test and fix parsehashkey

go.mod

@@ -0,0 +1,26 @@
+module red-apter
+
+go 1.24.0
+
+toolchain go1.24.12
+
+require (
+	github.com/lib/pq v1.11.1
+	github.com/redis/go-redis/v9 v9.17.3
+	modernc.org/sqlite v1.44.3
+)
+
+require (
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
+	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/ncruces/go-strftime v1.0.0 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 // indirect
+	golang.org/x/sys v0.37.0 // indirect
+	modernc.org/libc v1.67.6 // indirect
+	modernc.org/mathutil v1.7.1 // indirect
+	modernc.org/memory v1.11.0 // indirect
+)

go.sum

@@ -0,0 +1,65 @@
+github.com/bsm/ginkgo/v2 v2.12.0 h1:Ny8MWAHyOepLGlLKYmXG4IEkioBysk6GpaRTLC8zwWs=
+github.com/bsm/ginkgo/v2 v2.12.0/go.mod h1:SwYbGRRDovPVboqFv0tPTcG1sN61LM1Z4ARdbAV9g4c=
+github.com/bsm/gomega v1.27.10 h1:yeMWxP2pV2fG3FgAODIY8EiRE3dy0aeFYt4l7wh6yKA=
+github.com/bsm/gomega v1.27.10/go.mod h1:JyEr/xRbxbtgWNi8tIEVPUYZ5Dzef52k01W3YH0H+O0=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
+github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
+github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
+github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
+github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e h1:ijClszYn+mADRFY17kjQEVQ1XRhq2/JR1M3sGqeJoxs=
+github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e/go.mod h1:boTsfXsheKC2y+lKOCMpSfarhxDeIzfZG1jqGcPl3cA=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/hashicorp/golang-lru/v2 v2.0.7 h1:a+bsQ5rvGLjzHuww6tVxozPZFVghXaHOwFs4luLUK2k=
+github.com/hashicorp/golang-lru/v2 v2.0.7/go.mod h1:QeFd9opnmA6QUJc5vARoKUSoFhyfM2/ZepoAG6RGpeM=
+github.com/lib/pq v1.11.1 h1:wuChtj2hfsGmmx3nf1m7xC2XpK6OtelS2shMY+bGMtI=
+github.com/lib/pq v1.11.1/go.mod h1:/p+8NSbOcwzAEI7wiMXFlgydTwcgTr3OSKMsD2BitpA=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/ncruces/go-strftime v1.0.0 h1:HMFp8mLCTPp341M/ZnA4qaf7ZlsbTc+miZjCLOFAw7w=
+github.com/ncruces/go-strftime v1.0.0/go.mod h1:Fwc5htZGVVkseilnfgOVb9mKy6w1naJmn9CehxcKcls=
+github.com/redis/go-redis/v9 v9.17.3 h1:fN29NdNrE17KttK5Ndf20buqfDZwGNgoUr9qjl1DQx4=
+github.com/redis/go-redis/v9 v9.17.3/go.mod h1:u410H11HMLoB+TP67dz8rL9s6QW2j76l0//kSOd3370=
+github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec h1:W09IVJc94icq4NjY3clb7Lk8O1qJ8BdBEF8z0ibU0rE=
+github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
+golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 h1:mgKeJMpvi0yx/sU5GsxQ7p6s2wtOnGAHZWCHUM4KGzY=
+golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546/go.mod h1:j/pmGrbnkbPtQfxEe5D0VQhZC6qKbfKifgD0oM7sR70=
+golang.org/x/mod v0.29.0 h1:HV8lRxZC4l2cr3Zq1LvtOsi/ThTgWnUk/y64QSs8GwA=
