Make VM event streams look like real dart streams.

Make VM event streams look like real dart streams.

This is a bit ugly in that vm event streams are created
asynchronously, which is not very natural with the dart libs.

Update tests accordingly.

BUG=
R=johnmccutchan@google.com

Committed: https://github.com/dart-lang/sdk/commit/c4dad3117a700f8b0915388ed485de71c324bf79

[turnidge, 2015-07-07 20:23:56]

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

[Cutch, 2015-07-07 23:16:09]

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/lib...
File runtime/observatory/lib/src/elements/debugger.dart (right):

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/debugger.dart:1281:
_isolateSubscriptionFuture.then((subscription) => subscription.cancel());
Bracket with `if (_isolateSubscriptionFuture != null)` ? I might be being
paranoid but I wouldn't be surprised if Polymer called detached in a weird
order.

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/lib...
File runtime/observatory/lib/src/elements/heap_profile.dart (right):

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/heap_profile.dart:96: _subscriptionFuture =
app.vm.getGCEventStream().then((stream) {
This looks like the code in the previous file. Can this code be factored into a
helper?

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/heap_profile.dart:103:
_subscriptionFuture.then((subscription) => subscription.cancel());
ditto?

void cancelFutureSubscription(Future<StreamSubscription> futureSubscription) {
  if (futureSubscription == null) {
    return;
  }
  futureSubscription.then(.....
}

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/tes...
File runtime/observatory/tests/service/code_test.dart (right):

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/tes...
runtime/observatory/tests/service/code_test.dart:37:
isolate.vm.getDebugEventStream().then((stream) {
Replace with:

await isolate.addBreakpoint(script, line);
await hasStoppedAtBreakpoint(isolate);

?

[turnidge, 2015-07-08 20:23:39]

Please take another look.

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/lib...
File runtime/observatory/lib/src/elements/debugger.dart (right):

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/debugger.dart:1281:
_isolateSubscriptionFuture.then((subscription) => subscription.cancel());
On 2015/07/07 23:16:09, Cutch wrote:
> Bracket with `if (_isolateSubscriptionFuture != null)` ? I might be being
> paranoid but I wouldn't be surprised if Polymer called detached in a weird
> order.

Done.

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/lib...
File runtime/observatory/lib/src/elements/heap_profile.dart (right):

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/heap_profile.dart:96: _subscriptionFuture =
app.vm.getGCEventStream().then((stream) {
On 2015/07/07 23:16:09, Cutch wrote:
> This looks like the code in the previous file. Can this code be factored into
a
> helper?

Done.

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/lib...
runtime/observatory/lib/src/elements/heap_profile.dart:103:
_subscriptionFuture.then((subscription) => subscription.cancel());
On 2015/07/07 23:16:09, Cutch wrote:
> ditto?
> 
> void cancelFutureSubscription(Future<StreamSubscription> futureSubscription) {
>   if (futureSubscription == null) {
>     return;
>   }
>   futureSubscription.then(.....
> }

Done.

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/tes...
File runtime/observatory/tests/service/code_test.dart (right):

https://codereview.chromium.org/1217823009/diff/20001/runtime/observatory/tes...
runtime/observatory/tests/service/code_test.dart:37:
isolate.vm.getDebugEventStream().then((stream) {
On 2015/07/07 23:16:09, Cutch wrote:
> Replace with:
> 
> await isolate.addBreakpoint(script, line);
> await hasStoppedAtBreakpoint(isolate);
> 
> ?

My preference is to modify the tests as little as possible and allow test
cleanup/refactoring to go in a different cl.

[Cutch, 2015-07-08 20:27:03]

lgtm

[turnidge, 2015-07-08 21:19:04]

Committed patchset #6 (id:100001) manually as
c4dad3117a700f8b0915388ed485de71c324bf79 (presubmit successful).