1485526 - Consider allowing users to specify the order in which extensions' webRequest listeners are run

Status: RESOLVED WONTFIX

(WebExtensions :: Request Handling, defect)

Description

[martin f. krafft]

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.84 Safari/537.36
Build ID: 20180718215440

Steps to reproduce:

I am using two extensions, uMatrix and Decentraleyes on multiple machines.


Actual results:

On some machines, a request is first handled by one, then the other, while on other machines, it's the other way around. This seems to be random, as in I've found no data in the profile that would allow me to predict, let alone influence this. As both extensions filter and modify requests, this makes their configurations incompatible between the machines.


Expected results:

Extensions should either be run in a strict order, or I should be able to define dependencies between them, effecting a topological order at run-time.

Comment 1

[Andrew Swan [:aswan]]

At the moment, if multiple extensions have webRequest listeners that match some request, those listeners are run in parallel.  In bug 1421725, Kris argues against running them in serial.  We could consider creating a way to define the order in which listener results are applied but frankly I think this would be much more effectively handled within the extensions.

Comment 2

[Kris Maglione [:kmag]]

Listeners are explicitly documented to run in undefined order. We don't intend to change this.