1130317 - [UserDictionary] Pre-determine dict blob total byte length before building the blob

Status: RESOLVED FIXED

(Firefox OS Graveyard :: Gaia::Keyboard, defect)

Description

[John Lu [:mnjul][Please NI or I'll miss]]

In bug 1102834's user dictionary blob generation, the blob array grows dynamically as each byte is push()'ed into the array, which is later converted to a typed array. However, it should be possible that we pre-determine the length of the blob array and allocate a typed array of specific size and fill in the bytes directly on the typed array. We should investigate the possibility.

Comment 1

[John Lu [:mnjul][Please NI or I'll miss]]

* For better performance, for sure.

Comment 2

[John Lu [:mnjul][Please NI or I'll miss]]

On this. Target Milestone is set to S7 because S6's end-date is Chinese New Year.

Comment 3

[GitHub Autolander Bot]

Attachment: [PullReq] mnjul:bug_1130317_dict_blob_predetermine_length to mozilla-b2g:master

Comment 4

[John Lu [:mnjul][Please NI or I'll miss]]

Will request for review after testing is good.

Comment 5

[John Lu [:mnjul][Please NI or I'll miss]]

(In reply to John Lu [:mnjul] [MoCoTPE] from comment #1)
> * For better performance, for sure.

A very rough JSPerf: http://jsperf.com/typed-array-push-or-predetermined

Comment 6

[John Lu [:mnjul][Please NI or I'll miss]]

Comment on attachment 8561210 [details] [review]
[PullReq] mnjul:bug_1130317_dict_blob_predetermine_length to mozilla-b2g:master

Tim,

Please check out the patch. The rationale behind this is pretty simple. No tests were modified as we blackbox-test WordListConverter, and its internal performance improvement patch should, of course, not have an impact on blob end-result.

Thanks!

Comment 7

[GitHub Autolander Bot]

Pull request has landed in master: https://github.com/mozilla-b2g/gaia/commit/c026f6d6b7a58fcc15a3164b37a1c9de788ce1e6