fix(watchman): Parallelize Watchman calls in crawler again

This is a follow up to #5615 where it made all async watchman
commands serialized when converting them from promises to `async`
functions.

Existing Watchman crawler tests should pass, maybe slightly faster.

packages/jest-haste-map/src/crawlers/watchman.js

@@ -51,48 +51,52 @@ module.exports = async function watchmanCrawl(
 
  try {
  const watchmanRoots = new Map();
- for (const root of roots) {
- const response = await cmd('watch-project', root);
- const existing = watchmanRoots.get(response.watch);
- // A root can only be filtered if it was never seen with a relative_path before
- const canBeFiltered = !existing || existing.length > 0;
+ await Promise.all(
+ roots.map(async root => {
+ const response = await cmd('watch-project', root);
+ const existing = watchmanRoots.get(response.watch);
+ // A root can only be filtered if it was never seen with a relative_path before
+ const canBeFiltered = !existing || existing.length > 0;
 
- if (canBeFiltered) {
- if (response.relative_path) {
- watchmanRoots.set(
- response.watch,
- (existing || []).concat(response.relative_path),
- );
- } else {
- // Make the filter directories an empty array to signal that this root
- // was already seen and needs to be watched for all files/directories
- watchmanRoots.set(response.watch, []);
+ if (canBeFiltered) {
+ if (response.relative_path) {
+ watchmanRoots.set(
+ response.watch,
+ (existing || []).concat(response.relative_path),
+ );
+ } else {
+ // Make the filter directories an empty array to signal that this root
+ // was already seen and needs to be watched for all files/directories
+ watchmanRoots.set(response.watch, []);
+ }
  }
- }
- }
+ }),
+ );
 
  let shouldReset = false;
  const watchmanFileResults = new Map();
- for (const [root, directoryFilters] of watchmanRoots) {
- const expression = Array.from(defaultWatchExpression);
- if (directoryFilters.length > 0) {
- expression.push([
- 'anyof',
- ...directoryFilters.map(dir => ['dirname', dir]),
- ]);
- }
- const fields = ['name', 'exists', 'mtime_ms'];
+ await Promise.all(
+ Array.from(watchmanRoots).map(async ([root, directoryFilters]) => {
+ const expression = Array.from(defaultWatchExpression);
+ if (directoryFilters.length > 0) {
+ expression.push([
+ 'anyof',
+ ...directoryFilters.map(dir => ['dirname', dir]),
+ ]);
+ }
+ const fields = ['name', 'exists', 'mtime_ms'];
 
- const query = clocks[root]
- ? // Use the `since` generator if we have a clock available
- {expression, fields, since: clocks[root]}
- : // Otherwise use the `suffix` generator
- {expression, fields, suffix: extensions};
+  const query = clocks[root]
+  ? // Use the `since` generator if we have a clock available
+  {expression, fields, since: clocks[root]}
+  : // Otherwise use the `suffix` generator
+  {expression, fields, suffix: extensions};
 
- const response = await cmd('query', root, query);
- shouldReset = shouldReset || response.is_fresh_instance;
- watchmanFileResults.set(root, response);
- }
+ const response = await cmd('query', root, query);
+ shouldReset = shouldReset || response.is_fresh_instance;
+ watchmanFileResults.set(root, response);
+ }),
+ );
 
  // Reset the file map if watchman was restarted and sends us a list of files.
  if (shouldReset) {