perf(ivy): cache multiple reads to an element's stylingContext (angular#29818)

Because the styling context may be stored in a different location
and be apart of a sub array, reading the styling context each time
a host binding is evaluated is costly. This patch ensures that the
active styling context is cached so that multiple interactions with
styling bindings can easily retrieve the styling context efficiently.

PR Close angular#29818

Author: matsko

packages/core/src/debug/debug_node.ts

@@ -13,7 +13,7 @@ import {TElementNode, TNode, TNodeFlags, TNodeType} from '../render3/interfaces/
 import {StylingIndex} from '../render3/interfaces/styling';
 import {LView, NEXT, PARENT, TData, TVIEW, T_HOST} from '../render3/interfaces/view';
 import {getProp, getValue, isClassBasedValue} from '../render3/styling/class_and_style_bindings';
-import {getStylingContext} from '../render3/styling/util';
+import {getStylingContextFromLView} from '../render3/styling/util';
 import {getComponent, getContext, getInjectionTokens, getInjector, getListeners, getLocalRefs, isBrowserEvents, loadLContext, loadLContextFromNode} from '../render3/util/discovery_utils';
 import {INTERPOLATION_DELIMITER, isPropMetadataString, renderStringify} from '../render3/util/misc_utils';
 import {findComponentView} from '../render3/util/view_traversal_utils';
@@ -288,7 +288,7 @@ class DebugElement__POST_R3__ extends DebugNode__POST_R3__ implements DebugEleme
     const element = this.nativeElement;
     if (element) {
       const lContext = loadLContextFromNode(element);
-      const stylingContext = getStylingContext(lContext.nodeIndex, lContext.lView);
+      const stylingContext = getStylingContextFromLView(lContext.nodeIndex, lContext.lView);
       if (stylingContext) {
         for (let i = StylingIndex.SingleStylesStartPosition; i < stylingContext.length;
              i += StylingIndex.Size) {
@@ -317,7 +317,7 @@ class DebugElement__POST_R3__ extends DebugNode__POST_R3__ implements DebugEleme
     const element = this.nativeElement;
     if (element) {
       const lContext = loadLContextFromNode(element);
-      const stylingContext = getStylingContext(lContext.nodeIndex, lContext.lView);
+      const stylingContext = getStylingContextFromLView(lContext.nodeIndex, lContext.lView);
       if (stylingContext) {
         for (let i = StylingIndex.SingleStylesStartPosition; i < stylingContext.length;
              i += StylingIndex.Size) {

packages/core/src/render3/instructions/element.ts

@@ -13,13 +13,14 @@ import {registerPostOrderHooks} from '../hooks';
 import {TAttributes, TNodeFlags, TNodeType} from '../interfaces/node';
 import {RElement, isProceduralRenderer} from '../interfaces/renderer';
 import {SanitizerFn} from '../interfaces/sanitization';
+import {StylingContext} from '../interfaces/styling';
 import {BINDING_INDEX, QUERIES, RENDERER, TVIEW} from '../interfaces/view';
 import {assertNodeType} from '../node_assert';
 import {appendChild} from '../node_manipulation';
 import {applyOnCreateInstructions} from '../node_util';
 import {decreaseElementDepthCount, getActiveDirectiveId, getElementDepthCount, getIsParent, getLView, getNamespace, getPreviousOrParentTNode, getSelectedIndex, increaseElementDepthCount, setIsParent, setPreviousOrParentTNode} from '../state';
 import {getInitialClassNameValue, getInitialStyleStringValue, initializeStaticContext, patchContextWithStaticAttrs, renderInitialClasses, renderInitialStyles} from '../styling/class_and_style_bindings';
-import {getStylingContext, hasClassInput, hasStyleInput} from '../styling/util';
+import {getStylingContextFromLView, hasClassInput, hasStyleInput} from '../styling/util';
 import {NO_CHANGE} from '../tokens';
 import {attrsStylingIndexOf, setUpAttributes} from '../util/attrs_utils';
 import {renderStringify} from '../util/misc_utils';
@@ -156,13 +157,15 @@ export function ɵɵelementEnd(): void {
   // this is fired at the end of elementEnd because ALL of the stylingBindings code
   // (for directives and the template) have now executed which means the styling
   // context can be instantiated properly.
+  let stylingContext: StylingContext|null = null;
   if (hasClassInput(previousOrParentTNode)) {
-    const stylingContext = getStylingContext(previousOrParentTNode.index, lView);
+    stylingContext = getStylingContextFromLView(previousOrParentTNode.index, lView);
     setInputsForProperty(
         lView, previousOrParentTNode.inputs !['class'] !, getInitialClassNameValue(stylingContext));
   }
   if (hasStyleInput(previousOrParentTNode)) {
-    const stylingContext = getStylingContext(previousOrParentTNode.index, lView);
+    stylingContext =
+        stylingContext || getStylingContextFromLView(previousOrParentTNode.index, lView);
     setInputsForProperty(
         lView, previousOrParentTNode.inputs !['style'] !,
         getInitialStyleStringValue(stylingContext));

