avoiding allocations in FieldCollectorParameters and MergedField (#2074)

dfa1 · web-flow · commit 31f44d801e71 · 2020-10-21T20:31:07.000+11:00
* avoiding LinkedHashMap allocations

* avoiding ArrayList allocations

ArrayList allocated in the Builder never escapes the builder, so
it is possible to avoid one copy in the private ctor
diff --git a/src/main/java/graphql/execution/FieldCollectorParameters.java b/src/main/java/graphql/execution/FieldCollectorParameters.java
@@ -6,7 +6,6 @@
 import graphql.schema.GraphQLObjectType;
 import graphql.schema.GraphQLSchema;
 
-import java.util.LinkedHashMap;
 import java.util.Map;
 
 /**
@@ -48,8 +47,8 @@ public static Builder newParameters() {
 
     public static class Builder {
         private GraphQLSchema graphQLSchema;
-        private final Map<String, FragmentDefinition> fragmentsByName = new LinkedHashMap<>();
-        private final Map<String, Object> variables = new LinkedHashMap<>();
+        private Map<String, FragmentDefinition> fragmentsByName;
+        private Map<String, Object> variables;
         private GraphQLObjectType objectType;
 
         /**
@@ -70,12 +69,12 @@ public Builder objectType(GraphQLObjectType objectType) {
         }
 
         public Builder fragments(Map<String, FragmentDefinition> fragmentsByName) {
-            this.fragmentsByName.putAll(fragmentsByName);
+            this.fragmentsByName = fragmentsByName;
             return this;
         }
 
         public Builder variables(Map<String, Object> variables) {
-            this.variables.putAll(variables);
+            this.variables = variables;
             return this;
         }
 
diff --git a/src/main/java/graphql/execution/MergedField.java b/src/main/java/graphql/execution/MergedField.java
@@ -67,7 +67,7 @@ public class MergedField {
 
     private MergedField(List<Field> fields) {
         assertNotEmpty(fields);
-        this.fields = unmodifiableList(new ArrayList<>(fields));
+        this.fields = unmodifiableList(fields);
         this.singleField = fields.get(0);
         this.name = singleField.getName();
         this.resultKey = singleField.getAlias() != null ? singleField.getAlias() : name;
@@ -144,7 +144,8 @@ public MergedField transform(Consumer<Builder> builderConsumer) {
     }
 
     public static class Builder {
-        private List<Field> fields;
+
+        private final List<Field> fields;
 
         private Builder() {
             this.fields = new ArrayList<>();
@@ -155,7 +156,7 @@ private Builder(MergedField existing) {
         }
 
         public Builder fields(List<Field> fields) {
-            this.fields = fields;
+            this.fields.addAll(fields);
             return this;
         }
 
@@ -168,7 +169,6 @@ public MergedField build() {
             return new MergedField(fields);
         }
 
-
     }
 
     @Override

Original file line number	Diff line number	Diff line change
`@@ -67,7 +67,7 @@ public class MergedField {`
`67`	`67`
`68`	`68`	`private MergedField(List<Field> fields) {`
`69`	`69`	`assertNotEmpty(fields);`
`70`		`- this.fields = unmodifiableList(new ArrayList<>(fields));`
	`70`	`+ this.fields = unmodifiableList(fields);`
`71`	`71`	`this.singleField = fields.get(0);`
`72`	`72`	`this.name = singleField.getName();`
`73`	`73`	`this.resultKey = singleField.getAlias() != null ? singleField.getAlias() : name;`
`@@ -144,7 +144,8 @@ public MergedField transform(Consumer<Builder> builderConsumer) {`
`144`	`144`	`}`
`145`	`145`
`146`	`146`	`public static class Builder {`
`147`		`- private List<Field> fields;`
	`147`	`+`
	`148`	`+ private final List<Field> fields;`
`148`	`149`
`149`	`150`	`private Builder() {`
`150`	`151`	`this.fields = new ArrayList<>();`
`@@ -155,7 +156,7 @@ private Builder(MergedField existing) {`
`155`	`156`	`}`
`156`	`157`
`157`	`158`	`public Builder fields(List<Field> fields) {`
`158`		`- this.fields = fields;`
	`159`	`+ this.fields.addAll(fields);`
`159`	`160`	`return this;`
`160`	`161`	`}`
`161`	`162`
`@@ -168,7 +169,6 @@ public MergedField build() {`
`168`	`169`	`return new MergedField(fields);`
`169`	`170`	`}`
`170`	`171`
`171`		`-`
`172`	`172`	`}`
`173`	`173`
`174`	`174`	`@Override`