gh-ost/go/logic/server.go

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/*
Copyright 2016 GitHub Inc.
See https://github.com/github/gh-ost/blob/master/LICENSE
*/
package logic
import (
"bufio"
"fmt"
"io"
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"net"
"os"
"strconv"
"strings"
"sync/atomic"
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"github.com/github/gh-ost/go/base"
"github.com/outbrain/golib/log"
)
type printStatusFunc func(PrintStatusRule, io.Writer)
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// Server listens for requests on a socket file or via TCP
type Server struct {
migrationContext *base.MigrationContext
unixListener net.Listener
tcpListener net.Listener
hooksExecutor *HooksExecutor
printStatus printStatusFunc
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}
func NewServer(hooksExecutor *HooksExecutor, printStatus printStatusFunc) *Server {
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return &Server{
migrationContext: base.GetMigrationContext(),
hooksExecutor: hooksExecutor,
printStatus: printStatus,
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}
}
func (this *Server) BindSocketFile() (err error) {
if this.migrationContext.ServeSocketFile == "" {
return nil
}
if this.migrationContext.DropServeSocket && base.FileExists(this.migrationContext.ServeSocketFile) {
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os.Remove(this.migrationContext.ServeSocketFile)
}
this.unixListener, err = net.Listen("unix", this.migrationContext.ServeSocketFile)
if err != nil {
return err
}
log.Infof("Listening on unix socket file: %s", this.migrationContext.ServeSocketFile)
return nil
}
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func (this *Server) RemoveSocketFile() (err error) {
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log.Infof("Removing socket file: %s", this.migrationContext.ServeSocketFile)
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return os.Remove(this.migrationContext.ServeSocketFile)
}
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func (this *Server) BindTCPPort() (err error) {
if this.migrationContext.ServeTCPPort == 0 {
return nil
}
this.tcpListener, err = net.Listen("tcp", fmt.Sprintf(":%d", this.migrationContext.ServeTCPPort))
if err != nil {
return err
}
log.Infof("Listening on tcp port: %d", this.migrationContext.ServeTCPPort)
return nil
}
// Serve begins listening & serving on whichever device was configured
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func (this *Server) Serve() (err error) {
go func() {
for {
conn, err := this.unixListener.Accept()
if err != nil {
log.Errore(err)
}
go this.handleConnection(conn)
}
}()
go func() {
if this.tcpListener == nil {
return
}
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for {
conn, err := this.tcpListener.Accept()
if err != nil {
log.Errore(err)
}
go this.handleConnection(conn)
}
}()
return nil
}
func (this *Server) handleConnection(conn net.Conn) (err error) {
defer conn.Close()
command, _, err := bufio.NewReader(conn).ReadLine()
return this.onServerCommand(string(command), bufio.NewWriter(conn))
}
// onServerCommand responds to a user's interactive command
func (this *Server) onServerCommand(command string, writer *bufio.Writer) (err error) {
defer writer.Flush()
printStatusRule, err := this.applyServerCommand(command, writer)
if err == nil {
this.printStatus(printStatusRule, writer)
} else {
fmt.Fprintf(writer, "%s\n", err.Error())
}
return log.Errore(err)
}
// applyServerCommand parses and executes commands by user
func (this *Server) applyServerCommand(command string, writer *bufio.Writer) (printStatusRule PrintStatusRule, err error) {
printStatusRule = NoPrintStatusRule
tokens := strings.SplitN(command, "=", 2)
command = strings.TrimSpace(tokens[0])
arg := ""
if len(tokens) > 1 {
arg = strings.TrimSpace(tokens[1])
}
throttleHint := "# Note: you may only throttle for as long as your binary logs are not purged\n"
if err := this.hooksExecutor.onInteractiveCommand(command); err != nil {
return NoPrintStatusRule, err
}
switch command {
case "help":
{
fmt.Fprintln(writer, `available commands:
status # Print a detailed status message
sup # Print a short status message
chunk-size=<newsize> # Set a new chunk-size
nice-ratio=<ratio> # Set a new nice-ratio, immediate sleep after each row-copy operation, float (examples: 0 is agrressive, 0.7 adds 70% runtime, 1.0 doubles runtime, 2.0 triples runtime, ...)
