fix asset reloading (#29469)

packages/flutter_tools/lib/src/asset.dart

@@ -193,7 +193,7 @@ class _ManifestAssetBundle implements AssetBundle {
       }
       for (_Asset variant in assetVariants[asset]) {
         assert(variant.assetFileExists);
-        entries[variant.entryUri.path] = DevFSFileContent(variant.assetFile);
+        entries[variant.entryUri.path] ??= DevFSFileContent(variant.assetFile);
       }
     }
 
@@ -203,7 +203,7 @@ class _ManifestAssetBundle implements AssetBundle {
     }
     for (_Asset asset in materialAssets) {
       assert(asset.assetFileExists);
-      entries[asset.entryUri.path] = DevFSFileContent(asset.assetFile);
+      entries[asset.entryUri.path] ??= DevFSFileContent(asset.assetFile);
     }
 
     entries[_assetManifestJson] = _createAssetManifest(assetVariants);

packages/flutter_tools/lib/src/devfs.dart

@@ -385,7 +385,6 @@ class DevFS {
   final String fsName;
   final Directory rootDirectory;
   String _packagesFilePath;
-  final Map<Uri, DevFSContent> _entries = <Uri, DevFSContent>{};
   final Set<String> assetPathsToEvict = <String>{};
   List<Uri> sources = <Uri>[];
   DateTime lastCompiled;
@@ -434,7 +433,6 @@ class DevFS {
     AssetBundle bundle,
     DateTime firstBuildTime,
     bool bundleFirstUpload = false,
-    bool bundleDirty = false,
     @required ResidentCompiler generator,
     String dillOutputPath,
     @required bool trackWidgetCreation,
@@ -446,6 +444,11 @@ class DevFS {
     assert(trackWidgetCreation != null);
     assert(generator != null);
 
+    // Update modified files
+    final String assetBuildDirPrefix = _asUriPath(getAssetBuildDirectory());
+    final Map<Uri, DevFSContent> dirtyEntries = <Uri, DevFSContent>{};
+
+    int syncedBytes = 0;
     if (bundle != null) {
       printTrace('Scanning asset files');
       // We write the assets into the AssetBundle working dir so that they
@@ -453,29 +456,20 @@ class DevFS {
       final String assetDirectory = getAssetBuildDirectory();
       bundle.entries.forEach((String archivePath, DevFSContent content) {
         final Uri deviceUri = fs.path.toUri(fs.path.join(assetDirectory, archivePath));
-        _entries[deviceUri] = content;
+        if (deviceUri.path.startsWith(assetBuildDirPrefix)) {
+          archivePath = deviceUri.path.substring(assetBuildDirPrefix.length);
+        }
+        // Only update assets if they have been modified, or if this is the
+        // first upload of the asset bundle.
+        if (content.isModified || (bundleFirstUpload && archivePath != null)) {
+          dirtyEntries[deviceUri] = content;
+          syncedBytes += content.size;
+          if (archivePath != null && !bundleFirstUpload) {
+            assetPathsToEvict.add(archivePath);
+          }
+        }
       });
     }
-
-    // Update modified files
-    final String assetBuildDirPrefix = _asUriPath(getAssetBuildDirectory());
-    final Map<Uri, DevFSContent> dirtyEntries = <Uri, DevFSContent>{};
-
-    int syncedBytes = 0;
-    _entries.forEach((Uri deviceUri, DevFSContent content) {
-      String archivePath;
-      if (deviceUri.path.startsWith(assetBuildDirPrefix))
-        archivePath = deviceUri.path.substring(assetBuildDirPrefix.length);
-      // When doing full restart, copy content so that isModified does not
-      // reset last check timestamp because we want to report all modified
-      // files to incremental compiler next time user does hot reload.
-      if (content.isModified || ((bundleDirty || bundleFirstUpload) && archivePath != null)) {
-        dirtyEntries[deviceUri] = content;
-        syncedBytes += content.size;
-        if (archivePath != null && (!bundleFirstUpload || content.isModifiedAfter(firstBuildTime)))
-          assetPathsToEvict.add(archivePath);
-      }
-    });
     if (fullRestart) {
       generator.reset();
     }

packages/flutter_tools/lib/src/resident_runner.dart

@@ -455,7 +455,6 @@ class FlutterDevice {
         bundle: bundle,
         firstBuildTime: firstBuildTime,
         bundleFirstUpload: bundleFirstUpload,
-        bundleDirty: bundleDirty,
         generator: generator,
         fullRestart: fullRestart,
         dillOutputPath: dillOutputPath,

packages/flutter_tools/lib/src/run_hot.dart

@@ -936,7 +936,7 @@ class HotRunner extends ResidentRunner {
 }
 
 class ProjectFileInvalidator {
-  static const String _pubCachePathLinuxAndWindows = '.pub-cache';
+  static const String _pubCachePathLinuxAndMac = '.pub-cache';
   static const String _pubCachePathWindows = 'Pub/Cache';
 
   static List<Uri> findInvalidated({@required DateTime lastCompiled,
@@ -946,7 +946,7 @@ class ProjectFileInvalidator {
     final Stopwatch stopwatch = Stopwatch()..start();
     for (Uri uri in urisToMonitor) {
       if ((platform.isWindows && uri.path.contains(_pubCachePathWindows))
-          || uri.path.contains(_pubCachePathLinuxAndWindows)) {
+          || uri.path.contains(_pubCachePathLinuxAndMac)) {
         // Don't watch pub cache directories to speed things up a little.
         continue;
       }
@@ -963,4 +963,4 @@ class ProjectFileInvalidator {
     printTrace('Scanned through $scanned files in ${stopwatch.elapsedMilliseconds}ms');
     return invalidatedFiles;
   }
-}
+}
\ No newline at end of file

packages/flutter_tools/test/hot_test.dart

@@ -104,7 +104,6 @@ void main() {
       bundle: anyNamed('bundle'),
       firstBuildTime: anyNamed('firstBuildTime'),
       bundleFirstUpload: anyNamed('bundleFirstUpload'),
-      bundleDirty: anyNamed('bundleDirty'),
       generator: anyNamed('generator'),
       fullRestart: anyNamed('fullRestart'),
       dillOutputPath: anyNamed('dillOutputPath'),