Improve inspecting large Map and List types

packages/devtools_app/lib/src/debugger/debugger_controller.dart

@@ -774,6 +774,9 @@ class DebuggerController extends DisposableController
     // Collecting frames for Dart web applications can be slow. At the potential
     // cost of a flicker in the stack view, display only the top frame
     // initially.
+    // TODO(elliette): Find a better solution for this. Currently, this means
+    // we fetch all variable objects twice (once in _getFullStack and once in
+    // in_createStackFrameWithLocation).
     if (await serviceManager.connectedApp.isDartWebApp) {
       _populateFrameInfo(
         [

packages/devtools_app/lib/src/debugger/debugger_model.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:convert';
+import 'dart:math';
 import 'dart:typed_data';
 
 import 'package:flutter/foundation.dart';
@@ -380,10 +381,28 @@ Future<void> buildVariablesTree(
       }
     }
   }
-  if (instanceRef != null && serviceManager.service != null) {
+
+  if (variable.childCount > Variable.MAX_CHILDREN_IN_GROUPING) {
+    final numChildrenInGrouping =
+        variable.childCount >= pow(Variable.MAX_CHILDREN_IN_GROUPING, 2)
+            ? (roundToNearestPow10(variable.childCount) /
+                    Variable.MAX_CHILDREN_IN_GROUPING)
+                .floor()
+            : Variable.MAX_CHILDREN_IN_GROUPING;
+
+    var start = variable.offset ?? 0;
+    final end = start + variable.childCount;
+    while (start < end) {
+      final count = min(end - start, numChildrenInGrouping);
+      variable.addChild(
+        Variable.grouping(variable.ref, offset: start, count: count),
+      );
+      start += count;
+    }
+  } else if (instanceRef != null && serviceManager.service != null) {
     try {
-      final dynamic result = await serviceManager.service
-          .getObject(variable.ref.isolateRef.id, instanceRef.id);
+      final dynamic result =
+          await _getObjectWithRetry(instanceRef.id, variable);
       if (result is Instance) {
         if (result.associations != null) {
           variable.addAllChildren(
@@ -439,8 +458,8 @@ Future<void> buildVariablesTree(
         // TODO(jacobr): cache the full class hierarchy so we can cheaply check
         // instanceRef is DiagnosticsNode without having to do an eval.
         if (instanceRef != null &&
-            (instanceRef.classRef.name == 'DiagnosticableTreeNode' ||
-                instanceRef.classRef.name == 'DiagnosticsProperty')) {
+            (instanceRef.classRef?.name == 'DiagnosticableTreeNode' ||
+                instanceRef.classRef?.name == 'DiagnosticsProperty')) {
           // The user is expecting to see the object the DiagnosticsNode is
           // describing not the DiagnosticsNode itself.
           try {
@@ -475,6 +494,25 @@ Future<void> buildVariablesTree(
   variable.treeInitializeComplete = true;
 }
 
+// TODO(elliette): Remove once the fix for dart-lang/webdev/issues/1439
+// is landed. This works around a bug in DWDS where an error is thrown if
+// `getObject` is called with offset/count for an object that has no length.
+Future<Obj> _getObjectWithRetry(
+  String objectId,
+  Variable variable,
+) async {
+  try {
+    final dynamic result = await serviceManager.service.getObject(
+        variable.ref.isolateRef.id, objectId,
+        offset: variable.offset, count: variable.childCount);
+    return result;
+  } catch (e) {
+    final dynamic result = await serviceManager.service
+        .getObject(variable.ref.isolateRef.id, objectId);
+    return result;
+  }
+}
+
 Future<Variable> _buildVariable(
   RemoteDiagnosticsNode diagnostic,
   ObjectGroupBase inspectorService,
@@ -528,8 +566,9 @@ List<Variable> _createVariablesForAssociations(
       value: association.value,
       isolateRef: isolateRef,
     );
+    final entryNum = instance.offset == null ? i : i + instance.offset;
     variables.add(
-      Variable.text('[Entry $i]')
+      Variable.text('[Entry $entryNum]')
         ..addChild(key)
         ..addChild(value),
     );
@@ -604,9 +643,10 @@ List<Variable> _createVariablesForBytes(
   }
 
   for (int i = 0; i < result.length; i++) {
+    final name = instance.offset == null ? i : i + instance.offset;
     variables.add(
       Variable.fromValue(
-        name: '[$i]',
+        name: '[$name]',
         value: result[i],
         isolateRef: isolateRef,
       ),
@@ -621,9 +661,10 @@ List<Variable> _createVariablesForElements(
 ) {
   final variables = <Variable>[];
   for (int i = 0; i < instance.elements.length; i++) {
+    final name = instance.offset == null ? i : i + instance.offset;
     variables.add(
       Variable.fromValue(
-        name: '[$i]',
+        name: '[$name]',
         value: instance.elements[i],
         isolateRef: isolateRef,
       ),
@@ -656,8 +697,13 @@ List<Variable> _createVariablesForFields(
 // InstanceRef objects have become sentinels.
 // TODO(jacobr): consider a new class name. This class is more just the data
 // model for a tree of Dart objects with properties rather than a "Variable".
+// TODO(elliette): Refactor to make name, ref, text named (and potentially
+// required?) parameters. Give ref a type.
 class Variable extends TreeNode<Variable> {
-  Variable._(this.name, ref, this.text) : _ref = ref {
+  Variable._(this.name, ref, this.text, {int offset, int childCount})
+      : _ref = ref,
+        _offset = offset,
+        _childCount = childCount {
     indentChildren = ref?.diagnostic?.style != DiagnosticsTreeStyle.flat;
   }
 
