Reorganize code into separate files

1 files changed, 99 insertions, 0 deletions

diff --git a/statemachine.py b/statemachine.py
new file mode 100644
index 0000000..5c396eb
--- /dev/null
+++ b/statemachine.py
@@ -0,0 +1,99 @@
+__docformat__ = 'restructuredtext'
+
+from category import Category
+
+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.holds = {}
+        self.deps = []
+
+    def assert_state(self, cat):
+        """
+        Move states in the given Category `cat` from down to up.
+        """
+        found = None
+        for dependency in self.get_applicable_deps(cat):
+            res = self.get_satisfied_states(cat, dependency)
+            if len(res) == 0:
+                return False
+            if found == None:
+                found = res
+            else:
+                found = self.intersect_list(found, res)
+        if found == None:
+            self.add_hold(cat)
+            return True
+        if len(found) == 0:
+            return False
+        for x in found:
+            self.add_hold(x)
+        return True
+
+    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()
+        found = set()
+        for x in cats1:
+            for y in cats2:
+                if x == y: continue
+                inter = x.intersect(y)
+                if inter != None:
+                    retval.add(inter)
+                    found.add(x)
+                    found.add(y)
+        if len(found) == 0:
+            return cats1 & cats2
+        return (retval | ((cats1 & cats2) - found))
+
+    def add_hold(self, cat):
+        """
+        Add a hold to a state. Does not check dependencies.
+        """
+        if self.holds.has_key(cat):
+            self.holds[cat] = self.holds[cat] + 1
+        else:
+            self.holds[cat] = 1
+
+    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 key, val in self.holds.iteritems():
+            if dependencies.equiv(key) and val > 0:
+                retval.append(dependents.fill(key.args))
+        return set(retval)
+
+    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):
+                retval.append(y.fill(cat.intersect(x).args))
+        return retval
+
+if __name__ == "__main__":
+    sm = StateMachine()
+    sm.deps.append((Category("mounted", type="nfs"), Category("network_up")))
+    sm.deps.append((Category("mounted", uuid=None, devname=None, label=None), Category("found_disk", uuid=None, devname=None, label=None)))
+    sm.deps.append((Category("mounted", uuid=None, devname=None, label=None), Category("vol_conf", uuid=None, devname=None, label=None)))
+    sm.assert_state(Category("vol_conf", uuid=None, devname=None, label="myroot", type="ext3", mountpoint="/"))
+    sm.assert_state(Category("found_disk", uuid="d3adb3ef", devname="/dev/sda", label="myroot"))
+    sm.assert_state(Category("mounted", uuid=None, type="ext3", devname=None, label=None, mountpoint=None))
+    print sm.holds