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redis.go
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redis.go
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package main
import (
"context"
"errors"
"fmt"
"io"
"strings"
"github.com/rs/zerolog/log"
"github.com/tidwall/redcon"
)
const (
respOK = "OK"
)
type redis struct {
broker brokerer
}
func newRedis(b brokerer) *redis {
return &redis{
broker: b,
}
}
func (r *redis) handleCmd(conn redcon.Conn, rcmd redcon.Command) {
cmd := string(rcmd.Args[0])
switch strings.ToLower(cmd) {
default:
conn.WriteError(fmt.Sprintf("unknown command '%s'", cmd))
case "info":
conn.WriteString(fmt.Sprintf("redis_version:miniqueue_%s", version))
case "ping":
conn.WriteString("pong")
case "topics":
handleRedisTopics(r.broker)(conn, rcmd)
case "publish":
handleRedisPublish(r.broker)(conn, rcmd)
case "subscribe":
handleRedisSubscribe(r.broker)(conn, rcmd)
}
}
func handleRedisTopics(broker brokerer) redcon.HandlerFunc {
return func(conn redcon.Conn, rcmd redcon.Command) {
topics, err := broker.Topics()
if err != nil {
log.Err(err).Msg("failed to get topics")
conn.WriteError("failed to get topics")
return
}
conn.WriteString(fmt.Sprintf("%v", topics))
}
}
func handleRedisSubscribe(broker brokerer) redcon.HandlerFunc {
return func(conn redcon.Conn, rcmd redcon.Command) {
topic := string(rcmd.Args[1])
c := broker.Subscribe(topic)
defer func() {
if err := broker.Unsubscribe(topic, c.id); err != nil {
log.Err(err).Msg("failed to unsubscribe")
}
}()
log := log.With().Str("id", c.id).Logger()
log.Debug().Str("topic", topic).Msg("new connection")
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
// Detach the connection from the client so that we can control its
// lifecycle independently.
dconn := flushable{DetachedConn: conn.Detach()}
dconn.SetContext(ctx)
defer func() {
log.Debug().Msg("closing connection")
dconn.flush()
dconn.Close()
}()
if len(rcmd.Args) != 2 {
dconn.WriteError("invalid number of args, want: 2")
return
}
for {
select {
case <-ctx.Done():
return
default:
}
// Wait for a new value
val, err := c.Next(ctx)
if err != nil {
log.Err(err).Msg("getting next value")
dconn.WriteError("failed to get next value")
return
}
log.Debug().Str("msg", string(val.Raw)).Msg("sending msg")
dconn.WriteAny(val.Raw)
if err := dconn.flush(); err != nil {
log.Err(err).Msg("flushing msg")
return
}
log.Debug().Msg("awaiting ack")
cmd, err := dconn.ReadCommand()
if errors.Is(err, io.EOF) {
return
} else if err != nil {
log.Err(err).Msg("reading ack")
dconn.WriteError("failed to get next value")
return
}
if len(cmd.Args) != 1 {
log.Error().Str("cmd", string(cmd.Raw)).Int("len", len(cmd.Args)).Msg("invalid cmd length")
dconn.WriteError("invalid command")
return
}
ackCmd := string(cmd.Args[0])
log.Debug().Str("cmd", ackCmd).Msg("received ack cmd")
switch strings.ToUpper(ackCmd) {
case CmdAck:
if err := c.Ack(); err != nil {
log.Err(err).Msg("acking")
dconn.WriteError("failed to ack")
return
}
case CmdBack:
if err := c.Back(); err != nil {
log.Err(err).Msg("backing")
dconn.WriteError("failed to back")
return
}
case CmdNack:
if err := c.Nack(); err != nil {
log.Err(err).Msg("Nacking")
dconn.WriteError("failed to nack")
return
}
case CmdDack:
// TODO read extra arg
if err := c.Dack(1); err != nil {
log.Err(err).Msg("Nacking")
dconn.WriteError("failed to nack")
return
}
default:
log.Error().Str("cmd", ackCmd).Msg("invalid ack command")
dconn.WriteError("invalid ack command")
return
}
dconn.WriteString(respOK)
iferr(dconn.flush(), cancel)
}
}
}
func handleRedisPublish(broker brokerer) redcon.HandlerFunc {
return func(conn redcon.Conn, rcmd redcon.Command) {
if len(rcmd.Args) != 3 {
conn.WriteError("invalid number of args, want: 3")
return
}
var (
topic = string(rcmd.Args[1])
value = newValue(rcmd.Args[2])
)
if err := broker.Publish(topic, value); err != nil {
log.Err(err).Msg("failed to publish")
conn.WriteError("failed to publish")
return
}
log.Debug().
Str("topic", topic).
Str("msg", string(value.Raw)).
Msg("msg published")
conn.WriteString(respOK)
}
}
type flushable struct {
ctx context.Context
redcon.DetachedConn
}
// Flush flushes pending messages to the client, handling any errors by
// cancelling the receiver's context.
func (f *flushable) flush() error {
if err := f.DetachedConn.Flush(); err != nil {
return err
}
return nil
}
func iferr(err error, fn func()) {
if err != nil {
fn()
}
}