ducky/devices
ducky/devices/devices.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 "errors"
5 "fmt"
6 "log"
7 "time"
9 "golang.org/x/net/context"
11 "code.secondbit.org/uuid.hg"
12 )
14 var (
15 // ErrDeviceNotFound is returned when the specified device couldn't be found.
16 ErrDeviceNotFound = errors.New("device not found")
17 )
19 // Device represents a specific device that updates can be pushed to.
20 type Device struct {
21 ID uuid.ID
22 Name string
23 Owner uuid.ID
24 Type DeviceType
25 Created time.Time
26 LastSeen time.Time
27 PushToken string
28 }
30 // ApplyChange returns a Device that is a copy of the passed Device,
31 // but with the passed DeviceChange applied.
32 func ApplyChange(d Device, change DeviceChange) Device {
33 result := d
34 if change.Name != nil {
35 result.Name = *change.Name
36 }
37 if change.Owner != nil {
38 result.Owner = *change.Owner
39 } else {
40 // We don't want to accidentally leave a slice that
41 // is owned by both behind.
42 result.Owner = d.Owner.Copy()
43 }
44 if change.Type != nil {
45 result.Type = *change.Type
46 }
47 if change.Created != nil {
48 result.Created = *change.Created
49 }
50 if change.LastSeen != nil {
51 result.LastSeen = *change.LastSeen
52 }
53 if change.PushToken != nil {
54 result.PushToken = *change.PushToken
55 }
56 return result
57 }
59 // DeviceChange represents a set of changes to a Device that will be used
60 // to update a Device.
61 type DeviceChange struct {
62 DeviceID uuid.ID
63 Name *string
64 Owner *uuid.ID
65 Type *DeviceType
66 Created *time.Time
67 LastSeen *time.Time
68 PushToken *string
69 }
71 // Storer is an interface to control how data is stored in and retrieved from
72 // the datastore.
73 type Storer interface {
74 GetDevices(ids []uuid.ID, c context.Context) (map[string]Device, error)
75 UpdateDevice(change DeviceChange, c context.Context) error
76 DeleteDevices(ids []uuid.ID, c context.Context) error
77 CreateDevices(devices []Device, c context.Context) error
78 ListDevicesByOwner(user uuid.ID, c context.Context) ([]Device, error)
79 }
81 // ErrDeviceAlreadyExists is returned when a Device is added to a Storer, but a
82 // Device with the same ID already exists in the Storer. The ID underlying
83 // ErrDeviceAlreadyExists will hold the ID that already exists.
84 type ErrDeviceAlreadyExists uuid.ID
86 func (e ErrDeviceAlreadyExists) Error() string {
87 return fmt.Sprintf("device with ID %s already exists in datastore", uuid.ID(e).String())
88 }
90 // GetMany returns as many of the Devices specified by the passed IDs as possible.
91 // They are returned as a map, with the key being the string version of the ID.
92 // No error will be returned if a Device can't be found.
93 func GetMany(ids []uuid.ID, c context.Context) (map[string]Device, error) {
94 results := map[string]Device{}
95 storer, err := getStorer(c)
96 if err != nil {
97 log.Printf("Error retrieving Storer: %+v\n", err)
98 return results, err
99 }
100 results, err = storer.GetDevices(ids, c)
101 if err != nil {
102 log.Printf("Error retrieving Devices from %T: %+v\n", storer, err)
103 return results, err
104 }
105 return results, nil
106 }
108 // Get returns the Device specified by the passed ID. If the Device can't be found,
109 // an ErrDeviceNotFound error is returned.
110 func Get(id uuid.ID, c context.Context) (Device, error) {
111 results, err := GetMany([]uuid.ID{id}, c)
112 if err != nil {
113 return Device{}, err
114 }
115 result, ok := results[id.String()]
116 if !ok {
117 return Device{}, ErrDeviceNotFound
118 }
119 return result, nil
120 }
122 // Update applies the DeviceChange to the passed Device, and returns the result. If
123 // the Device can't be found, an ErrDeviceNotFound error was returned.
