Merge pull request #3029 from johnhaddon/pythonCommandCrashFix

PythonCommand improvements

python/GafferDispatch/PythonCommand.py

@@ -65,13 +65,16 @@ def hash( self, context ) :
 
 		h.append( command )
 
-		parser = _Parser( command )
-		for name in parser.contextReads :
+		for name in _contextReadsCache.get( command ) :
 			value = context.get( name )
 			if isinstance( value, IECore.Object ) :
 				value.hash( h )
-			else :
+			elif value is not None :
 				h.append( value )
+			else :
+				# Variable not in context. Hash a value that is
+				# extremely unlikely to be found in a context.
+				h.append( "__pythonCommandMissingContextVariable__" )
 
 		self["variables"].hash( h )
 
@@ -83,7 +86,7 @@ def hash( self, context ) :
 	def execute( self ) :
 
 		executionDict = self.__executionDict()
-		exec( self["command"].getValue(), executionDict, executionDict )
+		exec( _codeObjectCache.get( self["command"].getValue() ), executionDict, executionDict )
 
 	def executeSequence( self, frames ) :
 
@@ -207,4 +210,16 @@ def visit_Call( self, node ) :
 
 		ast.NodeVisitor.generic_visit( self, node )
 
+def __contextReadsCacheGetter( expression ) :
+
+	return _Parser( expression ).contextReads, 1
+
+_contextReadsCache = IECore.LRUCache( __contextReadsCacheGetter, 10000 )
+
+def __codeObjectCacheGetter( expression ) :
+
+	return compile( expression, "<string>", "exec" ), 1
+
+_codeObjectCache = IECore.LRUCache( __codeObjectCacheGetter, 10000 )
+
 IECore.registerRunTimeTyped( PythonCommand, typeName = "GafferDispatch::PythonCommand" )

python/GafferDispatchTest/PythonCommandTest.py

@@ -322,5 +322,34 @@ def testEmptyCommand( self ) :
 		self.assertEqual( c["command"].getValue(), "" )
 		self.assertEqual( c["task"].hash(), IECore.MurmurHash() )
 
+	def testContextGetNone( self ) :
+
+		command = Gaffer.PythonCommand()
+		command["command"].setValue( "print context.get( 'iAmNotHere' )" )
+
+		with Gaffer.Context() as c :
+			h = command["task"].hash()
+			c["iAmNotHere"] = 10
+			self.assertNotEqual( command["task"].hash(), h )
+
+	def testAlternateMissingContextVariables( self ) :
+
+		command = Gaffer.PythonCommand()
+		command["command"].setValue( "print 'a : ', context.get( 'a' ), 'b : ', context.get( 'b' )" )
+
+		neitherHash = command["task"].hash()
+
+		with Gaffer.Context() as c :
+			c["a"] = 10
+			aHash = command["task"].hash()
+
+		with Gaffer.Context() as c :
+			c["b"] = 10
+			bHash = command["task"].hash()
+			c["a"] = 10
+			bothHash = command["task"].hash()
+
+		self.assertEqual( len( { str( x ) for x in ( neitherHash, aHash, bHash, bothHash ) } ), 4 )
+
 if __name__ == "__main__":
 	unittest.main()