critical-load=<load> # Set a new set of max-load thresholds
max-lag-millis=<max-lag> # Set a new replication lag threshold
replication-lag-query=<query> # Set a new query that determines replication lag (no quotes)
max-load=<load> # Set a new set of max-load thresholds
throttle-query=<query> # Set a new throttle-query (no quotes)
throttle-control-replicas=<replicas> # Set a new comma delimited list of throttle control replicas
throttle # Force throttling
no-throttle # End forced throttling (other throttling may still apply)
unpostpone # Bail out a cut-over postpone; proceed to cut-over
panic # panic and quit without cleanup
help # This message
`)
}
case "sup":
return ForcePrintStatusOnlyRule, nil
case "info", "status":
return ForcePrintStatusAndHintRule, nil
case "chunk-size":
{
if chunkSize, err := strconv.Atoi(arg); err != nil {
return NoPrintStatusRule, err
} else {
this.migrationContext.SetChunkSize(int64(chunkSize))
return ForcePrintStatusAndHintRule, nil
}
}
case "max-lag-millis":
{
if maxLagMillis, err := strconv.Atoi(arg); err != nil {
return NoPrintStatusRule, err
} else {
this.migrationContext.SetMaxLagMillisecondsThrottleThreshold(int64(maxLagMillis))
return ForcePrintStatusAndHintRule, nil
}
}
case "replication-lag-query":
{
this.migrationContext.SetReplicationLagQuery(arg)
return ForcePrintStatusAndHintRule, nil
}
case "nice-ratio":
{
if niceRatio, err := strconv.ParseFloat(arg, 64); err != nil {
return NoPrintStatusRule, err
} else {
this.migrationContext.SetNiceRatio(niceRatio)
return ForcePrintStatusAndHintRule, nil
}
}
case "max-load":
{
if err := this.migrationContext.ReadMaxLoad(arg); err != nil {
return NoPrintStatusRule, err
}
return ForcePrintStatusAndHintRule, nil
}
case "critical-load":
{
if err := this.migrationContext.ReadCriticalLoad(arg); err != nil {
return NoPrintStatusRule, err
}
return ForcePrintStatusAndHintRule, nil
}
case "throttle-query":
{
this.migrationContext.SetThrottleQuery(arg)
fmt.Fprintf(writer, throttleHint)
return ForcePrintStatusAndHintRule, nil
}
case "throttle-control-replicas":
{
if err := this.migrationContext.ReadThrottleControlReplicaKeys(arg); err != nil {
return NoPrintStatusRule, err
}
fmt.Fprintf(writer, "%s\n", this.migrationContext.GetThrottleControlReplicaKeys().ToCommaDelimitedList())
return ForcePrintStatusAndHintRule, nil
}
case "throttle", "pause", "suspend":
{
atomic.StoreInt64(&this.migrationContext.ThrottleCommandedByUser, 1)
fmt.Fprintf(writer, throttleHint)
return ForcePrintStatusAndHintRule, nil
}
case "no-throttle", "unthrottle", "resume", "continue":
{
atomic.StoreInt64(&this.migrationContext.ThrottleCommandedByUser, 0)
return ForcePrintStatusAndHintRule, nil
}
case "unpostpone", "no-postpone", "cut-over":
{
if arg == "" && this.migrationContext.ForceNamedCutOverCommand {
err := fmt.Errorf("User commanded 'unpostpone' without specifying table name, but --force-named-cut-over is set")
return NoPrintStatusRule, err
}
if arg != "" && arg != this.migrationContext.OriginalTableName {
// User exlpicitly provided table name. This is a courtesy protection mechanism
err := fmt.Errorf("User commanded 'unpostpone' on %s, but migrated table is %s; ingoring request.", arg, this.migrationContext.OriginalTableName)
return NoPrintStatusRule, err
}
if atomic.LoadInt64(&this.migrationContext.IsPostponingCutOver) > 0 {
atomic.StoreInt64(&this.migrationContext.UserCommandedUnpostponeFlag, 1)
fmt.Fprintf(writer, "Unpostponed\n")
return ForcePrintStatusAndHintRule, nil
}
fmt.Fprintf(writer, "You may only invoke this when gh-ost is actively postponing migration. At this time it is not.\n")
return NoPrintStatusRule, nil
}
case "panic":
{
err := fmt.Errorf("User commanded 'panic'. I will now panic, without cleanup. PANIC!")
this.migrationContext.PanicAbort <- err
return NoPrintStatusRule, err
}
default:
err = fmt.Errorf("Unknown command: %s", command)
return NoPrintStatusRule, err
}
return NoPrintStatusRule, nil
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}