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/pipeline.go

@@ -1,120 +0,0 @@
-package redis
-
-import (
-	"sync"
-
-	"github.com/go-redis/redis/internal/pool"
-)
-
-type pipelineExecer func([]Cmder) error
-
-type Pipeliner interface {
-	StatefulCmdable
-	Do(args ...interface{}) *Cmd
-	Process(cmd Cmder) error
-	Close() error
-	Discard() error
-	Exec() ([]Cmder, error)
-}
-
-var _ Pipeliner = (*Pipeline)(nil)
-
-// Pipeline implements pipelining as described in
-// http://redis.io/topics/pipelining. It's safe for concurrent use
-// by multiple goroutines.
-type Pipeline struct {
-	statefulCmdable
-
-	exec pipelineExecer
-
-	mu     sync.Mutex
-	cmds   []Cmder
-	closed bool
-}
-
-func (c *Pipeline) Do(args ...interface{}) *Cmd {
-	cmd := NewCmd(args...)
-	_ = c.Process(cmd)
-	return cmd
-}
-
-// Process queues the cmd for later execution.
-func (c *Pipeline) Process(cmd Cmder) error {
-	c.mu.Lock()
-	c.cmds = append(c.cmds, cmd)
-	c.mu.Unlock()
-	return nil
-}
-
-// Close closes the pipeline, releasing any open resources.
-func (c *Pipeline) Close() error {
-	c.mu.Lock()
-	c.discard()
-	c.closed = true
-	c.mu.Unlock()
-	return nil
-}
-
-// Discard resets the pipeline and discards queued commands.
-func (c *Pipeline) Discard() error {
-	c.mu.Lock()
-	err := c.discard()
-	c.mu.Unlock()
-	return err
-}
-
-func (c *Pipeline) discard() error {
-	if c.closed {
-		return pool.ErrClosed
-	}
-	c.cmds = c.cmds[:0]
-	return nil
-}
-
-// Exec executes all previously queued commands using one
-// client-server roundtrip.
-//
-// Exec always returns list of commands and error of the first failed
-// command if any.
-func (c *Pipeline) Exec() ([]Cmder, error) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
-	if c.closed {
-		return nil, pool.ErrClosed
-	}
-
-	if len(c.cmds) == 0 {
-		return nil, nil
-	}
-
-	cmds := c.cmds
-	c.cmds = nil
-
-	return cmds, c.exec(cmds)
-}
-
-func (c *Pipeline) pipelined(fn func(Pipeliner) error) ([]Cmder, error) {
-	if err := fn(c); err != nil {
-		return nil, err
-	}
-	cmds, err := c.Exec()
-	_ = c.Close()
-	return cmds, err
-}
-
-func (c *Pipeline) Pipelined(fn func(Pipeliner) error) ([]Cmder, error) {
-	return c.pipelined(fn)
-}
-
-func (c *Pipeline) Pipeline() Pipeliner {
-	return c
-}
-
-func (c *Pipeline) TxPipelined(fn func(Pipeliner) error) ([]Cmder, error) {
-	return c.pipelined(fn)
-}
-
-func (c *Pipeline) TxPipeline() Pipeliner {
-	return c
-}