Reduce service isolate startup time from ~80ms to ~30ms

runtime/bin/main.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 #include "include/dart_api.h"
 #include "include/dart_debugger_api.h"
@@ skipping 55 matching lines @@
 static bool has_print_script = false;
 
 
 static const char* DEFAULT_VM_SERVICE_SERVER_IP = "127.0.0.1";
 static const int DEFAULT_VM_SERVICE_SERVER_PORT = 8181;
 // VM Service options.
 static bool start_vm_service = false;
 static const char* vm_service_server_ip = DEFAULT_VM_SERVICE_SERVER_IP;
 // The 0 port is a magic value which results in the first available port
 // being allocated.
-static int vm_service_server_port = 0;
+static int vm_service_server_port = -1;
 
 // The environment provided through the command line using -D options.
 static dart::HashMap* environment = NULL;
 
 static bool IsValidFlag(const char* name,
                         const char* prefix,
                         intptr_t prefix_length) {
   intptr_t name_length = strlen(name);
   return ((name_length > prefix_length) &&
           (strncmp(name, prefix, prefix_length) == 0));
@@ skipping 596 matching lines @@
   result = Dart_SetEnvironmentCallback(EnvironmentCallback);
   CHECK_RESULT(result);
   // Prepare builtin and its dependent libraries for use to resolve URIs.
   Dart_Handle builtin_lib =
       Builtin::LoadAndCheckLibrary(Builtin::kBuiltinLibrary);
   CHECK_RESULT(builtin_lib);
   // Prepare for script loading by setting up the 'print' and 'timer'
   // closures and setting up 'package root' for URI resolution.
   result = DartUtils::PrepareForScriptLoading(package_root, builtin_lib);
   CHECK_RESULT(result);
-  Platform::SetPackageRoot(package_root);
-  Dart_Handle io_lib_url = DartUtils::NewString(DartUtils::kIOLibURL);
-  CHECK_RESULT(io_lib_url);
-  Dart_Handle io_lib = Dart_LookupLibrary(io_lib_url);
-  CHECK_RESULT(io_lib);
-  Dart_Handle platform_type = DartUtils::GetDartType(DartUtils::kIOLibURL,
-                                                     "_Platform");
-  CHECK_RESULT(platform_type);
-  Dart_Handle script_name = DartUtils::NewString("_nativeScript");
-  CHECK_RESULT(script_name);
-  Dart_Handle dart_script = DartUtils::NewString(script_uri);
-  CHECK_RESULT(dart_script);
-  Dart_Handle set_script_name =
-      Dart_SetField(platform_type, script_name, dart_script);
-  CHECK_RESULT(set_script_name);
+
   Dart_ExitScope();
   Dart_ExitIsolate();
   return isolate;
 }
 
 #undef CHECK_RESULT
 
 static void PrintVersion() {
   Log::PrintErr("Dart VM version: %s\n", Dart_VersionString());
 }
@@ skipping 455 matching lines @@
   exit(Process::GlobalExitCode());
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   dart::bin::main(argc, argv);
   UNREACHABLE();
 }