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|
// Tideland Go Library - Redis Client - Subscription
//
// Copyright (C) 2009-2017 Frank Mueller / Oldenburg / Germany
//
// All rights reserved. Use of this source code is governed
// by the new BSD license.
package redis
//--------------------
// IMPORTS
//--------------------
import (
"strings"
"github.com/tideland/golib/errors"
)
//--------------------
// SUBSCRIPTION
//--------------------
// Subscription manages a subscription to Redis channels and allows
// to subscribe and unsubscribe from channels.
type Subscription struct {
database *Database
resp *resp
}
// newSubscription creates a new subscription.
func newSubscription(db *Database) (*Subscription, error) {
sub := &Subscription{
database: db,
}
err := sub.ensureProtocol()
if err != nil {
return nil, err
}
// Perform authentication and database selection.
err = sub.resp.authenticate()
if err != nil {
sub.database.pool.kill(sub.resp)
return nil, err
}
return sub, nil
}
// Subscribe adds one or more channels to the subscription.
func (sub *Subscription) Subscribe(channels ...string) error {
return sub.subUnsub("subscribe", channels...)
}
// Unsubscribe removes one or more channels from the subscription.
func (sub *Subscription) Unsubscribe(channels ...string) error {
return sub.subUnsub("unsubscribe", channels...)
}
// subUnsub is the generic subscription and unsubscription method.
func (sub *Subscription) subUnsub(cmd string, channels ...string) error {
err := sub.ensureProtocol()
if err != nil {
return err
}
pattern := false
args := []interface{}{}
for _, channel := range channels {
if containsPattern(channel) {
pattern = true
}
args = append(args, channel)
}
if pattern {
cmd = "p" + cmd
}
err = sub.resp.sendCommand(cmd, args...)
logCommand(cmd, args, err, sub.database.logging)
return err
}
// Pop waits for a published value and returns it.
func (sub *Subscription) Pop() (*PublishedValue, error) {
err := sub.ensureProtocol()
if err != nil {
return nil, err
}
result, err := sub.resp.receiveResultSet()
if err != nil {
return nil, err
}
// Analyse the result.
kind, err := result.StringAt(0)
if err != nil {
return nil, err
}
switch {
case strings.Contains(kind, "message"):
channel, err := result.StringAt(1)
if err != nil {
return nil, err
}
value, err := result.ValueAt(2)
if err != nil {
return nil, err
}
return &PublishedValue{
Kind: kind,
Channel: channel,
Value: value,
}, nil
case strings.Contains(kind, "subscribe"):
channel, err := result.StringAt(1)
if err != nil {
return nil, err
}
count, err := result.IntAt(2)
if err != nil {
return nil, err
}
return &PublishedValue{
Kind: kind,
Channel: channel,
Count: count,
}, nil
default:
return nil, errors.New(ErrInvalidResponse, errorMessages, result)
}
}
// Close ends the subscription.
func (sub *Subscription) Close() error {
err := sub.ensureProtocol()
if err != nil {
return err
}
err = sub.resp.sendCommand("punsubscribe")
if err != nil {
return err
}
for {
pv, err := sub.Pop()
if err != nil {
return err
}
if pv.Kind == "punsubscribe" {
break
}
}
sub.database.pool.push(sub.resp)
return nil
}
// ensureProtocol retrieves a protocol from the pool if needed.
func (sub *Subscription) ensureProtocol() error {
if sub.resp == nil {
p, err := sub.database.pool.pull(forcedPull)
if err != nil {
return err
}
sub.resp = p
}
return nil
}
// EOF
|