packages/core/src/render3/instructions/styling.ts

@@ -6,15 +6,17 @@
  * found in the LICENSE file at https://angular.io/license
  */
 import {StyleSanitizeFn} from '../../sanitization/style_sanitizer';
+import {assertEqual} from '../../util/assert';
 import {TNode, TNodeType} from '../interfaces/node';
 import {PlayerFactory} from '../interfaces/player';
-import {FLAGS, HEADER_OFFSET, LViewFlags, RENDERER, RootContextFlags} from '../interfaces/view';
+import {FLAGS, HEADER_OFFSET, LView, LViewFlags, RENDERER, RootContextFlags} from '../interfaces/view';
 import {getActiveDirectiveId, getActiveDirectiveSuperClassDepth, getLView, getPreviousOrParentTNode, getSelectedIndex} from '../state';
 import {getInitialClassNameValue, renderStyling, updateClassProp as updateElementClassProp, updateContextWithBindings, updateStyleProp as updateElementStyleProp, updateStylingMap} from '../styling/class_and_style_bindings';
 import {ParamsOf, enqueueHostInstruction, registerHostDirective} from '../styling/host_instructions_queue';
 import {BoundPlayerFactory} from '../styling/player_factory';
 import {DEFAULT_TEMPLATE_DIRECTIVE_INDEX} from '../styling/shared';
-import {allocateOrUpdateDirectiveIntoContext, createEmptyStylingContext, forceClassesAsString, forceStylesAsString, getStylingContext, hasClassInput, hasStyleInput} from '../styling/util';
+import {getCachedStylingContext, setCachedStylingContext} from '../styling/state';
+import {allocateOrUpdateDirectiveIntoContext, createEmptyStylingContext, forceClassesAsString, forceStylesAsString, getStylingContextFromLView, hasClassInput, hasStyleInput} from '../styling/util';
 import {NO_CHANGE} from '../tokens';
 import {renderStringify} from '../util/misc_utils';
 import {getRootContext} from '../util/view_traversal_utils';
@@ -170,9 +172,9 @@ export function ɵɵelementStyleProp(
     index: number, styleIndex: number, value: string | number | String | PlayerFactory | null,
     suffix?: string | null, forceOverride?: boolean): void {
   const valueToAdd = resolveStylePropValue(value, suffix);
+  const stylingContext = getStylingContext(index, getLView());
   updateElementStyleProp(
-      getStylingContext(index + HEADER_OFFSET, getLView()), styleIndex, valueToAdd,
-      DEFAULT_TEMPLATE_DIRECTIVE_INDEX, forceOverride);
+      stylingContext, styleIndex, valueToAdd, DEFAULT_TEMPLATE_DIRECTIVE_INDEX, forceOverride);
 }
 
 /**
@@ -206,9 +208,7 @@ export function ɵɵelementHostStyleProp(
   const directiveStylingIndex = getActiveDirectiveStylingIndex();
   const hostElementIndex = getSelectedIndex();
 
-  const lView = getLView();
-  const stylingContext = getStylingContext(hostElementIndex + HEADER_OFFSET, lView);
-
+  const stylingContext = getStylingContext(hostElementIndex, getLView());
   const valueToAdd = resolveStylePropValue(value, suffix);
   const args: ParamsOf<typeof updateElementStyleProp> =
       [stylingContext, styleIndex, valueToAdd, directiveStylingIndex, forceOverride];
@@ -259,9 +259,9 @@ export function ɵɵelementClassProp(
   const input = (value instanceof BoundPlayerFactory) ?
       (value as BoundPlayerFactory<boolean|null>) :
       booleanOrNull(value);
+  const stylingContext = getStylingContext(index, getLView());
   updateElementClassProp(
-      getStylingContext(index + HEADER_OFFSET, getLView()), classIndex, input,
-      DEFAULT_TEMPLATE_DIRECTIVE_INDEX, forceOverride);
+      stylingContext, classIndex, input, DEFAULT_TEMPLATE_DIRECTIVE_INDEX, forceOverride);
 }
 
