Drools: Firing a rule if a set of events has n distinct values for a property -

suppose have event type has 3 properties: constraint, common, , distinct. goal write rule in drools fires when subset of events exists meets following criteria:

• events happened in last t seconds; and
• events have known value constraint property; and
• share unknown value common property; and
• there @ least n different values distinct property

if rule fires, need set of participating events further processing.

how advise approach problem?

note 1: question similar link, , steve's answer there seems promising incomplete.

note 2: performance of essence. have developed rules task, reduce performance of whole rule-base dramatically, , unacceptable.

edit 1: current (poorly performing) solution looks this:

rule "" when     $event : event(constraint == constant_value)     $events : arraylist() collect(             event(constraint == constant_value,              common == $event.common)             on window:time( t ))     $distinctvals : set( size >= n ) accumulate(event($d : distinct) $events, collectset($d))     // process $events end 

drools isn't meant used computations require repeated evaluations of potentially big set of facts. in such situation you'll have offload details java code.

class collector {     string constraint;     string common;     list<event> events = ...; // or queue     map<string,list<event>> dist2events = ...;     int diversity;      public void addevent( event e ){         // 1. remove event sets x events older t         // 2. remove members of x dist2events,         //    delete map elements value list empty         events.add( e );         list<event> ofdistinct = dist2events.get( e.getdistinct() );         if( ofdistinct == null ){             ofdistinct = new arraylist<event>();              dist2events.put( ofdistinct );         }         ofdistinct.add( e );         diversity = dist2events.keyset().size();     } }   rule createcollector when     event( $constraint: constraint, $common: common )     not collector( constraint == constraint, common == $common )     insert( new collector( $constraint, $common ) ); end  rule addevent when     $event: event( $constraint: constraint, $common: common )     $collector: collector( constraint == constraint,                            common == $common,                            events not contains $event )     modify( $collector ){ addevent( $event ) } end  rule morethan when     collector( $constraint: constraint, $common: common,                $events: events,                diversity >= n )  // maybe when n-1 n?     ... process $events end 

you'll have decide whether want rule fire when threshold n exceeded or whenever set changes while diversity >= n.

you might want add rule remove empty collectors.