Scripting: Add instance and compiled classes to script contexts (#24868)

This commit modifies the compile method of ScriptService to be context
aware. The ScriptContext is now a generic class which contains both the
instance type and compiled type for a script. Instance type may be
stateful (for example, pre loading field information for the index a
script will execute on, like in expressions), while the compiled type is
stateless and used to construct instance type instances. This change is
only a first step to cutover ScriptService to the new paradigm. It only
converts callers to the script service, and has a small shim to wrap
compilation from the script engines to support the current two fixed
instance types, SearchScript and ExecutableScript.

2 files changed, 6 insertions, 8 deletions

diff --git a/core/src/main/java/org/elasticsearch/search/aggregations/metrics/scripted/InternalScriptedMetric.java b/core/src/main/java/org/elasticsearch/search/aggregations/metrics/scripted/InternalScriptedMetric.java
index 2bedd16ebf..b0a4836a69 100644
--- a/core/src/main/java/org/elasticsearch/search/aggregations/metrics/scripted/InternalScriptedMetric.java
+++ b/core/src/main/java/org/elasticsearch/search/aggregations/metrics/scripted/InternalScriptedMetric.java
@@ -22,7 +22,6 @@ package org.elasticsearch.search.aggregations.metrics.scripted;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.xcontent.XContentBuilder;
-import org.elasticsearch.script.CompiledScript;
 import org.elasticsearch.script.ExecutableScript;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptContext;
@@ -96,9 +95,9 @@ public class InternalScriptedMetric extends InternalAggregation implements Scrip
             if (firstAggregation.reduceScript.getParams() != null) {
                 vars.putAll(firstAggregation.reduceScript.getParams());
             }
-            CompiledScript compiledScript = reduceContext.scriptService().compile(
-                firstAggregation.reduceScript, ScriptContext.AGGS);
-            ExecutableScript script = reduceContext.scriptService().executable(compiledScript, vars);
+            ExecutableScript.Compiled compiled = reduceContext.scriptService().compile(
+                firstAggregation.reduceScript, ScriptContext.AGGS_EXECUTABLE);
+            ExecutableScript script = compiled.newInstance(vars);
             aggregation = Collections.singletonList(script.run());
         } else if (reduceContext.isFinalReduce())  {
             aggregation = Collections.singletonList(aggregationObjects);
diff --git a/core/src/main/java/org/elasticsearch/search/aggregations/metrics/scripted/ScriptedMetricAggregationBuilder.java b/core/src/main/java/org/elasticsearch/search/aggregations/metrics/scripted/ScriptedMetricAggregationBuilder.java
index 6d8c297eeb..6865d6a211 100644
--- a/core/src/main/java/org/elasticsearch/search/aggregations/metrics/scripted/ScriptedMetricAggregationBuilder.java
+++ b/core/src/main/java/org/elasticsearch/search/aggregations/metrics/scripted/ScriptedMetricAggregationBuilder.java
@@ -186,15 +186,14 @@ public class ScriptedMetricAggregationBuilder extends AbstractAggregationBuilder
         QueryShardContext queryShardContext = context.getQueryShardContext();
         Function<Map<String, Object>, ExecutableScript> executableInitScript;
         if (initScript != null) {
-            executableInitScript = queryShardContext.getLazyExecutableScript(initScript, ScriptContext.AGGS);
+            executableInitScript = queryShardContext.getLazyExecutableScript(initScript, ScriptContext.AGGS_EXECUTABLE);
         } else {
             executableInitScript = (p) -> null;
         }
-        Function<Map<String, Object>, SearchScript> searchMapScript = queryShardContext.getLazySearchScript(mapScript,
-            ScriptContext.AGGS);
+        Function<Map<String, Object>, SearchScript> searchMapScript = queryShardContext.getLazySearchScript(mapScript, ScriptContext.AGGS);
         Function<Map<String, Object>, ExecutableScript> executableCombineScript;
         if (combineScript != null) {
-            executableCombineScript = queryShardContext.getLazyExecutableScript(combineScript, ScriptContext.AGGS);
+            executableCombineScript = queryShardContext.getLazyExecutableScript(combineScript, ScriptContext.AGGS_EXECUTABLE);
         } else {
             executableCombineScript = (p) -> null;
         }