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client.go
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client.go
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package redis2
import (
"fmt"
"io"
"log"
"net"
"sync"
"sync/atomic"
"time"
"github.com/gallir/smart-relayer/lib"
"github.com/gallir/smart-relayer/redis/radix.improved/redis"
)
// Client is the thread that connect to the remote redis server
type Client struct {
sync.Mutex
config *lib.RelayerConfig
mode int
ready int32
connected int32
netConn net.Conn
rw *lib.NetReadWriter
requestChan chan *lib.Request // The relayer sends the requests via this channel
database int // The current selected database
queueChan chan *lib.Request // Requests sent to the Redis server, some pending of responses
lastConnectFailure time.Time
connectedAt time.Time
failures int64
pipelined int
}
// NewClient creates a new client that connect to a Redis server
func NewClient(c *lib.RelayerConfig) *Client {
clt := &Client{}
clt.Reload(c)
clt.requestChan = make(chan *lib.Request, requestBufferSize)
clt.setReady(true)
go clt.requestListener(clt.requestChan)
lib.Debugf("Client %s for target %s ready", clt.config.Listen, clt.config.Host())
return clt
}
// Reload initialize teh configuration
func (clt *Client) Reload(c *lib.RelayerConfig) {
clt.Lock()
defer clt.Unlock()
if clt.isReady() {
clt.flush(true)
}
clt.config = c
clt.mode = clt.config.Type()
}
func (clt *Client) setReady(s bool) {
if s {
atomic.StoreInt32(&clt.ready, 1)
} else {
atomic.StoreInt32(&clt.ready, 0)
}
}
func (clt *Client) isReady() bool {
if atomic.LoadInt32(&clt.ready) == 1 {
return true
}
return false
}
func (clt *Client) setConnected(s bool) {
if s {
atomic.StoreInt32(&clt.connected, 1)
} else {
atomic.StoreInt32(&clt.connected, 0)
}
}
func (clt *Client) isConnected() bool {
if atomic.LoadInt32(&clt.connected) == 1 {
return true
}
return false
}
func (clt *Client) connect() bool {
clt.Lock()
defer clt.Unlock()
if clt.failures > 10 {
// The pool manager will see we are invalid and kill us
clt.setReady(false)
return false
}
if clt.lastConnectFailure.Add(200 * time.Millisecond).After(time.Now()) {
// It failed too recently
return false
}
conn, err := net.DialTimeout(clt.config.Scheme(), clt.config.Host(), connectTimeout)
if err != nil {
lib.Debugf("Failed to connect to %s", clt.config.Host())
clt.netConn = nil
clt.lastConnectFailure = time.Now()
clt.failures++
return false
}
clt.failures = 0
clt.connectedAt = time.Now()
lib.Debugf("Connected to %s", conn.RemoteAddr())
clt.netConn = conn
clt.queueChan = make(chan *lib.Request, requestBufferSize)
clt.rw = lib.NewSingleReadWriter(conn, time.Duration(clt.config.Timeout)*time.Second, 0)
go clt.redisListener(clt.rw, clt.queueChan)
clt.setConnected(true)
return true
}
// Listen for clients' messages from the requestChan
func (clt *Client) requestListener(ch chan *lib.Request) {
defer lib.Debugf("Finished Redis client")
defer func() {
clt.setReady(false)
}()
timer := time.NewTimer(maxIdle)
defer func() {
// Clean timer gracefully
if !timer.Stop() {
select {
case <-timer.C:
default:
}
}
}()
clt.connect()
for {
select {
case req, more := <-ch:
if !more { // exit from the program because the channel was closed
clt.disconnect()
return
}
_, err := clt.write(req)
req.Resp.ReleaseBuffers()
if err != nil {
log.Println("Error writing:", clt.config.Host(), err)
if req.Conn != nil {
respKO.WriteTo(req.Conn)
}
clt.disconnect()
}
timer.Stop()
timer.Reset(maxIdle)
case <-timer.C:
if clt.netConn != nil {
lib.Debugf("Closing by idle %s", clt.config.Host())
clt.disconnect()
}
}
}
}
// This goroutine listens for incoming answers from the Redis server
func (clt *Client) redisListener(buf io.ReadWriter, queue chan *lib.Request) {
lib.Debugf("Net listener started")
defer clt.close() // Will force to close net connection
reader := redis.NewRespReader(buf)
for req := range queue {
r := reader.Read()
if req == nil {
continue
}
if r.Err != nil && r.IsType(redis.IOErr) {
if redis.IsTimeout(r) {
log.Printf("Timeout (%d secs) at %s", clt.config.Timeout, clt.config.Host())
} else {
log.Printf("Error with server %s connection: %s", clt.config.Host(), r.Err)
