Updated comments

packages/react-devtools-shared/src/backend/renderer.js

@@ -631,8 +631,8 @@ export function attach(
 
  // Note that by calling these functions we may be creating the ID for the first time.
  // If the Fiber is then never mounted, we are responsible for cleaning up after ourselves.
- // This is important because getPrimaryFiber() stores a Fiber in the primaryFibers Set.
- // If a Fiber never mounts, and we don't clean up after this code, we could leak.
+ // This is important because getOrGenerateFiberID() stores a Fiber in a couple of local Maps.
+ // If the Fiber never mounts and we don't clean up after this code, we could leak.
  // Fortunately we would only leak Fibers that have errors/warnings associated with them,
  // which is hopefully only a small set and only in DEV mode– but this is still not great.
  // We should clean up Fibers like this when flushing; see recordPendingErrorsAndWarnings().
@@ -983,6 +983,8 @@ export function attach(
  // When a mount or update is in progress, this value tracks the root that is being operated on.
  let currentRootID: number = -1;
 
+ // Returns the unique ID for a Fiber or generates and caches a new one if the Fiber hasn't been seen before.
+ // Once this method has been called for a Fiber, untrackFiberID() should always be called later to avoid leaking.
  function getOrGenerateFiberID(fiber: Fiber): number {
  let id = null;
  if (fiberToIDMap.has(fiber)) {
@@ -1020,6 +1022,7 @@ export function attach(
  return refinedID;
  }
 
+ // Returns an ID if one has already been generated for the Fiber or throws.
  function getFiberIDThrows(fiber: Fiber): number {
  const maybeID = getFiberIDUnsafe(fiber);
  if (maybeID !== null) {
@@ -1030,6 +1033,8 @@ export function attach(
  );
  }
 
+ // Returns an ID if one has already been generated for the Fiber or null if one has not been generated.
+ // Use this method while e.g. logging to avoid over-retaining Fibers.
  function getFiberIDUnsafe(fiber: Fiber): number | null {
  if (fiberToIDMap.has(fiber)) {
  return ((fiberToIDMap.get(fiber): any): number);
@@ -1042,6 +1047,8 @@ export function attach(
  return null;
  }
 
+ // Removes a Fiber (and its alternate) from the Maps used to track their id.
+ // This method should always be called when a Fiber is unmounting.
  function untrackFiberID(fiber: Fiber) {
  const fiberID = getFiberIDUnsafe(fiber);
  if (fiberID !== null) {
@@ -1696,8 +1703,6 @@ export function attach(
  // One example of this is a Lazy component that never resolves before being unmounted.
  //
  // TODO: This is fragile and can obscure actual bugs.
- //
- // Calling getPrimaryFiber() lazily adds fibers to the Map, so clean up after ourselves before returning.
  return;
  }