feat: invert call stack in flame graph to render as icicle graph

src/components/flame-graph/Canvas.tsx

@@ -125,7 +125,10 @@ class FlameGraphCanvasImpl extends React.PureComponent<Props> {
     // selection or applying a transform), move the viewport
     // vertically so that its offset from the base of the flame graph
     // is maintained.
-    if (prevProps.maxStackDepthPlusOne !== this.props.maxStackDepthPlusOne) {
+    if (
+      !this.props.isInverted &&
+      prevProps.maxStackDepthPlusOne !== this.props.maxStackDepthPlusOne
+    ) {
       this.props.viewport.moveViewport(
         0,
         (prevProps.maxStackDepthPlusOne - this.props.maxStackDepthPlusOne) *
@@ -151,16 +154,21 @@ class FlameGraphCanvasImpl extends React.PureComponent<Props> {
   }
 
   _scrollSelectionIntoView = () => {
-    const { selectedCallNodeIndex, maxStackDepthPlusOne, callNodeInfo } =
-      this.props;
+    const {
+      selectedCallNodeIndex,
+      maxStackDepthPlusOne,
+      callNodeInfo,
+      isInverted,
+    } = this.props;
 
     if (selectedCallNodeIndex === null) {
       return;
     }
 
-    const callNodeTable = callNodeInfo.getCallNodeTable();
-    const depth = callNodeTable.depth[selectedCallNodeIndex];
-    const y = (maxStackDepthPlusOne - depth - 1) * ROW_HEIGHT;
+    const depth = callNodeInfo.depthForNode(selectedCallNodeIndex);
+    const y = isInverted
+      ? depth * ROW_HEIGHT
+      : (maxStackDepthPlusOne - depth - 1) * ROW_HEIGHT;
 
     if (y < this.props.viewport.viewportTop) {
       this.props.viewport.moveViewport(0, this.props.viewport.viewportTop - y);
@@ -192,6 +200,7 @@ class FlameGraphCanvasImpl extends React.PureComponent<Props> {
         viewportTop,
         viewportBottom,
       },
+      isInverted,
     } = this.props;
 
     const { hoveredItem } = hoverInfo;
@@ -232,14 +241,12 @@ class FlameGraphCanvasImpl extends React.PureComponent<Props> {
     fastFillStyle.set(getBackgroundColor());
     ctx.fillRect(0, 0, deviceContainerWidth, deviceContainerHeight);
 
-    const callNodeTable = callNodeInfo.getCallNodeTable();
-
-    const startDepth = Math.floor(
-      maxStackDepthPlusOne - viewportBottom / stackFrameHeight
-    );
-    const endDepth = Math.ceil(
-      maxStackDepthPlusOne - viewportTop / stackFrameHeight
-    );
+    const startDepth = isInverted
+      ? Math.floor(viewportTop / stackFrameHeight)
+      : Math.floor(maxStackDepthPlusOne - viewportBottom / stackFrameHeight);
+    const endDepth = isInverted
+      ? Math.ceil(viewportBottom / stackFrameHeight)
+      : Math.ceil(maxStackDepthPlusOne - viewportTop / stackFrameHeight);
 
     // Only draw the stack frames that are vertically within view.
     // The graph is drawn from bottom to top, in order of increasing depth.
@@ -251,10 +258,12 @@ class FlameGraphCanvasImpl extends React.PureComponent<Props> {
         continue;
       }
 
