2016-03-05 02:08:16 +03:00
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package controller
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import (
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"strconv"
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"strings"
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"time"
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"github.com/tidwall/tile38/client"
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2016-03-06 17:55:00 +03:00
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"github.com/tidwall/tile38/controller/log"
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"github.com/tidwall/tile38/core"
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2016-03-05 02:08:16 +03:00
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)
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var errNoLongerFollowing = errors.New("no longer following")
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const checksumsz = 512 * 1024
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func (c *Controller) cmdFollow(line string) error {
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var host, sport string
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if line, host = token(line); host == "" {
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return errInvalidNumberOfArguments
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}
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if line, sport = token(line); sport == "" {
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return errInvalidNumberOfArguments
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}
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if line != "" {
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return errInvalidNumberOfArguments
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}
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host = strings.ToLower(host)
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sport = strings.ToLower(sport)
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var update bool
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pconfig := c.config
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if host == "no" && sport == "one" {
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update = c.config.FollowHost != "" || c.config.FollowPort != 0
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c.config.FollowHost = ""
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c.config.FollowPort = 0
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} else {
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n, err := strconv.ParseUint(sport, 10, 64)
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if err != nil {
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return errInvalidArgument(sport)
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}
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port := int(n)
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update = c.config.FollowHost != host || c.config.FollowPort != port
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if update {
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c.mu.Unlock()
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conn, err := client.DialTimeout(fmt.Sprintf("%s:%d", host, port), time.Second*2)
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if err != nil {
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c.mu.Lock()
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return fmt.Errorf("cannot follow: %v", err)
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}
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defer conn.Close()
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msg, err := conn.Stats()
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if err != nil {
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c.mu.Lock()
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return fmt.Errorf("cannot follow: %v", err)
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}
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if msg.Stats.ServerID == c.config.ServerID {
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c.mu.Lock()
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return fmt.Errorf("cannot follow self")
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}
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if msg.Stats.Following != "" {
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c.mu.Lock()
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return fmt.Errorf("cannot follow a follower")
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}
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c.mu.Lock()
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}
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c.config.FollowHost = host
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c.config.FollowPort = port
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}
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if err := c.writeConfig(); err != nil {
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c.config = pconfig // revert
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return err
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}
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if update {
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c.followc++
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if c.config.FollowHost != "" {
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log.Infof("following new host '%s' '%s'.", host, sport)
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go c.follow(c.config.FollowHost, c.config.FollowPort, c.followc)
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} else {
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log.Infof("following no one")
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}
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}
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return nil
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}
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func (c *Controller) followHandleCommand(line string, followc uint64, w io.Writer) (int, error) {
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c.mu.Lock()
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defer c.mu.Unlock()
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if c.followc != followc {
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return c.aofsz, errNoLongerFollowing
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}
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_, d, err := c.command(line, w)
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if err != nil {
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return c.aofsz, err
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}
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if err := c.writeAOF(line, &d); err != nil {
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return c.aofsz, err
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}
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return c.aofsz, nil
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}
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func (c *Controller) followStep(host string, port int, followc uint64) error {
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c.mu.Lock()
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if c.followc != followc {
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c.mu.Unlock()
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return errNoLongerFollowing
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}
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c.fcup = false
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c.mu.Unlock()
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addr := fmt.Sprintf("%s:%d", host, port)
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// check if we are following self
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conn, err := client.DialTimeout(addr, time.Second*2)
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if err != nil {
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return fmt.Errorf("cannot follow: %v", err)
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}
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defer conn.Close()
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stats, err := conn.Stats()
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if err != nil {
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return fmt.Errorf("cannot follow: %v", err)
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}
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if stats.Stats.ServerID == c.config.ServerID {
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return fmt.Errorf("cannot follow self")
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}
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if stats.Stats.Following != "" {
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return fmt.Errorf("cannot follow a follower")
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}
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// verify checksum
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pos, err := c.followCheckSome(addr, followc)
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if err != nil {
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return err
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}
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// make real connection
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conn, err = client.Dial(addr)
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if err != nil {
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return err
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}
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defer conn.Close()
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msg, err := conn.Do(fmt.Sprintf("aof %d", pos))
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if err != nil {
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return err
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}
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if string(msg) != client.LiveJSON {
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var m map[string]interface{}
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err := json.Unmarshal(msg, &m)
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if err != nil {
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return err
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}
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if errs, ok := m["err"].(string); ok && errs != "" {
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return errors.New(errs)
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}
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return errors.New("invalid response to aof live request")
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}
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2016-03-06 17:55:00 +03:00
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if core.ShowDebugMessages {
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2016-03-05 02:08:16 +03:00
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log.Debug("follow:", addr, ":read aof")
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}
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caughtUp := pos >= int64(stats.Stats.AOFSize)
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if caughtUp {
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c.mu.Lock()
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c.fcup = true
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c.mu.Unlock()
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log.Info("caught up")
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}
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nullw := ioutil.Discard
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rd := NewAOFReader(conn.Reader())
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for {
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buf, err := rd.ReadCommand()
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if err != nil {
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return err
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}
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aofsz, err := c.followHandleCommand(string(buf), followc, nullw)
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if err != nil {
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return err
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}
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if !caughtUp {
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if aofsz >= stats.Stats.AOFSize {
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caughtUp = true
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c.mu.Lock()
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c.fcup = true
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c.mu.Unlock()
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log.Info("caught up")
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}
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}
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}
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}
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func (c *Controller) follow(host string, port int, followc uint64) {
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for {
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err := c.followStep(host, port, followc)
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if err == errNoLongerFollowing {
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return
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}
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if err != nil && err != io.EOF {
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log.Debug("follow: " + err.Error())
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}
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time.Sleep(time.Second)
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}
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}
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