fix(graphcache): Replace selection iterator implementation for JSC memory reduction

.changeset/tender-moons-watch.md

@@ -0,0 +1,5 @@
+---
+'@urql/exchange-graphcache': patch
+---
+
+Update selection iterator implementation for JSC memory reduction

exchanges/graphcache/src/operations/query.ts

@@ -37,7 +37,7 @@ import { warn, pushDebugNode, popDebugNode } from '../helpers/help';
 
 import type { Context } from './shared';
 import {
- makeSelectionIterator,
+ SelectionIterator,
  ensureData,
  makeContext,
  updateContext,
@@ -142,7 +142,7 @@ const readRoot = (
  return input;
  }
 
- const iterate = makeSelectionIterator(
+ const selection = new SelectionIterator(
  entityKey,
  entityKey,
  false,
@@ -154,7 +154,7 @@ const readRoot = (
  let node: FormattedNode<FieldNode> | void;
  let hasChanged = InMemoryData.currentForeignData;
  const output = InMemoryData.makeData(input);
- while ((node = iterate())) {
+ while ((node = selection.next())) {
  const fieldAlias = getFieldAlias(node);
  const fieldValue = input[fieldAlias];
  // Add the current alias to the walked path before processing the field's value
@@ -387,7 +387,7 @@ const readSelection = (
  return;
  }
 
- const iterate = makeSelectionIterator(
+ const selection = new SelectionIterator(
  typename,
  entityKey,
  false,
@@ -402,7 +402,7 @@ const readSelection = (
  let node: FormattedNode<FieldNode> | void;
  const hasPartials = ctx.partial;
  const output = InMemoryData.makeData(input);
- while ((node = iterate()) !== undefined) {
+ while ((node = selection.next()) !== undefined) {
  // Derive the needed data from our node.
  const fieldName = getName(node);
  const fieldArgs = getFieldArguments(node, ctx.variables);

exchanges/graphcache/src/operations/shared.test.ts

@@ -7,7 +7,7 @@ import {
 } from '@urql/core';
 import { FieldNode } from '@0no-co/graphql.web';
 
-import { makeSelectionIterator, deferRef } from './shared';
+import { SelectionIterator, deferRef } from './shared';
 import { SelectionSet } from '../ast';
 
 const selectionOfDocument = (
@@ -21,7 +21,7 @@ const selectionOfDocument = (
 
 const ctx = {} as any;
 
-describe('makeSelectionIterator', () => {
+describe('SelectionIterator', () => {
  it('emits all fields', () => {
  const selection = selectionOfDocument(gql`
  {
@@ -30,7 +30,7 @@ describe('makeSelectionIterator', () => {
  c
  }
  `);
- const iterate = makeSelectionIterator(
+ const iterate = new SelectionIterator(
  'Query',
  'Query',
  false,
@@ -41,7 +41,7 @@ describe('makeSelectionIterator', () => {
  const result: FieldNode[] = [];
 
  let node: FieldNode | void;
- while ((node = iterate())) result.push(node);
+ while ((node = iterate.next())) result.push(node);
 
  expect(result).toMatchInlineSnapshot(`
  [
@@ -90,7 +90,7 @@ describe('makeSelectionIterator', () => {
  }
  `);
 
- const iterate = makeSelectionIterator(
+ const iterate = new SelectionIterator(
  'Query',
  'Query',
  false,
@@ -101,7 +101,7 @@ describe('makeSelectionIterator', () => {
  const result: FieldNode[] = [];
 
  let node: FieldNode | void;
- while ((node = iterate())) result.push(node);
+ while ((node = iterate.next())) result.push(node);
 
  expect(result).toMatchInlineSnapshot('[]');
  });
@@ -121,7 +121,7 @@ describe('makeSelectionIterator', () => {
  }
  `);
 
- const iterate = makeSelectionIterator(
+ const iterate = new SelectionIterator(
  'Query',
  'Query',
  false,
@@ -132,7 +132,7 @@ describe('makeSelectionIterator', () => {
  const result: FieldNode[] = [];
 
  let node: FieldNode | void;
- while ((node = iterate())) result.push(node);
+ while ((node = iterate.next())) result.push(node);
 
  expect(result).toMatchInlineSnapshot(`
  [
@@ -207,7 +207,7 @@ describe('makeSelectionIterator', () => {
  }
  `);
 