+golang.org/x/mod v0.29.0/go.mod h1:NyhrlYXJ2H4eJiRy/WDBO6HMqZQ6q9nk4JzS3NuCK+w=
+golang.org/x/sync v0.17.0 h1:l60nONMj9l5drqw6jlhIELNv9I0A4OFgRsG9k2oT9Ug=
+golang.org/x/sync v0.17.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.37.0 h1:fdNQudmxPjkdUTPnLn5mdQv7Zwvbvpaxqs831goi9kQ=
+golang.org/x/sys v0.37.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/tools v0.38.0 h1:Hx2Xv8hISq8Lm16jvBZ2VQf+RLmbd7wVUsALibYI/IQ=
+golang.org/x/tools v0.38.0/go.mod h1:yEsQ/d/YK8cjh0L6rZlY8tgtlKiBNTL14pGDJPJpYQs=
+modernc.org/cc/v4 v4.27.1 h1:9W30zRlYrefrDV2JE2O8VDtJ1yPGownxciz5rrbQZis=
+modernc.org/cc/v4 v4.27.1/go.mod h1:uVtb5OGqUKpoLWhqwNQo/8LwvoiEBLvZXIQ/SmO6mL0=
+modernc.org/ccgo/v4 v4.30.1 h1:4r4U1J6Fhj98NKfSjnPUN7Ze2c6MnAdL0hWw6+LrJpc=
+modernc.org/ccgo/v4 v4.30.1/go.mod h1:bIOeI1JL54Utlxn+LwrFyjCx2n2RDiYEaJVSrgdrRfM=
+modernc.org/fileutil v1.3.40 h1:ZGMswMNc9JOCrcrakF1HrvmergNLAmxOPjizirpfqBA=
+modernc.org/fileutil v1.3.40/go.mod h1:HxmghZSZVAz/LXcMNwZPA/DRrQZEVP9VX0V4LQGQFOc=
+modernc.org/gc/v2 v2.6.5 h1:nyqdV8q46KvTpZlsw66kWqwXRHdjIlJOhG6kxiV/9xI=
+modernc.org/gc/v2 v2.6.5/go.mod h1:YgIahr1ypgfe7chRuJi2gD7DBQiKSLMPgBQe9oIiito=
+modernc.org/gc/v3 v3.1.1 h1:k8T3gkXWY9sEiytKhcgyiZ2L0DTyCQ/nvX+LoCljoRE=
+modernc.org/gc/v3 v3.1.1/go.mod h1:HFK/6AGESC7Ex+EZJhJ2Gni6cTaYpSMmU/cT9RmlfYY=
+modernc.org/goabi0 v0.2.0 h1:HvEowk7LxcPd0eq6mVOAEMai46V+i7Jrj13t4AzuNks=
+modernc.org/goabi0 v0.2.0/go.mod h1:CEFRnnJhKvWT1c1JTI3Avm+tgOWbkOu5oPA8eH8LnMI=
+modernc.org/libc v1.67.6 h1:eVOQvpModVLKOdT+LvBPjdQqfrZq+pC39BygcT+E7OI=
+modernc.org/libc v1.67.6/go.mod h1:JAhxUVlolfYDErnwiqaLvUqc8nfb2r6S6slAgZOnaiE=
+modernc.org/mathutil v1.7.1 h1:GCZVGXdaN8gTqB1Mf/usp1Y/hSqgI2vAGGP4jZMCxOU=
+modernc.org/mathutil v1.7.1/go.mod h1:4p5IwJITfppl0G4sUEDtCr4DthTaT47/N3aT6MhfgJg=
+modernc.org/memory v1.11.0 h1:o4QC8aMQzmcwCK3t3Ux/ZHmwFPzE6hf2Y5LbkRs+hbI=
+modernc.org/memory v1.11.0/go.mod h1:/JP4VbVC+K5sU2wZi9bHoq2MAkCnrt2r98UGeSK7Mjw=
+modernc.org/opt v0.1.4 h1:2kNGMRiUjrp4LcaPuLY2PzUfqM/w9N23quVwhKt5Qm8=
+modernc.org/opt v0.1.4/go.mod h1:03fq9lsNfvkYSfxrfUhZCWPk1lm4cq4N+Bh//bEtgns=
+modernc.org/sortutil v1.2.1 h1:+xyoGf15mM3NMlPDnFqrteY07klSFxLElE2PVuWIJ7w=
+modernc.org/sortutil v1.2.1/go.mod h1:7ZI3a3REbai7gzCLcotuw9AC4VZVpYMjDzETGsSMqJE=
+modernc.org/sqlite v1.44.3 h1:+39JvV/HWMcYslAwRxHb8067w+2zowvFOUrOWIy9PjY=
+modernc.org/sqlite v1.44.3/go.mod h1:CzbrU2lSB1DKUusvwGz7rqEKIq+NUd8GWuBBZDs9/nA=
+modernc.org/strutil v1.2.1 h1:UneZBkQA+DX2Rp35KcM69cSsNES9ly8mQWD71HKlOA0=
+modernc.org/strutil v1.2.1/go.mod h1:EHkiggD70koQxjVdSBM3JKM7k6L0FbGE5eymy9i3B9A=
+modernc.org/token v1.1.0 h1:Xl7Ap9dKaEs5kLoOQeQmPWevfnk/DM5qcLcYlA8ys6Y=
+modernc.org/token v1.1.0/go.mod h1:UGzOrNV1mAFSEB63lOFHIpNRUVMvYTc6yu1SMY/XTDM=

