commit 57b128d35eb11abeeab63b083400f2c268d68c72
author Luke Huang <huangluke@google.com> Tue Jul 23 16:04:12 2019 -0700
committer Luke Huang <huangluke@google.com> Fri Jul 26 03:10:39 2019 +0800
tree 985059ac7c2f4f740189201a44849f3a025a7a4b
parent 9768ae29d113b7e69315a7fa785587f804b8cfec

Subsampling DNS events to reduce logs

Currently, each device generates about 4000 queries per day.
Reduce the number of events by subsampling events based on
how interesting they are:
- if return_code == 0 -> log 1 in 100 events (random sampling)
- if return_code == EAI_NODATA -> log 1 in 10 events (random sampling)
- else -> log 100%
Also allow to use experiment flag to update sub-sampling denom.

Example for dumpsys dnsresolver:
  NetId: 100
    DnsEvent subsampling map: default:1 0:100 7:10

Bug: 119862317
Test: manual test with using setprop to change subsampling map
      atest

Merged-In: Ibbe3c653bdf45fc03b56a61e3401fad11c05a010
(cherry picked from commit 79e5185780a94db0b2356edf987239da459433f4)

Change-Id: I170dda9247e94a17a7cac9e7e414d592bb4dccbf