.toYielder(OutType, io.druid.java.util.common.guava.YieldingAccumulator<OutType, T>) and Yielder.next(Object) on the wrapped yielder. Doesn't wrap before() and after(boolean, java.lang.Throwable).

sequenceProcessing.get() must be called just once. Implementation of this method should look like

 ... do something
 try {
   return sequenceProcessing.get();
 }
 finally {
   ... do something else
 }
 

Throws:

Exception

after

public void after(boolean isDone,
                  Throwable thrown)
           throws Exception

Executed after sequence processing, i. e. after Sequence.accumulate(OutType, io.druid.java.util.common.guava.Accumulator<OutType, T>) on the wrapped sequence or after Closeable.close() on the wrapped yielder, or if exception was thrown from any method called on the wrapped sequence or yielder, or from before(), or from wrap(com.google.common.base.Supplier<RetType>) methods of this SequenceWrapper.

Even if thrown is not null, implementation of this method shouldn't rethrow it, it is done outside.

Parameters:

isDone - true if all elements in the sequence were processed and no exception was thrown, false otherwise

thrown - an exception thrown from any method called on the wrapped sequence or yielder, or from before(), or from wrap(com.google.common.base.Supplier<RetType>) methods of this SequenceWrapper, or null if no exception was thrown.

Throws:

Exception