1374089 - LayerTransactionParent does unnecessary hashtable lookups

Status: RESOLVED FIXED

(Core :: Graphics: Layers, enhancement, P2)

Comment 1

[Mats Palmgren (:mats)]

Attachment: part 1 - Use LookupForAdd instead of Contains+Put, and remove an unnecessary Contains call before GetAndRemove, to avoid unnecessary hashtable lookups

Comment 2

[Mats Palmgren (:mats)]

Attachment: part 2 - Use nsRefPtrHashtable instead of nsDataHashtable with a RefPtr<> data type, since it's clearer and avoids unnecessary AddRef/Release calls

I think it's a bit silly to use nsDataHashtable with a RefPtr<> when we
have a dedicated nsRefPtrHashtable class for that use case.  Also, this
avoid unnecessary ref counting in AsLayer().

Comment 3

[Mats Palmgren (:mats)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=6fdeee5d5a146334132009f42b0e7a1697cecb02

Comment 4

[Nathan Froyd [:froydnj]]

Comment on attachment 8878912 [details] [diff] [review]
part 1 - Use LookupForAdd instead of Contains+Put, and remove an unnecessary Contains call before GetAndRemove, to avoid unnecessary hashtable lookups

Review of attachment 8878912 [details] [diff] [review]:
-----------------------------------------------------------------

::: gfx/layers/ipc/LayerTransactionParent.cpp
@@ +1028,2 @@
>    }
> +  return IPC_FAIL_NO_REASON(this);

Maybe write this as:

if (!aHandle) {
  return IPC_FAIL_NO_REASON(this);
}

Maybe<RefPtr<Layer>> maybeLayer = ...
if (!maybeLayer) {
  return IPC_FAIL_NO_REASON(this);
}
...

I know it duplicates the IPC_FAIL_NO_REASON bits, but I think this new version is more consistent with Gecko's general fail-fast/less-nesting-preferred coding style.

Comment 5

[Nathan Froyd [:froydnj]]

Comment on attachment 8878913 [details] [diff] [review]
part 2 - Use nsRefPtrHashtable instead of nsDataHashtable with a RefPtr<> data type, since it's clearer and avoids unnecessary AddRef/Release calls

Review of attachment 8878913 [details] [diff] [review]:
-----------------------------------------------------------------

Yay for less refcounting!

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/80e602014cf2
part 1 - Use LookupForAdd instead of Contains+Put, and remove an unnecessary Contains call before GetAndRemove, to avoid unnecessary hashtable lookups.  r=froydnj
https://hg.mozilla.org/integration/mozilla-inbound/rev/5d4bb1715f7c
part 2 - Use nsRefPtrHashtable instead of nsDataHashtable with a RefPtr<> data type, since it's clearer and avoids unnecessary AddRef/Release calls.  r=froydnj

Comment 7

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/80e602014cf2
https://hg.mozilla.org/mozilla-central/rev/5d4bb1715f7c