Package org.apache.lucene.search

Class TimeLimitingCollector

java.lang.Object

org.apache.lucene.search.Collector

org.apache.lucene.search.TimeLimitingCollector

public class TimeLimitingCollector
extends Collector

The TimeLimitingCollector is used to timeout search requests that take longer than the maximum allowed search time limit. After this time is exceeded, the search thread is stopped by throwing a TimeLimitingCollector.TimeExceededException.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	TimeLimitingCollector.TimeExceededException	Thrown when elapsed search time exceeds allowed search time.
static class	TimeLimitingCollector.TimerThread	Thread used to timeout search requests.

Constructor Summary

Constructors

Constructor	Description
TimeLimitingCollector(Collector collector, Counter clock, long ticksAllowed)	Create a TimeLimitedCollector wrapper over another Collector with a specified timeout.

Method Summary

Modifier and Type	Method	Description
boolean	acceptsDocsOutOfOrder()	Return true if this collector does not require the matching docIDs to be delivered in int sort order (smallest to largest) to Collector.collect(int).
void	collect(int doc)	Calls Collector.collect(int) on the decorated Collector unless the allowed time has passed, in which case it throws an exception.
static Counter	getGlobalCounter()	Returns the global TimerThreads Counter
static TimeLimitingCollector.TimerThread	getGlobalTimerThread()	Returns the global TimeLimitingCollector.TimerThread.
boolean	isGreedy()	Checks if this time limited collector is greedy in collecting the last hit.
void	setBaseline()	Syntactic sugar for setBaseline(long) using Counter.get() on the clock passed to the constructor.
void	setBaseline(long clockTime)	Sets the baseline for this collector.
void	setCollector(Collector collector)	This is so the same timer can be used with a multi-phase search process such as grouping.
void	setGreedy(boolean greedy)	Sets whether this time limited collector is greedy.
void	setNextReader(AtomicReaderContext context)	Called before collecting from each AtomicReaderContext.
void	setScorer(Scorer scorer)	Called before successive calls to Collector.collect(int).

Methods inherited from class java.lang.Object

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

Constructor Detail

TimeLimitingCollector

public TimeLimitingCollector(Collector collector,
                             Counter clock,
                             long ticksAllowed)

Create a TimeLimitedCollector wrapper over another Collector with a specified timeout.

Parameters:

collector - the wrapped Collector

clock - the timer clock

ticksAllowed - max time allowed for collecting hits after which TimeLimitingCollector.TimeExceededException is thrown

Method Detail

setBaseline

public void setBaseline(long clockTime)

Sets the baseline for this collector. By default the collectors baseline is initialized once the first reader is passed to the collector. To include operations executed in prior to the actual document collection set the baseline through this method in your prelude.

Example usage:

   Counter clock = ...;
   long baseline = clock.get();
   // ... prepare search
   TimeLimitingCollector collector = new TimeLimitingCollector(c, clock, numTicks);
   collector.setBaseline(baseline);
   indexSearcher.search(query, collector);
 

See Also:

setBaseline()

setBaseline

public void setBaseline()

Syntactic sugar for setBaseline(long) using Counter.get() on the clock passed to the constructor.

isGreedy

public boolean isGreedy()

Checks if this time limited collector is greedy in collecting the last hit. A non greedy collector, upon a timeout, would throw a TimeLimitingCollector.TimeExceededException without allowing the wrapped collector to collect current doc. A greedy one would first allow the wrapped hit collector to collect current doc and only then throw a TimeLimitingCollector.TimeExceededException.

See Also:

setGreedy(boolean)

setGreedy

public void setGreedy(boolean greedy)

Sets whether this time limited collector is greedy.

Parameters:

greedy - true to make this time limited greedy

See Also:

isGreedy()

collect

public void collect(int doc)
             throws java.io.IOException

Calls Collector.collect(int) on the decorated Collector unless the allowed time has passed, in which case it throws an exception.

Specified by:

collect in class Collector

Throws:

TimeLimitingCollector.TimeExceededException - if the time allowed has exceeded.

java.io.IOException

setNextReader

public void setNextReader(AtomicReaderContext context)
                   throws java.io.IOException

Description copied from class: Collector

Called before collecting from each AtomicReaderContext. All doc ids in Collector.collect(int) will correspond to IndexReaderContext.reader(). Add AtomicReaderContext.docBase to the current IndexReaderContext.reader()'s internal document id to re-base ids in Collector.collect(int).

Specified by:

setNextReader in class Collector

Parameters:

context - next atomic reader context

Throws:

java.io.IOException

setScorer

public void setScorer(Scorer scorer)
               throws java.io.IOException

Description copied from class: Collector

Called before successive calls to Collector.collect(int). Implementations that need the score of the current document (passed-in to Collector.collect(int)), should save the passed-in Scorer and call scorer.score() when needed.

Specified by:

setScorer in class Collector

Throws:

java.io.IOException

acceptsDocsOutOfOrder

public boolean acceptsDocsOutOfOrder()

Description copied from class: Collector

Return true if this collector does not require the matching docIDs to be delivered in int sort order (smallest to largest) to Collector.collect(int).

Most Lucene Query implementations will visit matching docIDs in order. However, some queries (currently limited to certain cases of BooleanQuery) can achieve faster searching if the Collector allows them to deliver the docIDs out of order.

Many collectors don't mind getting docIDs out of order, so it's important to return true here.

Specified by:

acceptsDocsOutOfOrder in class Collector

setCollector

public void setCollector(Collector collector)

This is so the same timer can be used with a multi-phase search process such as grouping. We don't want to create a new TimeLimitingCollector for each phase because that would reset the timer for each phase. Once time is up subsequent phases need to timeout quickly.

Parameters:

collector - The actual collector performing search functionality

getGlobalCounter

public static Counter getGlobalCounter()

Returns the global TimerThreads Counter

Invoking this creates may create a new instance of TimeLimitingCollector.TimerThread iff the global TimeLimitingCollector.TimerThread has never been accessed before. The thread returned from this method is started on creation and will be alive unless you stop the TimeLimitingCollector.TimerThread via TimeLimitingCollector.TimerThread.stopTimer().

Returns:

the global TimerThreads Counter

getGlobalTimerThread

public static TimeLimitingCollector.TimerThread getGlobalTimerThread()

Returns the global TimeLimitingCollector.TimerThread.

Invoking this creates may create a new instance of TimeLimitingCollector.TimerThread iff the global TimeLimitingCollector.TimerThread has never been accessed before. The thread returned from this method is started on creation and will be alive unless you stop the TimeLimitingCollector.TimerThread via TimeLimitingCollector.TimerThread.stopTimer().

Returns:

the global TimeLimitingCollector.TimerThread