Try to cache the clean version of flutter Dartdoc uses (#2802)

* Just try to get something working

* simplify

* Store the current date in output

* well it doesn't complain locally now?

* Empty commit to trigger CI

Author: jcollins-g

.github/workflows/test.yaml

@@ -38,6 +38,28 @@ jobs:
             job: sdk-analyzer
 
     steps:
+      - name: Store date
+        id: date
+        run: echo "::set-output name=today::$(date +'%Y-%m-%d')"
+        shell: bash
+      - name: Cache clean flutter
+        uses: actions/cache@v2
+        if: matrix.job == 'flutter'
+        env:
+          # Increment version to invalidate bad/obsolete caches.
+          cache-name: cache-grinder-flutter-v1
+        with:
+          path: ~/.dartdoc_grinder
+          key: ${{ runner.os }}-test-${{ env.cache-name }}-${{ steps.date.outputs.today }}
+      - name: Cache .pub-cache
+        uses: actions/cache@v2
+        if: matrix.job == 'flutter'
+        env:
+          # Increment version to invalidate bad/obsolete caches.
+          cache-name: cache-dart-pub-v1
+        with:
+          path: ~/.pub-cache
+          key: ${{ runner.os }}-test-${{ env.cache-name }}-${{ steps.date.outputs.today }}
       - name: Configure git
         if: runner.os == 'Windows'
         run: git config --global core.autocrlf input

tool/grind.dart

@@ -88,7 +88,7 @@ Future<FlutterRepo> get cleanFlutterRepo async {
           int.parse(lastSynced.readAsStringSync()));
     }
     if (lastSyncedTime == null ||
-        DateTime.now().difference(lastSyncedTime) > Duration(hours: 4)) {
+        DateTime.now().difference(lastSyncedTime) > Duration(hours: 24)) {
       // Rebuild the repository.
       if (cleanFlutterDir.existsSync()) {
         cleanFlutterDir.deleteSync(recursive: true);
@@ -185,7 +185,12 @@ final Directory flutterDirDevTools =
 Map<String, String> _createThrowawayPubCache() {
   var pubCache = Directory.systemTemp.createTempSync('pubcache');
   var pubCacheBin = Directory(path.join(pubCache.path, 'bin'));
-  pubCacheBin.createSync();
+  var defaultCache = Directory(defaultPubCache);
+  if (defaultCache.existsSync()) {
+    copy(defaultCache, pubCache);
+  } else {
+    pubCacheBin.createSync();
+  }
   return Map.fromIterables([
     'PUB_CACHE',
     'PATH'
@@ -870,11 +875,6 @@ class FlutterRepo {
       ['--version'],
       workingDirectory: flutterPath,
     );
-    await launcher.runStreamed(
-      bin,
-      ['precache'],
-      workingDirectory: flutterPath,
-    );
     await launcher.runStreamed(
       bin,
       ['update-packages'],