Compute retained size for every object, using dominator trees.

Compute retained size for every object, using dominator trees.

Uses the Lenguaer-Tarjan algorithm.

Next step is to provide interface for "get top N most retaining objects (of class C)".

R=johnmccutchan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=42116

[koda, 2014-12-04 14:10:20]

Added dominator_tree_test.dart, PTAL.

[Cutch, 2014-12-04 18:34:54]

lgtm with comments

https://codereview.chromium.org/777693002/diff/60001/runtime/bin/vmservice/ob...
File runtime/bin/vmservice/observatory/lib/object_graph.dart (right):

https://codereview.chromium.org/777693002/diff/60001/runtime/bin/vmservice/ob...
runtime/bin/vmservice/observatory/lib/object_graph.dart:85: // The retained size
for an object is the sum of the shallow sizes of
could you fast path by checking if _retainedSize != null and return the already
computed result?

https://codereview.chromium.org/777693002/diff/60001/runtime/bin/vmservice/ob...
File runtime/bin/vmservice/observatory/test/graph_test.dart (right):

https://codereview.chromium.org/777693002/diff/60001/runtime/bin/vmservice/ob...
runtime/bin/vmservice/observatory/test/graph_test.dart:20: // Create 3 instances
of Foo, with out-degrees 0 (for b), 1 (for a), and 2 (for staticFoo).
Over 80 column limit here and elsewhere

https://codereview.chromium.org/777693002/diff/60001/runtime/bin/vmservice/ob...
runtime/bin/vmservice/observatory/test/graph_test.dart:30: lst[1] = new
List(123456); // Larger than any other fixed-size list in a fresh heap.
Over 80 column limit here and elsewhere

[koda, 2014-12-04 19:27:27]

https://codereview.chromium.org/777693002/diff/60001/runtime/bin/vmservice/ob...
File runtime/bin/vmservice/observatory/lib/object_graph.dart (right):

https://codereview.chromium.org/777693002/diff/60001/runtime/bin/vmservice/ob...
runtime/bin/vmservice/observatory/lib/object_graph.dart:85: // The retained size
for an object is the sum of the shallow sizes of
On 2014/12/04 18:34:54, Cutch wrote:
> could you fast path by checking if _retainedSize != null and return the
already
> computed result?

This private method is currently always called exactly once after building the
entire object graph from scratch in the constructor. (In the future, we might
want to allow some kind of incremental refresh for large heaps.)

https://codereview.chromium.org/777693002/diff/60001/runtime/bin/vmservice/ob...
File runtime/bin/vmservice/observatory/test/graph_test.dart (right):

https://codereview.chromium.org/777693002/diff/60001/runtime/bin/vmservice/ob...
runtime/bin/vmservice/observatory/test/graph_test.dart:20: // Create 3 instances
of Foo, with out-degrees 0 (for b), 1 (for a), and 2 (for staticFoo).
On 2014/12/04 18:34:54, Cutch wrote:
> Over 80 column limit here and elsewhere

Done.

https://codereview.chromium.org/777693002/diff/60001/runtime/bin/vmservice/ob...
runtime/bin/vmservice/observatory/test/graph_test.dart:30: lst[1] = new
List(123456); // Larger than any other fixed-size list in a fresh heap.
On 2014/12/04 18:34:54, Cutch wrote:
> Over 80 column limit here and elsewhere

Done.

[koda, 2014-12-04 20:56:08]

Committed patchset #4 (id:60001) manually as r42116 (presubmit successful).