Avoid no-op field fetch adapter allocation

nwjsmith · nwjsmith · commit 2bc5bf5016b7 · 2026-05-08T14:21:37.000-04:00
The default field-fetching bridge still has to support legacy
beginFieldFetch implementations, but the inherited no-op path should not
allocate a per-field adapter. Return the canonical field-fetching no-op
when the legacy hook returns the canonical no-op context, while still
adapting real legacy contexts.
diff --git a/src/main/java/graphql/execution/instrumentation/Instrumentation.java b/src/main/java/graphql/execution/instrumentation/Instrumentation.java
@@ -241,6 +241,9 @@ default InstrumentationContext<Object> beginFieldFetch(InstrumentationFieldFetch
     @Nullable
     default FieldFetchingInstrumentationContext beginFieldFetching(InstrumentationFieldFetchParameters parameters, InstrumentationState state) {
         InstrumentationContext<Object> ctx = beginFieldFetch(parameters, state);
+        if (ctx == noOp()) {
+            return FieldFetchingInstrumentationContext.NOOP;
+        }
         return FieldFetchingInstrumentationContext.adapter(ctx);
     }
 
diff --git a/src/test/groovy/graphql/execution/instrumentation/FieldFetchingInstrumentationContextTest.groovy b/src/test/groovy/graphql/execution/instrumentation/FieldFetchingInstrumentationContextTest.groovy
@@ -0,0 +1,72 @@
+package graphql.execution.instrumentation
+
+import graphql.execution.instrumentation.parameters.InstrumentationFieldFetchParameters
+import spock.lang.Specification
+
+class FieldFetchingInstrumentationContextTest extends Specification {
+
+    def "default begin field fetching does not allocate an adapter for inherited no-op"() {
+        given:
+        def instrumentation = new Instrumentation() {}
+
+        when:
+        def context = instrumentation.beginFieldFetching(null, null)
+
+        then:
+        context.is(FieldFetchingInstrumentationContext.NOOP)
+    }
+
+    def "simple performant instrumentation begin field fetching does not allocate an adapter for inherited no-op"() {
+        when:
+        def context = SimplePerformantInstrumentation.INSTANCE.beginFieldFetching(null, null)
+
+        then:
+        context.is(FieldFetchingInstrumentationContext.NOOP)
+    }
+
+    def "default begin field fetching does not allocate an adapter when deprecated override returns no-op"() {
+        given:
+        def instrumentation = new Instrumentation() {
+            @Override
+            InstrumentationContext<Object> beginFieldFetch(InstrumentationFieldFetchParameters parameters, InstrumentationState state) {
+                return SimpleInstrumentationContext.noOp()
+            }
+        }
+
+        when:
+        def context = instrumentation.beginFieldFetching(null, null)
+
+        then:
+        context.is(FieldFetchingInstrumentationContext.NOOP)
+    }
+
+    def "default begin field fetching still adapts deprecated begin field fetch overrides"() {
+        given:
+        def events = []
+        def instrumentation = new Instrumentation() {
+            @Override
+            InstrumentationContext<Object> beginFieldFetch(InstrumentationFieldFetchParameters parameters, InstrumentationState state) {
+                return new InstrumentationContext<Object>() {
+                    @Override
+                    void onDispatched() {
+                        events.add("dispatched")
+                    }
+
+                    @Override
+                    void onCompleted(Object result, Throwable t) {
+                        events.add(result)
+                    }
+                }
+            }
+        }
+
+        when:
+        def context = instrumentation.beginFieldFetching(null, null)
+        context.onDispatched()
+        context.onFetchedValue("ignored")
+        context.onCompleted("completed", null)
+
+        then:
+        events == ["dispatched", "completed"]
+    }
+}

Original file line number	Diff line number	Diff line change
`@@ -241,6 +241,9 @@ default InstrumentationContext<Object> beginFieldFetch(InstrumentationFieldFetch`
`241`	`241`	`@Nullable`
`242`	`242`	`default FieldFetchingInstrumentationContext beginFieldFetching(InstrumentationFieldFetchParameters parameters, InstrumentationState state) {`
`243`	`243`	`InstrumentationContext<Object> ctx = beginFieldFetch(parameters, state);`
	`244`	`+ if (ctx == noOp()) {`
	`245`	`+ return FieldFetchingInstrumentationContext.NOOP;`
	`246`	`+ }`
`244`	`247`	`return FieldFetchingInstrumentationContext.adapter(ctx);`
`245`	`248`	`}`
`246`	`249`