main.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"context"
+	"os/signal"
+	"red-apter/src"
+	"syscall"
+)
+
+func main() {
+	ctx, can := signal.NotifyContext(context.Background(), syscall.SIGINT)
+	defer can()
+
+	if err := src.Main(ctx); err != nil {
+		panic(err)
+	}
+}

src/adapt.go

@@ -0,0 +1,148 @@
+package src
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"regexp"
+	"strconv"
+)
+
+func adapt(ctx context.Context, config Config, conn net.Conn) error {
+	reader := bufio.NewReader(conn)
+
+	for ctx.Err() == nil {
+		if err := adaptOne(ctx, config, conn, reader); err != nil {
+			return err
+		}
+	}
+
+	return io.EOF
+}
+
+func adaptOne(ctx context.Context, config Config, conn io.Writer, reader *bufio.Reader) error {
+	raw, err := readMessage(reader)
+	if err != nil {
+		return err
+	} else if len(raw) == 0 {
+		return nil
+	}
+	log.Printf("routing: %q", raw)
+
+	return config.WithConn(parseHashKey(raw), func(forwardConn net.Conn) error {
+		if _, err := io.Copy(forwardConn, bytes.NewReader(raw)); err != nil {
+			return err
+		}
+
+		return readMessageTo(conn, bufio.NewReader(forwardConn))
+	})
+}
+
+func readMessage(reader *bufio.Reader) ([]byte, error) {
+	w := bytes.NewBuffer(nil)
+	err := readMessageTo(w, reader)
+	return w.Bytes(), err
+}
+
+func readMessageTo(w io.Writer, reader *bufio.Reader) error {
+	w2 := bufio.NewWriter(w)
+	defer w2.Flush()
+	err := _readMessageTo(w2, reader)
+	if err != nil {
+		return err
+	}
+	return w2.Flush()
+}
+
+func _readMessageTo(w io.Writer, reader *bufio.Reader) error {
+	firstLine, _, err := reader.ReadLine()
+	if err != nil {
+		return err
+	}
+	firstLine = bytes.TrimSuffix(firstLine, []byte("\r\n"))
+	if len(firstLine) == 0 {
+		return nil
+	}
+	fmt.Fprintf(w, "%s\r\n", firstLine)
+
+	switch firstLine[0] {
+	case '+': // simple string, like +OK
+		return nil
+	case '-': // simple error, like -message
+		return nil
+	case ':': // number, like /[+-][0-9]+/
+		return err
+	case '$': // long string, like $-1 for nil, like $LEN\r\nSTRING\r\n
+		if firstLine[1] == '-' {
+			return nil
+		}
+		firstLine = bytes.TrimPrefix(firstLine[1:], []byte("+"))
+		n, err := strconv.Atoi(string(firstLine))
+		if err != nil {
+			return fmt.Errorf("num not a num: %q: %w", firstLine, err)
+		}
+		nextLine := make([]byte, n+2)
+		nAt := 0
+		for nAt < n+2 {
+			nMore, err := reader.Read(nextLine[nAt:])
+			if err != nil {
+				return fmt.Errorf("couldnt read %v more/%v bytes for long string: %w", n+2-nAt, n+2, err)
+			}
+			nAt += nMore
+		}
+		fmt.Fprintf(w, "%s", nextLine)
+		return err
+	case '*', '~', '%': // *=array ~=set %=map, like *-1 for nil, like *4 for [1,2,3,4]
+		n, err := strconv.Atoi(string(firstLine[1:]))
+		if err != nil {
+			return fmt.Errorf("arr not a num: %q: %w", firstLine, err)
+		} else if n == -1 {
+			return nil
+		}
+		if isMap := firstLine[0] == '%'; isMap {
+			n *= 2
+		}
+		for i := 0; i < n; i++ {
+			err := _readMessageTo(w, reader)
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	case '_': // nil
+		return nil
+	case '#': // boolean, like #t or #f
+		return nil
+	case ',': // double
+		return nil
+	}
+
+	log.Fatalf("not impl: %q", firstLine)
+	return nil
+}
+
+var alpha = regexp.MustCompile(`[a-zA-Z]`)
+var parts = regexp.MustCompile(`(.*?)\r\n*`)
+
+func parseHashKey(raw []byte) string {
+	matches := parts.FindAllSubmatch(raw, 5)
+	if len(matches) == 0 {
+		return ""
+	}
+	for i := range matches {
+		if isTheCommand := alpha.Match(matches[i][0]); isTheCommand {
+			for j := i + 1; j < len(matches); j++ {
+				if matches[j][0][0] == byte('$') {
+					continue
+				}
+				return string(matches[j][1])
+			}
+			return string(matches[i][1])
+		}
+	}
+	return ""
+}

