927035 - Don't use Date.now() as an ID

Status: RESOLVED FIXED

(DevTools :: Console, defect, P3)

Description

[Justin Dolske [:Dolske]]

We've fixed a number of bugs (bug 925771, bug 586153, bug 578589) that were a result of using Date.now() as an identifier. The problem is that Date.now() can return the same value if called again in a sufficiently short period of time. [In the past Windows was the worst, as the result only changed ~60Hz].

I just noticed this is being used in devtools:

browser/devtools/webconsole/hudservice.js

300 function WebConsole(aTarget, aIframeWindow, aChromeWindow)
301 {
302   this.iframeWindow = aIframeWindow;
303   this.chromeWindow = aChromeWindow;
304   this.hudId = "hud_" + Date.now();

Looks like this is a module, so should be trivial to change it to use a simple static counter. (Alternatively, something like nsIUUIDGenerator would be adequate overkill.)

Comment 1

[Peiyong Lin[:lpy](UTC+8)]

Attachment: bug927035.patch

replace it with nsIUUIDGenerator

Comment 2

[Mihai Sucan [:msucan]]

Can we please use a static counter? |hudId = "hud_" + (++gHudId)| where gHudId is a global variable. nsIUUIDGenerator is overkill for webconsole's needs.

Comment 3

[Peiyong Lin[:lpy](UTC+8)]

Attachment: bug927035.patch

Thank you msucan.

Comment 4

[Brandon Benvie [:benvie]]

Comment on attachment 8336786 [details] [diff] [review]
bug927035.patch

Review of attachment 8336786 [details] [diff] [review]:
-----------------------------------------------------------------

Looks good, just one small nit.

::: browser/devtools/webconsole/hudservice.js
@@ +302,5 @@
>  function WebConsole(aTarget, aIframeWindow, aChromeWindow)
>  {
>    this.iframeWindow = aIframeWindow;
>    this.chromeWindow = aChromeWindow;
> +  this.hudId = "hud_" + (++gHudId);

Nit: No need to parenthesize this.

Comment 5

[Brandon Benvie [:benvie]]

For good measure: https://tbpl.mozilla.org/?tree=Try&rev=da5e3c671bd7

Comment 6

[Peiyong Lin[:lpy](UTC+8)]

Attachment: bug927035.patch

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/integration/fx-team/rev/0aeb98afb35d

Comment 8

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

https://hg.mozilla.org/mozilla-central/rev/0aeb98afb35d