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 and Description
static class	TimeLimitingCollector.TimeExceededException Thrown when elapsed search time exceeds allowed search time.

Field Summary

Fields

Modifier and Type	Field and Description
boolean	DEFAULT_GREEDY Default for isGreedy().
static int	DEFAULT_RESOLUTION Default timer resolution.

Constructor Summary

Constructors

Constructor and Description
TimeLimitingCollector(Collector collector, long timeAllowed) Create a TimeLimitedCollector wrapper over another Collector with a specified timeout.

Method Summary

Methods

Modifier and Type	Method and 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 long	getResolution() Return the timer resolution.
boolean	isGreedy() Checks if this time limited collector is greedy in collecting the last hit.
void	setGreedy(boolean greedy) Sets whether this time limited collector is greedy.
void	setNextReader(IndexReader reader, int base) Called before collecting from each IndexReader.
static void	setResolution(long newResolution) Set the timer resolution.
void	setScorer(Scorer scorer) Called before successive calls to Collector.collect(int).

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_RESOLUTION

public static final int DEFAULT_RESOLUTION

Default timer resolution.

See Also:

setResolution(long), Constant Field Values

DEFAULT_GREEDY

public boolean DEFAULT_GREEDY

Default for isGreedy().

See Also:

isGreedy()

Constructor Detail

TimeLimitingCollector

public TimeLimitingCollector(Collector collector,
                     long timeAllowed)

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

Parameters:

collector - the wrapped Collector

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

Method Detail

getResolution

public static long getResolution()

Return the timer resolution.

See Also:

setResolution(long)

setResolution

public static void setResolution(long newResolution)

Set the timer resolution. The default timer resolution is 20 milliseconds. This means that a search required to take no longer than 800 milliseconds may be stopped after 780 to 820 milliseconds.
Note that:

• Finer (smaller) resolution is more accurate but less efficient.
• Setting resolution to less than 5 milliseconds will be silently modified to 5 milliseconds.
• Setting resolution smaller than current resolution might take effect only after current resolution. (Assume current resolution of 20 milliseconds is modified to 5 milliseconds, then it can take up to 20 milliseconds for the change to have effect.

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 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.

IOException

setNextReader

public void setNextReader(IndexReader reader,
                 int base)
                   throws IOException

Description copied from class: Collector

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

Specified by:

setNextReader in class Collector

Parameters:

reader - next IndexReader

Throws:

IOException

setScorer

public void setScorer(Scorer scorer)
               throws 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:

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