- Fixes #139 driver station crash

wpilib/setup.py

@@ -49,7 +49,7 @@
     url='https://github.com/robotpy/robotpy-wpilib',
     keywords='frc first robotics wpilib',
     packages=find_packages(),
-    install_requires=['pynetworktables>=2015.1.2'],
+    install_requires=['pynetworktables>=2015.2.1'],
     license="BSD License",
     classifiers=[
         "Development Status :: 5 - Production/Stable",

wpilib/wpilib/motorsafety.py

@@ -6,6 +6,7 @@
 #----------------------------------------------------------------------------
 
 import weakref
+import threading
 
 from .robotstate import RobotState
 from .timer import Timer
@@ -27,6 +28,7 @@ class MotorSafety:
     """
     DEFAULT_SAFETY_EXPIRATION = 0.1
     helpers = weakref.WeakSet()
+    helpers_lock = threading.Lock()
 
     def __init__(self):
         """The constructor for a MotorSafety object.
@@ -39,7 +41,8 @@ def __init__(self):
         self.safetyEnabled = False
         self.safetyExpiration = MotorSafety.DEFAULT_SAFETY_EXPIRATION
         self.safetyStopTime = Timer.getFPGATimestamp()
-        MotorSafety.helpers.add(self)
+        with MotorSafety.helpers_lock:
+            MotorSafety.helpers.add(self)
 
     def feed(self):
         """Feed the motor safety object.
@@ -111,7 +114,6 @@ def checkMotors():
         This static method is called periodically to poll all the motors and
         stop any that have timed out.
         """
-        # TODO: these should be synchronized with the setting methods
-        # in case it's called from a different thread
-        for msh in MotorSafety.helpers:
-            msh.check()
+        with MotorSafety.helpers_lock:
+            for msh in MotorSafety.helpers:
+                msh.check()

wpilib/wpilib/samplerobot.py

@@ -38,6 +38,10 @@ class SampleRobot(RobotBase):
     #: is recommended to use this instead of print statements.
     logger = logging.getLogger("robot")
 
+    def prestart(self):
+        """Don't immediately say that the robot's ready to be enabled, see below"""
+        pass
+
     def robotInit(self):
         """Robot-wide initialization code should go here.
 
@@ -96,6 +100,14 @@ def robotMain(self):
         called. If it has not been overridden by a user subclass (i.e. the
         default version runs), then the robotInit(), disabled(), autonomous()
         and operatorControl() methods will be called.
+        
+        If you override this function, you must call ``hal.HALNetworkCommunicationObserveUserProgramStarting()``
+        to indicate that your robot is ready to be enabled, as it will not
+        be called for you.
+        
+        .. warning:: Nobody actually wants to override this function. Neither
+                     do you.
+        
         """
         self._no_robot_main = True
 
@@ -117,6 +129,12 @@ def startCompetition(self):
             # first and one-time initialization
             LiveWindow.setEnabled(False)
             self.robotInit()
+            
+            #We call this now (not in prestart like default) so that the robot
+            #won't enable until the initialization has finished. This is useful
+            #because otherwise it's sometimes possible to enable the robot before
+            #the code is ready.
+            hal.HALNetworkCommunicationObserveUserProgramStarting()
 
             while True:
                 if self.isDisabled():