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worker.go
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worker.go
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package worker
import (
"fmt"
"reflect"
"github.com/TetAlius/GoSyncMyCalendars/api"
"github.com/TetAlius/GoSyncMyCalendars/backend/db"
"github.com/TetAlius/GoSyncMyCalendars/convert"
log "github.com/TetAlius/GoSyncMyCalendars/logger"
)
const (
stateInitial = iota
stateQuit
)
// Object that manages the different kinds of synchronization
type Worker struct {
Events chan api.EventManager
state int
database db.Database
}
// Function that returns a new worker from given info
func New(maxWorkers int, database db.Database) (worker *Worker) {
worker = &Worker{Events: make(chan api.EventManager), state: stateInitial, database: database}
return
}
// Method that returns whether the channel is closed
func (worker *Worker) IsClosed() bool {
return worker.state == stateQuit
}
// Method that starts the processing of the worker
func (worker *Worker) Start() {
worker.Process()
}
// Method that stops the processing of the worker
func (worker *Worker) Stop() (err error) {
worker.state = stateQuit
log.Debugln("closing workers")
close(worker.Events)
log.Debugln("close workers")
return
}
// Method that process all requests of sync
func (worker *Worker) Process() {
var event api.EventManager
for worker.state != stateQuit {
event = <-worker.Events
worker.processSynchronization(event)
}
for event = range worker.Events {
worker.processSynchronization(event)
}
}
// Specific synchronization error
type SynchronizeError struct {
State int
ID string
}
// Method to implement the interface error
func (err SynchronizeError) Error() string {
return fmt.Sprintf("state: %d not suported for event with ID: %s", err.State, err.ID)
}
// Method that process a specific request of sync
func (worker *Worker) processSynchronization(event api.EventManager) {
if event.GetState() == api.Updated && worker.database.EventAlreadyUpdated(event) {
return
}
if event.GetState() == api.Deleted && !worker.database.ExistsEvent(event) {
return
}
switch event.GetState() {
case api.Created:
worker.database.SavePrincipalEvent(event)
case api.Updated:
worker.database.UpdateModificationDate(event)
case api.Deleted:
worker.database.DeleteEvent(event)
}
for _, toSync := range event.GetRelations() {
err := toSync.GetCalendar().GetAccount().Refresh()
go worker.database.UpdateAccount(toSync.GetCalendar().GetAccount())
err = worker.synchronizeEvents(event, toSync)
if err != nil && reflect.TypeOf(err).Kind() != reflect.TypeOf(SynchronizeError{}).Kind() {
go func() {
for toSync.CanProcessAgain() {
toSync.IncrementBackoff()
err := worker.synchronizeEvents(event, toSync)
if err != nil {
continue
} else {
//Synchronized correctly
break
}
}
}()
}
}
return
}
// Method that synchronize to events. If the request gets here, all database checks have passed
func (worker *Worker) synchronizeEvents(from api.EventManager, to api.EventManager) (err error) {
switch from.GetState() {
case api.Created:
err = worker.createEvent(from, to)
case api.Updated:
err = worker.updateEvent(from, to)
case api.Deleted:
err = worker.deleteEvent(from, to)
default:
return SynchronizeError{State: from.GetState(), ID: from.GetID()}
}
return
}
// Method that manages an update
func (worker *Worker) updateEvent(from api.EventManager, to api.EventManager) (err error) {
convert.Convert(from, to)
err = to.Update()
if err != nil {
log.Errorf("error updating event: %s, from event: %s", to.GetID(), from.GetID())
return err
}
return worker.database.UpdateModificationDate(to)
}
// Method that manages a creation
func (worker *Worker) createEvent(from api.EventManager, to api.EventManager) (err error) {
convert.Convert(from, to)
err = to.Create()
if err != nil {
log.Errorf("error updating event: %s, from event: %s", to.GetID(), from.GetID())
return err
}
return worker.database.SaveEventsRelation(from, to)
}
// Method that manages a deletion
func (worker *Worker) deleteEvent(from api.EventManager, to api.EventManager) (err error) {
if !worker.database.ExistsEvent(to) {
return nil
}
err = to.Delete()
if err != nil {
log.Errorf("error updating event: %s, from event: %s", to.GetID(), from.GetID())
return err
}
return worker.database.DeleteEvent(to)
}