make sure that their loss is not concatenated
Signed-off-by: EstherLerouzic <esther.lerouzic@orange.com>
Change-Id: I63678dd5b72f7f6984101c4367320f3f981cb573
The old code assumed that the Fused node only connects Fiber nodes. In a
sequence of Fused - Amplifier - Fused - Fiber, the Amplifier would be
included by a mistake. In addition, the code was not that easy to read,
and it just instantiated StopIteration without raising that (which would
be an error in a generator context). It was also rather strict, failing
if the iterator was requested for an "edge node" (a transponder), and
one of the exceptions was not actually an f-string.
Finally, the span_loss function would occasionally report wrong values
(for example in the provided test case, span_loss("fused7") would say 1
instead of 17).
Fix this by making sure that prev_node_generator() and
next_node_generator() never return anything but Fiber and Fused nodes,
which made it possible to simplify the span_loss() function. This should
now properly account for the accumulated losses of an arbitrary sequence
of Fiber and Fused elements.
I went over this a few times because set_egress_amplifier() calls
span_loss() on a *ROADM* node type. That does not make any sense, and
the code deals with this "properly" by returning a loss of 0 dB. It was
a bit confusing for me to see that it's actually OK to ask for a "span
loss" that's identified by a ROADM.
A side effect of this code is that Fused instances that are isolated
from the rest of the topology no longer raise an exception. I was
thinking about preserving this (because for GNPy, the only element with
no previous or no next nodes are the transceivers, but then Esther's
test topology contains an isolated `fused4` element. If we want to make
this strict, we can do that easily like this:
--- a/gnpy/core/network.py
+++ b/gnpy/core/network.py
@@ -162,10 +162,12 @@ _fiber_fused_types = (elements.Fused, elements.Fiber)
def prev_node_generator(network, node):
"""fused spans interest:
iterate over all predecessors while they are Fused or Fiber type"""
try:
prev_node = next(network.predecessors(node))
except StopIteration:
- return
+ if isinstance(node, elements.Transceiver):
+ return
+ raise NetworkTopologyError(f'Node {node.uid} is not properly connected, please check network topology')
if isinstance(prev_node, _fiber_fused_types) and isinstance(node, _fiber_fused_types):
yield prev_node
yield from prev_node_generator(network, prev_node)
Signed-off-by: EstherLerouzic <esther.lerouzic@orange.com>
Co-authored-by: Jan Kundrát <jan.kundrat@telecominfraproject.com>
Change-Id: I41a65e89eef763f82e41e52bc325ed2d488cb601
