org.apache.lucene.search
Class TimeLimitingCollector

java.lang.Object
  extended by org.apache.lucene.search.Collector
      extended by 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
static class TimeLimitingCollector.TimeExceededException
          Thrown when elapsed search time exceeds allowed search time.
static class TimeLimitingCollector.TimerThread
           
 
Constructor Summary
TimeLimitingCollector(Collector collector, Counter clock, long ticksAllowed)
          Create a TimeLimitedCollector wrapper over another Collector with a specified timeout.
 
Method Summary
 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 construcutor.
 void setBaseline(long clockTime)
          Sets the baseline for this collector.
 void setGreedy(boolean greedy)
          Sets whether this time limited collector is greedy.
 void setNextReader(IndexReader reader, int base)
          Called before collecting from each IndexReader.
 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
 

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);
 

Parameters:
clockTime -
See Also:
setBaseline()

setBaseline

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


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

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.


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