Merge pull request #3395 from felipe-gdr/defer-support-in-enf

Defer support on ENFs

src/main/java/graphql/Directives.java

@@ -1,6 +1,7 @@
 package graphql;
 
 
+import graphql.language.BooleanValue;
 import graphql.language.Description;
 import graphql.language.DirectiveDefinition;
 import graphql.language.StringValue;
@@ -33,14 +34,14 @@ public class Directives {
     private static final String SPECIFIED_BY = "specifiedBy";
     private static final String DEPRECATED = "deprecated";
     private static final String ONE_OF = "oneOf";
+    private static final String DEFER = "defer";
 
     public static final String NO_LONGER_SUPPORTED = "No longer supported";
     public static final DirectiveDefinition DEPRECATED_DIRECTIVE_DEFINITION;
     public static final DirectiveDefinition SPECIFIED_BY_DIRECTIVE_DEFINITION;
     @ExperimentalApi
     public static final DirectiveDefinition ONE_OF_DIRECTIVE_DEFINITION;
 
-
     static {
         DEPRECATED_DIRECTIVE_DEFINITION = DirectiveDefinition.newDirectiveDefinition()
                 .name(DEPRECATED)
@@ -77,6 +78,34 @@ public class Directives {
                 .build();
     }
 
+    /**
+     * The @defer directive can be used to defer sending data for a fragment until later in the query.
+     * This is an opt-in directive that is not available unless it is explicitly put into the schema.
+     * <p>
+     * This implementation is based on the state of <a href="https://github.com/graphql/graphql-spec/pull/742">Defer/Stream PR</a>
+     * More specifically at the state of this
+     * <a href="https://github.com/graphql/graphql-spec/commit/c630301560d9819d33255d3ba00f548e8abbcdc6">commit</a>
+     * <p>
+     * The execution behaviour should match what we get from running Apollo Server 4.9.5 with graphql-js v17.0.0-alpha.2
+     */
+    @ExperimentalApi
+    public static final GraphQLDirective DeferDirective = GraphQLDirective.newDirective()
+            .name(DEFER)
+            .description("This directive allows results to be deferred during execution")
+            .validLocations(FRAGMENT_SPREAD, INLINE_FRAGMENT)
+            .argument(newArgument()
+                    .name("if")
+                    .type(nonNull(GraphQLBoolean))
+                    .description("Deferred behaviour is controlled by this argument")
+                    .defaultValueLiteral(BooleanValue.newBooleanValue(true).build())
+            )
+            .argument(newArgument()
+                    .name("label")
+                    .type(GraphQLString)
+                    .description("A unique label that represents the fragment being deferred")
+            )
+            .build();
+
     public static final GraphQLDirective IncludeDirective = GraphQLDirective.newDirective()
             .name("include")
             .description("Directs the executor to include this field or fragment only when the `if` argument is true")

src/main/java/graphql/ExperimentalApi.java

@@ -12,9 +12,9 @@
 
 /**
  * This represents code that the graphql-java project considers experimental API and while our intention is that it will
- * progress to be {@link PublicApi}, its existence, signature of behavior may change between releases.
- *
- * In general unnecessary changes will be avoided but you should not depend on experimental classes being stable
+ * progress to be {@link PublicApi}, its existence, signature or behavior may change between releases.
+ * <p>
+ * In general unnecessary changes will be avoided, but you should not depend on experimental classes being stable.
  */
 @Retention(RetentionPolicy.RUNTIME)
 @Target(value = {CONSTRUCTOR, METHOD, TYPE, FIELD})

src/main/java/graphql/execution/FieldCollector.java

@@ -25,7 +25,7 @@
 
 /**
  * A field collector can iterate over field selection sets and build out the sub fields that have been selected,
- * expanding named and inline fragments as it goes.s
+ * expanding named and inline fragments as it goes.
  */
 @Internal
 public class FieldCollector {

