Add base::TaskTraits::Override().

Add base::TaskTraits::Override().

Returns TaskTraits constructed by combining two TaskTraits. If a trait
is in both TaskTraits, the returned TaskTraits will have the value from
the second TaskTraits.

BUG=713683
R=gab@chromium.org,robliao@chromium.org

Review-Url: https://codereview.chromium.org/2873453002
Cr-Commit-Position: refs/heads/master@{#470377}
Committed: https://chromium.googlesource.com/chromium/src/+/6ef24a2589286dd4939a20dc1afddf4ecd9212a0

[fdoray, 2017-05-08 20:15:09]

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

[fdoray, 2017-05-08 20:15:19]

PTAL

[commit-bot: I haz the power, 2017-05-08 20:15:58]

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, 2017-05-08 21:11:40]

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

[commit-bot: I haz the power, 2017-05-08 21:11:41]

Dry run: Try jobs failed on following builders:
  cast_shell_linux on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)

[gab, 2017-05-09 14:32:32]

lgtm w/ comments

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
File base/task_scheduler/task.cc (right):

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task.cc:32: : traits.shutdown_behavior()})),
This is weird, I'd prefer not doing anything by default and overriding if
BLOCK_SHUTDOWN && delay

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
File base/task_scheduler/task_traits.h (right):

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task_traits.h:181: static constexpr TaskTraits Merge(const
TaskTraits& left,
s/Merge/Override/ as discussed.

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task_traits.h:232: // pattern.
drive-by thought:

Actually, this TODO will not be possible because of the need to support
operator=() for the STL.

But you'll still be able to say it's an immutable object in its meta-comment per
all its public methods being const (once builders are removed).

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
File base/task_scheduler/task_traits_unittest.cc (right):

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task_traits_unittest.cc:81:
TEST(TaskSchedulerTaskTraitsTest, MergePriority) {
Rename tests to "Override" too.

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task_traits_unittest.cc:87:
EXPECT_EQ(TaskShutdownBehavior::SKIP_ON_SHUTDOWN, merged.shutdown_behavior());
EXPECT_FALSE(shutdown_behavior_set_explitly) also + below

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task_traits_unittest.cc:151: }
Also test a big override of all values with some overriden, some not, e.g. :

left = {MayBlock(), TaskPriority::BACKGROUND,
TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN}

right = {WithBaseSyncPrimitives(), TaskPriority::USER_BLOCKING}

expected = {MayBlock(), WithBaseSyncPrimitives(), TaskPriority::USER_BLOCKING,
TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN}

[fdoray, 2017-05-09 14:57:37]

Description was changed from

==========
Add base::TaskTraits::Merge().

Returns TaskTraits constructed by merging two TaskTraits. If a trait
in both TaskTraits, the returned TaskTraits will have the value from
the second TaskTraits argument.

BUG=713683
R=gab@chromium.org,robliao@chromium.org
==========

to

==========
Add base::TaskTraits::Override().

Returns TaskTraits constructed by combining two TaskTraits. If a trait
is in both TaskTraits, the returned TaskTraits will have the value from
the second TaskTraits argument.

BUG=713683
R=gab@chromium.org,robliao@chromium.org
==========

[fdoray, 2017-05-09 14:57:48]

Description was changed from

==========
Add base::TaskTraits::Override().

Returns TaskTraits constructed by combining two TaskTraits. If a trait
is in both TaskTraits, the returned TaskTraits will have the value from
the second TaskTraits argument.

BUG=713683
R=gab@chromium.org,robliao@chromium.org
==========

to

==========
Add base::TaskTraits::Override().

Returns TaskTraits constructed by combining two TaskTraits. If a trait
is in both TaskTraits, the returned TaskTraits will have the value from
the second TaskTraits.

