Introduce PlatformThread::Detach

Introduce PlatformThread::Detach

This will allow callers to decide at runtime if they want to detach or join
against a thread. This is particularly useful for threadpools that need to
detach to release resources or join to clean up during unit tests.

BUG=616867
Committed: https://crrev.com/fecb785376a19f0ee4fd965b9568c59fa26fae01
Cr-Commit-Position: refs/heads/master@{#399280}

[robliao, 2016-06-02 21:40:54]

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

[commit-bot: I haz the power, 2016-06-02 21:42:13]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2033243002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/2033243002/1

[commit-bot: I haz the power, 2016-06-03 03:00:37]

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

[commit-bot: I haz the power, 2016-06-03 03:00:39]

Dry run: This issue passed the CQ dry run.

[robliao, 2016-06-07 16:00:33]

robliao@chromium.org changed reviewers:
+ danakj@chromium.org

[robliao, 2016-06-07 16:00:34]

danakj: Please review this CL. Thanks!

[danakj, 2016-06-09 22:58:07]

https://codereview.chromium.org/2033243002/diff/1/base/threading/platform_thr...
File base/threading/platform_thread.h (right):

https://codereview.chromium.org/2033243002/diff/1/base/threading/platform_thr...
base/threading/platform_thread.h:184: // after this call.
And the PlatformThreadHandle becomes invalid?

On windows this has no effect if the thread is the current thread. What happens
on posix? Do we want to support this?

https://codereview.chromium.org/2033243002/diff/1/base/threading/platform_thr...
File base/threading/platform_thread_win.cc (right):

https://codereview.chromium.org/2033243002/diff/1/base/threading/platform_thr...
base/threading/platform_thread_win.cc:222: // Debug info for bug 127931.
Oh fun, this bug is fixed, maybe you can clean this up, and change the CHECK to
a DCHECK again? (maybe in another CL?)

[robliao, 2016-06-10 14:24:31]

https://codereview.chromium.org/2033243002/diff/1/base/threading/platform_thr...
File base/threading/platform_thread.h (right):

https://codereview.chromium.org/2033243002/diff/1/base/threading/platform_thr...
base/threading/platform_thread.h:184: // after this call.
On 2016/06/09 22:58:07, danakj wrote:
> And the PlatformThreadHandle becomes invalid?
> 
> On windows this has no effect if the thread is the current thread. What
happens
> on posix? Do we want to support this?

Yup, the PlatformThreadHandle becomes invalid. Updated comment.

I think what you mean is Windows is okay if the handle represents the current
thread. Yes, as handles apply to the entire process. POSIX doesn't seem to mind
either (return value 0). Since the underlying platforms support it, I think it's
fine if we support it as well. I don't see a reason why not.

https://codereview.chromium.org/2033243002/diff/1/base/threading/platform_thr...
File base/threading/platform_thread_win.cc (right):

https://codereview.chromium.org/2033243002/diff/1/base/threading/platform_thr...
base/threading/platform_thread_win.cc:222: // Debug info for bug 127931.
Clean up done at https://codereview.chromium.org/2053393002/

We should keep this as a CHECK similar to POSIX, as failing to join is quite
bad.

[danakj, 2016-06-10 17:40:07]

LGTM

[robliao, 2016-06-10 18:07:01]

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

[commit-bot: I haz the power, 2016-06-10 18:07:30]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2033243002/20001

[commit-bot: I haz the power, 2016-06-10 20:23:00]

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

[commit-bot: I haz the power, 2016-06-10 20:23:01]

Dry run: This issue passed the CQ dry run.

[robliao, 2016-06-10 21:40:07]

The CQ bit was checked by robliao@chromium.org

[commit-bot: I haz the power, 2016-06-10 21:40:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2033243002/20001

[commit-bot: I haz the power, 2016-06-10 21:47:35]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-06-10 21:48:01]

CQ bit was unchecked

[commit-bot: I haz the power, 2016-06-10 21:51:03]

Description was changed from

==========
Introduce PlatformThread::Detach

This will allow callers to decide at runtime if they want to detach or join
against a thread. This is particularly useful for threadpools that need to
detach to release resources or join to clean up during unit tests.

BUG=616867
==========

to

==========
Introduce PlatformThread::Detach

This will allow callers to decide at runtime if they want to detach or join
against a thread. This is particularly useful for threadpools that need to
detach to release resources or join to clean up during unit tests.

BUG=616867

Committed: https://crrev.com/fecb785376a19f0ee4fd965b9568c59fa26fae01
Cr-Commit-Position: refs/heads/master@{#399280}
==========

[commit-bot: I haz the power, 2016-06-10 21:51:04]

Patchset 2 (id:??) landed as
https://crrev.com/fecb785376a19f0ee4fd965b9568c59fa26fae01
Cr-Commit-Position: refs/heads/master@{#399280}