Adhoc fix for async GraphQL fetchers to log an exception

Author: ygree

dd-java-agent/instrumentation/graphql-java-14.0/src/main/java8/datadog/trace/instrumentation/graphqljava/InstrumentedDataFetcher.java

@@ -11,6 +11,8 @@
 import graphql.schema.DataFetchingEnvironment;
 import graphql.schema.GraphQLNamedType;
 import graphql.schema.GraphQLOutputType;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
 
 public class InstrumentedDataFetcher implements DataFetcher<Object> {
   private final DataFetcher<?> dataFetcher;
@@ -41,7 +43,20 @@ public Object get(DataFetchingEnvironment environment) throws Exception {
         fieldSpan.setTag("graphql.type", typeName);
       }
       try (AgentScope scope = activateSpan(fieldSpan)) {
-        return dataFetcher.get(environment);
+        Object result = dataFetcher.get(environment);
+        if (result instanceof CompletableFuture) {
+          return ((CompletableFuture<?>) result)
+              .whenComplete(
+                  (r, e) -> {
+                    if (e instanceof CompletionException) {
+                      CompletionException ce = (CompletionException) e;
+                      DECORATE.onError(fieldSpan, ce.getCause());
+                    }
+                  });
+          // TODO if it's a CompletableFuture then add a callback to set fieldSpan's error tags when
+          // it fails
+        }
+        return result;
       } catch (Exception e) {
         fieldSpan.addThrowable(e);
         throw e;

dd-java-agent/instrumentation/graphql-java-14.0/src/test/groovy/GraphQLAsyncTest.groovy

@@ -115,18 +115,6 @@ class GraphQLAsyncTest extends AgentTestRunner {
             defaultTags()
           }
         }
-        span {
-          operationName "getBookById"
-          resourceName "book"
-          childOf(span(3))
-          spanType null
-          errored false
-          measured false
-          tags {
-            "$Tags.COMPONENT" "trace"
-            defaultTags()
-          }
-        }
         span {
           operationName "graphql.field"
           resourceName "graphql.field"
@@ -140,6 +128,18 @@ class GraphQLAsyncTest extends AgentTestRunner {
             defaultTags()
           }
         }
+        span {
+          operationName "getBookById"
+          resourceName "book"
+          childOf(span(2))
+          spanType null
+          errored false
+          measured false
+          tags {
+            "$Tags.COMPONENT" "trace"
+            defaultTags()
+          }
+        }
         span {
           operationName "graphql.validation"
           resourceName "graphql.validation"
@@ -210,15 +210,14 @@ class GraphQLAsyncTest extends AgentTestRunner {
           resourceName "graphql.field"
           childOf(span(0))
           spanType DDSpanTypes.GRAPHQL
-          // TODO this span is not marked as errored when async fetcher is in use
-          //          errored true
+          errored true
           measured true
           tags {
             "$Tags.COMPONENT" "graphql-java"
             "graphql.type" "String"
-            //            "error.type" "java.lang.IllegalStateException"
-            //            "error.msg" "TEST"
-            //            "error.stack" String
+            "error.type" "java.lang.IllegalStateException"
+            "error.msg" "TEST"
+            "error.stack" String
             defaultTags()
           }
         }