Add ticks counter to Timer.

Add ticks counter to Timer.

Avoid VM scheduling multiple timer events if it gets delayed. This doesn't
scale for processes that are suspended for extended amounts of time.

R=floitsch@google.com

Committed: https://github.com/dart-lang/sdk/commit/39c8f64ea3cc55d6d866a184a18f379b8b6fa3bf

[Lasse Reichstein Nielsen, 2017-08-25 08:46:55]

lrn@google.com changed reviewers:
+ floitsch@google.com

[floitsch, 2017-08-25 09:16:48]

LGTM.

Write a test that busy-loops until 2 timer durations have passed and then check
that the timer ticks are correct.

https://codereview.chromium.org/3003853002/diff/1/sdk/lib/async/timer.dart
File sdk/lib/async/timer.dart (right):

https://codereview.chromium.org/3003853002/diff/1/sdk/lib/async/timer.dart#ne...
sdk/lib/async/timer.dart:105: * that more than one event is due at the time when
the timer gets to run,
If a periodic timer with a non-zero duration is delayed too much, ticks in the
past are considered "missed", and no callback is invoked for them. The [tick]
count reflects the number of durations that have passed and not the number of
callback invocations that have happened.

[Lasse Reichstein Nielsen, 2017-08-28 09:44:23]

PTAL

[floitsch, 2017-08-28 10:54:08]

LGTM.

[Lasse Reichstein Nielsen, 2017-08-28 10:57:48]

Description was changed from

==========
Add ticks counter to Timer.

Avoid VM scheduling multiple timer events if it gets delayed. This doesn't
scale for processes that are suspended for extended amounts of time.
==========

to

==========
Add ticks counter to Timer.

Avoid VM scheduling multiple timer events if it gets delayed. This doesn't
scale for processes that are suspended for extended amounts of time.

R=floitsch@google.com

Committed:
https://github.com/dart-lang/sdk/commit/39c8f64ea3cc55d6d866a184a18f379b8b6fa3bf
==========

[Lasse Reichstein Nielsen, 2017-08-28 10:57:50]

Committed patchset #4 (id:60001) manually as
39c8f64ea3cc55d6d866a184a18f379b8b6fa3bf (presubmit successful).

[floitsch, 2017-09-21 23:06:46]

https://codereview.chromium.org/3003853002/diff/60001/sdk/lib/async/timer.dart
File sdk/lib/async/timer.dart (right):

https://codereview.chromium.org/3003853002/diff/60001/sdk/lib/async/timer.dar...
sdk/lib/async/timer.dart:99: * The number of durations preceeding the most
recent timer event.
preceding