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>

modules/nosql/redis.go

@@ -0,0 +1,102 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package nosql
+
+import (
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+// The file contains common redis connection functions
+
+// ToRedisURI converts old style connections to a RedisURI
+//
+// A RedisURI matches the pattern:
+//
+// redis://[username:password@]host[:port][/database][?[option=value]*]
+// rediss://[username:password@]host[:port][/database][?[option=value]*]
+// redis+socket://[username:password@]path[/database][?[option=value]*]
+// redis+sentinel://[password@]host1 [: port1][, host2 [:port2]][, hostN [:portN]][/ database][?[option=value]*]
+// redis+cluster://[password@]host1 [: port1][, host2 [:port2]][, hostN [:portN]][/ database][?[option=value]*]
+//
+// We have previously used a URI like:
+// addrs=127.0.0.1:6379 db=0
+// network=tcp,addr=127.0.0.1:6379,password=macaron,db=0,pool_size=100,idle_timeout=180
+//
+// We need to convert this old style to the new style
+func ToRedisURI(connection string) *url.URL {
+	uri, err := url.Parse(connection)
+	if err == nil && strings.HasPrefix(uri.Scheme, "redis") {
+		// OK we're going to assume that this is a reasonable redis URI
+		return uri
+	}
+
+	// Let's set a nice default
+	uri, _ = url.Parse("redis://127.0.0.1:6379/0")
+	network := "tcp"
+	query := uri.Query()
+
+	// OK so there are two types: Space delimited and Comma delimited
+	// Let's assume that we have a space delimited string - as this is the most common
+	fields := strings.Fields(connection)
+	if len(fields) == 1 {
+		// It's a comma delimited string, then...
+		fields = strings.Split(connection, ",")
+
+	}
+	for _, f := range fields {
+		items := strings.SplitN(f, "=", 2)
+		if len(items) < 2 {
+			continue
+		}
+		switch strings.ToLower(items[0]) {
+		case "network":
+			if items[1] == "unix" {
+				uri.Scheme = "redis+socket"
+			}
+			network = items[1]
+		case "addrs":
+			uri.Host = items[1]
+			// now we need to handle the clustering
+			if strings.Contains(items[1], ",") && network == "tcp" {
+				uri.Scheme = "redis+cluster"
+			}
+		case "addr":
+			uri.Host = items[1]
+		case "password":
+			uri.User = url.UserPassword(uri.User.Username(), items[1])
+		case "username":
+			password, set := uri.User.Password()
+			if !set {
+				uri.User = url.User(items[1])
+			} else {
+				uri.User = url.UserPassword(items[1], password)
+			}
+		case "db":
+			uri.Path = "/" + items[1]
+		case "idle_timeout":
+			_, err := strconv.Atoi(items[1])
+			if err == nil {
+				query.Add("idle_timeout", items[1]+"s")
+			} else {
+				query.Add("idle_timeout", items[1])
+			}
+		default:
+			// Other options become query params
+			query.Add(items[0], items[1])
+		}
+	}
+
+	// Finally we need to fix up the Host if we have a unix port
+	if uri.Scheme == "redis+socket" {
+		query.Set("db", uri.Path)
+		uri.Path = uri.Host
+		uri.Host = ""
+	}
+	uri.RawQuery = query.Encode()
+
+	return uri
+}