lib:py: bugfix check return value async_recv

Without this patch the code was returning an empty message in case MockTurtle had nothing to deliver. This is wrong, an empty message could be a valid message, but in this case we want to tell the user that the buffer was empty. We do this by returning None. Signed-off-by: Federico Vaga <federico.vaga@cern.ch>

lib:py: bugfix check return value async_recv
Without this patch the code was returning an empty message in case MockTurtle had nothing to deliver. This is wrong, an empty message could be a valid message, but in this case we want to tell the user that the buffer was empty. We do this by returning None. Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
358f6a73 · Federico Vaga · a2a67870 · 358f6a73
Commit 358f6a73 authored Apr 03, 2019 by Federico Vaga
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PyMockTurtle.py software/lib/PyMockTurtle/PyMockTurtle/PyMockTurtle.py +5 -5

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--- a/software/lib/PyMockTurtle/PyMockTurtle/PyMockTurtle.py
+++ b/software/lib/PyMockTurtle/PyMockTurtle/PyMockTurtle.py
@@ -552,16 +552,16 @@ class TrtlHmq(object):

        :param timeout: time to wait before returning
        :type timeout: int
-        :return: an asynchronous message
+        :return: an asynchronous message or None
        :rtype: TrtlMessage
        :raises OSError: from C library errors
        """
        set_errno(0)
        msg = TrtlMessage()
-        self.libtrtl.trtl_msg_async_recv(self.trtl_dev.tkn,
-                                         self.idx_cpu, self.idx_hmq,
-                                         pointer(msg), 1)
-        return msg
+        ret = self.libtrtl.trtl_msg_async_recv(self.trtl_dev.tkn,
+                                               self.idx_cpu, self.idx_hmq,
+                                               pointer(msg), 1)
+        return None if ret == 0 else msg

    def sync_msg(self, msg_s, timeout=1000):
        """