SOLR-7239: improved performance of min & max in StatsComponent, as well as situations where local params disable all stats

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1666294 13f79535-47bb-0310-9956-ffa450edef68

solr/CHANGES.txt

@@ -243,6 +243,9 @@ Optimizations
  * SOLR-7116: Distributed facet refinement requests would needlessly compute other types
    of faceting that have already been computed. (David Smiley, Hossman)
 
+ * SOLR-7239: improved performance of min & max in StatsComponent, as well as situations 
+   where local params disable all stats (hossman)
+
 Other Changes
 ----------------------
 

solr/core/src/java/org/apache/solr/handler/component/StatsField.java

@@ -346,6 +346,12 @@ public class StatsField {
    */
   public StatsValues computeLocalStatsValues(DocSet base) throws IOException {
 
+    if (statsToCalculate.isEmpty()) { 
+      // perf optimization for the case where we compute nothing
+      // ie: stats.field={!min=$domin}myfield&domin=false
+      return StatsValuesFactory.createStatsValues(this);
+    }
+
     if (null != schemaField 
         && (schemaField.multiValued() || schemaField.getType().multiValuedFieldCache())) {
 

solr/core/src/java/org/apache/solr/handler/component/StatsValuesFactory.java

@@ -347,6 +347,9 @@ class NumericStatsValues extends AbstractStatsValues<Number> {
   double sum;
   double sumOfSquares;
 
+  double minD; // perf optimization, only valid if (null != this.min)
+  double maxD; // perf optimization, only valid if (null != this.max)
+
   final protected boolean computeSum;
   final protected boolean computeSumOfSquares;
 
@@ -405,13 +408,19 @@ class NumericStatsValues extends AbstractStatsValues<Number> {
     if (computeMin) { // nested if to encourage JIT to optimize aware final var?
       if (null != min) {
         double minD = min.doubleValue();
-        this.min = (null == this.min) ? minD : Math.min(this.min.doubleValue(), minD);
+        if (null == this.min || minD < this.minD) {
+          // Double for result & cached primitive doulbe to minimize unboxing in future comparisons
+          this.min = this.minD = minD;
+        }
       }
     }
     if (computeMax) { // nested if to encourage JIT to optimize aware final var?
       if (null != max) {
         double maxD = max.doubleValue();
-        this.max = (null == this.max) ? maxD : Math.max(this.max.doubleValue(), maxD);
+        if (null == this.max || this.maxD < maxD) {
+          // Double for result & cached primitive doulbe to minimize unboxing in future comparisons
+          this.max = this.maxD = maxD;
+        }
       }
     }
   }

solr/core/src/test/org/apache/solr/TestDistributedSearch.java

@@ -494,6 +494,26 @@ public class TestDistributedSearch extends BaseDistributedSearchTestCase {
       assertNull("expected null for sum", s.getSum());
     }
 
+    // request stats, but disable them all via param refs
+    rsp = query("q","*:*", "sort",i1+" desc", "stats", "true", "doMin", "false",
+                "stats.field", "{!min=$doMin}" + i1);
+    { // don't leak variables 
+      FieldStatsInfo s = rsp.getFieldStatsInfo().get(i1);
+      // stats section should exist, even though stats should be null
+      assertNotNull("no stats for " + i1, s);
+      //
+      assertNull("expected null for min", s.getMin() );
+      assertNull("expected null for mean", s.getMean() );
+      assertNull("expected null for stddev", s.getStddev() );
+      //
+      assertNull("expected null for count", s.getCount());
+      assertNull("expected null for calcDistinct", s.getCountDistinct());
+      assertNull("expected null for distinct vals", s.getDistinctValues());
+      assertNull("expected null for max", s.getMax());
+      assertNull("expected null for missing", s.getMissing());
+      assertNull("expected null for sum", s.getSum());
+    }
+
     final String[] stats = new String[] {
       "min", "max", "sum", "sumOfSquares", "stddev", "mean", "missing", "count"
     };

solr/core/src/test/org/apache/solr/handler/component/StatsComponentTest.java

@@ -1163,6 +1163,9 @@ public class StatsComponentTest extends AbstractSolrTestCase {
             "but since only local param is false no stats should be returned",
             req("q","*:*", "stats", "true",
                 "stats.field", "{!key=k min=false}a_i")
+            // section of stats for this field should exist ...
+            , XPRE + "lst[@name='stats_fields']/lst[@name='k']"
+            // ...but be empty 
             , "count(" + kpre + "*)=0"
             );