close #351. in storm.py: turn off stdout to avoid messing with JSON payload sent back to JAVA layer

storm-core/src/multilang/py/storm.py

@@ -55,9 +55,9 @@ def readTuple():
  return Tuple(cmd["id"], cmd["comp"], cmd["stream"], cmd["task"], cmd["tuple"])
 
 def sendMsgToParent(msg):
- print json_encode(msg)
- print "end"
- sys.stdout.flush()
+ original_stdout.write(json_encode(msg) + '\n')
+ original_stdout.write("end\n")
+ original_stdout.flush()
 
 def sync():
  sendMsgToParent({'command':'sync'})
@@ -123,6 +123,28 @@ def initComponent():
  sendpid(setupInfo['pidDir'])
  return [setupInfo['conf'], setupInfo['context']]
 
+# prevent custom code's print methods pollute stdout, resulting in wrong
+# message sent to JAVA layer.
+
+original_stdout = sys.stdout
+
+def nullify_stdout(func):
+ # a wrapper function nullify all print methods of its wrapped funcs.
+
+ class NullDevice():
+ def write(self, s):
+ pass
+
+ def wrapper(*args):
+ sys.stdout = NullDevice()
+ try:
+ result = func(*args)
+ finally:
+ sys.stdout = original_stdout
+ return result
+
+ return wrapper
+
 class Tuple(object):
  def __init__(self, id, component, stream, task, values):
  self.id = id