Better rate limited message.

.travis.yml

@@ -5,7 +5,6 @@ services:
   - redis-server
 
 go:
-  - 1.3
   - 1.4
   - 1.5
   - tip

multi.go

@@ -46,16 +46,15 @@ func (c *Client) Multi() *Multi {
 	return multi
 }
 
-func (c *Multi) putConn(cn *conn, ei error) {
-	var err error
-	if isBadConn(cn, ei) {
+func (c *Multi) putConn(cn *conn, err error) {
+	if isBadConn(cn, err) {
 		// Close current connection.
-		c.base.connPool.(*stickyConnPool).Reset()
+		c.base.connPool.(*stickyConnPool).Reset(err)
 	} else {
-		err = c.base.connPool.Put(cn)
-	}
-	if err != nil {
-		log.Printf("redis: putConn failed: %s", err)
+		err := c.base.connPool.Put(cn)
+		if err != nil {
+			log.Printf("redis: putConn failed: %s", err)
+		}
 	}
 }
 

pool.go

@@ -20,7 +20,7 @@ type pool interface {
 	First() *conn
 	Get() (*conn, bool, error)
 	Put(*conn) error
-	Remove(*conn) error
+	Remove(*conn, error) error
 	Len() int
 	FreeLen() int
 	Close() error
@@ -130,7 +130,7 @@ type connPool struct {
 
 	_closed int32
 
-	lastDialErr error
+	lastErr atomic.Value
 }
 
 func newConnPool(opt *Options) *connPool {
@@ -204,15 +204,15 @@ func (p *connPool) wait() *conn {
 func (p *connPool) new() (*conn, error) {
 	if p.rl.Limit() {
 		err := fmt.Errorf(
-			"redis: you open connections too fast (last error: %v)",
-			p.lastDialErr,
+			"redis: you open connections too fast (last_error=%q)",
+			p.loadLastErr(),
 		)
 		return nil, err
 	}
 
 	cn, err := p.dialer()
 	if err != nil {
-		p.lastDialErr = err
+		p.storeLastErr(err.Error())
 		return nil, err
 	}
 
@@ -255,8 +255,9 @@ func (p *connPool) Get() (cn *conn, isNew bool, err error) {
 func (p *connPool) Put(cn *conn) error {
 	if cn.rd.Buffered() != 0 {
 		b, _ := cn.rd.Peek(cn.rd.Buffered())
-		log.Printf("redis: connection has unread data: %q", b)
-		return p.Remove(cn)
+		err := fmt.Errorf("redis: connection has unread data: %q", b)
+		log.Print(err)
+		return p.Remove(cn, err)
 	}
 	if p.opt.getIdleTimeout() > 0 {
 		cn.usedAt = time.Now()
@@ -275,7 +276,9 @@ func (p *connPool) replace(cn *conn) (*conn, error) {
 	return newcn, nil
 }
 
-func (p *connPool) Remove(cn *conn) error {
+func (p *connPool) Remove(cn *conn, reason error) error {
+	p.storeLastErr(reason.Error())
+
 	// Replace existing connection with new one and unblock waiter.
 	newcn, err := p.replace(cn)
 	if err != nil {
@@ -330,6 +333,17 @@ func (p *connPool) reaper() {
 	}
 }
 
+func (p *connPool) storeLastErr(err string) {
+	p.lastErr.Store(err)
+}
+
+func (p *connPool) loadLastErr() string {
+	if v := p.lastErr.Load(); v != nil {
+		return v.(string)
+	}
+	return ""
+}
+
 //------------------------------------------------------------------------------
 
 type singleConnPool struct {
@@ -357,7 +371,7 @@ func (p *singleConnPool) Put(cn *conn) error {
 	return nil
 }
 
-func (p *singleConnPool) Remove(cn *conn) error {
+func (p *singleConnPool) Remove(cn *conn, _ error) error {
 	if p.cn != cn {
 		panic("p.cn != cn")
 	}
@@ -440,13 +454,13 @@ func (p *stickyConnPool) Put(cn *conn) error {
 	return nil
 }
 
-func (p *stickyConnPool) remove() (err error) {
-	err = p.pool.Remove(p.cn)
+func (p *stickyConnPool) remove(reason error) (err error) {
+	err = p.pool.Remove(p.cn, reason)
 	p.cn = nil
 	return err
 }
 
-func (p *stickyConnPool) Remove(cn *conn) error {
+func (p *stickyConnPool) Remove(cn *conn, _ error) error {
 	defer p.mx.Unlock()
 	p.mx.Lock()
 	if p.closed {
@@ -479,10 +493,10 @@ func (p *stickyConnPool) FreeLen() int {
 	return 0
 }
 