- const iterate = makeSelectionIterator(
+ const iterate = new SelectionIterator(
  'Query',
  'Query',
  false,
@@ -217,7 +217,7 @@ describe('makeSelectionIterator', () => {
  );
 
  const deferred: boolean[] = [];
- while (iterate()) deferred.push(deferRef);
+ while (iterate.next()) deferred.push(deferRef);
  expect(deferred).toEqual([
  false, // a
  true, // b
@@ -243,7 +243,7 @@ describe('makeSelectionIterator', () => {
  }
  `);
 
- const iterate = makeSelectionIterator(
+ const iterate = new SelectionIterator(
  'Query',
  'Query',
  true,
@@ -253,7 +253,7 @@ describe('makeSelectionIterator', () => {
  );
 
  const deferred: boolean[] = [];
- while (iterate()) deferred.push(deferRef);
+ while (iterate.next()) deferred.push(deferRef);
  expect(deferred).toEqual([true, true, true]);
  });
 });

exchanges/graphcache/src/operations/shared.ts

@@ -1,7 +1,6 @@
 import type { CombinedError, ErrorLike, FormattedNode } from '@urql/core';
 
 import type {
- FieldNode,
  InlineFragmentNode,
  FragmentDefinitionNode,
 } from '@0no-co/graphql.web';
@@ -161,114 +160,133 @@ const isFragmentHeuristicallyMatching = (
  });
 };
 
-interface SelectionIterator {
- (): FormattedNode<FieldNode> | undefined;
-}
+export class SelectionIterator {
+ typename: undefined | string;
+ entityKey: string;
+ ctx: Context;
+ stack: {
+ selectionSet: FormattedNode<SelectionSet>;
+ index: number;
+ defer: boolean;
+ optional: boolean | undefined;
+ }[];
 
-// NOTE: Outside of this file, we expect `_defer` to always be reset to `false`
-export function makeSelectionIterator(
- typename: undefined | string,
- entityKey: string,
- _defer: false,
- _optional: undefined,
- selectionSet: FormattedNode<SelectionSet>,
- ctx: Context
-): SelectionIterator;
-// NOTE: Inside this file we expect the state to be recursively passed on
-export function makeSelectionIterator(
- typename: undefined | string,
- entityKey: string,
- _defer: boolean,
- _optional: undefined | boolean,
- selectionSet: FormattedNode<SelectionSet>,
- ctx: Context
-): SelectionIterator;
+ // NOTE: Outside of this file, we expect `_defer` to always be reset to `false`
+ constructor(
+  typename: undefined | string,
+  entityKey: string,
+  _defer: false,
+  _optional: undefined,
+  selectionSet: FormattedNode<SelectionSet>,
+  ctx: Context
+ );
+ // NOTE: Inside this file we expect the state to be recursively passed on
+ constructor(
+  typename: undefined | string,
+  entityKey: string,
+  _defer: boolean,
+  _optional: undefined | boolean,
+  selectionSet: FormattedNode<SelectionSet>,
+  ctx: Context
+ );
 
-export function makeSelectionIterator(
- typename: undefined | string,
- entityKey: string,
- _defer: boolean,
- _optional: boolean | undefined,
- selectionSet: FormattedNode<SelectionSet>,
- ctx: Context
-): SelectionIterator {
- let child: SelectionIterator | void;
- let index = 0;
+ constructor(
+ typename: undefined | string,
+ entityKey: string,
+ _defer: boolean,
+ _optional: boolean | undefined,
+ selectionSet: FormattedNode<SelectionSet>,
+ ctx: Context
+ ) {
+ this.typename = typename;
+ this.entityKey = entityKey;
+ this.ctx = ctx;
+ this.stack = [
+ {
+ selectionSet,
+ index: 0,
+ defer: _defer,
+ optional: _optional,
+ },
+ ];
+ }
 
