SOLR-11388: Add monteCarlo Stream Evaluator to support Monte Carlo simulations WIP

solr/core/src/java/org/apache/solr/handler/StreamHandler.java

@@ -299,6 +299,8 @@ public class StreamHandler extends RequestHandlerBase implements SolrCoreAware,
         .withFunctionName("primes", PrimesEvaluator.class)
         .withFunctionName("factorial", FactorialEvaluator.class)
         .withFunctionName("movingMedian", MovingMedianEvaluator.class)
+        .withFunctionName("monteCarlo", MonteCarloEvaluator.class)
+        .withFunctionName("constantDistribution", ConstantDistributionEvaluator.class)
 
         // Boolean Stream Evaluators
 

solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/ConstantDistributionEvaluator.java

@@ -0,0 +1,44 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.solr.client.solrj.io.eval;
+
+import java.io.IOException;
+import java.util.Locale;
+
+import org.apache.commons.math3.distribution.ConstantRealDistribution;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+
+public class ConstantDistributionEvaluator extends RecursiveNumericEvaluator implements OneValueWorker {
+
+  private static final long serialVersionUID = 1;
+
+  public ConstantDistributionEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
+    super(expression, factory);
+  }
+
+  @Override
+  public Object doWork(Object first) throws IOException{
+    if(null == first){
+      throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - null found for the first value",toExpression(constructingFactory)));
+    }
+
+    Number constant = (Number)first;
+
+    return new ConstantRealDistribution(constant.doubleValue());
+  }
+}

solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/MonteCarloEvaluator.java

@@ -0,0 +1,76 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.solr.client.solrj.io.eval;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+
+import org.apache.solr.client.solrj.io.Tuple;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+
+public class MonteCarloEvaluator extends RecursiveEvaluator {
+  protected static final long serialVersionUID = 1L;
+
+  public MonteCarloEvaluator(StreamExpression expression, StreamFactory factory) throws IOException{
+    super(expression, factory);
+
+    init();
+  }
+
+  public MonteCarloEvaluator(StreamExpression expression, StreamFactory factory, List<String> ignoredNamedParameters) throws IOException{
+    super(expression, factory, ignoredNamedParameters);
+
+    init();
+  }
+
+  private void init() throws IOException{
+    if(2 != containedEvaluators.size()){
+      throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting exactly 2 parameters but found %d", toExpression(constructingFactory), containedEvaluators.size()));
+    }
+  }
+
+  @Override
+  public Object evaluate(Tuple tuple) throws IOException {
+    try{
+
+      StreamEvaluator function = containedEvaluators.get(0);
+      StreamEvaluator iterationsEvaluator = containedEvaluators.get(1);
+      Number itNum = (Number)iterationsEvaluator.evaluate(tuple);
+      int it = itNum.intValue();
+      List<Number> results = new ArrayList();
+      for(int i=0; i<it; i++) {
+        Number result = (Number)function.evaluate(tuple);
+        results.add(result);
+      }
+
+      return results;
+    }
+    catch(UncheckedIOException e){
+      throw e.getCause();
+    }
+  }
+
+  @Override
+  public Object doWork(Object... values) throws IOException {
+    // Nothing to do here
+    throw new IOException("This call should never occur");
+  }
+}

solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/SampleEvaluator.java

@@ -27,7 +27,7 @@ import org.apache.commons.math3.distribution.RealDistribution;
 import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
 import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
 
-public class SampleEvaluator extends RecursiveObjectEvaluator implements TwoValueWorker {
+public class SampleEvaluator extends RecursiveObjectEvaluator implements ManyValueWorker {
 
   private static final long serialVersionUID = 1;
 
@@ -36,26 +36,36 @@ public class SampleEvaluator extends RecursiveObjectEvaluator implements TwoValu
   }
   
   @Override
-  public Object doWork(Object first, Object second) throws IOException{
-    if(null == first){
+  public Object doWork(Object ... objects) throws IOException{
+    if(objects.length < 1){
       throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - null found for the first value",toExpression(constructingFactory)));
     }
-    if(null == second){
-      throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - null found for the second value",toExpression(constructingFactory)));
-    }
+
+    Object first = objects[0];
+
     if(!(first instanceof RealDistribution) && !(first instanceof IntegerDistribution)){
       throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - found type %s for the first value, expecting a Real or Integer Distribution",toExpression(constructingFactory), first.getClass().getSimpleName()));
     }
-    if(!(second instanceof Number)){
-      throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - found type %s for the second value, expecting a Number",toExpression(constructingFactory), first.getClass().getSimpleName()));
+
+    Object second = null;
+    if(objects.length > 1) {
+      second = objects[2];
     }
 
     if(first instanceof RealDistribution) {
       RealDistribution realDistribution = (RealDistribution) first;
-      return Arrays.stream(realDistribution.sample(((Number) second).intValue())).mapToObj(item -> item).collect(Collectors.toList());
+      if(second != null) {
+        return Arrays.stream(realDistribution.sample(((Number) second).intValue())).mapToObj(item -> item).collect(Collectors.toList());
+      } else {
+        return realDistribution.sample();
+      }
     } else {
       IntegerDistribution integerDistribution = (IntegerDistribution) first;
-      return Arrays.stream(integerDistribution.sample(((Number) second).intValue())).mapToObj(item -> item).collect(Collectors.toList());
+      if(second != null) {
+        return Arrays.stream(integerDistribution.sample(((Number) second).intValue())).mapToObj(item -> item).collect(Collectors.toList());
+      } else {
+        return integerDistribution.sample();
+      }
     }
   }
 }