Files
play-with-docker/task/scheduler.go
Jonathan Leibiusky @xetorthio 91c7ec3bd5 WIP
2017-07-26 19:15:31 -03:00

148 lines
3.3 KiB
Go

package task
import (
"context"
"fmt"
"time"
"github.com/play-with-docker/play-with-docker/pwd/types"
"github.com/play-with-docker/play-with-docker/storage"
)
type Task interface {
Name() string
Run(ctx context.Context, instance *types.Instance) error
}
type SchedulerApi interface {
Schedule(session *types.Session) error
Unschedule(session *types.Session) error
Start()
Stop()
AddTask(task Task) error
RemoveTask(task Task) error
}
type scheduledSession struct {
session *types.Session
cancel context.CancelFunc
ctx context.Context
ticker *time.Ticker
}
type scheduler struct {
scheduledSessions map[string]*scheduledSession
storage storage.StorageApi
tasks map[string]Task
started bool
}
func NewScheduler(s storage.StorageApi) (*scheduler, error) {
sch := &scheduler{storage: s}
sch.tasks = make(map[string]Task)
err := sch.loadFromStorage()
if err != nil {
return nil, err
}
return sch, nil
}
func (s *scheduler) loadFromStorage() error {
sessions, err := s.storage.SessionGetAll()
if err != nil {
return err
}
s.scheduledSessions = make(map[string]*scheduledSession, len(sessions))
for _, session := range sessions {
s.register(session)
}
return nil
}
func (s *scheduler) AddTask(task Task) error {
if _, found := s.tasks[task.Name()]; found {
return fmt.Errorf("Task [%s] was already added", task.Name())
}
s.tasks[task.Name()] = task
return nil
}
func (s *scheduler) RemoveTask(task Task) error {
if _, found := s.tasks[task.Name()]; !found {
return fmt.Errorf("Task [%s] doesn't exist", task.Name())
}
delete(s.tasks, task.Name())
return nil
}
func (s *scheduler) Start() {
for _, session := range s.scheduledSessions {
go s.cron(session)
}
s.started = true
}
func (s *scheduler) register(session *types.Session) *scheduledSession {
ctx, cancel := context.WithCancel(context.Background())
s.scheduledSessions[session.Id] = &scheduledSession{session: session, cancel: cancel, ctx: ctx}
return s.scheduledSessions[session.Id]
}
func (s *scheduler) cron(session *scheduledSession) {
session.ticker = time.NewTicker(1 * time.Second)
for {
select {
case <-session.ticker.C:
s.processSession(session.ctx, session.session)
case <-session.ctx.Done():
return
}
}
}
func (s *scheduler) processSession(ctx context.Context, session *types.Session) {
for _, ins := range session.Instances {
go s.processInstance(ctx, ins)
}
}
func (s *scheduler) processInstance(ctx context.Context, instance *types.Instance) {
for _, task := range s.tasks {
task.Run(ctx, instance)
}
}
func (s *scheduler) Schedule(session *types.Session) error {
if !s.started {
return fmt.Errorf("Can only schedule sessions after the scheduler has been started.")
}
if _, found := s.scheduledSessions[session.Id]; found {
return fmt.Errorf("Session [%s] was already scheduled", session.Id)
}
go s.cron(s.register(session))
return nil
}
func (s *scheduler) Unschedule(session *types.Session) error {
if !s.started {
return fmt.Errorf("Can only schedule sessions after the scheduler has been started.")
}
if _, found := s.scheduledSessions[session.Id]; !found {
return fmt.Errorf("Session [%s] in not scheduled", session.Id)
}
scheduledSession := s.scheduledSessions[session.Id]
scheduledSession.cancel()
scheduledSession.ticker.Stop()
delete(s.scheduledSessions, session.Id)
return nil
}