abe related dns resolution problem for cached failures

[al_9x]

xp32sp3, Fx 3.6.6, NS 1.9.9.99

to see this better, configure a bogus dns server (live routable ip that doesn't respond to dns queries)

The initial failed resolution behavior is the the same whether abe is on or off:

activity indicator spins, status bar indicates dns resolution in progress

The differences show on subsequent attempts. Without abe, the failure is almost instantaneous, and I think there is still UI feedback (very brief, since the failure comes so quickly).

With abe, there is no longer any UI feedback (no spinning activity indicator, no status bar message, nothing else to indicate that a navigation/resolution is in progress) made very noticeable by the resolution taking significantly longer to fail (about the same as the initial attempt)

[al_9x]

Another issue, is that these problematic subsequent resolutions are not cancelable, navigating away to about:blank while one is in progress does does not abort it, it continues and then shows the error page.

[Giorgio Maone]

The DNS-related machinery, like lots of other back-end stuff, is gonna change soon (NSA/NoScript 3) for adapting to E10s (Firefox 4 Mobile/Firefox 7), so investigating and fixing this, albeit desirable, is not worth the effort for me.

External patches are welcome, though.

[al_9x]

Another symptom, if you are opening the non resolving link in a new tab (middle click on a bookmark) the tab doesn't open until the lookup fails. Combined with the symptoms from the first two posts, its really a bad experience, a much longer timeout than without ABE, no tab, no ui feedback (no clue what's happening), no ability to cancel. Please look into this, NS should not be degrading the DNS experience to this extent.

[al_9x]

Another symptom, if you are opening the non resolving link in a new tab (middle click on a bookmark) the tab doesn't open until the lookup fails. Combined with the symptoms from the first two posts, its really a bad experience, a much longer timeout than without ABE, no tab, no ui feedback (no clue what's happening), no ability to cancel. Please look into this, NS should not be degrading the DNS experience to this extent.

Furthermore, for the duration of the resolution, until the tab showing DNS failure finally opens, new tabs with successful navigations don't open (the navigation appears to take place in the focused tab), the tabs are somehow queued and open all at once with the dns failing tab.

[Giorgio Maone]

Furthermore, for the duration of the resolution, until the tab showing DNS failure finally opens, new tabs with successful navigations don't open (the navigation appears to take place in the focused tab), the tabs are somehow queued and open all at once with the dns failing tab.

That's weird: only resolutions to the same hosts should get serialized. Investigating...

[al_9x]

In Fx 7.0b1 + NS 2.1.2.7rc3, this problem extends to even the first resolution, the "resolving" status message disappears immediately, activity indicator does not spin.

[al_9x]

since some of the symptoms from the previous posts seem to be gone in Fx 7 and latest NS, here's the list of outstanding issues:

1. no feedback/progress on initial uncached resolution
2. no feedback/progress on subsequent cached failure resolutions
3. the subsequent resolutions take much longer than without ABE/NS, about the same as the initial one
4. the subsequent resolutions can't be cancelled either explicitly (stop) or implicitly by navigating somewhere. If you open another page, the "server not found" page will replace it when the resolution finishes.
5. The tab issues are still preset, but are intermittent. When the cached failure navigation is launched in a new tab (middle click on a bookmark), frequently, the tab does not open until resolution completes, and when that happens, tab creation for other new tab navigations is serialized. This seems to happen more frequently if the bookmark is in a folder on the bookmark bar.

[Giorgio Maone]

Thanks, I'll look into them as soon as I'm done with the overdue NSA milestones.

[Giorgio Maone]

Please check latest development build 2.1.2.7rc4.

[al_9x]

Please check latest development build 2.1.2.7rc4.

This takes care of 1, but not 2-5.