org.apache.lucene.search

Class TimeLimitingCollector

java.lang.Object

org.apache.lucene.search.TimeLimitingCollector

All Implemented Interfaces:

Collector

public class TimeLimitingCollector
extends Object
implements 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 and 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 and 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 and Description
static Counter	getGlobalCounter() Returns the global TimerThreads Counter
static TimeLimitingCollector.TimerThread	getGlobalTimerThread() Returns the global TimeLimitingCollector.TimerThread.
LeafCollector	getLeafCollector(LeafReaderContext context) Create a new collector to collect the given context.
boolean	isGreedy() Checks if this time limited collector is greedy in collecting the last hit.
boolean	needsScores() Indicates if document scores are needed by this collector.
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.

Methods inherited from class java.lang.Object

clone, equals, finalize, 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. However, if the timeout is detected in getLeafCollector(org.apache.lucene.index.LeafReaderContext) then no current document is collected.

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()

getLeafCollector

public LeafCollector getLeafCollector(LeafReaderContext context)
                               throws IOException

Description copied from interface: Collector

Create a new collector to collect the given context.

Specified by:

getLeafCollector in interface Collector

Parameters:

context - next atomic reader context

Throws:

IOException

needsScores

public boolean needsScores()

Description copied from interface: Collector

Indicates if document scores are needed by this collector.

Specified by:

needsScores in interface Collector

Returns:

true if scores are needed.

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

WARNING: This API is experimental and might change in incompatible ways in the next release.

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

WARNING: This API is experimental and might change in incompatible ways in the next release.