1430938 - [e10s a11y] Eliminate some pointless cross-process QueryService calls by JAWS and UI Automation

Status: RESOLVED FIXED

(Core :: Disability Access APIs, enhancement)

Description

[James Teh [:Jamie]]

By looking at our mscom logs, I've observed some pointless cross-process QueryService calls from JAWS and UI Automation. Some of these are services we simply don't support. We can just add those to the existing kUnsupportedServices list in the handler. However, JAWS also uses QueryService to get IAccessibleText and IAccessibleAction. Aside from this being a pointless cross-proc call (we have these interfaces cached for QI), the handler also won't get used if the interface isn't fetched via QI. So, we can just silently convert these calls to a QI.

From what I can see, this doesn't provide a significant perf boost for JAWS, but it may provide something and it will certainly have an impact on use of handler caching.

Comment 1

[James Teh [:Jamie]]

Attachment: Bug 1430938 part 1: AccessibleHandler: Handle some additional unsupported services queried by JAWS and UI Automation.

We just return failure for these, thus avoiding a pointless cross-process call.
I also updated the comment for an existing service, since I discovered its constant name.

Review commit: https://reviewboard.mozilla.org/r/213370/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/213370/

Comment 2

[James Teh [:Jamie]]

Attachment: Bug 1430938 part 2: AccessibleHandler: When QueryService is called for IAccessibleAction or IAccessibleText, just use QI.

JAWS uses QueryService for these.
Using QI avoids a cross-process call, since we have these interfaces cached.
More importantly, if QS is used, the handler won't get used for that object, so our caching won't be used.

Review commit: https://reviewboard.mozilla.org/r/213372/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/213372/

Comment 3

[Marco Zehe (:MarcoZ)]

Comment on attachment 8943079 [details]
Bug 1430938 part 1: AccessibleHandler: Handle some additional unsupported services queried by JAWS and UI Automation.

https://reviewboard.mozilla.org/r/213370/#review219166

Comment 4

[Marco Zehe (:MarcoZ)]

Comment on attachment 8943080 [details]
Bug 1430938 part 2: AccessibleHandler: When QueryService is called for IAccessibleAction or IAccessibleText, just use QI.

https://reviewboard.mozilla.org/r/213372/#review219170

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a5075d257701
part 1: AccessibleHandler: Handle some additional unsupported services queried by JAWS and UI Automation. r=MarcoZ
https://hg.mozilla.org/integration/autoland/rev/b38266ed3cd4
part 2: AccessibleHandler: When QueryService is called for IAccessibleAction or IAccessibleText, just use QI. r=MarcoZ

Comment 6

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/a5075d257701
https://hg.mozilla.org/mozilla-central/rev/b38266ed3cd4