forked from Cloud-Foundations/Dominator
/
watchd.go
175 lines (165 loc) · 4.39 KB
/
watchd.go
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package mdbd
import (
"bufio"
"encoding/gob"
"encoding/json"
"fmt"
"io"
"os"
"path"
"reflect"
"sort"
"time"
"github.com/Cloud-Foundations/Dominator/lib/fsutil"
jsonwriter "github.com/Cloud-Foundations/Dominator/lib/json"
"github.com/Cloud-Foundations/Dominator/lib/log"
"github.com/Cloud-Foundations/Dominator/lib/mdb"
"github.com/Cloud-Foundations/Dominator/lib/srpc"
"github.com/Cloud-Foundations/Dominator/proto/mdbserver"
)
func startMdbDaemon(mdbFileName string, logger log.Logger) <-chan *mdb.Mdb {
mdbChannel := make(chan *mdb.Mdb, 1)
if *mdbServerHostname != "" && *mdbServerPortNum > 0 {
go serverWatchDaemon(*mdbServerHostname, *mdbServerPortNum, mdbFileName,
mdbChannel, logger)
} else {
go fileWatchDaemon(mdbFileName, mdbChannel, logger)
}
return mdbChannel
}
type genericDecoder interface {
Decode(v interface{}) error
}
func fileWatchDaemon(mdbFileName string, mdbChannel chan<- *mdb.Mdb,
logger log.Logger) {
var lastMdb *mdb.Mdb
for readCloser := range fsutil.WatchFile(mdbFileName, logger) {
mdb := loadFile(readCloser, mdbFileName, logger)
readCloser.Close()
if mdb == nil {
continue
}
compareStartTime := time.Now()
if lastMdb == nil || !reflect.DeepEqual(lastMdb, mdb) {
if lastMdb != nil {
mdbCompareTimeDistribution.Add(time.Since(compareStartTime))
}
mdbChannel <- mdb
lastMdb = mdb
}
}
}
func serverWatchDaemon(mdbServerHostname string, mdbServerPortNum uint,
mdbFileName string, mdbChannel chan<- *mdb.Mdb, logger log.Logger) {
if file, err := os.Open(mdbFileName); err == nil {
fileMdb := loadFile(file, mdbFileName, logger)
file.Close()
if fileMdb != nil {
sort.Sort(fileMdb)
mdbChannel <- fileMdb
}
}
address := fmt.Sprintf("%s:%d", mdbServerHostname, mdbServerPortNum)
for ; ; time.Sleep(time.Second) {
client, err := srpc.DialHTTP("tcp", address, time.Second*15)
if err != nil {
logger.Println(err)
continue
}
conn, err := client.Call("MdbServer.GetMdbUpdates")
if err != nil {
logger.Println(err)
client.Close()
continue
}
lastMdb := &mdb.Mdb{}
for {
var mdbUpdate mdbserver.MdbUpdate
if err := conn.Decode(&mdbUpdate); err != nil {
logger.Println(err)
break
} else {
lastMdb = processUpdate(lastMdb, mdbUpdate)
sort.Sort(lastMdb)
mdbChannel <- lastMdb
if file, err := os.Create(mdbFileName + "~"); err != nil {
logger.Println(err)
} else {
writer := bufio.NewWriter(file)
var err error
if isGob(mdbFileName) {
encoder := gob.NewEncoder(writer)
err = encoder.Encode(lastMdb.Machines)
} else {
err = jsonwriter.WriteWithIndent(writer, " ",
lastMdb.Machines)
}
if err != nil {
logger.Println(err)
os.Remove(mdbFileName + "~")
} else {
writer.Flush()
file.Close()
os.Rename(mdbFileName+"~", mdbFileName)
}
}
}
}
conn.Close()
client.Close()
}
}
func loadFile(reader io.Reader, filename string, logger log.Logger) *mdb.Mdb {
decoder := getDecoder(reader, filename)
var mdb mdb.Mdb
decodeStartTime := time.Now()
if err := decoder.Decode(&mdb.Machines); err != nil {
logger.Printf("Error decoding MDB data: %s\n", err)
return nil
}
sortStartTime := time.Now()
mdbDecodeTimeDistribution.Add(sortStartTime.Sub(decodeStartTime))
sort.Sort(&mdb)
mdbSortTimeDistribution.Add(time.Since(sortStartTime))
return &mdb
}
func isGob(filename string) bool {
switch path.Ext(filename) {
case ".gob":
return true
default:
return false
}
}
func getDecoder(reader io.Reader, filename string) genericDecoder {
if isGob(filename) {
return gob.NewDecoder(reader)
} else {
return json.NewDecoder(reader)
}
}
func processUpdate(oldMdb *mdb.Mdb, mdbUpdate mdbserver.MdbUpdate) *mdb.Mdb {
newMdb := &mdb.Mdb{}
if len(oldMdb.Machines) < 1 {
newMdb.Machines = mdbUpdate.MachinesToAdd
return newMdb
}
newMachines := make(map[string]mdb.Machine)
for _, machine := range oldMdb.Machines {
newMachines[machine.Hostname] = machine
}
for _, machine := range mdbUpdate.MachinesToAdd {
newMachines[machine.Hostname] = machine
}
for _, machine := range mdbUpdate.MachinesToUpdate {
newMachines[machine.Hostname] = machine
}
for _, name := range mdbUpdate.MachinesToDelete {
delete(newMachines, name)
}
newMdb.Machines = make([]mdb.Machine, 0, len(newMachines))
for _, machine := range newMachines {
newMdb.Machines = append(newMdb.Machines, machine)
}
return newMdb
}