Allow common redis and leveldb connections (#12385)

* Allow common redis and leveldb connections

Prevents multiple reopening of redis and leveldb connections to the same
place by sharing connections.

Further allows for more configurable redis connection type using the
redisURI and a leveldbURI scheme.

Signed-off-by: Andrew Thornton <art27@cantab.net>

* add unit-test

Signed-off-by: Andrew Thornton <art27@cantab.net>

* as per @lunny

Signed-off-by: Andrew Thornton <art27@cantab.net>

* add test

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Update modules/cache/cache_redis.go

* Update modules/queue/queue_disk.go

* Update modules/cache/cache_redis.go

* Update modules/cache/cache_redis.go

* Update modules/queue/unique_queue_disk.go

* Update modules/queue/queue_disk.go

* Update modules/queue/unique_queue_disk.go

* Update modules/session/redis.go

Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: Lauris BH <lauris@nix.lv>

vendor/github.com/go-redis/redis/v7/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(hashes ...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.hash)
+}
+
+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
+}