Scripting: Add StatefulFactoryType as optional intermediate factory in script contexts (#24974)

ScriptContexts currently understand a FactoryType that can produce
instances of the script InstanceType. However, for search scripts, this
does not work as we have the concept of LeafSearchScript that is created
per lucene segment. This commit effectively renames the existing
SearchScript class into SearchScript.LeafFactory, which is a new,
optional, class that can be defined within a ScriptContext.
LeafSearchScript is effectively renamed back into SearchScript. This
change allows the model of stateless factory -> stateful factory ->
script instance to continue, but in a generic way that any script
context may take advantage of.

relates #20426

1 files changed, 3 insertions, 3 deletions

diff --git a/core/src/main/java/org/elasticsearch/search/fetch/subphase/ScriptFieldsContext.java b/core/src/main/java/org/elasticsearch/search/fetch/subphase/ScriptFieldsContext.java
index 79bacd7f93..9e43b0bdd3 100644
--- a/core/src/main/java/org/elasticsearch/search/fetch/subphase/ScriptFieldsContext.java
+++ b/core/src/main/java/org/elasticsearch/search/fetch/subphase/ScriptFieldsContext.java
@@ -28,10 +28,10 @@ public class ScriptFieldsContext {
 
     public static class ScriptField {
         private final String name;
-        private final SearchScript script;
+        private final SearchScript.LeafFactory script;
         private final boolean ignoreException;
 
-        public ScriptField(String name, SearchScript script, boolean ignoreException) {
+        public ScriptField(String name, SearchScript.LeafFactory script, boolean ignoreException) {
             this.name = name;
             this.script = script;
             this.ignoreException = ignoreException;
@@ -41,7 +41,7 @@ public class ScriptFieldsContext {
             return name;
         }
 
-        public SearchScript script() {
+        public SearchScript.LeafFactory script() {
             return this.script;
         }