 
@@ -287,9 +287,7 @@ export function ɵɵelementHostClassProp(
     classIndex: number, value: boolean | PlayerFactory, forceOverride?: boolean): void {
   const directiveStylingIndex = getActiveDirectiveStylingIndex();
   const hostElementIndex = getSelectedIndex();
-
-  const lView = getLView();
-  const stylingContext = getStylingContext(hostElementIndex + HEADER_OFFSET, lView);
+  const stylingContext = getStylingContext(hostElementIndex, getLView());
 
   const input = (value instanceof BoundPlayerFactory) ?
       (value as BoundPlayerFactory<boolean|null>) :
@@ -330,8 +328,8 @@ export function ɵɵelementStylingMap(
     index: number, classes: {[key: string]: any} | string | NO_CHANGE | null,
     styles?: {[styleName: string]: any} | NO_CHANGE | null): void {
   const lView = getLView();
+  const stylingContext = getStylingContext(index, lView);
   const tNode = getTNode(index, lView);
-  const stylingContext = getStylingContext(index + HEADER_OFFSET, lView);
 
   // inputs are only evaluated from a template binding into a directive, therefore,
   // there should not be a situation where a directive host bindings function
@@ -384,10 +382,7 @@ export function ɵɵelementHostStylingMap(
     styles?: {[styleName: string]: any} | NO_CHANGE | null): void {
   const directiveStylingIndex = getActiveDirectiveStylingIndex();
   const hostElementIndex = getSelectedIndex();
-
-  const lView = getLView();
-  const stylingContext = getStylingContext(hostElementIndex + HEADER_OFFSET, lView);
-
+  const stylingContext = getStylingContext(hostElementIndex, getLView());
   const args: ParamsOf<typeof updateStylingMap> =
       [stylingContext, classes, styles, directiveStylingIndex];
   enqueueHostInstruction(stylingContext, directiveStylingIndex, updateStylingMap, args);
@@ -432,13 +427,22 @@ export function elementStylingApplyInternal(directiveStylingIndex: number, index
   // the styling apply code knows not to actually apply the values...
   const renderer = tNode.type === TNodeType.Element ? lView[RENDERER] : null;
   const isFirstRender = (lView[FLAGS] & LViewFlags.FirstLViewPass) !== 0;
-  const stylingContext = getStylingContext(index + HEADER_OFFSET, lView);
+  const stylingContext = getStylingContext(index, lView);
   const totalPlayersQueued = renderStyling(
       stylingContext, renderer, lView, isFirstRender, null, null, directiveStylingIndex);
   if (totalPlayersQueued > 0) {
     const rootContext = getRootContext(lView);
     scheduleTick(rootContext, RootContextFlags.FlushPlayers);
   }
+
+  // because select(n) may not run between every instruction, the cached styling
+  // context may not get cleared between elements. The reason for this is because
+  // styling bindings (like `[style]` and `[class]`) are not recognized as property
+  // bindings by default so a select(n) instruction is not generated. To ensure the
+  // context is loaded correctly for the next element the cache below is pre-emptively
+  // cleared because there is no code in Angular that applies more styling code after a
+  // styling flush has occurred. Note that this will be fixed once FW-1254 lands.
+  setCachedStylingContext(null);
 }
 
 export function getActiveDirectiveStylingIndex() {
@@ -450,3 +454,15 @@ export function getActiveDirectiveStylingIndex() {
   // sub-classed directive the inheritance depth is taken into account as well.
   return getActiveDirectiveId() + getActiveDirectiveSuperClassDepth();
 }
+
+function getStylingContext(index: number, lView: LView) {
+  let context = getCachedStylingContext();
+  if (!context) {
+    context = getStylingContextFromLView(index + HEADER_OFFSET, lView);
+    setCachedStylingContext(context);
+  } else if (ngDevMode) {
+    const actualContext = getStylingContextFromLView(index + HEADER_OFFSET, lView);
+    assertEqual(context, actualContext, 'The cached styling context is invalid');
+  }
+  return context;
+}

packages/core/src/render3/players.ts

@@ -11,7 +11,7 @@ import {getLContext} from './context_discovery';
 import {scheduleTick} from './instructions/shared';
 import {ComponentInstance, DirectiveInstance, Player} from './interfaces/player';
 import {RootContextFlags} from './interfaces/view';
-import {addPlayerInternal, getOrCreatePlayerContext, getPlayerContext, getPlayersInternal, getStylingContext, throwInvalidRefError} from './styling/util';
+import {addPlayerInternal, getOrCreatePlayerContext, getPlayerContext, getPlayersInternal, getStylingContextFromLView, throwInvalidRefError} from './styling/util';
 import {getRootContext} from './util/view_traversal_utils';
 
 
@@ -61,7 +61,7 @@ export function getPlayers(ref: ComponentInstance | DirectiveInstance | HTMLElem
     return [];
   }
 
