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streams.go
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/
streams.go
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package redis
import (
"context"
"encoding/json"
"errors"
"fmt"
"github.com/go-redis/redis/v8"
"github.com/mainflux/mainflux/logger"
"github.com/mainflux/mainflux/lora"
)
const (
keyType = "lora"
keyDevEUI = "dev_eui"
keyAppID = "app_id"
group = "mainflux.lora"
stream = "mainflux.things"
thingPrefix = "thing."
thingCreate = thingPrefix + "create"
thingUpdate = thingPrefix + "update"
thingRemove = thingPrefix + "remove"
thingConnect = thingPrefix + "connect"
thingDisconnect = thingPrefix + "disconnect"
channelPrefix = "channel."
channelCreate = channelPrefix + "create"
channelUpdate = channelPrefix + "update"
channelRemove = channelPrefix + "remove"
exists = "BUSYGROUP Consumer Group name already exists"
)
var (
errMetadataType = errors.New("field lora is missing in the metadata")
errMetadataFormat = errors.New("malformed metadata")
errMetadataAppID = errors.New("application ID not found in channel metadatada")
errMetadataDevEUI = errors.New("device EUI not found in thing metadatada")
)
// Subscriber represents event source for things and channels provisioning.
type Subscriber interface {
// Subscribes to geven subject and receives events.
Subscribe(context.Context, string) error
}
type eventStore struct {
svc lora.Service
client *redis.Client
consumer string
logger logger.Logger
}
// NewEventStore returns new event store instance.
func NewEventStore(svc lora.Service, client *redis.Client, consumer string, log logger.Logger) Subscriber {
return eventStore{
svc: svc,
client: client,
consumer: consumer,
logger: log,
}
}
func (es eventStore) Subscribe(ctx context.Context, subject string) error {
err := es.client.XGroupCreateMkStream(ctx, stream, group, "$").Err()
if err != nil && err.Error() != exists {
return err
}
for {
streams, err := es.client.XReadGroup(ctx, &redis.XReadGroupArgs{
Group: group,
Consumer: es.consumer,
Streams: []string{stream, ">"},
Count: 100,
}).Result()
if err != nil || len(streams) == 0 {
continue
}
for _, msg := range streams[0].Messages {
event := msg.Values
var err error
switch event["operation"] {
case thingCreate:
cte, derr := decodeCreateThing(event)
if derr != nil {
err = derr
break
}
err = es.svc.CreateThing(ctx, cte.id, cte.loraDevEUI)
case thingUpdate:
ute, derr := decodeCreateThing(event)
if derr != nil {
err = derr
break
}
err = es.svc.CreateThing(ctx, ute.id, ute.loraDevEUI)
case channelCreate:
cce, derr := decodeCreateChannel(event)
if derr != nil {
err = derr
break
}
err = es.svc.CreateChannel(ctx, cce.id, cce.loraAppID)
case channelUpdate:
uce, derr := decodeCreateChannel(event)
if derr != nil {
err = derr
break
}
err = es.svc.CreateChannel(ctx, uce.id, uce.loraAppID)
case thingRemove:
rte := decodeRemoveThing(event)
err = es.svc.RemoveThing(ctx, rte.id)
case channelRemove:
rce := decodeRemoveChannel(event)
err = es.svc.RemoveChannel(ctx, rce.id)
case thingConnect:
tce := decodeConnectionThing(event)
err = es.svc.ConnectThing(ctx, tce.chanID, tce.thingID)
case thingDisconnect:
tde := decodeConnectionThing(event)
err = es.svc.DisconnectThing(ctx, tde.chanID, tde.thingID)
}
if err != nil && err != errMetadataType {
es.logger.Warn(fmt.Sprintf("Failed to handle event sourcing: %s", err.Error()))
break
}
es.client.XAck(ctx, stream, group, msg.ID)
}
}
}
func decodeCreateThing(event map[string]interface{}) (createThingEvent, error) {
strmeta := read(event, "metadata", "{}")
var metadata map[string]interface{}
if err := json.Unmarshal([]byte(strmeta), &metadata); err != nil {
return createThingEvent{}, err
}
cte := createThingEvent{
id: read(event, "id", ""),
}
m, ok := metadata[keyType]
if !ok {
return createThingEvent{}, errMetadataType
}
lm, ok := m.(map[string]interface{})
if !ok {
return createThingEvent{}, errMetadataFormat
}
val, ok := lm[keyDevEUI].(string)
if !ok {
return createThingEvent{}, errMetadataDevEUI
}
cte.loraDevEUI = val
return cte, nil
}
func decodeRemoveThing(event map[string]interface{}) removeThingEvent {
return removeThingEvent{
id: read(event, "id", ""),
}
}
func decodeCreateChannel(event map[string]interface{}) (createChannelEvent, error) {
strmeta := read(event, "metadata", "{}")
var metadata map[string]interface{}
if err := json.Unmarshal([]byte(strmeta), &metadata); err != nil {
return createChannelEvent{}, err
}
cce := createChannelEvent{
id: read(event, "id", ""),
}
m, ok := metadata[keyType]
if !ok {
return createChannelEvent{}, errMetadataType
}
lm, ok := m.(map[string]interface{})
if !ok {
return createChannelEvent{}, errMetadataFormat
}
val, ok := lm[keyAppID].(string)
if !ok {
return createChannelEvent{}, errMetadataAppID
}
cce.loraAppID = val
return cce, nil
}
func decodeConnectionThing(event map[string]interface{}) connectionThingEvent {
return connectionThingEvent{
chanID: read(event, "chan_id", ""),
thingID: read(event, "thing_id", ""),
}
}
func decodeRemoveChannel(event map[string]interface{}) removeChannelEvent {
return removeChannelEvent{
id: read(event, "id", ""),
}
}
func read(event map[string]interface{}, key, def string) string {
val, ok := event[key].(string)
if !ok {
return def
}
return val
}