-      const cssRowTop: CssPixels =
-        (maxStackDepthPlusOne - depth - 1) * ROW_HEIGHT - viewportTop;
-      const cssRowBottom: CssPixels =
-        (maxStackDepthPlusOne - depth) * ROW_HEIGHT - viewportTop;
+      const cssRowTop: CssPixels = isInverted
+        ? depth * ROW_HEIGHT - viewportTop
+        : (maxStackDepthPlusOne - depth - 1) * ROW_HEIGHT - viewportTop;
+      const cssRowBottom: CssPixels = isInverted
+        ? (depth + 1) * ROW_HEIGHT - viewportTop
+        : (maxStackDepthPlusOne - depth) * ROW_HEIGHT - viewportTop;
       const deviceRowTop: DevicePixels = snap(cssRowTop * cssToDeviceScale);
       const deviceRowBottom: DevicePixels =
         snap(cssRowBottom * cssToDeviceScale) - 1;
@@ -300,7 +309,7 @@ class FlameGraphCanvasImpl extends React.PureComponent<Props> {
           i === hoveredItem.flameGraphTimingIndex;
         const isHighlighted = isSelected || isRightClicked || isHovered;
 
-        const categoryIndex = callNodeTable.category[callNodeIndex];
+        const categoryIndex = callNodeInfo.categoryForNode(callNodeIndex);
         const category = categories[categoryIndex];
         const colorStyles = mapCategoryColorNameToStackChartStyles(
           category.color
@@ -322,7 +331,7 @@ class FlameGraphCanvasImpl extends React.PureComponent<Props> {
           deviceBoxLeft + deviceHorizontalPadding;
         const deviceTextWidth: DevicePixels = deviceBoxRight - deviceTextLeft;
         if (deviceTextWidth > textMeasurement.minWidth) {
-          const funcIndex = callNodeTable.func[callNodeIndex];
+          const funcIndex = callNodeInfo.funcForNode(callNodeIndex);
           const funcName = thread.stringTable.getString(
             thread.funcTable.name[funcIndex]
           );
@@ -472,11 +481,12 @@ class FlameGraphCanvasImpl extends React.PureComponent<Props> {
       flameGraphTiming,
       maxStackDepthPlusOne,
       viewport: { viewportTop, containerWidth },
+      isInverted,
     } = this.props;
     const pos = x / containerWidth;
-    const depth = Math.floor(
-      maxStackDepthPlusOne - (y + viewportTop) / ROW_HEIGHT
-    );
+    const depth = isInverted
+      ? Math.floor((y + viewportTop) / ROW_HEIGHT)
+      : Math.floor(maxStackDepthPlusOne - (y + viewportTop) / ROW_HEIGHT);
     const stackTiming = flameGraphTiming[depth];
 
     if (!stackTiming) {

src/components/flame-graph/FlameGraph.tsx

@@ -4,7 +4,10 @@
 import * as React from 'react';
 
 import { explicitConnectWithForwardRef } from '../../utils/connect';
-import { FlameGraphCanvas } from './Canvas';
+import {
+  FlameGraphCanvas,
+  type OwnProps as FlameGraphCanvasProps,
+} from './Canvas';
 
 import {
   getCategories,
@@ -28,7 +31,6 @@ import {
   updateBottomBoxContentsAndMaybeOpen,
 } from 'firefox-profiler/actions/profile-view';
 import { extractNonInvertedCallTreeTimings } from 'firefox-profiler/profile-logic/call-tree';
-import { ensureExists } from 'firefox-profiler/utils/types';
 
 import type {
   Thread,
@@ -352,10 +354,7 @@ class FlameGraphImpl
     // different, and the flame graph is only used with non-inverted timings.)
     const tracedTimingNonInverted =
       tracedTiming !== null
-        ? ensureExists(
-            extractNonInvertedCallTreeTimings(tracedTiming),
-            'The flame graph should only ever see non-inverted timings, see UrlState.getInvertCallstack'
-          )
+        ? extractNonInvertedCallTreeTimings(tracedTiming)
         : null;
 
     const maxViewportHeight = maxStackDepthPlusOne * STACK_FRAME_HEIGHT;
@@ -376,7 +375,7 @@ class FlameGraphImpl
               maxViewportHeight,
               maximumZoom: 1,
               previewSelection,
-              startsAtBottom: true,
+              startsAtBottom: !isInverted,
               disableHorizontalMovement: true,
               viewportNeedsUpdate,
               marginLeft: 0,
@@ -416,12 +415,16 @@ class FlameGraphImpl
   }
 }
 
