PLT-5308 Caching layer part 2 (#6973)

* Adding Reaction store cache layer example

* Implementing reaction store in new caching system.

* Redis for reaction store

* Adding redis library

* Adding invalidation for DeleteAllWithEmojiName and other minor enhancements

vendor/github.com/go-redis/redis/script.go

@@ -0,0 +1,62 @@
+package redis
+
+import (
+	"crypto/sha1"
+	"encoding/hex"
+	"io"
+	"strings"
+)
+
+type scripter interface {
+	Eval(script string, keys []string, args ...interface{}) *Cmd
+	EvalSha(sha1 string, keys []string, args ...interface{}) *Cmd
+	ScriptExists(scripts ...string) *BoolSliceCmd
+	ScriptLoad(script string) *StringCmd
+}
+
+var _ scripter = (*Client)(nil)
+var _ scripter = (*Ring)(nil)
+var _ scripter = (*ClusterClient)(nil)
+
+type Script struct {
+	src, hash string
+}
+
+func NewScript(src string) *Script {
+	h := sha1.New()
+	io.WriteString(h, src)
+	return &Script{
+		src:  src,
+		hash: hex.EncodeToString(h.Sum(nil)),
+	}
+}
+
+func (s *Script) Hash() string {
+	return s.hash
+}
+
+func (s *Script) Load(c scripter) *StringCmd {
+	return c.ScriptLoad(s.src)
+}
+
+func (s *Script) Exists(c scripter) *BoolSliceCmd {
+	return c.ScriptExists(s.src)
+}
+
+func (s *Script) Eval(c scripter, keys []string, args ...interface{}) *Cmd {
+	return c.Eval(s.src, keys, args...)
+}
+
+func (s *Script) EvalSha(c scripter, keys []string, args ...interface{}) *Cmd {
+	return c.EvalSha(s.hash, keys, args...)
+}
+
+// Run optimistically uses EVALSHA to run the script. If script does not exist
+// it is retried using EVAL.
+func (s *Script) Run(c scripter, keys []string, args ...interface{}) *Cmd {
+	r := s.EvalSha(c, keys, args...)
+	if err := r.Err(); err != nil && strings.HasPrefix(err.Error(), "NOSCRIPT ") {
+		return s.Eval(c, keys, args...)
+	}
+	return r
+}