src/adapt_test.go

@@ -0,0 +1,64 @@
+package src
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"strings"
+	"testing"
+)
+
+func TestParseHashKey(t *testing.T) {
+	cases := map[string]string{
+		"+OK\r\n":                        "+OK",
+		"+string\r\n":                    "+string",
+		"*1\r\n$4\r\nping\r\n":           "ping",
+		"*2\r\n$3\r\nget\r\n$1\r\nx\r\n": "x",
+		"*2\r\n$3\r\nset\r\n$1\r\nx\r\n$1\r\ny\r\n": "x",
+	}
+
+	for given, expect := range cases {
+		given, expect := given, expect
+		t.Run(fmt.Sprintf("%q", given), func(t *testing.T) {
+			got := parseHashKey([]byte(given))
+			if string(got) != expect {
+				t.Errorf("expected %q=>%q but got =>%q", given, expect, got)
+			}
+		})
+	}
+}
+
+func TestReadMessage(t *testing.T) {
+	cases := map[string]string{
+		"ok":              "+OK\r\n",
+		"simple string":   "+my string\r\n",
+		"error":           "-my err\r\n",
+		"number":          ":1\r\n",
+		"negative number": ":-1\r\n",
+		"positive number": ":+1\r\n",
+		"nil string":      "$-1\r\n",
+		"long string":     "$100\r\n" + strings.Repeat("a", 100) + "\r\n",
+		"longer string":   "$10000\r\n" + strings.Repeat("a", 10000) + "\r\n",
+		"zero array":      "*0\r\n",
+		"array":           "*3\r\n+hello\r\n:world\r\n$1\r\n!\r\n",
+		"set":             "~3\r\n+hello\r\n:world\r\n$1\r\n!\r\n",
+		"map":             "%1\r\n+foo\r\n+bar\r\n",
+		"nil":             "_\r\n",
+		"boolean":         "#t\r\n",
+		"double":          ",1.5\r\n",
+		// "empty":           "", (eof)
+	}
+
+	for name, payload := range cases {
+		payload := payload
+		t.Run(name, func(t *testing.T) {
+			got, err := readMessage(bufio.NewReader(strings.NewReader(payload)))
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !bytes.Equal(got, []byte(payload)) {
+				t.Errorf("expected %q but got %q", payload, got)
+			}
+		})
+	}
+}