@@ -702,18 +748,58 @@ class Variable extends TreeNode<Variable> {
     return Variable._(null, null, text);
   }
 
+  factory Variable.grouping(
+    GenericInstanceRef ref, {
+    @required int offset,
+    @required int count,
+  }) {
+    return Variable._(
+      null,
+      ref,
+      '[$offset - ${offset + count - 1}]',
+      offset: offset,
+      childCount: count,
+    );
+  }
+
+  static const MAX_CHILDREN_IN_GROUPING = 100;
+
   final String text;
   final String name;
   GenericInstanceRef get ref => _ref;
   GenericInstanceRef _ref;
 
+  /// The point to fetch the variable from (in the case of large variables that
+  /// we fetch only parts of at a time).
+  int get offset => _offset ?? 0;
+
+  int _offset;
+
+  int get childCount {
+    if (_childCount != null) return _childCount;
+
+    final value = this.value;
+    if (value is InstanceRef) {
+      if (value.kind != null &&
+          (value.kind.endsWith('List') ||
+              value.kind == InstanceKind.kList ||
+              value.kind == InstanceKind.kMap)) {
+        return value.length ?? 0;
+      }
+    }
+
+    return 0;
+  }
+
+  int _childCount;
+
   bool treeInitializeStarted = false;
   bool treeInitializeComplete = false;
 
   @override
   bool get isExpandable {
-    if (treeInitializeComplete || children.isNotEmpty) {
-      return children.isNotEmpty;
+    if (treeInitializeComplete || children.isNotEmpty || childCount > 0) {
+      return children.isNotEmpty || childCount > 0;
     }
     final diagnostic = ref.diagnostic;
     if (diagnostic != null &&

packages/devtools_app/lib/src/utils.dart

@@ -188,7 +188,14 @@ T nullSafeMax<T extends num>(T a, T b) {
   return max<T>(a, b);
 }
 
-int log2(num x) => (log(x) / log(2)).floor();
+double logBase({@required int x, @required int base}) {
+  return log(x) / log(base);
+}
+
+int log2(num x) => (logBase(x: x.floor(), base: 2)).floor();
+
+int roundToNearestPow10(int x) =>
+    pow(10, logBase(x: x, base: 10).ceil()).floor();
 
 String isolateName(IsolateRef ref) {
   // analysis_server.dart.snapshot$main

packages/devtools_app/lib/src/vm_service_wrapper.dart

@@ -401,7 +401,14 @@ class VmServiceWrapper implements VmService {
     int offset,
     int count,
   }) {
-    return trackFuture('getObject', _vmService.getObject(isolateId, objectId));
+    return trackFuture(
+        'getObject',
+        _vmService.getObject(
+          isolateId,
+          objectId,
+          offset: offset,
+          count: count,
+        ));
   }
 
   @override

packages/devtools_app/macos/Runner.xcodeproj/project.pbxproj

@@ -308,9 +308,14 @@
 			files = (
 			);
 			inputPaths = (
+				"${PODS_ROOT}/Target Support Files/Pods-Runner/Pods-Runner-frameworks.sh",
+				"${BUILT_PRODUCTS_DIR}/file_selector_macos/file_selector_macos.framework",
+				"${BUILT_PRODUCTS_DIR}/url_launcher_macos/url_launcher_macos.framework",
 			);
 			name = "[CP] Embed Pods Frameworks";
 			outputPaths = (
+				"${TARGET_BUILD_DIR}/${FRAMEWORKS_FOLDER_PATH}/file_selector_macos.framework",
+				"${TARGET_BUILD_DIR}/${FRAMEWORKS_FOLDER_PATH}/url_launcher_macos.framework",
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;

packages/devtools_app/test/association_variable_test.dart

@@ -47,6 +47,7 @@ void main() {
       kind: InstanceKind.kMap,
       id: '123',
       classRef: null,
+      length: 2,
       associations: [
         MapAssociation(
           key: InstanceRef(
@@ -83,7 +84,8 @@ void main() {
       ),
       isolateRef,
     );
-    when(manager.service.getObject(any, any)).thenAnswer((_) async {
+    when(manager.service.getObject(any, any, offset: 0, count: 2))
+        .thenAnswer((_) async {
       return instance;
     });
 
@@ -111,6 +113,7 @@ void main() {
       kind: InstanceKind.kMap,
       id: '123',
       classRef: null,
+      length: 2,
       associations: [
         MapAssociation(
           key: InstanceRef(
@@ -141,7 +144,8 @@ void main() {
       ),
       isolateRef,
     );
-    when(manager.service.getObject(any, any)).thenAnswer((_) async {
+    when(manager.service.getObject(any, any, offset: 0, count: 2))
+        .thenAnswer((_) async {
       return instance;
     });
 
@@ -168,6 +172,7 @@ void main() {
       kind: InstanceKind.kMap,
       id: '123',
       classRef: null,
+      length: 2,
       associations: [
         MapAssociation(
           key: InstanceRef(
@@ -197,7 +202,8 @@ void main() {
       ),
       isolateRef,
     );
-    when(manager.service.getObject(any, any)).thenAnswer((_) async {
+    when(manager.service.getObject(any, any, offset: 0, count: 2))
+        .thenAnswer((_) async {
       return instance;
     });