Improve profile stats performace.

Improve profile stats performace.

Collecting stats on prefs can take a lot of allocations and times to copy the whole preferences tree.

Adds an iterator-with-callback API to read the preferences without copying. This is now used in prefs stats. The other two similar APIs in the preferences service have been coalesced with a flag controlling whether you want default prefs.

BUG=708793
Review-Url: https://codereview.chromium.org/2799143002
Cr-Commit-Position: refs/heads/master@{#465374}
Committed: https://chromium.googlesource.com/chromium/src/+/ebf7184f6f68e5b60a5247b65bb008a7b3ca1fb0

[brettw, 2017-04-05 23:59:34]

Description was changed from

==========
Improve profile stats performace.

Collecting stats on prefs can take a lot of allocations and times to copy the
whole preferences tree.

This change first collects profile stats only 1/100 times. This is enough
sampling to get good stats on bookmarks and prefs usage while mostly eliminating
the overhead.

Also adds an iterator-with-callback API to read the preferences without copying.
This is now used in prefs stats. The other two similar APIs in the preferences
service have been coalesced with a flag controlling whether you want default
prefs.
==========

to

==========
Improve profile stats performace.

Collecting stats on prefs can take a lot of allocations and times to copy the
whole preferences tree.

This change first collects profile stats only 1/100 times. This is enough
sampling to get good stats on bookmarks and prefs usage while mostly eliminating
the overhead.

Also adds an iterator-with-callback API to read the preferences without copying.
This is now used in prefs stats. The other two similar APIs in the preferences
service have been coalesced with a flag controlling whether you want default
prefs.

BUG=708793
==========

[brettw, 2017-04-06 00:00:50]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-04-06 00:01:52]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-06 00:16:49]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-04-06 00:16:51]

Dry run: Try jobs failed on following builders:
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[brettw, 2017-04-10 18:01:56]

Description was changed from

==========
Improve profile stats performace.

Collecting stats on prefs can take a lot of allocations and times to copy the
whole preferences tree.

This change first collects profile stats only 1/100 times. This is enough
sampling to get good stats on bookmarks and prefs usage while mostly eliminating
the overhead.

Also adds an iterator-with-callback API to read the preferences without copying.
This is now used in prefs stats. The other two similar APIs in the preferences
service have been coalesced with a flag controlling whether you want default
prefs.

BUG=708793
==========

to

==========
Improve profile stats performace.

Collecting stats on prefs can take a lot of allocations and times to copy the
whole preferences tree.

Adds an iterator-with-callback API to read the preferences without copying. This
is now used in prefs stats. The other two similar APIs in the preferences
service have been coalesced with a flag controlling whether you want default
prefs.

BUG=708793
==========

[brettw, 2017-04-10 18:02:46]

Always

[brettw, 2017-04-10 18:04:53]

brettw@chromium.org changed reviewers:
+ rogerta@chromium.org

[brettw, 2017-04-10 18:04:53]

Hi, you worked on the code review that added this here:
https://codereview.chromium.org/1248613003

[brettw, 2017-04-10 18:04:58]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-04-10 18:05:36]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-10 20:09:06]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-04-10 20:09:07]

Dry run: This issue passed the CQ dry run.

[brettw, 2017-04-11 19:53:08]

For context I wrote this before I decided it would be better to delete the code.
Since it may take a while to remove, it seems better to land in the meantime.

[Roger Tawa OOO till Jul 10th, 2017-04-11 21:04:30]

lgtm with one comment below.  Thanks Brett.

https://codereview.chromium.org/2799143002/diff/20001/components/prefs/pref_s...
File components/prefs/pref_service.h (right):

https://codereview.chromium.org/2799143002/diff/20001/components/prefs/pref_s...
components/prefs/pref_service.h:268: bool include_defaults) const;
Would be better if this were an enum instead of a bool to make it more explicit.
 As I started this code review, I could not tell what true or false meant until
I got to the end.

[brettw, 2017-04-18 19:28:39]

https://codereview.chromium.org/2799143002/diff/20001/components/prefs/pref_s...
File components/prefs/pref_service.h (right):

https://codereview.chromium.org/2799143002/diff/20001/components/prefs/pref_s...
components/prefs/pref_service.h:268: bool include_defaults) const;
Done

[brettw, 2017-04-18 19:28:43]

Use enum

[brettw, 2017-04-18 19:28:44]

The CQ bit was checked by brettw@chromium.org

[brettw, 2017-04-18 19:28:44]

The patchset sent to the CQ was uploaded after l-g-t-m from rogerta@chromium.org
Link to the patchset: https://codereview.chromium.org/2799143002/#ps40001
(title: "Use enum")

[commit-bot: I haz the power, 2017-04-18 19:29:18]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-18 21:10:56]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1492543724004500,
"parent_rev": "31b31da235decd6c593745e98f77b55ff9270cb4", "commit_rev":
"ebf7184f6f68e5b60a5247b65bb008a7b3ca1fb0"}

[commit-bot: I haz the power, 2017-04-18 21:11:07]

Description was changed from

==========
Improve profile stats performace.

Collecting stats on prefs can take a lot of allocations and times to copy the
whole preferences tree.

Adds an iterator-with-callback API to read the preferences without copying. This
is now used in prefs stats. The other two similar APIs in the preferences
service have been coalesced with a flag controlling whether you want default
prefs.

BUG=708793
==========

to

==========
Improve profile stats performace.

Collecting stats on prefs can take a lot of allocations and times to copy the
whole preferences tree.

Adds an iterator-with-callback API to read the preferences without copying. This
is now used in prefs stats. The other two similar APIs in the preferences
service have been coalesced with a flag controlling whether you want default
prefs.

BUG=708793

Review-Url: https://codereview.chromium.org/2799143002
Cr-Commit-Position: refs/heads/master@{#465374}
Committed:
https://chromium.googlesource.com/chromium/src/+/ebf7184f6f68e5b60a5247b65bb0...
==========

[commit-bot: I haz the power, 2017-04-18 21:11:08]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/chromium/src/+/ebf7184f6f68e5b60a5247b65bb0...