[client] Add support of UPower to detect battery status on linux

[AenBleidd]

Signed-off-by: Vitalii Koshura lestat.de.lionkur@gmail.com

[KeithMyers]

Thanks so much Vitalii for getting this new on-battery detect structure put into the module.

[AenBleidd]

@BOINC/committer, could anyone review this PR, please?

[TheAspens]

I was taking a look at this and I ran watch "upower -d | grep on-battery" while I unplugged my laptop. I waited over a minute and the on-battery indicator never changed from "no". Here is what it showed:

[knreed@oc4182665077 ~]$ upower -d
Device: /org/freedesktop/UPower/devices/line_power_AC
  native-path:          AC
  power supply:         yes
  updated:              Tue 28 Jan 2020 07:31:04 AM CST (7027 seconds ago)
  has history:          no
  has statistics:       no
  line-power
    warning-level:       none
    online:              yes
    icon-name:          'ac-adapter-symbolic'

Device: /org/freedesktop/UPower/devices/battery_BAT0
  native-path:          BAT0
  vendor:               LGC
  model:                01AV495
  serial:               304
  power supply:         yes
  updated:              Tue 28 Jan 2020 09:27:02 AM CST (69 seconds ago)
  has history:          yes
  has statistics:       yes
  battery
    present:             yes
    rechargeable:        yes
    state:               discharging
    warning-level:       none
    energy:              59.43 Wh
    energy-empty:        0 Wh
    energy-full:         61.71 Wh
    energy-full-design:  90.06 Wh
    energy-rate:         0 W
    voltage:             12.469 V
    percentage:          96%
    capacity:            68.521%
    technology:          lithium-polymer
    icon-name:          'battery-full-symbolic'

Device: /org/freedesktop/UPower/devices/DisplayDevice
  power supply:         yes
  updated:              Tue 28 Jan 2020 09:27:02 AM CST (69 seconds ago)
  has history:          no
  has statistics:       no
  battery
    present:             yes
    state:               discharging
    warning-level:       none
    energy:              59.43 Wh
    energy-full:         61.71 Wh
    energy-rate:         0 W
    percentage:          96%
    icon-name:          'battery-full-symbolic'

Daemon:
  daemon-version:  0.99.7
  on-battery:      no
  lid-is-closed:   no
  lid-is-present:  yes
  critical-action: PowerOff

As a result, BOINC never stopped running. However with the previous version of the code the client stopped immediately. I'm running

[knreed@oc4182665077 ~]$ cat /etc/redhat-release 
Red Hat Enterprise Linux Workstation release 7.7 (Maipo)

I'm not sure why upower isn't updating the on-battery state since it recognized that the batteries were discharging.

[AenBleidd]

There is an open issue for this: https://gitlab.freedesktop.org/upower/upower/issues/22
Sometimes it takes too long to update the status. I don't know why. As a solution I can put this detection method last.

[KeithMyers]

Sounds like no one has tested the upower detect on a UPS battery backed system. Which was the whole impetus for asking for the new detect method.

Exactly what do I need to do to test this for you. I assume I need to pull in the new revised module and compile the client. How do I get the new module?

[AenBleidd]

@KeithMyers, if you feel confident working with command line:

git checkout -b AenBleidd-implement_upower_detect_for_pr master
git pull https://github.com/AenBleidd/boinc.git implement_upower_detect_for_pr

Then just build it

[KeithMyers]

I was trying to read the code and I wonder if a better choice for the detected status would be "discharging" instead of "on-battery".

if (strstr(upower_out, "on-battery:"))

Or does the code read the daemon output of on-battery state? yes||no?

Daemon:
  daemon-version:  0.99.7
  on-battery:      no
  lid-is-closed:   no
  lid-is-present:  no
  critical-action: PowerOff

Trying to understand what the upower docs mean. So what does 'b' represent?

The "OnBattery" property
'OnBattery' read 'b'

[AenBleidd]

@KeithMyers, I'm not sure that detecting 'discharging' string is a good idea. 'on-battery' should be either 'yes' or 'no', and we actually read this boolean state. If daemon for some reason doesn't change correctly this status, shame on it. But if we add 'discharging' as a criteria of search, then we will have next matrix:

#	Discharging	On-Battery	Result (Use battery)
1	Yes	Yes	Yes
2	Yes	No	Yes?
3	No	Yes	Yes?
4	No	No	No

And even if case 2 I can accept as 'Yes', so what about case 3? I definitely can't reproduce this

[KeithMyers]

Don't know. I don't understand programming syntax. I can read it is about all I can do. Comprehension is beyond my skills presently.

I have your branch. Now just have to compile it into a new client for testing. Will get to it tomorrow. Then I can pull the plug on my UPS while watching upower state and see if the Manager drops the compute load.

[truboxl]

I think need to add dependency in https://github.com/BOINC/boinc/blob/master/client/scripts/boinc-client.service.in just to be sure

https://fedoramagazine.org/systemd-unit-dependencies-and-order/

[AenBleidd]

@truboxl, which dependency?

[truboxl]

@AenBleidd Sorry for the long delay, I am thinking upower.service

[davidpanderson]

A couple of suggestions:

1. read_upower_status() should return bool (whether we're on batteries) rather than std::string
2. Now is a good time to change the logic of HOST_INFO::host_is_running_on_batteries()
   so that if none of the methods is available, it doesn't test them all again on each call.

[AenBleidd]

@davidpanderson, thanks for the review. I'll make necessary changes asap