124 func Update(device Device, change DeviceChange, c context.Context) (Device, error) {
125 storer, err := getStorer(c)
126 if err != nil {
127 log.Printf("Error retrieving Storer: %+v\n", err)
128 return Device{}, err
129 }
130 change.DeviceID = device.ID
131 err = storer.UpdateDevice(change, c)
132 if err != nil {
133 return Device{}, err
134 }
135 return ApplyChange(device, change), nil
136 }
138 // DeleteMany removes the passed IDs from the datastore. No error is returned if the
139 // ID doesn't correspond to a Device in the datastore.
140 func DeleteMany(ids []uuid.ID, c context.Context) error {
141 storer, err := getStorer(c)
142 if err != nil {
143 log.Printf("Error retrieving Storer: %+v\n", err)
144 return err
145 }
146 return storer.DeleteDevices(ids, c)
147 }
149 // Delete removes the passed ID from the datastore. No error is returned if the ID doesn't
150 // correspond to a Device in the datastore.
151 func Delete(id uuid.ID, c context.Context) error {
152 return DeleteMany([]uuid.ID{id}, c)
153 }
155 // CreateMany stores the passed Devices in the datastore, assigning default values if
156 // necessary. The Devices that were ultimately stored (including any default values, if
157 // applicable) are returned.
158 func CreateMany(devices []Device, c context.Context) ([]Device, error) {
159 storer, err := getStorer(c)
160 if err != nil {
161 log.Printf("Error retrieving Storer: %+v\n", err)
162 return []Device{}, err
163 }
164 modified := make([]Device, 0, len(devices))
165 for _, device := range devices {
166 if device.ID.IsZero() {
167 device.ID = uuid.NewID()
168 }
169 if device.Created.IsZero() {
170 device.Created = time.Now()
171 }
172 if device.LastSeen.IsZero() {
173 device.LastSeen = time.Now()
174 }
175 modified = append(modified, device)
176 }
177 err = storer.CreateDevices(devices, c)
178 if err != nil {
179 return []Device{}, err
180 }
181 return modified, nil
182 }
184 // Create stores the passed Device in the datastore, assigning default values if
185 // necessary. The Devices that were ultimately stored (including any default values, if
186 // applicable) are returned.
187 func Create(device Device, c context.Context) (Device, error) {
188 devices, err := CreateMany([]Device{device}, c)
189 if err != nil {
190 return Device{}, err
191 }
192 // There should never be a case where we don't return a result.
193 // Ideally, we'd return an error here instead of letting the panic
194 // happen, but seeing as I can't come up with a reason the error would
195 // occur, I'm having trouble coming up with a reasonable error to return.
196 return devices[0], nil
197 }
199 // ListByOwner returns a slice of all the Devices with an Owner property that
200 // matches the passed ID. There's no guarantee on the order the Devices will be
201 // returned in.
202 func ListByOwner(user uuid.ID, c context.Context) ([]Device, error) {
203 // BUG(paddy): Eventually, we'll need to support paging for devices. But right now, I don't foresee any user creating enough of them to make pagination worthwhile.
204 storer, err := getStorer(c)
205 if err != nil {
206 log.Printf("Error retrieving Storer: %+v\n", err)
207 return []Device{}, err
208 }
209 devices, err := storer.ListDevicesByOwner(user, c)
210 return devices, err
211 }
213 // ToMap transforms the passed slice into a map by using the String method of
214 // each Device's ID as the key, and the Device as the value.
215 func ToMap(devices []Device) map[string]Device {
216 results := make(map[string]Device, len(devices))
217 for _, device := range devices {
218 results[device.ID.String()] = device
219 }
220 return results
221 }
223 // ToSlice transforms the passed map of Devices into a slice of Devices.
224 func ToSlice(devices map[string]Device) []Device {
225 results := make([]Device, 0, len(devices))
226 for _, device := range devices {
227 results = append(results, device)
228 }
229 return results
230 }