inhibit suspend if camera block is in use

plugins/camera_sensor/camera_sensor.py

@@ -37,6 +37,8 @@
 from TurtleArt.taprimitive import (ConstantArg, Primitive)
 from TurtleArt.tatype import TYPE_NUMBER
 
+from power import get_power_manager
+
 
 class Camera_sensor(Plugin):
 
@@ -147,6 +149,7 @@ def start(self):
             if self._status and len(self.cameras) == 0:
                 for device in self.devices:
                     self.cameras.append(Camera(device))
+                get_power_manager().inhibit_suspend()
 
     def quit(self):
         ''' This gets called when the activity quits '''
@@ -165,6 +168,7 @@ def _reset_the_camera(self):
             for i, camera in enumerate(self.cameras):
                 camera.stop_camera_input()
                 self._set_autogain(1, camera=i)  # enable AUTOGAIN
+        get_power_manager().restore_suspend()
 
     def _status_report(self):
         debug_output('Reporting camera status: %s' % (str(self._status)),

plugins/camera_sensor/power.py

@@ -0,0 +1,85 @@
+# Copyright (C) 2014, Sugarlabs
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+
+import os
+import logging
+
+_POWERD_INHIBIT_DIR = '/var/run/powerd-inhibit-suspend'
+
+_power_manager = None
+
+
+def get_power_manager():
+    global _power_manager
+    if _power_manager is None:
+        _power_manager = PowerManager()
+    return _power_manager
+
+
+class PowerManager():
+    """ control of powerd idle suspend,
+        reference counted,
+        does nothing if powerd is not present
+    """
+
+    def __init__(self):
+        self._suspend_inhibit_counter = 0
+
+    def __del__(self):
+        self._remove_flag_file()
+
+    def suspend_breaks_collaboration(self):
+        return True
+
+    def inhibit_suspend(self):
+        if not os.path.exists(_POWERD_INHIBIT_DIR):
+            return
+
+        if self._suspend_inhibit_counter == 0:
+            path = os.path.join(_POWERD_INHIBIT_DIR, str(os.getpid()))
+            try:
+                with open(path, 'w') as flag_file:
+                    flag_file.write('')
+            except IOError:
+                logging.error("Inhibit Suspend: Could not create file %s",
+                              path)
+
+        self._suspend_inhibit_counter += 1
+
+    def restore_suspend(self):
+        self._suspend_inhibit_counter -= 1
+        if self._suspend_inhibit_counter > 0:
+            return
+        self._remove_flag_file()
+
+    def is_suspend_inhibited(self):
+        return self._suspend_inhibit_counter > 0
+
+    def shutdown(self):
+        """
+        This method clean the flag file if exists,
+        is already called when the activity is closed.
+        """
+        self._remove_flag_file()
+
+    def _remove_flag_file(self):
+        path = os.path.join(_POWERD_INHIBIT_DIR, str(os.getpid()))
+        try:
+            os.unlink(path)
+        except OSError:
+            logging.error("Inhibit Suspend: Could not delete file %s", path)
+        self._suspend_inhibit_counter = 0