def share_edge(s1, s2):
"""Determine whether two slices share a physical edge."""
# This is only correct if we have a guarantee that the topologies are sane,
# and only give us real internal edges.
s1_ls = set(map_edges(edges_of_topo(s1.l_topo), s1.node_map, s1.port_map))
s2_ls = set(map_edges(edges_of_topo(s2.l_topo), s2.node_map, s2.port_map))
return not s1_ls.isdisjoint(s2_ls)
def edge_in(edge, slic, memo=None):
"""Determine whether a slice uses a given physical edge"""
if memo is not None:
if slic not in memo:
memo[slic] = set(map_edges(edges_of_topo(slic.l_topo),
slic.node_map, slic.port_map))
return edge in memo[slic]
else:
return edge in set(map_edges(edges_of_topo(slic.l_topo),
slic.node_map, slic.port_map))
def edge_optimal(topo, slices, verbose=False):
"""Return the minimum per-slice-per-edge vlan assignment.
verbose: print a '.' every 1000 edges processed
RETURNS: {edge: {slice: tag}}. Note that while this is inconvenient to work
with from slices, it's much more convenient to generate. If you want
{slice: {edge: tag}}, there's a converter in edge_compile.py
"""
if verbose:
import sys
count = 0
edges = edges_of_topo(topo, undirected=True)
edge_slices = {}
slice_edges = {}
for edge in edges:
edge_slices[edge] = set()
for slic in slices:
if edge_in(edge, slic, memo=slice_edges):
edge_slices[edge].add(slic)
if verbose:
count +=1
if count % 1000 == 0:
print '.',
sys.stdout.flush()
edge_vlans = {}
for (edge, slics) in edge_slices.items():
edge_vlans[edge] = dict(zip(slics, range(1, len(slics) + 1)))
return edge_vlans
