Fix duplicated scripts and prep to publish dwds (#1414)

* Fix duplicated scripts and prep to publish dwds

Make inspector initializer wait on the same future as
getScripts call in ChromeProxyService to make sure
we populate caches only once.

Prep to publish to support file picker work in devtools.

Closes: #1413

* Populate script caches only once using async memoizer

* Memoize the list of scripts as well

* Addressed CR comments

Author: Anna Gringauze

dwds/CHANGELOG.md

@@ -1,5 +1,6 @@
-## 11.3.1-dev
+## 11.4.0
 
+- Fix duplicated scripts returned by `VmService.getScripts` API.
 - Encode extension url asynchronously.
 - Use default constant port for debug service.
   - If we fail binding to the port, fall back to previous strategy

dwds/lib/src/debugging/inspector.dart

@@ -4,6 +4,7 @@
 
 // @dart = 2.9
 
+import 'package:async/async.dart';
 import 'package:logging/logging.dart';
 import 'package:vm_service/vm_service.dart';
 import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';
@@ -29,9 +30,9 @@ import 'libraries.dart';
 /// Provides information about currently loaded scripts and objects and support
 /// for eval.
 class AppInspector extends Domain {
-  Future<List<ScriptRef>> _cachedScriptRefs;
+  final _scriptCacheMemoizer = AsyncMemoizer<List<ScriptRef>>();
 
-  Future<List<ScriptRef>> get scriptRefs => _cachedScriptRefs ??= _getScripts();
+  Future<List<ScriptRef>> get scriptRefs => _populateScriptCaches();
 
   final _logger = Logger('AppInspector');
 
@@ -87,7 +88,7 @@ class AppInspector extends Domain {
     isolate.libraries.addAll(libraries);
     await DartUri.recordAbsoluteUris(libraries.map((lib) => lib.uri));
 
-    var scripts = await _getScripts();
+    var scripts = await scriptRefs;
     await DartUri.recordAbsoluteUris(scripts.map((script) => script.uri));
 
     isolate.extensionRPCs.addAll(await _getExtensionRpcs());
@@ -483,38 +484,38 @@ function($argsString) {
     return ScriptList(scripts: await scriptRefs);
   }
 
-  Future<List<ScriptRef>> _getScripts() async {
-    await _populateScriptCaches();
-    return _scriptRefsById.values.toList();
-  }
-
   /// Request and cache <ScriptRef>s for all the scripts in the application.
   ///
   /// This populates [_scriptRefsById], [_scriptIdToLibraryId] and
   /// [_serverPathToScriptRef]. It is a one-time operation, because if we do a
   /// reload the inspector will get re-created.
-  Future<void> _populateScriptCaches() async {
-    var libraryUris = [for (var library in isolate.libraries) library.uri];
-    var scripts = await globalLoadStrategy
-        .metadataProviderFor(appConnection.request.entrypointPath)
-        .scripts;
-    // For all the non-dart: libraries, find their parts and create scriptRefs
-    // for them.
-    var userLibraries = libraryUris.where((uri) => !uri.startsWith('dart:'));
-    for (var uri in userLibraries) {
-      var parts = scripts[uri];
-      var scriptRefs = [
-        ScriptRef(uri: uri, id: createId()),
-        for (var part in parts) ScriptRef(uri: part, id: createId())
-      ];
-      var libraryRef = await libraryHelper.libraryRefFor(uri);
-      for (var scriptRef in scriptRefs) {
-        _scriptRefsById[scriptRef.id] = scriptRef;
-        _scriptIdToLibraryId[scriptRef.id] = libraryRef.id;
-        _serverPathToScriptRef[DartUri(scriptRef.uri, _root).serverPath] =
-            scriptRef;
+  ///
+  /// Returns the list of scripts refs cached.
+  Future<List<ScriptRef>> _populateScriptCaches() async {
+    return _scriptCacheMemoizer.runOnce(() async {
+      var libraryUris = [for (var library in isolate.libraries) library.uri];
+      var scripts = await globalLoadStrategy
+          .metadataProviderFor(appConnection.request.entrypointPath)
+          .scripts;
+      // For all the non-dart: libraries, find their parts and create scriptRefs
+      // for them.
+      var userLibraries = libraryUris.where((uri) => !uri.startsWith('dart:'));
+      for (var uri in userLibraries) {
+        var parts = scripts[uri];
+        var scriptRefs = [
+          ScriptRef(uri: uri, id: createId()),
+          for (var part in parts) ScriptRef(uri: part, id: createId())
+        ];
+        var libraryRef = await libraryHelper.libraryRefFor(uri);
+        for (var scriptRef in scriptRefs) {
+          _scriptRefsById[scriptRef.id] = scriptRef;
+          _scriptIdToLibraryId[scriptRef.id] = libraryRef.id;
+          _serverPathToScriptRef[DartUri(scriptRef.uri, _root).serverPath] =
+              scriptRef;
+        }
       }
-    }
+      return _scriptRefsById.values.toList();
+    });
   }
 
   /// Look up the script by id in an isolate.