src/config.go

@@ -0,0 +1,157 @@
+package src
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"hash/crc32"
+	"io"
+	"log"
+	"net"
+	"os"
+	"slices"
+	"strings"
+	"sync"
+)
+
+type Config struct {
+	ctx      context.Context
+	Listen   string `json:"LISTEN"`
+	Forwards string `json:"FORWARDS"`
+	Hello    string `json:"HELLO_B64"`
+	forwards []*sync.Pool
+}
+
+func NewConfig(ctx context.Context) (Config, error) {
+	config := Config{
+		ctx:      ctx,
+		Listen:   ":10000",
+		Forwards: "",
+		Hello:    base64.StdEncoding.EncodeToString([]byte("*1\r\n$4\r\nping\r\n")),
+	}
+
+	if err := config.loadEnv(); err != nil {
+		return config, err
+	}
+
+	if err := config.setForwards(); err != nil {
+		return config, err
+	}
+
+	return config, nil
+}
+
+func (c *Config) loadEnv() error {
+	b, _ := json.Marshal(*c)
+	var m map[string]any
+	if err := json.Unmarshal(b, &m); err != nil {
+		return err
+	}
+	for k := range m {
+		if v := os.Getenv(k); v != "" {
+			m[k] = v
+		}
+	}
+	b2, _ := json.Marshal(m)
+	return json.Unmarshal(b2, c)
+}
+
+func (c *Config) setForwards() error {
+	hello, err := base64.StdEncoding.DecodeString(c.Hello)
+	if err != nil {
+		return err
+	}
+
+	addresses := strings.Split(c.Forwards, ",")
+	addresses = slices.DeleteFunc(addresses, func(s string) bool { return s == "" })
+	if len(addresses) == 0 {
+		return fmt.Errorf("at least one $FORWARD required")
+	}
+
+	c.forwards = make([]*sync.Pool, len(addresses))
+	for i := range addresses {
+		address := addresses[i]
+		c.forwards[i] = &sync.Pool{
+			New: func() any {
+				conn, err := c.dial(address, hello)
+				if err != nil {
+					log.Printf("! failed to dial %q: %v", address, err)
+				}
+				return conn
+			},
+		}
+	}
+	return nil
+}
+
+func (c *Config) dial(address string, hello []byte) (net.Conn, error) {
+	if err := c.ctx.Err(); err != nil {
+		return nil, err
+	}
+
+	log.Printf("dialing %q with %q", address, hello)
+	v, err := (&net.Dialer{}).DialContext(c.ctx, "tcp", address)
+	if err != nil {
+		return nil, err
+	}
+
+	if _, err := v.Write([]byte(hello)); err != nil {
+		v.Close()
+		return nil, err
+	}
+
+	if raw, err := readMessage(bufio.NewReader(v)); err != nil {
+		v.Close()
+		return nil, err
+	} else if bytes.HasPrefix(raw, []byte("-")) {
+		v.Close()
+		return nil, fmt.Errorf("failed hello: %s", raw)
+	}
+
+	return v, nil
+}
+
+func (c Config) Close() {
+	for i := range c.forwards {
+		if c.forwards[i] != nil {
+			i := i
+			func() {
+				c.forwards[i].New = nil
+				for {
+					got := c.forwards[i].Get()
+					if got == nil {
+						break
+					}
+					got.(net.Conn).Close()
+				}
+			}()
+		}
+	}
+}
+
+func (c Config) WithConn(hashKey string, foo func(net.Conn) error) error {
+	hash := int(crc32.ChecksumIEEE([]byte(hashKey)))
+	hashIdx := hash % len(c.forwards)
+	forward := c.forwards[hashIdx]
+
+	log.Printf("acquire conn %v", hashIdx)
+	forwardCon := forward.Get()
+	if forwardCon == nil {
+		log.Printf("got a nil conn to %v", hashIdx)
+		return io.EOF
+	}
+	forwardConn := forwardCon.(net.Conn)
+
+	if err := foo(forwardConn); err != nil {
+		log.Printf("errored with conn %v: %v", hashIdx, err)
+		forwardConn.Close()
+		return err
+	}
+
+	log.Printf("release conn %v", hashIdx)
+	forward.Put(forwardConn)
+	return nil
+}