src/main/java/graphql/normalized/ENFMerger.java

@@ -19,7 +19,12 @@
 @Internal
 public class ENFMerger {
 
-    public static void merge(ExecutableNormalizedField parent, List<ExecutableNormalizedField> childrenWithSameResultKey, GraphQLSchema schema) {
+    public static void merge(
+            ExecutableNormalizedField parent,
+            List<ExecutableNormalizedField> childrenWithSameResultKey,
+            GraphQLSchema schema,
+            boolean deferSupport
+    ) {
         // they have all the same result key
         // we can only merge the fields if they have the same field name + arguments + all children are the same
         List<Set<ExecutableNormalizedField>> possibleGroupsToMerge = new ArrayList<>();
@@ -28,7 +33,7 @@ public static void merge(ExecutableNormalizedField parent, List<ExecutableNormal
             overPossibleGroups:
             for (Set<ExecutableNormalizedField> group : possibleGroupsToMerge) {
                 for (ExecutableNormalizedField fieldInGroup : group) {
-                    if(field.getFieldName().equals(Introspection.TypeNameMetaFieldDef.getName())) {
+                    if (field.getFieldName().equals(Introspection.TypeNameMetaFieldDef.getName())) {
                         addToGroup = true;
                         group.add(field);
                         continue overPossibleGroups;
@@ -63,8 +68,15 @@ && isFieldInSharedInterface(field, fieldInGroup, schema)
                 // patching the first one to contain more objects, remove all others
                 Iterator<ExecutableNormalizedField> iterator = groupOfFields.iterator();
                 ExecutableNormalizedField first = iterator.next();
+
                 while (iterator.hasNext()) {
-                    parent.getChildren().remove(iterator.next());
+                    ExecutableNormalizedField next = iterator.next();
+                    parent.getChildren().remove(next);
+
+                    if (deferSupport) {
+                        // Move defer executions from removed field into the merged field's entry
+                        first.addDeferExecutions(next.getDeferExecutions());
+                    }
                 }
                 first.setObjectTypeNames(mergedObjects);
             }

src/main/java/graphql/normalized/ExecutableNormalizedField.java

@@ -3,12 +3,14 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import graphql.Assert;
+import graphql.ExperimentalApi;
 import graphql.Internal;
 import graphql.Mutable;
 import graphql.PublicApi;
 import graphql.collect.ImmutableKit;
 import graphql.introspection.Introspection;
 import graphql.language.Argument;
+import graphql.normalized.incremental.DeferExecution;
 import graphql.schema.GraphQLFieldDefinition;
 import graphql.schema.GraphQLInterfaceType;
 import graphql.schema.GraphQLNamedOutputType;
@@ -63,6 +65,8 @@ public class ExecutableNormalizedField {
     private final String fieldName;
     private final int level;
 
+    // Mutable List on purpose: it is modified after creation
+    private final LinkedHashSet<DeferExecution> deferExecutions;
 
     private ExecutableNormalizedField(Builder builder) {
         this.alias = builder.alias;
@@ -74,6 +78,7 @@ private ExecutableNormalizedField(Builder builder) {
         this.children = builder.children;
         this.level = builder.level;
         this.parent = builder.parent;
+        this.deferExecutions = builder.deferExecutions;
     }
 
     /**
@@ -129,6 +134,7 @@ private ExecutableNormalizedField(Builder builder) {
      * NOT {@code Cat} or {@code Dog} as their respective implementations would say.
      *
      * @param schema - the graphql schema in play
+     *
      * @return true if the field is conditional
      */
     public boolean isConditional(@NotNull GraphQLSchema schema) {
@@ -255,6 +261,16 @@ public void clearChildren() {
         this.children.clear();
     }
 
+    @Internal
+    public void setDeferExecutions(Collection<DeferExecution> deferExecutions) {
+        this.deferExecutions.clear();
+        this.deferExecutions.addAll(deferExecutions);
+    }
+
+    public void addDeferExecutions(Collection<DeferExecution> deferExecutions) {
+        this.deferExecutions.addAll(deferExecutions);
+    }
+
     /**
      * All merged fields have the same name so this is the name of the {@link ExecutableNormalizedField}.
      * <p>
@@ -364,7 +380,6 @@ public String getSingleObjectTypeName() {
         return objectTypeNames.iterator().next();
     }
 
-
     /**
      * @return a helper method show field details
      */
@@ -461,6 +476,15 @@ public ExecutableNormalizedField getParent() {
         return parent;
     }
 
+    /**
+     * @return the {@link DeferExecution}s associated with this {@link ExecutableNormalizedField}.
+     * @see DeferExecution
+     */
+    @ExperimentalApi
+    public LinkedHashSet<DeferExecution> getDeferExecutions() {
+        return deferExecutions;
+    }
+
     @Internal
     public void replaceParent(ExecutableNormalizedField newParent) {
         this.parent = newParent;
@@ -588,6 +612,8 @@ public static class Builder {
         private LinkedHashMap<String, Object> resolvedArguments = new LinkedHashMap<>();
         private ImmutableList<Argument> astArguments = ImmutableKit.emptyList();
 
+        private LinkedHashSet<DeferExecution> deferExecutions = new LinkedHashSet<>();
+
         private Builder() {
         }
 
@@ -601,6 +627,7 @@ private Builder(ExecutableNormalizedField existing) {
             this.children = new ArrayList<>(existing.children);
             this.level = existing.getLevel();
             this.parent = existing.getParent();
+            this.deferExecutions = existing.getDeferExecutions();
         }
 
         public Builder clearObjectTypesNames() {
@@ -656,6 +683,11 @@ public Builder parent(ExecutableNormalizedField parent) {
             return this;
         }
 
+        public Builder deferExecutions(LinkedHashSet<DeferExecution> deferExecutions) {
+            this.deferExecutions = deferExecutions;
+            return this;
+        }
+
         public ExecutableNormalizedField build() {
             return new ExecutableNormalizedField(this);
         }