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/cache/cache_redis.go

@@ -0,0 +1,140 @@
+// 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 cache
+
+import (
+	"fmt"
+	"time"
+
+	"code.gitea.io/gitea/modules/nosql"
+
+	"gitea.com/macaron/cache"
+	"github.com/go-redis/redis/v7"
+	"github.com/unknwon/com"
+)
+
+// RedisCacher represents a redis cache adapter implementation.
+type RedisCacher struct {
+	c          redis.UniversalClient
+	prefix     string
+	hsetName   string
+	occupyMode bool
+}
+
+// Put puts value into cache with key and expire time.
+// If expired is 0, it lives forever.
+func (c *RedisCacher) Put(key string, val interface{}, expire int64) error {
+	key = c.prefix + key
+	if expire == 0 {
+		if err := c.c.Set(key, com.ToStr(val), 0).Err(); err != nil {
+			return err
+		}
+	} else {
+		dur, err := time.ParseDuration(com.ToStr(expire) + "s")
+		if err != nil {
+			return err
+		}
+		if err = c.c.Set(key, com.ToStr(val), dur).Err(); err != nil {
+			return err
+		}
+	}
+
+	if c.occupyMode {
+		return nil
+	}
+	return c.c.HSet(c.hsetName, key, "0").Err()
+}
+
+// Get gets cached value by given key.
+func (c *RedisCacher) Get(key string) interface{} {
+	val, err := c.c.Get(c.prefix + key).Result()
+	if err != nil {
+		return nil
+	}
+	return val
+}
+
+// Delete deletes cached value by given key.
+func (c *RedisCacher) Delete(key string) error {
+	key = c.prefix + key
+	if err := c.c.Del(key).Err(); err != nil {
+		return err
+	}
+
+	if c.occupyMode {
+		return nil
+	}
+	return c.c.HDel(c.hsetName, key).Err()
+}
+
+// Incr increases cached int-type value by given key as a counter.
+func (c *RedisCacher) Incr(key string) error {
+	if !c.IsExist(key) {
+		return fmt.Errorf("key '%s' not exist", key)
+	}
+	return c.c.Incr(c.prefix + key).Err()
+}
+
+// Decr decreases cached int-type value by given key as a counter.
+func (c *RedisCacher) Decr(key string) error {
+	if !c.IsExist(key) {
+		return fmt.Errorf("key '%s' not exist", key)
+	}
+	return c.c.Decr(c.prefix + key).Err()
+}
+
+// IsExist returns true if cached value exists.
+func (c *RedisCacher) IsExist(key string) bool {
+	if c.c.Exists(c.prefix+key).Val() == 1 {
+		return true
+	}
+
+	if !c.occupyMode {
+		c.c.HDel(c.hsetName, c.prefix+key)
+	}
+	return false
+}
+
+// Flush deletes all cached data.
+func (c *RedisCacher) Flush() error {
+	if c.occupyMode {
+		return c.c.FlushDB().Err()
+	}
+
+	keys, err := c.c.HKeys(c.hsetName).Result()
+	if err != nil {
+		return err
+	}
+	if err = c.c.Del(keys...).Err(); err != nil {
+		return err
+	}
+	return c.c.Del(c.hsetName).Err()
+}
+
+// StartAndGC starts GC routine based on config string settings.
+// AdapterConfig: network=tcp,addr=:6379,password=macaron,db=0,pool_size=100,idle_timeout=180,hset_name=MacaronCache,prefix=cache:
+func (c *RedisCacher) StartAndGC(opts cache.Options) error {
+	c.hsetName = "MacaronCache"
+	c.occupyMode = opts.OccupyMode
+
+	uri := nosql.ToRedisURI(opts.AdapterConfig)
+
+	c.c = nosql.GetManager().GetRedisClient(uri.String())
+
+	for k, v := range uri.Query() {
+		switch k {
+		case "hset_name":
+			c.hsetName = v[0]
+		case "prefix":
+			c.prefix = v[0]
+		}
+	}
+
+	return c.c.Ping().Err()
+}
+
+func init() {
+	cache.Register("redis", &RedisCacher{})
+}