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

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

- Get access to dart:io internal signal listening function using API instead of mirrors.

- Service isolate can start with service deactivated.
- Load Observatory front end resources only when service activated.
- Do not execute Dart Service code until service is activated.
- Register live isolates when service is activated.

- Startup refactored to allow for future use of script snapshots.

R=asiva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=40124

[Cutch, 2014-09-08 20:54:03]

johnmccutchan@google.com changed reviewers:
+ asiva@google.com

[siva, 2014-09-09 00:40:59]

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
File runtime/bin/vmservice_impl.cc (right):

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
runtime/bin/vmservice_impl.cc:106: {"VMServiceIO_TriggerResourceLoad", 0,
TriggerResourceLoad},
in resources.dart triggerResourceLoad is not declared as a static
function but here you have 0 arguments for it, how will this
get resolved correctly?

void _triggerResourceLoad() native "VMServiceIO_TriggerResourceLoad";

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
runtime/bin/vmservice_impl.cc:164: }
Why is this is a special scope?

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
runtime/bin/vmservice_impl.cc:203: Dart_NewBoolean(is_windows));
Can write this:
#if defined(TARGET_OS_WINDOWS)
Dart_Handle is_windows = Dart_True();
#else
Dart_Handle is_windows = Dart_False();
#endif

Dart_SetField(...., is_windows);

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
runtime/bin/vmservice_impl.cc:209: Dart_Handle dart_io_str =
Dart_NewStringFromCString("dart:io");
use DartUtils::kIOLibURL instead of "dart:io"

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
runtime/bin/vmservice_impl.cc:218: }
Ditto question about why these two blocks are setup in special scopes?

https://codereview.chromium.org/533073005/diff/120001/runtime/vm/service.cc
File runtime/vm/service.cc (right):

https://codereview.chromium.org/533073005/diff/120001/runtime/vm/service.cc#n...
runtime/vm/service.cc:343: return ReceivePort::Cast(rp).Id();
The more standard way to write this is:

static Dart_port ExtractPort(Isolate* isolate, Dart_Handle receivePort) {
  HANDLESCOPE(isolate);
  const ReceivePort rp = Api::UnwrapReceivePortHandle(isolate, receivePort);
  if (rp.IsNull()) {
    return ILLEGAL_PORT;
  }

Also since you are calling this from OnStart which already has a HANDLESCOPE not
sure if another handle scope is needed here, it seems to create only 1 handle
and there is no loop.
  return rp.Id();
}

https://codereview.chromium.org/533073005/diff/120001/runtime/vm/service.cc#n...
runtime/vm/service.cc:360: result = Dart_Invoke(library,
Dart_NewStringFromCString("boot"), 0, NULL);
Dart_Handle result = Dart_Invoke(...);

https://codereview.chromium.org/533073005/diff/120001/runtime/vm/service.cc#n...
runtime/vm/service.cc:362: Dart_Port port = ExtractPort(result);
ExtractPort(isolate, result);

[Cutch, 2014-09-10 15:11:23]

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
File runtime/bin/vmservice_impl.cc (right):

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
runtime/bin/vmservice_impl.cc:164: }
On 2014/09/09 00:40:58, siva wrote:
> Why is this is a special scope?

I was using scoped timers. Removing extra scopes.

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
runtime/bin/vmservice_impl.cc:203: Dart_NewBoolean(is_windows));
On 2014/09/09 00:40:58, siva wrote:
> Can write this:
> #if defined(TARGET_OS_WINDOWS)
> Dart_Handle is_windows = Dart_True();
> #else
> Dart_Handle is_windows = Dart_False();
> #endif
> 
> Dart_SetField(...., is_windows);

Done.

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
runtime/bin/vmservice_impl.cc:209: Dart_Handle dart_io_str =
Dart_NewStringFromCString("dart:io");
On 2014/09/09 00:40:58, siva wrote:
> use DartUtils::kIOLibURL instead of "dart:io"

Done.

https://codereview.chromium.org/533073005/diff/120001/runtime/bin/vmservice_i...
runtime/bin/vmservice_impl.cc:218: }
On 2014/09/09 00:40:58, siva wrote:
> Ditto question about why these two blocks are setup in special scopes?

Done here and elsewhere.

https://codereview.chromium.org/533073005/diff/120001/runtime/vm/service.cc
File runtime/vm/service.cc (right):

https://codereview.chromium.org/533073005/diff/120001/runtime/vm/service.cc#n...
runtime/vm/service.cc:343: return ReceivePort::Cast(rp).Id();
On 2014/09/09 00:40:58, siva wrote:
> The more standard way to write this is:
> 
> static Dart_port ExtractPort(Isolate* isolate, Dart_Handle receivePort) {
>   HANDLESCOPE(isolate);
>   const ReceivePort rp = Api::UnwrapReceivePortHandle(isolate, receivePort);
>   if (rp.IsNull()) {
>     return ILLEGAL_PORT;
>   }
> 
> Also since you are calling this from OnStart which already has a HANDLESCOPE
not
> sure if another handle scope is needed here, it seems to create only 1 handle
> and there is no loop.
>   return rp.Id();
> }

Done.

https://codereview.chromium.org/533073005/diff/120001/runtime/vm/service.cc#n...
runtime/vm/service.cc:360: result = Dart_Invoke(library,
Dart_NewStringFromCString("boot"), 0, NULL);
On 2014/09/09 00:40:58, siva wrote:
> Dart_Handle result = Dart_Invoke(...);

Done.

https://codereview.chromium.org/533073005/diff/120001/runtime/vm/service.cc#n...
runtime/vm/service.cc:362: Dart_Port port = ExtractPort(result);
On 2014/09/09 00:40:58, siva wrote:
> ExtractPort(isolate, result);

Done.

[siva, 2014-09-10 22:20:08]

lgtm

[Cutch, 2014-09-10 22:38:41]

Committed patchset #9 (id:160001) manually as 40124 (presubmit successful).