CPU can be throttled in UI.

app/src/api.js

@@ -487,3 +487,54 @@ export async function setHotspot(on) {
         }
     }
 }
+
+export async function getThrottleStatus() {
+    let response = await apiGet(`${API_URI}/throttle`);
+    if (response.status === 200) {
+        let {status} = await response.json();
+        return status;
+    } else {
+        let code = (await response.json())['code'];
+        if (response.status === 400 && code === 34) {
+            // Must not be running on a RPi.  Don't warn the user.
+            return null;
+        } else {
+            toast({
+                type: 'error',
+                title: "Can't get throttle status",
+                description: 'Failed to get CPU Throttle status.  Check client and server logs.',
+                time: 5000,
+            });
+        }
+    }
+    return null;
+}
+
+export async function setThrottle(on) {
+    let response;
+    if (on) {
+        response = await apiPost(`${API_URI}/throttle/on`);
+    } else {
+        response = await apiPost(`${API_URI}/throttle/off`);
+    }
+    if (response.status === 204) {
+        return null;
+    } else {
+        let code = (await response.json())['code'];
+        if (code === 34) {
+            toast({
+                type: 'error',
+                title: 'Unsupported!',
+                description: 'Throttle is only supported on a Raspberry Pi!',
+                time: 5000,
+            });
+        } else {
+            toast({
+                type: 'error',
+                title: 'Error!',
+                description: 'Could not modify throttle.  See server logs.',
+                time: 5000,
+            });
+        }
+    }
+}

app/src/components/Admin.js

@@ -21,6 +21,7 @@ import {
     secondsToFrequency,
     TabLinks,
     textEllipsis,
+    ThrottleToggle,
     WROLModeMessage
 } from "./Common";
 import {Route} from "react-router-dom";
@@ -80,6 +81,8 @@ class Settings extends React.Component {
                 <WROLModeMessage content='Settings are disabled because WROL Mode is enabled.'/>
 
                 <HotspotToggle/>
+                <br/>
+                <ThrottleToggle style={{marginTop: '0.5em'}}/>
 
                 <Divider/>
                 <p>

app/src/components/Common.js

@@ -5,7 +5,7 @@ import Button from "semantic-ui-react/dist/commonjs/elements/Button";
 import Grid from "semantic-ui-react/dist/commonjs/collections/Grid";
 import Message from "semantic-ui-react/dist/commonjs/collections/Message";
 import {getConfig} from "../api";
-import {useDownloaders, useHotspot} from "../hooks/customHooks";
+import {useDownloaders, useHotspot, useThrottle} from "../hooks/customHooks";
 
 export const API_URI = `http://${window.location.host}/api`;
 export const VIDEOS_API = `${API_URI}/videos`;
@@ -645,9 +645,9 @@ export function CardGroupCentered(props) {
     )
 }
 
-export function HotspotToggle() {
+export function HotspotToggle(props) {
     let {on, setHotspot} = useHotspot();
-    return <Checkbox toggle
+    return <Checkbox toggle {...props}
                      label='WiFi Hotspot'
                      disabled={on === null}
                      checked={on === true}
@@ -655,6 +655,16 @@ export function HotspotToggle() {
     />;
 }
 
+export function ThrottleToggle(props) {
+    let {on, setThrottle} = useThrottle();
+    return <Checkbox toggle {...props}
+                     label='CPU Power-save'
+                     disabled={on === null}
+                     checked={on === true}
+                     onChange={(e, data) => setThrottle(data.checked)}
+    />;
+}
+
 export function DisableDownloadsToggle() {
     let {on, setDownloads} = useDownloaders();
     return <Checkbox toggle

app/src/hooks/customHooks.js

@@ -5,11 +5,13 @@ import {
     getDownloaders,
     getFiles,
     getHotspotStatus,
+    getThrottleStatus,
     getVersion,
     killDownloads,
     searchArchives,
     searchVideos,
     setHotspot,
+    setThrottle,
     startDownloads
 } from "../api";
 import {useHistory} from "react-router-dom";
@@ -247,3 +249,30 @@ export const useDownloaders = () => {
 
     return {on, setOn, downloaders, setDownloads: localSetDownloads};
 }
+
+export const useThrottle = () => {
+    const [on, setOn] = useState(null);
+
+    const fetchThrottleStatus = async () => {
+        const status = await getThrottleStatus();
+        if (status === 'powersave') {
+            setOn(true);
+        } else if (status === 'ondemand') {
+            setOn(false);
+        } else {
+            setOn(null);
+        }
+    }
+
+    useEffect(() => {
+        fetchThrottleStatus();
+    }, []);
+
+    const localSetThrottle = async (on) => {
+        setOn(null);
+        await setThrottle(on);
+        await fetchThrottleStatus();
+    }
+
+    return {on, setOn, setThrottle: localSetThrottle};
+}

wrolpi/admin.py

@@ -3,7 +3,7 @@ import pathlib
 import subprocess
 
 from wrolpi.common import logger
-from wrolpi.vars import PYTEST
+from wrolpi.vars import PYTEST, DEFAULT_CPU_FREQUENCY
 
 logger = logger.getChild(__name__)
 
@@ -11,10 +11,21 @@ logger = logger.getChild(__name__)
 SUDO_BIN = pathlib.Path('/usr/bin/sudo')
 if not SUDO_BIN.is_file() and not PYTEST:
     logger.error('COULD NOT FIND sudo!!!')
+
 NMCLI_BIN = pathlib.Path('/usr/bin/nmcli')
 if not NMCLI_BIN.is_file() and not PYTEST:
     logger.error('COULD NOT FIND nmcli!!!')
 
