1476380 - Remove the spin wait in Android gfxVRExternal PullState calls

Status: RESOLVED FIXED

(Core :: WebVR, enhancement)

Description

[Imanol Fernandez]

gfxVRExternal is using spin wait on Android instead of condition variables to wait for some conditions. This drains the battery on Android, specially when the headset goes to sleep, or Android activity gets paused: WebVR thread is constantly waiting for an update.

Comment 1

[Imanol Fernandez]

Attachment: Patch that gets rid of Android spin waits

This patch that gets rid Android spin waits and used condition variables instead. I added a optional lambda function to PullState method which makes the Pullstate method to wait for state changes until the lambda condition is satisfied (== returns true). This way we can reuse the smae wait algorithm from different places (e.g. waiting for enumaration and waiting for a SubmitFrame result)

Comment 2

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

Comment on attachment 8992735 [details] [diff] [review]
Patch that gets rid of Android spin waits

checkin will be requested once the patch has been reviewed. Setting the keyword 'checkin-needed' is preferred.

Comment 3

[Imanol Fernandez]

Attachment: spin_wait_patch_v2.diff

Implemented the changes that Kip requested

Comment 4

[:kip (Kearwood Gilbert)]

Comment on attachment 8992923 [details] [diff] [review]
spin_wait_patch_v2.diff

This LGTM, Thanks!

Comment 5

[Imanol Fernandez]

Attachment: Bug 1476380 - Remove the spin wait in Android gfxVRExternal PullState calls;

Review commit: https://reviewboard.mozilla.org/r/259086/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/259086/

Comment 6

[:kip (Kearwood Gilbert)]

Comment on attachment 8994537 [details]
Bug 1476380 - Remove the spin wait in Android gfxVRExternal PullState calls;

https://reviewboard.mozilla.org/r/259086/#review266148

LGTM, Thanks!

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/30b7766e0f82
Remove the spin wait in Android gfxVRExternal PullState calls; r=kip

Comment 8

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/30b7766e0f82

Comment 9

[:kip (Kearwood Gilbert)]

Comment on attachment 8992735 [details] [diff] [review]
Patch that gets rid of Android spin waits

Clearing review request, as other patch was landed.