- return function next() {
- let node: FormattedNode<FieldNode> | undefined;
- while (child || index < selectionSet.length) {
- node = undefined;
- deferRef = _defer;
- optionalRef = _optional;
- if (child) {
- if ((node = child())) {
- return node;
- } else {
- child = undefined;
- if (process.env.NODE_ENV !== 'production') popDebugNode();
- }
- } else {
- const select = selectionSet[index++];
- if (!shouldInclude(select, ctx.variables)) {
+ next() {
+ while (this.stack.length > 0) {
+ let state = this.stack[this.stack.length - 1];
+ while (state.index < state.selectionSet.length) {
+ const select = state.selectionSet[state.index++];
+ if (!shouldInclude(select, this.ctx.variables)) {
  /*noop*/
  } else if (select.kind !== Kind.FIELD) {
  // A fragment is either referred to by FragmentSpread or inline
  const fragment =
  select.kind !== Kind.INLINE_FRAGMENT
- ? ctx.fragments[getName(select)]
+ ? this.ctx.fragments[getName(select)]
  : select;
  if (fragment) {
  const isMatching =
  !fragment.typeCondition ||
- (ctx.store.schema
- ? isInterfaceOfType(ctx.store.schema, fragment, typename)
+ (this.ctx.store.schema
+ ? isInterfaceOfType(
+ this.ctx.store.schema,
+ fragment,
+ this.typename
+ )
  : (currentOperation === 'read' &&
  isFragmentMatching(
  fragment.typeCondition.name.value,
- typename
+ this.typename
  )) ||
  isFragmentHeuristicallyMatching(
  fragment,
- typename,
- entityKey,
- ctx.variables,
- ctx.store.logger
+ this.typename,
+ this.entityKey,
+ this.ctx.variables,
+ this.ctx.store.logger
  ));
-
  if (
  isMatching ||
- (currentOperation === 'write' && !ctx.store.schema)
+ (currentOperation === 'write' && !this.ctx.store.schema)
  ) {
  if (process.env.NODE_ENV !== 'production')
- pushDebugNode(typename, fragment);
+ pushDebugNode(this.typename, fragment);
  const isFragmentOptional = isOptional(select);
  if (
  isMatching &&
  fragment.typeCondition &&
- typename !== fragment.typeCondition.name.value
+ this.typename !== fragment.typeCondition.name.value
  ) {
- writeConcreteType(fragment.typeCondition.name.value, typename!);
+ writeConcreteType(
+ fragment.typeCondition.name.value,
+ this.typename!
+ );
  }
 
- child = makeSelectionIterator(
- typename,
- entityKey,
- _defer || isDeferred(select, ctx.variables),
- isFragmentOptional !== undefined
- ? isFragmentOptional
- : _optional,
- getSelectionSet(fragment),
- ctx
+ this.stack.push(
+ (state = {
+ selectionSet: getSelectionSet(fragment),
+ index: 0,
+ defer: state.defer || isDeferred(select, this.ctx.variables),
+ optional:
+ isFragmentOptional !== undefined
+ ? isFragmentOptional
+ : state.optional,
+ })
  );
  }
  }
  } else if (currentOperation === 'write' || !select._generated) {
+ deferRef = state.defer;
+ optionalRef = state.optional;
  return select;
  }
  }
+ this.stack.pop();
+ if (process.env.NODE_ENV !== 'production') popDebugNode();
  }
- };
+ return undefined;
+ }
 }
 
 const isFragmentMatching = (typeCondition: string, typename: string | void) => {

exchanges/graphcache/src/operations/write.ts

@@ -39,7 +39,7 @@ import * as InMemoryData from '../store/data';
 
 import type { Context } from './shared';
 import {
- makeSelectionIterator,
+ SelectionIterator,
  ensureData,
  makeContext,
  updateContext,
@@ -237,7 +237,7 @@ const writeSelection = (
  }
 
  const updates = ctx.store.updates[typename];
- const iterate = makeSelectionIterator(
+ const selection = new SelectionIterator(
  typename,
  entityKey || typename,
  false,
@@ -247,7 +247,7 @@ const writeSelection = (
  );
 
  let node: FormattedNode<FieldNode> | void;
- while ((node = iterate())) {
+ while ((node = selection.next())) {
  const fieldName = getName(node);
  const fieldArgs = getFieldArguments(node, ctx.variables);
  const fieldKey = keyOfField(fieldName, fieldArgs);