BUG=713683
R=gab@chromium.org,robliao@chromium.org
==========

[fdoray, 2017-05-09 14:57:57]

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

[fdoray, 2017-05-09 14:58:29]

The CQ bit was unchecked by fdoray@chromium.org

[fdoray, 2017-05-09 14:58:34]

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
File base/task_scheduler/task.cc (right):

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task.cc:32: : traits.shutdown_behavior()})),
On 2017/05/09 14:32:31, gab wrote:
> This is weird, I'd prefer not doing anything by default and overriding if
> BLOCK_SHUTDOWN && delay

Done.

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
File base/task_scheduler/task_traits.h (right):

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task_traits.h:181: static constexpr TaskTraits Merge(const
TaskTraits& left,
On 2017/05/09 14:32:31, gab wrote:
> s/Merge/Override/ as discussed.

Done.

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task_traits.h:232: // pattern.
On 2017/05/09 14:32:31, gab wrote:
> drive-by thought:
> 
> Actually, this TODO will not be possible because of the need to support
> operator=() for the STL.
> 
> But you'll still be able to say it's an immutable object in its meta-comment
per
> all its public methods being const (once builders are removed).

Acknowledged. TODO removed by upcoming CL.

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
File base/task_scheduler/task_traits_unittest.cc (right):

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task_traits_unittest.cc:81:
TEST(TaskSchedulerTaskTraitsTest, MergePriority) {
On 2017/05/09 14:32:31, gab wrote:
> Rename tests to "Override" too.

Done.

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task_traits_unittest.cc:87:
EXPECT_EQ(TaskShutdownBehavior::SKIP_ON_SHUTDOWN, merged.shutdown_behavior());
On 2017/05/09 14:32:31, gab wrote:
> EXPECT_FALSE(shutdown_behavior_set_explitly) also + below

Done.

https://codereview.chromium.org/2873453002/diff/20001/base/task_scheduler/tas...
base/task_scheduler/task_traits_unittest.cc:151: }
On 2017/05/09 14:32:31, gab wrote:
> Also test a big override of all values with some overriden, some not, e.g. :
> 
> left = {MayBlock(), TaskPriority::BACKGROUND,
> TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN}
> 
> right = {WithBaseSyncPrimitives(), TaskPriority::USER_BLOCKING}
> 
> expected = {MayBlock(), WithBaseSyncPrimitives(), TaskPriority::USER_BLOCKING,
> TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN}
> 

Done.

[fdoray, 2017-05-09 14:59:38]

The CQ bit was checked by fdoray@chromium.org

[fdoray, 2017-05-09 14:59:38]

The patchset sent to the CQ was uploaded after l-g-t-m from gab@chromium.org
Link to the patchset: https://codereview.chromium.org/2873453002/#ps40001
(title: "CR-gab")

[commit-bot: I haz the power, 2017-05-09 14:59:57]

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, 2017-05-09 18:00:24]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1494341978292060,
"parent_rev": "884274a17f127dcd2f60f545262c873a7fbbdfee", "commit_rev":
"6ef24a2589286dd4939a20dc1afddf4ecd9212a0"}

[commit-bot: I haz the power, 2017-05-09 18:00:35]

Description was changed from

==========
Add base::TaskTraits::Override().

Returns TaskTraits constructed by combining two TaskTraits. If a trait
is in both TaskTraits, the returned TaskTraits will have the value from
the second TaskTraits.

BUG=713683
R=gab@chromium.org,robliao@chromium.org
==========

to

==========
Add base::TaskTraits::Override().

Returns TaskTraits constructed by combining two TaskTraits. If a trait
is in both TaskTraits, the returned TaskTraits will have the value from
the second TaskTraits.

BUG=713683
R=gab@chromium.org,robliao@chromium.org

Review-Url: https://codereview.chromium.org/2873453002
Cr-Commit-Position: refs/heads/master@{#470377}
Committed:
https://chromium.googlesource.com/chromium/src/+/6ef24a2589286dd4939a20dc1afd...
==========

[commit-bot: I haz the power, 2017-05-09 18:00:37]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/chromium/src/+/6ef24a2589286dd4939a20dc1afd...

[robliao, 2017-05-09 22:01:33]

lgtm