layout: Load Web fonts asynchronously.

[pcwalton]

Improves page load times significantly.

Closes #7343.

[highfive]

Warning

• These commits modify layout code, but no reftests are modified. Please consider adding a reftest!

[pcwalton]

r? @mbrubeck

[jdm]

I think I'd prefer this use the official async network request API, rather than the ad-hoc version it currently does.

[pcwalton]

Updated to use the API suggested by @jdm.

[bors-servo]

☔ The latest upstream changes (presumably #7559) made this pull request unmergeable. Please resolve the merge conflicts.

[pcwalton]

@jdm Did you have any more comments on this? I don't recall if we discussed anything more on IRC.

[jdm]

My preference would be to integrate the network requests with some existing thread's event loop, rather than spawning two new threads per requested font.

[pcwalton]

I eliminated one thread by using the router and the other one by integrating into the layout task event loop. r? @mbrubeck

[jdm]

Thanks!

[mbrubeck]

-S-awaiting-review +S-needs-code-changes

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Reviewed 9 of 9 files at r1.
Review status: all files reviewed at latest revision, 3 unresolved discussions, all commit checks successful.

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^{components/gfx/font_cache_task.rs, line 158 [r1] (raw file):}
This should check whether the ResponseComplete message contains an Err status.

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^{components/gfx/font_cache_task.rs, line 358 [r1] (raw file):}
This result isn't read anywhere. Should we remove it and just send and empty message?

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^{components/layout/layout_task.rs, line 481 [r1] (raw file):}
Could we switch these to use descriptive names?

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Comments from the review on Reviewable.io

[bors-servo]

☔ The latest upstream changes (presumably #7662) made this pull request unmergeable. Please resolve the merge conflicts.

[pcwalton]

Review status: 1 of 9 files reviewed at latest revision, 3 unresolved discussions, all commit checks successful.

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^{components/layout/layout_task.rs, line 0 [r1] (raw file):}
Hmm, Reviewable didn't seem to save the context here. Could you specify which names you're referring to?

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Comments from the review on Reviewable.io

[pcwalton]

Rebased and comments addressed except for the naming one. r? @mbrubeck

[jdm]

If you click on the link in the comment on github you'll see the right context.

[mbrubeck]

-S-awaiting-review +S-needs-code-changes

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Reviewed 9 of 9 files at r2.
Review status: all files reviewed at latest revision, 1 unresolved discussion, all commit checks successful.

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^{components/layout/layout_task.rs, line 481 [r1] (raw file):}
port1, port2, port3, port4

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Comments from the review on Reviewable.io

[pcwalton]

@mbrubeck Addressed the naming comment. r?

[mbrubeck]

Reviewed 4 of 4 files at r3.
Review status: all files reviewed at latest revision, 1 unresolved discussion, all commit checks successful.

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Comments from the review on Reviewable.io

[mbrubeck]

@bors-servo r+

[bors-servo]

📌 Commit 1892b27 has been approved by mbrubeck

[bors-servo]

⌛ Testing commit 1892b27 with merge 7933b48...

[bors-servo]

☀️ Test successful - android, gonk, linux-dev, linux-rel, mac-dev-ref-unit, mac-rel-css, mac-rel-wpt