-func (p *stickyConnPool) Reset() (err error) {
+func (p *stickyConnPool) Reset(reason error) (err error) {
 	p.mx.Lock()
 	if p.cn != nil {
-		err = p.remove()
+		err = p.remove(reason)
 	}
 	p.mx.Unlock()
 	return err
@@ -500,7 +514,8 @@ func (p *stickyConnPool) Close() error {
 		if p.reusable {
 			err = p.put()
 		} else {
-			err = p.remove()
+			reason := errors.New("redis: sticky not reusable connection")
+			err = p.remove(reason)
 		}
 	}
 	return err

pool_test.go

@@ -1,6 +1,7 @@
 package redis_test
 
 import (
+	"errors"
 	"sync"
 	"testing"
 	"time"
@@ -36,7 +37,6 @@ var _ = Describe("pool", func() {
 	})
 
 	AfterEach(func() {
-		Expect(client.FlushDb().Err()).NotTo(HaveOccurred())
 		Expect(client.Close()).NotTo(HaveOccurred())
 	})
 
@@ -141,12 +141,12 @@ var _ = Describe("pool", func() {
 		pool := client.Pool()
 
 		// Reserve one connection.
-		cn, _, err := client.Pool().Get()
+		cn, _, err := pool.Get()
 		Expect(err).NotTo(HaveOccurred())
 
 		// Reserve the rest of connections.
 		for i := 0; i < 9; i++ {
-			_, _, err := client.Pool().Get()
+			_, _, err := pool.Get()
 			Expect(err).NotTo(HaveOccurred())
 		}
 
@@ -168,7 +168,8 @@ var _ = Describe("pool", func() {
 			// ok
 		}
 
-		Expect(pool.Remove(cn)).NotTo(HaveOccurred())
+		err = pool.Remove(cn, errors.New("test"))
+		Expect(err).NotTo(HaveOccurred())
 
 		// Check that Ping is unblocked.
 		select {
@@ -179,6 +180,23 @@ var _ = Describe("pool", func() {
 		}
 		Expect(ping.Err()).NotTo(HaveOccurred())
 	})
+
+	It("should rate limit dial", func() {
+		pool := client.Pool()
+
+		var rateErr error
+		for i := 0; i < 1000; i++ {
+			cn, _, err := pool.Get()
+			if err != nil {
+				rateErr = err
+				break
+			}
+
+			_ = pool.Remove(cn, errors.New("test"))
+		}
+
+		Expect(rateErr).To(MatchError(`redis: you open connections too fast (last_error="test")`))
+	})
 })
 
 func BenchmarkPool(b *testing.B) {

pubsub.go

@@ -233,9 +233,9 @@ func (c *PubSub) Receive() (interface{}, error) {
 	return c.ReceiveTimeout(0)
 }
 
-func (c *PubSub) reconnect() {
+func (c *PubSub) reconnect(reason error) {
 	// Close current connection.
-	c.connPool.(*stickyConnPool).Reset()
+	c.connPool.(*stickyConnPool).Reset(reason)
 
 	if len(c.channels) > 0 {
 		if err := c.Subscribe(c.channels...); err != nil {
@@ -276,7 +276,7 @@ func (c *PubSub) ReceiveMessage() (*Message, error) {
 			if errNum > 2 {
 				time.Sleep(time.Second)
 			}
-			c.reconnect()
+			c.reconnect(err)
 			continue
 		}
 

redis.go

@@ -20,10 +20,9 @@ func (c *baseClient) conn() (*conn, bool, error) {
 	return c.connPool.Get()
 }
 
-func (c *baseClient) putConn(cn *conn, ei error) {
-	var err error
-	if isBadConn(cn, ei) {
-		err = c.connPool.Remove(cn)
+func (c *baseClient) putConn(cn *conn, err error) {
+	if isBadConn(cn, err) {
+		err = c.connPool.Remove(cn, err)
 	} else {
 		err = c.connPool.Put(cn)
 	}

sentinel.go

@@ -2,6 +2,7 @@ package redis
 
 import (
 	"errors"
+	"fmt"
 	"log"
 	"net"
 	"strings"
@@ -227,11 +228,12 @@ func (d *sentinelFailover) closeOldConns(newMaster string) {
 			break
 		}
 		if cn.RemoteAddr().String() != newMaster {
-			log.Printf(
+			err := fmt.Errorf(
 				"redis-sentinel: closing connection to the old master %s",
 				cn.RemoteAddr(),
 			)
-			d.pool.Remove(cn)
+			log.Print(err)
+			d.pool.Remove(cn, err)
 		} else {
 			cnsToPut = append(cnsToPut, cn)
 		}