Reviewers: mp+168827_code.launchpad.net,

Message:
Please take a look.

Description:
Add Parent() to Machine

This branch provides the ability to ask a container for its parent
machine.

https://code.launchpad.net/~wallyworld/juju-core/add-machine-parent-getter/+merge/168827

(do not edit description out of merge proposal)


Please review this at https://codereview.appspot.com/10203043/

Affected files:
   A [revision details]
   M state/container.go
   M state/machine.go
   M state/machine_test.go


Index: [revision details]
=== added file '[revision details]'
--- [revision details]	2012-01-01 00:00:00 +0000
+++ [revision details]	2012-01-01 00:00:00 +0000
@@ -0,0 +1,2 @@
+Old revision: <email address hidden>
+New revision: <email address hidden>

Index: state/container.go
=== modified file 'state/container.go'
--- state/container.go	2013-06-11 20:56:00 +0000
+++ state/container.go	2013-06-11 22:40:34 +0000
@@ -88,6 +88,16 @@
  	return ops
  }

+// parentId returns the id of the host machine if machineId a container  
id, or ""
+// if machineId is not for a container.
+func parentId(machineId string) string {
+	idParts := strings.Split(machineId, "/")
+	if len(idParts) < 3 {
+		return ""
+	}
+	return strings.Join(idParts[:len(idParts)-2], "/")
+}
+
  // removeContainerRefOps returns the txn.Op's necessary to remove a  
machine container record.
  // These include removing the record itself and updating the host  
machine's children property.
  func removeContainerRefOps(st *State, machineId string) []txn.Op {
@@ -98,11 +108,10 @@
  		Remove: true,
  	}
  	// If the machine is a container, figure out it's parent host.
-	idParts := strings.Split(machineId, "/")
-	if len(idParts) < 3 {
+	parentId := parentId(machineId)
+	if parentId == "" {
  		return []txn.Op{removeRefOp}
  	}
-	parentId := strings.Join(idParts[:len(idParts)-2], "/")
  	removeParentRefOp := txn.Op{
  		C:      st.containerRefs.Name,
  		Id:     parentId,


Index: state/machine.go
=== modified file 'state/machine.go'
--- state/machine.go	2013-06-11 20:56:00 +0000
+++ state/machine.go	2013-06-11 22:40:34 +0000
@@ -235,6 +235,14 @@
  	return nil, err
  }

+func (m *Machine) Parent() (*Machine, error) {
+	parentId := parentId(m.Id())
+	if parentId == "" {
+		return nil, nil
+	}
+	return m.st.Machine(parentId)
+}
+
  type HasContainersError struct {
  	MachineId    string
  	ContainerIds []string


Index: state/machine_test.go
=== modified file 'state/machine_test.go'
--- state/machine_test.go	2013-06-11 02:15:31 +0000
+++ state/machine_test.go	2013-06-11 22:40:34 +0000
@@ -35,6 +35,23 @@
  	c.Assert(containers, DeepEquals, []string(nil))
  }

+func (s *MachineSuite) TestParent(c *C) {
+	parent, err := s.machine.Parent()
+	c.Assert(err, IsNil)
+	c.Assert(parent, IsNil)
+	params := state.AddMachineParams{
+		ParentId:      s.machine.Id(),
+		ContainerType: state.LXC,
+		Series:        "series",
+		Jobs:          []state.MachineJob{state.JobHostUnits},
+	}
+	container, err := s.State.AddMachineWithConstraints(&params)
+	c.Assert(err, IsNil)
+	parent, err = container.Parent()
+	c.Assert(err, IsNil)
+	c.Assert(parent.Id(), Equals, s.machine.Id())
+}
+
  func (s *MachineSuite) TestLifeJobManageEnviron(c *C) {
  	// A JobManageEnviron machine must never advance lifecycle.
  	m, err := s.State.AddMachine("series", state.JobManageEnviron)