Add flags for disabling the diagnostic server or setting its port (#3352)

Fixes https://github.com/flutter/flutter/issues/7557

common/settings.h

@@ -17,6 +17,8 @@ struct Settings {
   // Port on target will be auto selected by the OS. A message will be printed
   // on the target with the port after it has been selected.
   uint32_t observatory_port = 0;
+  bool enable_diagnostic = false;
+  uint32_t diagnostic_port = 0;
   bool start_paused = false;
   bool trace_startup = false;
   bool endless_trace_buffer = false;

shell/common/diagnostic/diagnostic_server.cc

@@ -31,6 +31,7 @@ using tonic::DartLibraryNatives;
 using blink::EmbedderResources;
 using tonic::DartInvokeField;
 using tonic::LogIfError;
+using tonic::ToDart;
 
 namespace {
 
@@ -60,7 +61,7 @@ void SendNull(Dart_Port port_id) {
 
 DART_NATIVE_CALLBACK_STATIC(DiagnosticServer, HandleSkiaPictureRequest);
 
-void DiagnosticServer::Start() {
+void DiagnosticServer::Start(uint32_t port) {
   if (!g_natives) {
     g_natives = new DartLibraryNatives();
     g_natives->Register({
@@ -91,7 +92,7 @@ void DiagnosticServer::Start() {
 
   FTL_CHECK(!LogIfError(Dart_FinalizeLoading(false)));
 
-  DartInvokeField(Dart_RootLibrary(), "diagnosticServerStart", {});
+  DartInvokeField(Dart_RootLibrary(), "diagnosticServerStart", {ToDart(port)});
 }
 
 void DiagnosticServer::HandleSkiaPictureRequest(Dart_Handle send_port) {

shell/common/diagnostic/diagnostic_server.dart

@@ -11,8 +11,8 @@ import 'dart:typed_data';
 void handleSkiaPictureRequest(SendPort sendPort)
     native 'DiagnosticServer_HandleSkiaPictureRequest';
 
-void diagnosticServerStart() {
-  HttpServer.bind('127.0.0.1', 0).then((HttpServer server) {
+void diagnosticServerStart(int port) {
+  HttpServer.bind('127.0.0.1', port).then((HttpServer server) {
     server.listen(dispatchRequest, cancelOnError: true);
 
     String ip = server.address.address.toString();

shell/common/diagnostic/diagnostic_server.h

@@ -11,7 +11,7 @@ namespace shell {
 
 class DiagnosticServer {
  public:
-  static void Start();
+  static void Start(uint32_t port);
   static void HandleSkiaPictureRequest(Dart_Handle send_port);
 
  private:

shell/common/shell.cc

@@ -42,6 +42,18 @@ bool IsViewInvalid(const ftl::WeakPtr<PlatformView>& platform_view) {
   return !platform_view;
 }
 
+template <typename T> bool GetSwitchValue(const base::CommandLine& command_line,
+                                          Switch sw, T* result) {
+  auto port_string = command_line.GetSwitchValueASCII(FlagForSwitch(sw));
+  std::stringstream stream(port_string);
+  T value = 0;
+  if (stream >> value) {
+    *result = value;
+    return true;
+  }
+  return false;
+}
+
 class NonDiscardableMemory : public base::DiscardableMemory {
  public:
   explicit NonDiscardableMemory(size_t size) : data_(new uint8_t[size]) {}
@@ -66,8 +78,8 @@ base::LazyInstance<NonDiscardableMemoryAllocator> g_discardable;
 void ServiceIsolateHook(bool running_precompiled) {
   if (!running_precompiled) {
     const blink::Settings& settings = blink::Settings::Get();
-    if (settings.enable_observatory)
-      DiagnosticServer::Start();
+    if (settings.enable_diagnostic)
+      DiagnosticServer::Start(settings.diagnostic_port);
   }
 }
 
@@ -135,19 +147,26 @@ void Shell::InitStandalone(std::string icu_data_path,
 
   // Set Observatory Port
   if (command_line.HasSwitch(FlagForSwitch(Switch::DeviceObservatoryPort))) {
-    auto port_string = command_line.GetSwitchValueASCII(
-        FlagForSwitch(Switch::DeviceObservatoryPort));
-    std::stringstream stream(port_string);
-    uint32_t port = 0;
-    if (stream >> port) {
-      settings.observatory_port = port;
-    } else {
+    if (!GetSwitchValue(command_line, Switch::DeviceObservatoryPort,
+                        &settings.observatory_port)) {
       FTL_LOG(INFO)
           << "Observatory port specified was malformed. Will default to "
           << settings.observatory_port;
     }
   }
 
+  settings.enable_diagnostic =
+      !command_line.HasSwitch(FlagForSwitch(Switch::DisableDiagnostic));
+
+  if (command_line.HasSwitch(FlagForSwitch(Switch::DeviceDiagnosticPort))) {
+    if (!GetSwitchValue(command_line, Switch::DeviceDiagnosticPort,
+                        &settings.diagnostic_port)) {
+      FTL_LOG(INFO)
+          << "Diagnostic port specified was malformed. Will default to "
+          << settings.diagnostic_port;
+    }
+  }
+
   settings.start_paused =
       command_line.HasSwitch(FlagForSwitch(Switch::StartPaused));
 

shell/common/switches.h

@@ -43,6 +43,13 @@ DEF_SWITCH(DisableObservatory,
            "disable-observatory",
            "Disable the Dart Observatory. The observatory is never available "
            "in release mode.")
+DEF_SWITCH(DeviceDiagnosticPort,
+           "diagnostic-port",
+           "A custom diagnostic server port.")
+DEF_SWITCH(DisableDiagnostic,
+           "disable-diagnostic",
+           "Disable the diagnostic server. The diagnostic server is never "
+           "available in release mode.")
 DEF_SWITCH(EnableDartProfiling,
            "enable-dart-profiling",
            "Enable Dart profiling. Profiling information can be viewed from "