-function viewportNeedsUpdate() {
-  // By always returning false we prevent the viewport from being
+function viewportNeedsUpdate(
+  prevProps: FlameGraphCanvasProps,
+  nextProps: FlameGraphCanvasProps
+) {
+  // By returning false we prevent the viewport from being
   // reset and scrolled all the way to the bottom when doing
   // operations like changing the time selection or applying a
   // transform.
-  return false;
+  // We only reset the viewport if the invertCallstack setting changes.
+  return prevProps.isInverted !== nextProps.isInverted;
 }
 
 export const FlameGraph = explicitConnectWithForwardRef<

src/components/flame-graph/MaybeFlameGraph.tsx

@@ -4,36 +4,23 @@
 import * as React from 'react';
 
 import { explicitConnectWithForwardRef } from 'firefox-profiler/utils/connect';
-import { getInvertCallstack } from '../../selectors/url-state';
 import { selectedThreadSelectors } from '../../selectors/per-thread';
-import { changeInvertCallstack } from '../../actions/profile-view';
 import { FlameGraphEmptyReasons } from './FlameGraphEmptyReasons';
 import { FlameGraph, type FlameGraphHandle } from './FlameGraph';
 
 import type { ConnectedProps } from 'firefox-profiler/utils/connect';
 
 import './MaybeFlameGraph.css';
 
-// TODO: This component isn't needed any more. Whenever the selected tab
-// is "flame-graph", `invertCallstack` will be `false`. <MaybeFlameGraph /> is
-// only used in the "flame-graph" tab.
-
 type StateProps = {
   readonly isPreviewSelectionEmpty: boolean;
-  readonly invertCallstack: boolean;
-};
-type DispatchProps = {
-  readonly changeInvertCallstack: typeof changeInvertCallstack;
 };
+type DispatchProps = {};
 type Props = ConnectedProps<{}, StateProps, DispatchProps>;
 
 class MaybeFlameGraphImpl extends React.PureComponent<Props> {
   _flameGraph: React.RefObject<FlameGraphHandle | null> = React.createRef();
 
-  _onSwitchToNormalCallstackClick = () => {
-    this.props.changeInvertCallstack(false);
-  };
-
   override componentDidMount() {
     const flameGraph = this._flameGraph.current;
     if (flameGraph) {
@@ -42,28 +29,12 @@ class MaybeFlameGraphImpl extends React.PureComponent<Props> {
   }
 
   override render() {
-    const { isPreviewSelectionEmpty, invertCallstack } = this.props;
+    const { isPreviewSelectionEmpty } = this.props;
 
     if (isPreviewSelectionEmpty) {
       return <FlameGraphEmptyReasons />;
     }
 
-    if (invertCallstack) {
-      return (
-        <div className="flameGraphDisabledMessage">
-          <h3>The Flame Graph is not available for inverted call stacks</h3>
-          <p>
-            <button
-              type="button"
-              onClick={this._onSwitchToNormalCallstackClick}
-            >
-              Switch to the normal call stack
-            </button>{' '}
-            to show the Flame Graph.
-          </p>
-        </div>
-      );
-    }
     return <FlameGraph ref={this._flameGraph} />;
   }
 }
@@ -76,13 +47,10 @@ export const MaybeFlameGraph = explicitConnectWithForwardRef<
 >({
   mapStateToProps: (state) => {
     return {
-      invertCallstack: getInvertCallstack(state),
       isPreviewSelectionEmpty:
         !selectedThreadSelectors.getHasPreviewFilteredCtssSamples(state),
     };
   },
-  mapDispatchToProps: {
-    changeInvertCallstack,
-  },
+  mapDispatchToProps: {},
   component: MaybeFlameGraphImpl,
 });

