Merge pull request #24935 from vespa-engine/bratseth/xxhash

Hash to 64 bits using xxhash

1 files changed, 14 insertions, 2 deletions

diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/StringValue.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/StringValue.java
index a585c989954..c668292c0ab 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/StringValue.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/StringValue.java
@@ -5,6 +5,8 @@ import com.yahoo.javacc.UnicodeUtilities;
 import com.yahoo.searchlib.rankingexpression.rule.Function;
 import com.yahoo.tensor.Tensor;
 import com.yahoo.tensor.TensorType;
+import net.openhft.hashing.LongHashFunction;
+import java.nio.charset.StandardCharsets;
 
 /**
  * A string value.
@@ -31,10 +33,20 @@ public class StringValue extends Value {
     @Override
     public TensorType type() { return TensorType.empty; }
 
-    /** Returns the hashcode of this, to enable strings to be encoded (with reasonable safely) as doubles for optimization */
+    /**
+     * Returns the XXHash hashcode of this, to enable strings to be encoded (with reasonable safely)
+     * as doubles for optimization.
+     */
     @Override
     public double asDouble() {
-        return value.hashCode();
+        // Hash using the xxh3 algorithm which is also used on content nodes
+        byte[] data = value.getBytes(StandardCharsets.UTF_8);
+        long h = LongHashFunction.xx3().hashBytes(data);
+        if ((h & 0x7ff0000000000000L) == 0x7ff0000000000000L) {
+            // Avoid nan
+            h = h & 0xffefffffffffffffL;
+        }
+        return Double.longBitsToDouble(h);
     }
 
     @Override