cmd/jujud: implement uniter upgrade

state/machine.go

 package state
 
 import (
         "fmt"
         "labix.org/v2/mgo"
         "labix.org/v2/mgo/txn"
         "launchpad.net/juju-core/state/presence"
         "launchpad.net/juju-core/trivial"
         "strconv"
         "time"
@@ skipping 23 matching lines @@
 // Id returns the machine id.
 func (m *Machine) Id() int {
         return m.doc.Id
 }
 
 // globalKey returns the global database key for the machine.
 func (m *Machine) globalKey() string {
         return "m#" + m.String()
 }
 
+// PathKey returns a name identifying the machine that can be used as a
+// file name.  The returned key will be different from other
+// PathKeys returned by any other entities from the same state.

[niemeyer, 2012/09/28 14:39:34]

s/PathKeys/PathKey values/

As a good convention, when we name methods/functions/types, they should be the
real ones.

[rog, 2012/09/28 15:28:58]

done. i changed the one it was copied from too.

+func (m *Machine) PathKey() string {
+        return fmt.Sprintf("machine-%d", m.doc.Id)
+}
+
 // Life returns whether the machine is Alive, Dying or Dead.
 func (m *Machine) Life() Life {
         return m.doc.Life
 }
 
 // Workers returns the workers that the machine agent for m must run.
 func (m *Machine) Workers() []WorkerKind {
         return m.doc.Workers
 }
 
@@ skipping 148 matching lines @@
                 return fmt.Errorf("cannot set instance id of machine %s: %v", m, onAbort(err, errNotAlive))
         }
         m.doc.InstanceId = id
         return nil
 }
 
 // String returns a unique description of this machine.
 func (m *Machine) String() string {
         return strconv.Itoa(m.doc.Id)
 }