mstate: state package replacement using mgo.

mstate/open.go

+package mstate
+
+import (
+        "launchpad.net/juju-core/juju/log"
+        "launchpad.net/mgo"
+)
+
+func Dial(servers string) (st *State, err error) {
+        log.Printf("state: opening state; MongoDB servers: %q", servers)
+        session, err := mgo.Dial(servers)
+        if err != nil {
+                return
+        }
+        db := session.DB("juju")
+        db.Session = session.Clone()
+        session.Close()
+        st = &State{
+                db:       db,
+                machines: db.C("machines"),
+        }
+        return
+}
+
+func (st *State) Close() (err error) {
+        st.db.Session.Close()
+        return
+}