Add Idle Shutdown Timer support

This adds an optional idle shutdown timer which can be enabled
via timers.idle_shutdown.timeout_sec in the jukebox.yaml config.

The system will shut down after the given number of seconds if no
activity has been detected during that time. Activity is defined as:
- music playing
- active SSH sessions
- changes in configs or audio content.

documentation/developers/status.md

@@ -166,7 +166,8 @@ Topics marked _in progress_ are already in the process of implementation by comm
 - [x] Publish mechanism of timer status
 - [x] Change multitimer function call interface such that endless timer etc. won't pass the `iteration` kwarg
 - [ ] Make timer settings persistent
-- [ ] Idle timer
+- [x] Idle timer (basic implementation covering player, SSH, config and audio content changes)
+- [ ] Idle timer: Do we need further extensions?
   - This needs clearer specification: Idle is when no music is playing and no user interaction is taking place
   - i.e., needs information from RPC AND from player status. Let's do this when we see a little clearer about Spotify
 

resources/default-settings/jukebox.default.yaml

@@ -102,6 +102,10 @@ gpioz:
   enable: false
   config_file: ../../shared/settings/gpio.yaml
 timers:
+  idle_shutdown:
+    # If you uncomment the following line, the box will shutdown approximately after that many seconds of inactivity.
+    # Inactivity is defined as: no music playing, no active SSH sessions, no changes in configs or audio content.
+    #timeout_sec: 900
   # These timers are always disabled after start
   # The following values only give the default values.
   # These can be changed when enabling the respective timer on a case-by-case basis w/o saving

src/jukebox/components/timers/__init__.py

@@ -5,6 +5,7 @@
 import logging
 import jukebox.cfghandler
 import jukebox.plugs as plugin
+from .idle_shutdown_timer import IdleShutdownTimer
 
 
 logger = logging.getLogger('jb.timers')
@@ -46,6 +47,7 @@ def __call__(self, iteration):
 timer_shutdown: GenericTimerClass
 timer_stop_player: GenericTimerClass
 timer_fade_volume: GenericMultiTimerClass
+timer_idle_shutdown: IdleShutdownTimer
 
 
 @plugin.finalize
@@ -77,6 +79,15 @@ def finalize():
     timer_fade_volume.__doc__ = "Timer step-wise volume fade out and shutdown"
     plugin.register(timer_fade_volume, name='timer_fade_volume', package=plugin.loaded_as(__name__))
 
+    global timer_idle_shutdown
+    timeout = cfg.setndefault('timers', 'idle_shutdown', 'timeout_sec', value=None)
+    if timeout is None:
+        timer_idle_shutdown = None
+    else:
+        timer_idle_shutdown = IdleShutdownTimer(timeout)
+        timer_idle_shutdown.__doc__ = 'Timer for automatic shutdown on idle'
+        timer_idle_shutdown.start()
+
     # The idle Timer does work in a little sneaky way
     # Idle is when there are no calls through the plugin module
     # Ahh, but also when music is playing this is not idle...
@@ -101,4 +112,9 @@ def atexit(**ignored_kwargs):
     timer_stop_player.cancel()
     global timer_fade_volume
     timer_fade_volume.cancel()
-    return [timer_shutdown.timer_thread, timer_stop_player.timer_thread, timer_fade_volume.timer_thread]
+    ret = [timer_shutdown.timer_thread, timer_stop_player.timer_thread, timer_fade_volume.timer_thread]
+    global timer_idle_shutdown
+    if timer_idle_shutdown is not None:
+        timer_idle_shutdown.cancel()
+        ret += [timer_idle_shutdown]
+    return ret

