Add isSampleWithNonEmptyStack and remove now-unused getFuncNamesAndOriginsForPath.

Author: mstange

src/components/shared/SampleTooltipContents.js

@@ -9,8 +9,7 @@ import { Backtrace } from './Backtrace';
 import { TooltipDetailSeparator } from '../tooltip/TooltipDetails';
 import {
   getCategoryPairLabel,
-  getFuncNamesAndOriginsForPath,
-  convertStackToCallNodeAndCategoryPath,
+  isSampleWithNonEmptyStack,
 } from 'firefox-profiler/profile-logic/profile-data';
 import { getFormattedTimelineValue } from 'firefox-profiler/profile-logic/committed-ranges';
 import {
@@ -26,7 +25,6 @@ import type {
   Milliseconds,
 } from 'firefox-profiler/types';
 import type { CpuRatioInTimeRange } from './thread/ActivityGraphFills';
-import { ensureExists } from '../../utils/flow';
 
 type CPUProps = CpuRatioInTimeRange;
 
@@ -134,21 +132,10 @@ export class SampleTooltipContents extends React.PureComponent<Props> {
     let hasStack = false;
     let formattedSampleTime = null;
     if (sampleIndex !== null) {
-      const { samples, stackTable } = rangeFilteredThread;
+      const { samples } = rangeFilteredThread;
       const sampleTime = samples.time[sampleIndex];
-      const stackIndex = samples.stack[sampleIndex];
-      const hasSamples = samples.length > 0 && stackTable.length > 1;
-
-      if (hasSamples) {
-        const stack = getFuncNamesAndOriginsForPath(
-          convertStackToCallNodeAndCategoryPath(
-            rangeFilteredThread,
-            ensureExists(stackIndex)
-          ),
-          rangeFilteredThread
-        );
-        hasStack = stack.length > 1 || stack[0].funcName !== '(root)';
-      }
+
+      hasStack = isSampleWithNonEmptyStack(sampleIndex, rangeFilteredThread);
 
       formattedSampleTime = getFormattedTimelineValue(
         sampleTime - zeroAt,

src/profile-logic/profile-data.js

@@ -2883,34 +2883,32 @@ export function reserveFunctionsInThread(
 }
 
 /**
- * From a valid call node path, this function returns a list of information
- * about each function in this path: their names and their origins.
+ * Returns whether the given sample has a stack which is non-null and not just
+ * a single function with the name '(root)'.
  */
-export function getFuncNamesAndOriginsForPath(
-  path: CallNodeAndCategoryPath,
+export function isSampleWithNonEmptyStack(
+  sampleIndex: IndexIntoSamplesTable,
   thread: Thread
-): Array<{
-  funcName: string,
-  category: IndexIntoCategoryList,
-  isFrameLabel: boolean,
-  origin: string,
-}> {
-  const { funcTable, stringTable, resourceTable } = thread;
+): boolean {
+  const { samples, stackTable, frameTable, funcTable, stringTable } = thread;
 
-  return path.map((frame) => {
-    const { category, func } = frame;
-    return {
-      funcName: stringTable.getString(funcTable.name[func]),
-      category: category,
-      isFrameLabel: funcTable.resource[func] === -1,
-      origin: getOriginAnnotationForFunc(
-        func,
-        funcTable,
-        resourceTable,
-        stringTable
-      ),
-    };
-  });
+  const stackIndex = samples.stack[sampleIndex];
+  if (stackIndex === null) {
+    return false;
+  }
+
+  if (stackTable.prefix[stackIndex] !== null) {
+    // Stack contains at least two frames.
+    return true;
+  }
+
+  // Stack is only a single frame. Is it the '(root)' frame that Firefox puts
+  // in its profiles?
+  const frameIndex = stackTable.frame[stackIndex];
+  const funcIndex = frameTable.func[frameIndex];
+  const funcNameStringIndex = funcTable.name[funcIndex];
+  const funcName = stringTable.getString(funcNameStringIndex);
+  return funcName !== '(root)';
 }
 
 /**