-  const stylingContext = getStylingContext(context.nodeIndex, context.lView);
+  const stylingContext = getStylingContextFromLView(context.nodeIndex, context.lView);
   const playerContext = stylingContext ? getPlayerContext(stylingContext) : null;
   return playerContext ? getPlayersInternal(playerContext) : [];
 }

packages/core/src/render3/state.ts

@@ -13,6 +13,7 @@ import {executeHooks} from './hooks';
 import {ComponentDef, DirectiveDef} from './interfaces/definition';
 import {TElementNode, TNode, TViewNode} from './interfaces/node';
 import {BINDING_INDEX, CONTEXT, DECLARATION_VIEW, FLAGS, InitPhaseState, LView, LViewFlags, OpaqueViewState, TVIEW} from './interfaces/view';
+import {setCachedStylingContext} from './styling/state';
 import {resetPreOrderHookFlags} from './util/view_utils';
 
 
@@ -456,6 +457,7 @@ export function leaveView(newView: LView): void {
       lView[BINDING_INDEX] = tView.bindingStartIndex;
     }
   }
+  setCachedStylingContext(null);
   enterView(newView, null);
 }
 
@@ -482,6 +484,10 @@ export function getSelectedIndex() {
  */
 export function setSelectedIndex(index: number) {
   _selectedIndex = index;
+
+  // remove the styling context from the cache
+  // because we are now on a different element
+  setCachedStylingContext(null);
 }
 
 

packages/core/src/render3/styling/state.ts

@@ -0,0 +1,30 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import {StylingContext} from '../interfaces/styling';
+
+let stylingContext: StylingContext|null = null;
+
+/**
+ * Gets the most recent styling context value.
+ *
+ * Note that only one styling context is stored at a given time.
+ */
+export function getCachedStylingContext() {
+  return stylingContext;
+}
+
+/**
+ * Sets the most recent styling context value.
+ *
+ * Note that only one styling context is stored at a given time.
+ *
+ * @param context The styling context value that will be stored
+ */
+export function setCachedStylingContext(context: StylingContext | null) {
+  stylingContext = context;
+}

packages/core/src/render3/styling/util.ts

@@ -124,7 +124,7 @@ export function allocStylingContext(
  * @param index Index of the style allocation. See: `elementStyling`.
  * @param viewData The view to search for the styling context
  */
-export function getStylingContext(index: number, viewData: LView): StylingContext {
+export function getStylingContextFromLView(index: number, viewData: LView): StylingContext {
   let storageIndex = index;
   let slotValue: LContainer|LView|StylingContext|RElement = viewData[storageIndex];
   let wrapper: LContainer|LView|StylingContext = viewData;
@@ -252,7 +252,7 @@ export function getOrCreatePlayerContext(target: {}, context?: LContext | null):
   }
 
   const {lView, nodeIndex} = context;
-  const stylingContext = getStylingContext(nodeIndex, lView);
+  const stylingContext = getStylingContextFromLView(nodeIndex, lView);
   return getPlayerContext(stylingContext) || allocPlayerContext(stylingContext);
 }
 

packages/core/test/bundling/cyclic_import/bundle.golden_symbols.json

@@ -408,7 +408,7 @@
     "name": "getRootView"
   },
   {
-    "name": "getStylingContext"
+    "name": "getStylingContextFromLView"
   },
   {
     "name": "getTNode"
@@ -614,6 +614,9 @@
   {
     "name": "setBindingRoot"
   },
+  {
+    "name": "setCachedStylingContext"
+  },
   {
     "name": "setClass"
   },

packages/core/test/bundling/hello_world/bundle.golden_symbols.json

@@ -440,6 +440,9 @@
   {
     "name": "setBindingRoot"
   },
+  {
+    "name": "setCachedStylingContext"
+  },
   {
     "name": "setClass"
   },

packages/core/test/bundling/todo/bundle.golden_symbols.json

@@ -641,6 +641,9 @@
   {
     "name": "getBindingsEnabled"
   },
+  {
+    "name": "getCachedStylingContext"
+  },
   {
     "name": "getCheckNoChangesMode"
   },
@@ -824,6 +827,9 @@
   {
     "name": "getStylingContext"
   },
+  {
+    "name": "getStylingContextFromLView"
+  },
   {
     "name": "getSymbolIterator"
   },
@@ -1178,6 +1184,9 @@
   {
     "name": "setBindingRoot"
   },
+  {
+    "name": "setCachedStylingContext"
+  },
   {
     "name": "setCheckNoChangesMode"
   },
@@ -1265,6 +1274,9 @@
   {
     "name": "stringify"
   },
+  {
+    "name": "stylingContext"
+  },
   {
     "name": "syncViewWithBlueprint"
   },