+CPUFREQ_INFO_BIN = pathlib.Path('/usr/bin/cpufreq-info')
+if not CPUFREQ_INFO_BIN.is_file() and not PYTEST:
+    logger.error('COULD NOT FIND cpufreq-info!!!')
+
+CPUFREQ_SET_BIN = pathlib.Path('/usr/bin/cpufreq-set')
+if not CPUFREQ_SET_BIN.is_file() and not PYTEST:
+    logger.error('COULD NOT FIND cpufreq-set!!!')
+
+POWER_SAVE_FREQ = 'powersave'  # noqa
+
 
 class HotspotStatus(enum.Enum):
     disconnected = enum.auto()  # Radio is on, but Hotspot is not connected.
@@ -65,3 +76,45 @@ def disable_hotspot():
     cmd = (SUDO_BIN, NMCLI_BIN, 'radio', 'wifi', 'off')
     subprocess.check_call(cmd)
     return True
+
+
+class GovernorStatus(enum.Enum):
+    ondemand = enum.auto()
+    powersave = enum.auto()
+    unknown = enum.auto()
+    # These are unused by WROLPi.
+    # performance = enum.auto()
+    # schedutil = enum.auto()
+    # userspace = enum.auto()
+    # conservative = enum.auto()
+
+
+GOVERNOR_MAP = {
+    'The governor "ondemand" may decide ': GovernorStatus.ondemand,
+    'The governor "powersave" may decide ': GovernorStatus.powersave,
+}
+
+
+def throttle_status() -> GovernorStatus:
+    cmd = (CPUFREQ_INFO_BIN,)
+    output = subprocess.check_output(cmd)
+    output = output.decode().strip()
+
+    for line in output.splitlines():
+        for governor, status in GOVERNOR_MAP.items():
+            if governor in line:
+                return status
+
+    return GovernorStatus.unknown
+
+
+def throttle_cpu_on() -> bool:
+    cmd = (SUDO_BIN, CPUFREQ_SET_BIN, '-g', POWER_SAVE_FREQ)
+    subprocess.check_call(cmd)
+    return True
+
+
+def throttle_cpu_off() -> bool:
+    cmd = (SUDO_BIN, CPUFREQ_SET_BIN, '-g', DEFAULT_CPU_FREQUENCY)
+    subprocess.check_call(cmd)
+    return True

wrolpi/root_api.py

@@ -15,7 +15,6 @@ from sanic_ext import validate
 from sanic_ext.extensions.openapi import openapi
 
 from wrolpi import admin
-from wrolpi.admin import HotspotStatus
 from wrolpi.common import set_sanic_url_parts, logger, get_config, wrol_mode_enabled, save_settings_config, \
     Base, get_media_directory, wrol_mode_check, native_only
 from wrolpi.dates import set_timezone
@@ -244,6 +243,38 @@ async def hotspot_off(_: Request):
     return response.empty(HTTPStatus.INTERNAL_SERVER_ERROR)
 
 
+@root_api.get('/throttle')
+@openapi.description('Get status of CPU throttling')
+@native_only
+async def throttle_status(_: Request):
+    status = admin.throttle_status()
+    # Get the name of the enum.
+    status = status.name
+
+    ret = dict(status=status)
+    return json_response(ret)
+
+
+@root_api.post('/throttle/on')
+@openapi.description('Turn on CPU throttling')
+@native_only
+async def throttle_on(_: Request):
+    result = admin.throttle_cpu_on()
+    if result:
+        return response.empty()
+    return response.empty(HTTPStatus.INTERNAL_SERVER_ERROR)
+
+
+@root_api.post('/throttle/off')
+@openapi.description('Turn off CPU throttling')
+@native_only
+async def throttle_off(_: Request):
+    result = admin.throttle_cpu_off()
+    if result:
+        return response.empty()
+    return response.empty(HTTPStatus.INTERNAL_SERVER_ERROR)
+
+
 class CustomJSONEncoder(json.JSONEncoder):
 
     def default(self, obj):

wrolpi/test/test_admin.py

@@ -61,3 +61,19 @@ def test_enable_hotspot_connected():
                 call((PosixPath('/usr/bin/sudo'), PosixPath('/usr/bin/nmcli'), 'device', 'wifi', 'hotspot', 'ifname',
                       'wlan0', 'ssid', 'WROLPi', 'password', 'wrolpi hotspot'))]
         )
+
+
+def test_throttle_on():
+    with mock.patch('wrolpi.admin.subprocess') as mock_subprocess:
+        assert admin.throttle_cpu_on()
+        mock_subprocess.check_call.assert_called_once_with(
+            (PosixPath('/usr/bin/sudo'), PosixPath('/usr/bin/cpufreq-set'), '-g', 'powersave')
+        )
+
+
+def test_throttle_off():
+    with mock.patch('wrolpi.admin.subprocess') as mock_subprocess:
+        assert admin.throttle_cpu_off()
+        mock_subprocess.check_call.assert_called_once_with(
+            (PosixPath('/usr/bin/sudo'), PosixPath('/usr/bin/cpufreq-set'), '-g', 'ondemand')
+        )

wrolpi/vars.py

@@ -19,6 +19,7 @@ LAST_MODIFIED_DATE_FORMAT = '%a, %d %b %Y %H:%M:%S GMT'
 DATE_FORMAT = '%Y-%M-%d'
 DATETIME_FORMAT = '%Y-%m-%d %H:%M:%S'
 DATETIME_FORMAT_MS = '%Y-%m-%d %H:%M:%S.%f'
+DEFAULT_CPU_FREQUENCY = 'ondemand'
 
 DEFAULT_FILE_PERMISSIONS = 0o644