tree 8d979bf5d20ec8548ab16731965b761af6f493d0
parent 44dfd0bbd1d82877d8f527752959822c0bb105da
author Miriam Zimmerman <mutexlox@google.com> 1608085627 -0800
committer Commit Bot <commit-bot@chromium.org> 1608190465 +0000

metrics: Initialize "last update time".

Before this change, when metrics_daemon started, it initialized its
"last update time" to 0 ticks and used this as the basis for computing
daily usage time statistics. If metrics daemon starts right after boot
(and ticks start counting from 0 on boot) this is reasonably accurate,
but if metrics daemon restarts for some reason (e.g. it crashes),
counting from 0 will provide a measure of total system uptime rather
than recent usage.

To fix this, initialize the "last update time" to the current number of
ticks when metrics daemon is initialized.

BUG=chromium:1159236
TEST=unit tests

Change-Id: I31151c00865d34708a83d6cd045e1c6e05e70912
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2593717
Tested-by: Miriam Zimmerman <mutexlox@chromium.org>
Reviewed-by: Ian Barkley-Yeung <iby@chromium.org>
Commit-Queue: Miriam Zimmerman <mutexlox@chromium.org>