1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
// Copyright 2012, 2013 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.
package state
import (
"fmt"
"launchpad.net/juju-core/charm"
)
// counterpartRole returns the RelationRole that this RelationRole
// can relate to.
// This should remain an internal method because the relation
// model does not guarantee that for every role there will
// necessarily exist a single counterpart role that is sensible
// for basing algorithms upon.
func counterpartRole(r charm.RelationRole) charm.RelationRole {
switch r {
case charm.RoleProvider:
return charm.RoleRequirer
case charm.RoleRequirer:
return charm.RoleProvider
case charm.RolePeer:
return charm.RolePeer
}
panic(fmt.Errorf("unknown relation role %q", r))
}
// Endpoint represents one endpoint of a relation.
type Endpoint struct {
ServiceName string
charm.Relation
}
// String returns the unique identifier of the relation endpoint.
func (ep Endpoint) String() string {
return ep.ServiceName + ":" + ep.Name
}
// CanRelateTo returns whether a relation may be established between e and other.
func (ep Endpoint) CanRelateTo(other Endpoint) bool {
return ep.ServiceName != other.ServiceName &&
ep.Interface == other.Interface &&
ep.Role != charm.RolePeer &&
counterpartRole(ep.Role) == other.Role
}
type epSlice []Endpoint
var roleOrder = map[charm.RelationRole]int{
charm.RoleRequirer: 0,
charm.RoleProvider: 1,
charm.RolePeer: 2,
}
func (eps epSlice) Len() int { return len(eps) }
func (eps epSlice) Swap(i, j int) { eps[i], eps[j] = eps[j], eps[i] }
func (eps epSlice) Less(i, j int) bool {
ep1 := eps[i]
ep2 := eps[j]
if ep1.Role != ep2.Role {
return roleOrder[ep1.Role] < roleOrder[ep2.Role]
}
return ep1.String() < ep2.String()
}
|