src/jukebox/components/timers/idle_shutdown_timer.py

@@ -0,0 +1,131 @@
+# RPi-Jukebox-RFID Version 3
+# Copyright (c) See file LICENSE in project root folder
+
+import time
+import os
+import re
+import logging
+import threading
+import jukebox.plugs as plugin
+
+
+logger = logging.getLogger('jb.timers.idle_shutdown_timer')
+SSH_CHILD_RE = re.compile(r'sshd: [^/].*')
+PATHS = ['shared/settings',
+         'shared/audiofolders']
+
+
+def get_seconds_since_boot():
+    # We may not have a stable clock source when there is no network
+    # connectivity (yet). As we only need to measure the relative time which
+    # has passed, we can just calculate based on the seconds since boot.
+    with open('/proc/uptime') as f:
+        line = f.read()
+    seconds_since_boot, _ = line.split(' ', 1)
+    return float(seconds_since_boot)
+
+
+class IdleShutdownTimer(threading.Thread):
+    """
+    Shuts down the system if no activity is detected.
+    The following activity is covered:
+        - playing music
+        - active SSH sessions
+        - changes of configs or audio content
+
+    Note: This does not use one of the generic timers as there don't seem
+    to be any benefits here. The shutdown timer is kind of special in that it
+    is a timer which is expected *not* to fire most of the time, because some
+    activity would restart it. Using threading.Thread directly allows us to
+    keep using a single, persistent thread.
+    """
+    shutdown_after_seconds: int
+    last_activity: float = 0
+    files_num_entries: int = 0
+    files_latest_mtime: float = 0
+    running: bool = True
+    last_player_status = None
+    SLEEP_INTERVAL_SECONDS: int = 10
+
+    def __init__(self, timeout_seconds):
+        super().__init__(name=__class__.__name__)
+        self.shutdown_after_seconds = timeout_seconds
+        self.base_path = os.path.join(os.path.dirname(__file__), '..', '..', '..', '..')
+        self.record_activity()
+        logger.debug('Started IdleShutdownTimer')
+
+    def record_activity(self):
+        self.last_activity = get_seconds_since_boot()
+
+    def check(self):
+        if self.last_activity + self.shutdown_after_seconds > get_seconds_since_boot():
+            return
+        logger.info('No player activity, starting further checks')
+        if self._has_active_ssh_sessions():
+            logger.info('Active SSH sessions found, will not shutdown now')
+            self.record_activity()
+            return
+        if self._has_changed_files():
+            logger.info('Changes files found, will not shutdown now')
+            self.record_activity()
+            return
+        logger.info(f'No activity since {self.shutdown_after_seconds} seconds, shutting down')
+        plugin.call_ignore_errors('host', 'shutdown')
+
+    def run(self):
+        # We need this once as a baseline:
+        self._has_changed_files()
+        # We rely on playerstatus being sent in regular intervals. If this
+        # is no longer the case at some point, we would need an additional
+        # timer thread.
+        while self.running:
+            time.sleep(self.SLEEP_INTERVAL_SECONDS)
+            player_status = plugin.call('player', 'ctrl', 'playerstatus')
+            if player_status == self.last_player_status:
+                self.check()
+            else:
+                self.record_activity()
+            self.last_player_status = player_status.copy()
+
+    def cancel(self):
+        self.running = False
+
+    @staticmethod
+    def _has_active_ssh_sessions():
+        logger.debug('Checking for SSH activity')
+        with os.scandir('/proc') as proc_dir:
+            for proc_path in proc_dir:
+                if not proc_path.is_dir():
+                    continue
+                try:
+                    with open(os.path.join(proc_path, 'cmdline')) as f:
+                        cmdline = f.read()
+                except (FileNotFoundError, PermissionError):
+                    continue
+                if SSH_CHILD_RE.match(cmdline):
+                    return True
+
+    def _has_changed_files(self):
+        # This is a rather expensive check, but it only runs twice
+        # when an idle shutdown is initiated.
+        # Only when there are actual changes (file transfers via
+        # SFTP, Samba, etc.), the check may run multiple times.
+        logger.debug('Scanning for file changes')
+        latest_mtime = 0
+        num_entries = 0
+        for path in PATHS:
+            for root, dirs, files in os.walk(os.path.join(self.base_path, path)):
+                for p in dirs + files:
+                    mtime = os.stat(os.path.join(root, p)).st_mtime
+                    latest_mtime = max(latest_mtime, mtime)
+                    num_entries += 1
+
+        logger.debug(f'Completed file scan ({num_entries} entries, latest_mtime={latest_mtime})')
+        if self.files_latest_mtime != latest_mtime or self.files_num_entries != num_entries:
+            # We compare the number of entries to have a chance to detect file
+            # deletions as well.
+            self.files_latest_mtime = latest_mtime
+            self.files_num_entries = num_entries
+            return True
+
+        return False