Add generic toggle button module, and implement caffeine with it

modules/caffeine.py

@@ -1,19 +1,16 @@
 import subprocess
 import logging
 
-import time
 
-from .core import AbstractControl, action
+from modules.toggle import ToggleAction, ToggleControl
+from .util import process_reaper, backoff
 
 logger = logging.getLogger(__name__)
 
 
-class CaffeineControl(AbstractControl):
+class CaffeineToggleAction(ToggleAction):
     def __init__(self):
-        super().__init__()
-        self.caffeine_enabled = False
-        self._activity_proc = None
-        self._activity_proc_lastrun = 0
+        super().__init__(False)
 
     def configure(self, argument_parser):
         argument_parser.add_argument('--caffeine-timeout',
@@ -21,31 +18,17 @@ class CaffeineControl(AbstractControl):
                                      type=int,
                                      default=10)
 
-    def respond_to(self, command):
-        if command == 'caffeine':
-            self.caffeine_enabled = not self.caffeine_enabled
-            logger.info("Set caffeine enabled %r", self.caffeine_enabled)
-            return True
-
-    def __str__(self):
-        return action(self.create_pipe_command('caffeine'), 'C' if self.caffeine_enabled else 'c')
-
-    def periodic(self):
-        if self._activity_proc is not None:
-            if self._activity_proc.returncode is None:
-                self._activity_proc.poll()
-            else:
-                logger.debug("Reaped subprocess: %s", self._activity_proc)
-                self._activity_proc = None
-
-        if self.caffeine_enabled and self._activity_proc is None:
-            if self._activity_proc_lastrun + self.args.caffeine_timeout < time.time():
+    def bind_arguments(self, args):
+        super().bind_arguments(args)
+        self.periodic = process_reaper(backoff(self.args.caffeine_timeout)(self.__periodic))
+
+    def __periodic(self):
+        if self.state:
             logger.debug("Poking screensaver")
-                self._activity_proc = subprocess.Popen(['xscreensaver-command', '-deactivate'], stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
-                self._activity_proc_lastrun = time.time()
+            return subprocess.Popen(['xscreensaver-command', '-deactivate'],
+                                    stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL,
+                                    stderr=subprocess.DEVNULL)
 
-    def dump_state(self):
-        return dict(caffeine_enabled=self.caffeine_enabled)
 
-    def load_state(self, state):
-        self.caffeine_enabled = state['caffeine_enabled']
+def CaffeineControl():
+    return ToggleControl('c', CaffeineToggleAction())

modules/toggle.py

@@ -0,0 +1,61 @@
+from .core import AbstractControl, WrappingControl, action
+import abc
+import functools
+
+
+class ToggleAction(AbstractControl, metaclass=abc.ABCMeta):
+    def __init__(self, initial_state: bool = False):
+        super().__init__()
+        self.__state = initial_state
+
+    def dump_state(self):
+        return {'state': self.__state}
+
+    def load_state(self, state):
+        if 'state' in state:
+            self.state = state['state']
+
+    def toggle(self):
+        self.state = not self.state
+
+    @property
+    def state(self):
+        return self.__state
+
+    @state.setter
+    def state(self, state: bool):
+        if self.__state == state:
+            return
+        if state:
+            self.enable()
+        else:
+            self.disable()
+        self.__state = state
+
+    def enable(self):
+        pass
+
+    def disable(self):
+        pass
+
+
+class ToggleControl(WrappingControl):
+    """Implements a simple toggle button"""
+
+    def __init__(self, letter: str, toggle_action: ToggleAction):
+        super().__init__(toggle_action)
+        self.__letter = letter
+
+    def __get_control_command(self):
+        return '%s:%s:%s' % (self.__class__.__name__, self.__letter, self.child.__class__.__name__)
+
+    def respond_to(self, command):
+        if command == self.__get_control_command():
+            self.child.toggle()
+            return True
+
+    def __str__(self):
+        return action(
+            self.create_pipe_command(self.__get_control_command()),
+            self.__letter.upper() if self.child.state else self.__letter.lower()
+        )

modules/util.py

@@ -1,5 +1,9 @@
 import sys
 import os.path
+from functools import wraps
+
+import time
+
 from .core import AbstractControl
 
 
@@ -26,3 +30,36 @@ class ChildReaperControl(AbstractControl):
         except:
             pass
 
+
+def backoff(backoff, default=None):
+    def decorator(fn):
+        last_called = 0
+
+        @wraps(fn)
+        def wrapper(*a, **kw):
+            nonlocal last_called
+            if last_called + backoff > time.time():
+                return default
+            last_called = time.time()
+            return fn(*a, **kw)
+
+        return wrapper
+
+    return decorator
+
+
+def process_reaper(fn):
+    process = None
+
+    @wraps(fn)
+    def wrapper(*a, **kw):
+        nonlocal process
+        if process is not None:
+            process.poll()
+            if process.returncode is not None:
+                process = None
+
+        if process is None:
+            process = fn(*a, **kw)
+
+    return wrapper