fix: remove mutex from pipeline

Author: vmihailenco

CHANGELOG.md

@@ -1,35 +1,17 @@
-# [9.0.0-rc.2](https://github.com/go-redis/redis/compare/v9.0.0-rc.1...v9.0.0-rc.2) (2022-11-26)
-
-
-### Bug Fixes
-
-* capture error correctly in withConn ([d1bfaba](https://github.com/go-redis/redis/commit/d1bfaba549fe380d269c26cea0a0183ed1520a85))
-* fixes ring.SetAddrs and rebalance race  ([#2283](https://github.com/go-redis/redis/issues/2283)) ([d83436b](https://github.com/go-redis/redis/commit/d83436b321cd9ed52ba33c3edbe8f63bb0444c59))
-* read in route_randomly query param correctly ([f236053](https://github.com/go-redis/redis/commit/f236053735d10aec5e6e31fc3ced1b2e53292554))
-* reduce `SetAddrs` shards lock contention ([6c05a9f](https://github.com/go-redis/redis/commit/6c05a9f6b17f8e32593d3f7d594f82ba3dbcafb1)), closes [/github.com/go-redis/redis/pull/2190#discussion_r953040289](https://github.com//github.com/go-redis/redis/pull/2190/issues/discussion_r953040289) [#2077](https://github.com/go-redis/redis/issues/2077)
-* wrap cmds in Conn.TxPipeline ([5053db2](https://github.com/go-redis/redis/commit/5053db2f9c8b3ca25f497a75f70012c7ad6cd775))
-
-
-### Features
-
-* add HasErrorPrefix ([d3d8002](https://github.com/go-redis/redis/commit/d3d8002e894a1eab5bab2c9fff13439527e330d8))
-* add support for SINTERCARD command ([bc51c61](https://github.com/go-redis/redis/commit/bc51c61a458d1bc4fb4424c7c3e912325ef980cc))
-
-
-
 ## v9 UNRELEASED
 
 ### Added
 
-- Added support for [RESP3](https://github.com/antirez/RESP3/blob/master/spec.md) protocol.
-  Contributed by @monkey92t who has done a lot of work recently.
+- Added support for [RESP3](https://github.com/antirez/RESP3/blob/master/spec.md) protocol. It was
+  contributed by @monkey92t who has done the majority of work in this release.
 - Added `ContextTimeoutEnabled` option that controls whether the client respects context timeouts
   and deadlines. See
   [Redis Timeouts](https://redis.uptrace.dev/guide/go-redis-debugging.html#timeouts) for details.
 - Added `ParseClusterURL` to parse URLs into `ClusterOptions`, for example,
   `redis://user:password@localhost:6789?dial_timeout=3&read_timeout=6s&addr=localhost:6790&addr=localhost:6791`.
 - Added metrics instrumentation using `redisotel.IstrumentMetrics`. See
   [documentation](https://redis.uptrace.dev/guide/go-redis-monitoring.html)
+- Added `redis.HasErrorPrefix` to help working with errors.
 
 ### Changed
 
@@ -48,8 +30,9 @@
 - Removed `Pipeline.Close` since there is no real need to explicitly manage pipeline resources and
   it can be safely reused via `sync.Pool` etc. `Pipeline.Discard` is still available if you want to
   reset commands for some reason.
+- Changed Pipelines to not be thread-safe any more.
 
 ### Fixed
 
 - Improved and fixed pipeline retries.
-- As usual, added more commands and fixed some bugs.
+- As usually, added support for more commands and fixed some bugs.

pipeline.go

@@ -2,7 +2,6 @@ package redis
 
 import (
 	"context"
-	"sync"
 )
 
 type pipelineExecer func(context.Context, []Cmder) error
@@ -39,8 +38,6 @@ type Pipeline struct {
 	statefulCmdable
 
 	exec pipelineExecer
-
-	mu   sync.Mutex
 	cmds []Cmder
 }
 
@@ -51,10 +48,7 @@ func (c *Pipeline) init() {
 
 // Len returns the number of queued commands.
 func (c *Pipeline) Len() int {
-	c.mu.Lock()
-	ln := len(c.cmds)
-	c.mu.Unlock()
-	return ln
+	return len(c.cmds)
 }
 
 // Do queues the custom command for later execution.
@@ -66,17 +60,13 @@ func (c *Pipeline) Do(ctx context.Context, args ...interface{}) *Cmd {
 
 // Process queues the cmd for later execution.
 func (c *Pipeline) Process(ctx context.Context, cmd Cmder) error {
-	c.mu.Lock()
 	c.cmds = append(c.cmds, cmd)
-	c.mu.Unlock()
 	return nil
 }
 
 // Discard resets the pipeline and discards queued commands.
 func (c *Pipeline) Discard() {
-	c.mu.Lock()
 	c.cmds = c.cmds[:0]
-	c.mu.Unlock()
 }
 
 // Exec executes all previously queued commands using one
@@ -85,9 +75,6 @@ func (c *Pipeline) Discard() {
 // Exec always returns list of commands and error of the first failed
 // command if any.
 func (c *Pipeline) Exec(ctx context.Context) ([]Cmder, error) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
 	if len(c.cmds) == 0 {
 		return nil, nil
 	}

race_test.go

@@ -214,53 +214,6 @@ var _ = Describe("races", func() {
 		Expect(val).To(Equal(int64(C * N)))
 	})
 
-	It("should Pipeline", func() {
-		perform(C, func(id int) {
-			pipe := client.Pipeline()
-			for i := 0; i < N; i++ {
-				pipe.Echo(ctx, fmt.Sprint(i))
-			}
-
-			cmds, err := pipe.Exec(ctx)
-			Expect(err).NotTo(HaveOccurred())
-			Expect(cmds).To(HaveLen(N))
-
-			for i := 0; i < N; i++ {
-				Expect(cmds[i].(*redis.StringCmd).Val()).To(Equal(fmt.Sprint(i)))
-			}
-		})
-	})
-
-	It("should Pipeline", func() {
-		pipe := client.Pipeline()
-		perform(N, func(id int) {
-			pipe.Incr(ctx, "key")
-		})
-
-		cmds, err := pipe.Exec(ctx)
-		Expect(err).NotTo(HaveOccurred())
-		Expect(cmds).To(HaveLen(N))
-
-		n, err := client.Get(ctx, "key").Int64()
-		Expect(err).NotTo(HaveOccurred())
-		Expect(n).To(Equal(int64(N)))
-	})
-
-	It("should TxPipeline", func() {
-		pipe := client.TxPipeline()
-		perform(N, func(id int) {
-			pipe.Incr(ctx, "key")
-		})
-
-		cmds, err := pipe.Exec(ctx)
-		Expect(err).NotTo(HaveOccurred())
-		Expect(cmds).To(HaveLen(N))
-
-		n, err := client.Get(ctx, "key").Int64()
-		Expect(err).NotTo(HaveOccurred())
-		Expect(n).To(Equal(int64(N)))
-	})
-
 	PIt("should BLPop", func() {
 		var received uint32