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forward.go
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forward.go
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package forward
import (
"encoding/json"
"fmt"
"strings"
"github.com/go-redis/redis"
"github.com/pkg/errors"
)
// PubSub is a wrapper for the redis pubsub
type PubSub interface {
Channel() (EventChannel, chan error)
Close()
}
// Key strips off the keyspace prefix
func Key(key string) string {
return strings.Replace(key, "__keyspace@0__:", "", 1)
}
// RedisKV wraps the result of a fetch
type RedisKV struct {
Key string
Data string
Type string
}
func (kv RedisKV) String() (string, error) {
var i interface{}
err := json.Unmarshal([]byte(kv.Data), &i)
if err != nil {
return "", errors.Wrap(err, "failed to unmarshal Data of event")
}
return fmt.Sprintf(`{"Key": "%v", "Type": "%v", "Data": "%v"}`, kv.Key, kv.Type, i.(string)), err
}
// EventChannel is an alias for a channel of rediskv events
type EventChannel chan RedisKV
type conn struct {
*redis.Client
}
type pubsub struct {
*redis.PubSub
Conn conn
}
// Fetcher interface
type Fetcher interface {
Fetch(op, key string) (RedisKV, error)
Close()
}
// PubSubConfig holds the config options for Forward
type PubSubConfig struct {
Addr string
Pattern string
KeyspaceID int64
}
// NewRedisClient returns a wrapped redis client
func NewRedisClient(r *redis.Client) Fetcher {
return conn{r}
}
// NewPubSub returns a wrapper inerface
func NewPubSub(config PubSubConfig) PubSub {
r := redis.NewClient(&redis.Options{
Addr: config.Addr,
})
_, err := r.Ping().Result()
if err != nil {
panic(err)
}
_, err = r.ConfigSet("notify-keyspace-events", "KA").Result()
if err != nil {
panic(errors.Wrap(err, "unable to turn notifications on the server"))
}
pattern := fmt.Sprintf(`__keyspace@%v__:%v`, config.KeyspaceID, config.Pattern)
return pubsub{r.PSubscribe(pattern), conn{r}}
}
// Channel returns the channel of events
func (ps pubsub) Channel() (EventChannel, chan error) {
fmt.Println("Starting Forward event listener...")
events := make(EventChannel, 2)
errs := make(chan error, 2)
go func() {
msgs := ps.PubSub.Channel()
for msg := range msgs {
op, key := msg.Payload, Key(msg.Channel)
go func() {
event, err := ps.Conn.Fetch(op, key)
if err != nil {
errs <- errors.Wrap(err, "failed to fetch redis key-value pair")
} else {
events <- event
}
}()
}
}()
return events, errs
}
func (ps pubsub) Close() {
ps.Conn.Close()
ps.Close()
}
func (c conn) del(key string) (RedisKV, error) {
return RedisKV{key, "", "delete"}, nil
}
func (c conn) fetchString(key string) (RedisKV, error) {
s, err := c.Get(key).Result()
return RedisKV{key, s, "string"}, err
}
func (c conn) fetchHash(key string) (RedisKV, error) {
h, err := c.HGetAll(key).Result()
if err != nil {
return RedisKV{}, err
}
data, err := json.Marshal(h)
return RedisKV{key, string(data), "hash"}, err
}
func (c conn) fetchSet(key string) (RedisKV, error) {
s, err := c.SMembers(key).Result()
if err != nil {
return RedisKV{}, err
}
data, err := json.Marshal(s)
return RedisKV{key, string(data), "set"}, err
}
func (c conn) fetchZSet(key string) (RedisKV, error) {
z, err := c.ZRange(key, 0, -1).Result()
if err != nil {
return RedisKV{}, err
}
data, err := json.Marshal(z)
return RedisKV{key, string(data), "zset"}, err
}
func (c conn) fetchList(key string) (RedisKV, error) {
l, err := c.LRange(key, 0, -1).Result()
if err != nil {
return RedisKV{}, err
}
data, err := json.Marshal(l)
return RedisKV{key, string(data), "list"}, err
}
func (c conn) expire(key string) (RedisKV, error) {
return RedisKV{key, "", "expire"}, nil
}
func (c conn) expired(key string) (RedisKV, error) {
return RedisKV{key, "", "expired"}, nil
}
func (c conn) renameFrom(key string) (RedisKV, error) {
return RedisKV{key, "", "rename_from"}, nil
}
func (c conn) renameTo(key string) (RedisKV, error) {
return RedisKV{key, "", "rename_to"}, nil
}
func (c conn) evicted(key string) (RedisKV, error) {
return RedisKV{key, "", "evicted"}, nil
}
// Handler is a function type to fetch keys
type Handler func(string) (RedisKV, error)
func actionMap(c conn) map[string]Handler {
return map[string]Handler{
"expire": c.expire,
"expired": c.expired,
"evicted": c.evicted,
"rename_to": c.renameTo,
"rename_from": c.renameFrom,
"sadd": c.fetchSet,
"srem": c.fetchSet,
"spop": c.fetchSet,
"sinterstore": c.fetchSet,
"sunionstore": c.fetchSet,
"sdiffstore": c.fetchSet,
"zadd": c.fetchZSet,
"zrem": c.fetchZSet,
"zrembyscore": c.fetchZSet,
"zrembyrank": c.fetchZSet,
"znterstore": c.fetchZSet,
"zdiffstore": c.fetchZSet,
"zunionstore": c.fetchZSet,
"set": c.fetchString,
"append": c.fetchString,
"setrange": c.fetchString,
"incrby": c.fetchString,
"incrbyfloat": c.fetchString,
"incr": c.fetchString,
"decrby": c.fetchString,
"decr": c.fetchString,
"lpush": c.fetchList,
"sortstore": c.fetchList,
"lpop": c.fetchList,
"linsert": c.fetchList,
"blpop": c.fetchList,
"brpop": c.fetchList,
"rpop": c.fetchList,
"rpush": c.fetchList,
"lpushx": c.fetchList,
"rpushx": c.fetchList,
"ltrim": c.fetchList,
"lpoprpush": c.fetchList,
"lset": c.fetchList,
"hset": c.fetchHash,
"hincrby": c.fetchHash,
"hincrbyfloat": c.fetchHash,
"hmset": c.fetchHash,
"hsetnx": c.fetchHash,
"del": c.del,
}
}
var actions map[string]Handler
func (c conn) Fetch(op, key string) (RedisKV, error) {
if actions == nil {
actions = actionMap(c)
}
method := actions[op]
if method == nil {
return RedisKV{}, fmt.Errorf("could not find a redis action for operation %v", op)
}
return method(key)
}
func (c conn) Close() {
c.Close()
}