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__docformat__ = 'restructuredtext'
from category import Category
from pattern import Pattern
import setcross
class StateMachine:
"""
The state machine contains a list of dependencies between states, and a list
of states which are "up."
"""
def __init__(self):
"""
Create a new state machine
"""
self.up = set()
self.deps = []
def bring_up(self, cat):
"""
Move states in the given Category `cat` from down to up.
"""
found = None
for (match, dependency) in self.get_applicable_deps(cat):
res = self.get_satisfied_states(match, dependency)
if len(res) == 0:
return False
if found == None:
found = [res]
else:
found.append(res)
if found == None:
self.up.add(cat)
return True
to_add = self.cat_cross(found)
for x in to_add:
self.up.add(x)
return True
def cat_cross(self, found):
"""
Given a list of sets, where each set contains Category objects, return a
set of all categories that can be made by intersecting one element from
each set.
"""
to_add = set()
for tup in setcross.cross(*found):
orig = tup
while len(tup) > 1:
newtup = (tup[0].intersect(tup[1]),)
if newtup[0] == None:
tup = ()
break
tup = newtup + tup[2:len(tup)]
if len(tup) == 0 or tup[0] == None:
continue
to_add.add(tup[0])
return to_add
def intersect_list(self, cats1, cats2):
"""
Given two lists of categories, return a list of categories such that a
state appearing in at least one category in each list will appear in at
least one category in the returned list.
"""
retval = set()
for x in cats1:
for y in cats2:
inter = x.intersect(y)
if inter != None:
retval.add(inter)
return retval
def add_hold(self, cat):
"""
Add a hold to a state. Does not check dependencies.
"""
for x in self.up:
if cat.subset_of(x):
return
self.up.add(cat)
def get_satisfied_states(self, dependents, dependencies):
"""
Given that states in `dependents` depend on states in `dependencies`,
return a new Category that contains only the states in `dependents` that
could match states in `dependencies`.
"""
retval = []
for cat in self.up:
if dependencies.equiv(cat):
retval.append(dependents.fill(cat.args))
return set(retval) | dependents.inverse_set()
def get_applicable_deps(self, cat):
"""
Find dependencies that might apply to members of `cat`
"""
retval = []
for (x, y) in self.deps:
if x.equiv(cat):
un = cat.intersect(x)
retval.append((un, y.fill(un.args)))
return retval
def __str__(self):
return "\n".join(["%s" % k for k in self.up])
def __repr__(self):
return str(self)
if __name__ == "__main__":
sm = StateMachine()
sm.deps.append((Category("mounted", type=Pattern(True, "nfs")), Category("network_up")))
sm.deps.append((Category("mounted", uuid=Pattern(False), devname=Pattern(False), label=Pattern(False), type=Pattern(False, "nfs")), Category("found_disk", uuid=Pattern(False), devname=Pattern(False), label=Pattern(False))))
sm.deps.append((Category("mounted", uuid=Pattern(False), devname=Pattern(False), label=Pattern(False)), Category("vol_conf", uuid=Pattern(False), devname=Pattern(False), label=Pattern(False))))
sm.bring_up(Category("network_up"))
sm.bring_up(Category("vol_conf", uuid=Pattern(False), devname=Pattern(False), label=Pattern(True, "myroot"), type=Pattern(True, "ext3"), mountpoint=Pattern(True, "/")))
sm.bring_up(Category("vol_conf", uuid=Pattern(False), devname=Pattern(True, "foosrv.com:/vol/home"), label=Pattern(False), type=Pattern(True, "nfs"), mountpoint=Pattern(True, "/home")))
sm.bring_up(Category("found_disk", uuid=Pattern(True, "d3adb3ef"), devname=Pattern(True, "/dev/sda"), label=Pattern(True, "myroot")))
sm.bring_up(Category("mounted", uuid=Pattern(False), type=Pattern(False), devname=Pattern(False), label=Pattern(False), mountpoint=Pattern(False)))
print sm
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