ducky/devices
2015-11-29
Parent:03c49b4d3d9f
ducky/devices/memstore.go
Set up DeleteDevices in Memstore. Implement the DeleteDevices method for our Memstore, removing the Devices specified by the passed IDs. Also, create a simple test that verifies that when Devices are deleted, only the Devices you intend to delete are actually deleted. Further tests should be written to verify that this extends to ListDevicesByOwner (e.g., deleted devices will not be returned when listing them), CreateDevices (e.g., will not result in an ErrDeviceAlreadyExists error), and UpdateDevice (e.g., will return an ErrDeviceNotFound error after the Device is deleted). But for now, we're confident that it works in the simplest possible case.
1 package devices
3 import (
4 "sync"
6 "code.secondbit.org/uuid.hg"
7 "golang.org/x/net/context"
8 )
10 // Memstore is an in-memory implementation of Storer, and should
11 // only be used for testing or for temporary local servers.
12 type Memstore struct {
13 devices map[string]Device
14 lock sync.RWMutex
15 }
17 // NewMemstore returns a Memstore that is ready to be used as a
18 // Storer implementation.
19 func NewMemstore() *Memstore {
20 return &Memstore{
21 devices: map[string]Device{},
22 }
23 }
25 // GetDevices returns any Devices in the Memstore that match the
26 // passed IDs. If an ID cannot be matched to a Device in the
27 // Memstore, it is ignored. The result is a map, with the values
28 // being the Devices that could be found, and the keys being the
29 // result of the String() method for each Device's ID.
30 //
31 // An empty map is a possible response, if none of the IDs could
32 // be found.
33 func (m *Memstore) GetDevices(ids []uuid.ID, c context.Context) (map[string]Device, error) {
34 m.lock.RLock()
35 defer m.lock.RUnlock()
37 results := map[string]Device{}
39 for _, id := range ids {
40 device, ok := m.devices[id.String()]
41 if !ok {
42 continue
43 }
44 results[id.String()] = device
45 }
46 return results, nil
47 }
49 // UpdateDevice applies the passed DeviceChange to the Device
50 // in the Memstore specified by the DeviceChange's DeviceID
51 // property. If no Device in the Memstore matches the DeviceChange's
52 // DeviceID property, then an ErrDeviceNotFound error will be
53 // returned.
54 func (m *Memstore) UpdateDevice(change DeviceChange, c context.Context) error {
55 m.lock.Lock()
56 defer m.lock.Unlock()
58 device, ok := m.devices[change.DeviceID.String()]
59 if !ok {
60 return ErrDeviceNotFound
61 }
63 device = ApplyChange(device, change)
64 m.devices[change.DeviceID.String()] = device
66 return nil
67 }
69 // DeleteDevices will remove any Devices from the Memstore that match
70 // the IDs passed in. If an ID can't be matched to a Device in the
71 // Memstore, then it is ignored.
72 func (m *Memstore) DeleteDevices(ids []uuid.ID, c context.Context) error {
73 m.lock.Lock()
74 defer m.lock.Unlock()
76 for _, id := range ids {
77 delete(m.devices, id.String())
78 }
80 return nil
81 }
83 // CreateDevices stores the passed devices in the Memstore as a single
84 // transaction. If a Device's ID already exists in the Memstore, an
85 // ErrDeviceAlreadyExists error with that Device's ID is returned, and
86 // none of the passed Devices are stored.
87 func (m *Memstore) CreateDevices(devices []Device, c context.Context) error {
88 m.lock.Lock()
89 defer m.lock.Unlock()
91 for _, device := range devices {
92 if _, ok := m.devices[device.ID.String()]; ok {
93 return ErrDeviceAlreadyExists(device.ID)
94 }
95 }
97 for _, device := range devices {
98 m.devices[device.ID.String()] = device
99 }
100 return nil
101 }
103 // ListDevicesByOwner returns all the Devices in the Memstore that have an
104 // Owner property that matches the passed ID. If no Devices have an Owner
105 // property matching the passed ID, an empty slice is returned.
106 //
107 // ListDevicesByOwner does not guarantee any sort order for the Devices.
108 func (m *Memstore) ListDevicesByOwner(user uuid.ID, c context.Context) ([]Device, error) {
109 var devices []Device
110 for _, device := range m.devices {
111 if !device.Owner.Equal(user) {
112 continue
113 }
114 devices = append(devices, device)
115 }
116 return devices, nil
117 }