}
if req.Conn != nil {
respKO.WriteTo(req.Conn)
}
clt.disconnect()
return
}
if clt.config.Compress || clt.config.Uncompress || clt.config.Gzip != 0 || clt.config.Gunzip {
r.Uncompress()
}
if req.Conn != nil {
r.WriteTo(req.Conn)
}
r.ReleaseBuffers()
}
lib.Debugf("Net listener exiting")
}
func (clt *Client) purgeRequests() {
for {
select {
case req := <-clt.queueChan:
if req.Conn != nil {
respKO.WriteTo(req.Conn)
}
default:
return
}
}
}
func (clt *Client) write(r *lib.Request) (int64, error) {
if !clt.isConnected() && !clt.connect() {
return 0, fmt.Errorf("Connection failed")
}
if r.Command == selectCommand {
if clt.mode == lib.ModeSmart && clt.database == r.Database { // There is no need to select again
return 0, nil
}
clt.database = r.Database
} else if clt.database != r.Database {
err := clt.changeDB(r.Database)
if err != nil {
clt.disconnect()
return 0, err
}
clt.queueChan <- nil
}
resp := r.Resp
// Use compression just if is not an EVAL command
if r.Command != evalCommand {
switch {
case clt.config.Gzip != 0:
resp.CompressGz(lib.MinCompressSize, clt.config.Gzip)
case clt.config.Compress:
resp.CompressSnappy(lib.MinCompressSize, redis.MarkerSnappy)
}
}
c, err := resp.WriteTo(clt.rw)
if err == io.EOF {
log.Println("W: Closed connection at write():", clt.netConn.RemoteAddr(), "retrying")
// The other end has closed the connection, give it a second chance
clt.disconnect()
clt.connect()
c, err = resp.WriteTo(clt.rw)
}
if err != nil {
lib.Debugf("Failed in write: %s", err)
clt.disconnect()
return 0, err
}
err = clt.flush(r.Conn != nil) // Force flush if it's an sync command
if err != nil {
return 0, err
}
clt.queueChan <- r
return c, err
}
func (clt *Client) changeDB(db int) (err error) {
changer := redis.NewResp([]interface{}{
selectCommand,
fmt.Sprintf("%d", db),
})
_, err = changer.WriteTo(clt.rw)
if err != nil {
log.Println("Error changing database", err)
return
}
err = clt.flush(false)
if err != nil {
return
}
clt.database = db
return
}
func (clt *Client) flush(force bool) error {
if force || clt.config.Pipeline == 0 && clt.pipelined >= clt.config.Pipeline || len(clt.requestChan) == 0 {
err := clt.rw.Flush()
clt.pipelined = 0
if err != nil {
lib.Debugf("Failed in flush: %s", err)
clt.disconnect()
return err
}
} else {
// Don't flush yet, for pipelining
clt.pipelined++
}
return nil
}
// Start disconnection
func (clt *Client) disconnect() {
clt.Lock()
defer clt.Unlock()
clt.setConnected(false)
if clt.queueChan != nil {
clt.purgeRequests()
close(clt.queueChan)
clt.queueChan = nil
}
clt.database = 0
}
// Close connection
func (clt *Client) close() {
if clt.isConnected() {
clt.disconnect() // Double check
}
clt.Lock()
defer clt.Unlock()
if clt.netConn != nil {
clt.rw.Flush()
lib.Debugf("Closing connection")
clt.netConn.Close()
clt.netConn = nil
}
}
// Exit closes the connection and destroy all the client resources
func (clt *Client) Exit() {
clt.Lock()
defer clt.Unlock()
clt.setReady(false)
if clt.requestChan != nil {
// Closing the request channel triggers all disconnections
close(clt.requestChan)
clt.requestChan = nil
}
}
// IsValid is used for pool management, it ignores disconnect clients
func (clt *Client) IsValid() bool {
return clt.isReady() && clt.isConnected()
}
// send sends a request to Redis through the requestChan
func (clt *Client) send(req interface{}) (e error) {
r := req.(*lib.Request)
defer func() {
r := recover() // To avoid panic due to closed channels
if r != nil {
log.Printf("sendRequest: Recovered from error %s, channel length %d", e, len(clt.requestChan))
e = r.(error)
}
}()
if clt.requestChan == nil {
lib.Debugf("Nil channel in send request %s", clt.config.Host())
return errKO
}
if !clt.isReady() {
lib.Debugf("Client not ready %s", clt.config.Host())
return errKO
}
if f := clt.failures; f > 0 {
if clt.lastConnectFailure.Add(connectTimeout).After(time.Now()) {
lib.Debugf("Client is failing to connect %s", clt.config.Host())
return errKO
}
}
if len(clt.requestChan) == requestBufferSize {
log.Println("Redis overloaded", clt.config.Host())
return errOverloaded
}
clt.requestChan <- r
return nil
}