src/components/flame-graph/index.tsx

@@ -13,7 +13,7 @@ const FlameGraphView = () => (
     role="tabpanel"
     aria-labelledby="flame-graph-tab-button"
   >
-    <StackSettings hideInvertCallstack={true} />
+    <StackSettings />
     <TransformNavigator />
     <MaybeFlameGraph />
   </div>

src/profile-logic/flame-graph.ts

@@ -8,7 +8,7 @@ import type {
   IndexIntoCallNodeTable,
 } from 'firefox-profiler/types';
 import type { StringTable } from 'firefox-profiler/utils/string-table';
-import type { CallTreeTimingsNonInverted } from './call-tree';
+import type { CallTreeTimingsNonInverted, CallTree } from './call-tree';
 
 import { bisectionRightByStrKey } from 'firefox-profiler/utils/bisect';
 
@@ -307,3 +307,75 @@ export function getFlameGraphTiming(
 
   return timing;
 }
+
+export function computeFlameGraphTimingFromCallTree(
+  callTree: CallTree
+): FlameGraphTiming {
+  const rootTotalSummary = callTree.getTotal();
+  if (rootTotalSummary === 0) {
+    return [];
+  }
+
+  const timing: FlameGraphTiming = [];
+
+  function traverse(
+    nodeIndex: IndexIntoCallNodeTable,
+    depth: number,
+    startX: number
+  ): number {
+    const { self, total } = callTree.getNodeData(nodeIndex);
+    if (total === 0) {
+      return startX;
+    }
+
+    const totalRelative = Math.abs(total / rootTotalSummary);
+    const endX = startX + totalRelative;
+
+    if (!timing[depth]) {
+      timing[depth] = {
+        start: [],
+        end: [],
+        selfRelative: [],
+        callNode: [],
+        length: 0,
+      };
+    }
+
+    timing[depth].start.push(startX);
+    timing[depth].end.push(endX);
+    timing[depth].selfRelative.push(Math.abs(self / rootTotalSummary));
+    timing[depth].callNode.push(nodeIndex);
+    timing[depth].length++;
+
+    const children = [...callTree.getChildren(nodeIndex)];
+    if (children.length > 0) {
+      // Sort children alphabetically by function name.
+      children.sort((a, b) => {
+        const nameA = callTree.getNodeData(a).funcName;
+        const nameB = callTree.getNodeData(b).funcName;
+        return nameA.localeCompare(nameB);
+      });
+
+      let currentChildStart = startX;
+      for (const child of children) {
+        currentChildStart = traverse(child, depth + 1, currentChildStart);
+      }
+    }
+
+    return endX;
+  }
+
+  const roots = [...callTree.getRoots()];
+  roots.sort((a, b) => {
+    const nameA = callTree.getNodeData(a).funcName;
+    const nameB = callTree.getNodeData(b).funcName;
+    return nameA.localeCompare(nameB);
+  });
+
+  let currentStart = 0;
+  for (const root of roots) {
+    currentStart = traverse(root, 0, currentStart);
+  }
+
+  return timing;
+}

src/profile-logic/profile-data.ts

@@ -2686,7 +2686,6 @@ export function computeCallNodeMaxDepthPlusOne(
   // computed for the filtered thread, but a samples-like table can use the preview
   // filtered thread, which involves a subset of the total call nodes.
   let maxDepth = -1;
-  const callNodeTable = callNodeInfo.getCallNodeTable();
   // TODO: Use sampleCallNodes instead
   const stackIndexToCallNodeIndex =
     callNodeInfo.getStackIndexToNonInvertedCallNodeIndex();
@@ -2696,7 +2695,7 @@ export function computeCallNodeMaxDepthPlusOne(
       continue;
     }
     const callNodeIndex = stackIndexToCallNodeIndex[stackIndex];
-    const depth = callNodeTable.depth[callNodeIndex];
+    const depth = callNodeInfo.depthForNode(callNodeIndex);
     if (depth > maxDepth) {
       maxDepth = depth;
     }