src/config_test.go

@@ -0,0 +1,72 @@
+package src
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"os"
+	"strconv"
+	"sync"
+	"testing"
+)
+
+func TestConfigLoadEnv(t *testing.T) {
+	c := Config{
+		Listen:   "default",
+		Forwards: "default",
+		Hello:    "default",
+	}
+
+	os.Setenv("LISTEN", "$LISTEN")
+	os.Setenv("FORWARDS", "")
+	os.Setenv("HELLO_B64", "$HELLO_B64")
+
+	if err := c.loadEnv(); err != nil {
+		t.Fatal(err)
+	}
+
+	if c.Listen != "$LISTEN" {
+		t.Error("listen", c.Listen)
+	}
+	if c.Forwards != "default" {
+		t.Error("forwards", c.Forwards)
+	}
+	if c.Hello != "$HELLO_B64" {
+		t.Error("hello", c.Hello)
+	}
+}
+
+func TestConfigWithConn(t *testing.T) {
+	log.SetOutput(io.Discard)
+
+	c := Config{}
+
+	seen0, seen1 := false, false
+	conn0, conn1 := &net.IPConn{}, &net.IPConn{}
+	pool0, pool1 := &sync.Pool{}, &sync.Pool{}
+	pool0.Put(conn0)
+	pool1.Put(conn1)
+	c.forwards = []*sync.Pool{pool0, pool1}
+
+	for i := 0; i < 10; i++ {
+		i := strconv.Itoa(i)
+		t.Run(i, func(t *testing.T) {
+			if err := c.WithConn(i, func(c net.Conn) error {
+				c, _ = c.(*net.IPConn)
+				seen0 = seen0 || c == conn0
+				seen1 = seen1 || c == conn1
+				if c != conn0 && c != conn1 {
+					return fmt.Errorf("got unexepcted conn %v", c)
+				}
+				return nil
+			}); err != nil {
+				t.Fatal(err)
+			}
+		})
+	}
+
+	if !seen0 || !seen1 {
+		t.Fatalf("didnt see both conns")
+	}
+}

src/listen.go

@@ -0,0 +1,60 @@
+package src
+
+import (
+	"context"
+	"log"
+	"net"
+	"sync"
+)
+
+func listen(ctx context.Context, config Config) error {
+	defer log.Println("/listen()")
+
+	wg := &sync.WaitGroup{}
+	defer wg.Wait()
+
+	listener, err := net.Listen("tcp", config.Listen)
+	if err != nil {
+		return err
+	}
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		<-ctx.Done()
+		listener.Close()
+	}()
+
+	for ctx.Err() == nil {
+		conn, err := listener.Accept()
+		if err != nil {
+			log.Println("error accepting:", err)
+		} else {
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
+				handle(ctx, config, conn)
+			}()
+		}
+	}
+
+	return ctx.Err()
+}
+
+func handle(ctx context.Context, config Config, conn net.Conn) {
+	if err := _handle(ctx, config, conn); err != nil {
+		log.Println("error handling:", err)
+	}
+}
+
+func _handle(ctx context.Context, config Config, conn net.Conn) error {
+	defer conn.Close()
+
+	ctx, can := context.WithCancel(ctx)
+	defer can()
+	go func() {
+		<-ctx.Done()
+		conn.Close()
+	}()
+
+	return adapt(ctx, config, conn)
+}

src/main.go

@@ -0,0 +1,22 @@
+package src
+
+import (
+	"context"
+	"log"
+)
+
+func Main(ctx context.Context) error {
+	defer log.Println("/Main()")
+
+	config, err := NewConfig(ctx)
+	if err != nil {
+		return err
+	}
+	defer config.Close()
+
+	if err := listen(ctx, config); err != nil && ctx.Err() == nil {
+		return err
+	}
+
+	return nil
+}

src/testdata/redises.sh

@@ -0,0 +1,22 @@
+#! /usr/bin/bash
+
+bin=valkey-server
+if ! which valkey-server; then
+   bin=redis-server
+fi
+
+d=$(mktemp -d)
+mkdir -p $d/1
+mkdir -p $d/2
+$bin --dir $d/1 --port 60113 --logfile $d/1.log &
+bg=${!}
+cleanup() {
+   kill $bg
+}
+trap cleanup EXIT
+(
+   sleep 5
+   echo FORWARDS=127.0.0.1:60113,127.0.0.1:60114
+) &
+$bin --dir $d/2 --port 60114 --logfile $d/2.log
+