Don't count requests blocked during private browsing
Background
We keep track of the total number of requests blocked in the blocked_total preference. Doing so while in private browsing is leaking information that may invade privacy. Moreover, on Firefox, during private browsing writes of those data make up for 50% of disk IO.
What to change
Stop updating blocked_total for requests coming from tabs with the incognito property set.
Original report
Environment
Operating system: Windows 10 Professional version 1909 (64 bit) Browser: Firefox 72.0.2 Adblock Plus version: 3.7 Filter lists: Easy List (upstream), Easy List Germany (upstream), Easy Privacy (upstream) Important settings: Permanent private browsing mode is enabled in Firefox; Automatic filter list updates are disabled in Adblock Plus
How to reproduce
- Apply the reported system configuration as close as possible.
- Open Firefox and go to https://www.twitch.tv/directory .
- Monitor your disk activities (for example with Windows's resource monitor).
Observed behavior
The disk is busy writing 50+% of the time.
Expected behavior
The HDD should be mostly silent on idle.