connmux.go
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// Copyright 2014 Gary Burd
//
// Licensed under the Apache License, Version 2.0 (the "License"): you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.
package redisx
import (
"errors"
"sync"
"github.com/garyburd/redigo/internal"
"github.com/garyburd/redigo/redis"
)
// ConnMux multiplexes one or more connections to a single underlying
// connection. The ConnMux connections do not support concurrency, commands
// that associate server side state with the connection or commands that put
// the connection in a special mode.
type ConnMux struct {
c redis.Conn
sendMu sync.Mutex
sendID uint
recvMu sync.Mutex
recvID uint
recvWait map[uint]chan struct{}
}
func NewConnMux(c redis.Conn) *ConnMux {
return &ConnMux{c: c, recvWait: make(map[uint]chan struct{})}
}
// Get gets a connection. The application must close the returned connection.
func (p *ConnMux) Get() redis.Conn {
c := &muxConn{p: p}
c.ids = c.buf[:0]
return c
}
// Close closes the underlying connection.
func (p *ConnMux) Close() error {
return p.c.Close()
}
type muxConn struct {
p *ConnMux
ids []uint
buf [8]uint
}
func (c *muxConn) send(flush bool, cmd string, args ...interface{}) error {
if internal.LookupCommandInfo(cmd).Set != 0 {
return errors.New("command not supported by mux pool")
}
p := c.p
p.sendMu.Lock()
id := p.sendID
c.ids = append(c.ids, id)
p.sendID++
err := p.c.Send(cmd, args...)
if flush {
err = p.c.Flush()
}
p.sendMu.Unlock()
return err
}
func (c *muxConn) Send(cmd string, args ...interface{}) error {
return c.send(false, cmd, args...)
}
func (c *muxConn) Flush() error {
p := c.p
p.sendMu.Lock()
err := p.c.Flush()
p.sendMu.Unlock()
return err
}
func (c *muxConn) Receive() (interface{}, error) {
if len(c.ids) == 0 {
return nil, errors.New("mux pool underflow")
}
id := c.ids[0]
c.ids = c.ids[1:]
if len(c.ids) == 0 {
c.ids = c.buf[:0]
}
p := c.p
p.recvMu.Lock()
if p.recvID != id {
ch := make(chan struct{})
p.recvWait[id] = ch
p.recvMu.Unlock()
<-ch
p.recvMu.Lock()
if p.recvID != id {
panic("out of sync")
}
}
v, err := p.c.Receive()
id++
p.recvID = id
ch, ok := p.recvWait[id]
if ok {
delete(p.recvWait, id)
}
p.recvMu.Unlock()
if ok {
ch <- struct{}{}
}
return v, err
}
func (c *muxConn) Close() error {
var err error
if len(c.ids) == 0 {
return nil
}
c.Flush()
for _ = range c.ids {
_, err = c.Receive()
}
return err
}
func (c *muxConn) Do(cmd string, args ...interface{}) (interface{}, error) {
if err := c.send(true, cmd, args...); err != nil {
return nil, err
}
return c.Receive()
}
func (c *muxConn) Err() error {
return c.p.c.Err()
}