package safe import ( "context" "fmt" "runtime/debug" "sync" "github.com/cenkalti/backoff" "github.com/containous/traefik/log" ) type routine struct { goroutine func(chan bool) stop chan bool } type routineCtx func(ctx context.Context) // Pool is a pool of go routines type Pool struct { routines []routine routinesCtx []routineCtx waitGroup sync.WaitGroup lock sync.Mutex baseCtx context.Context baseCancel context.CancelFunc ctx context.Context cancel context.CancelFunc } // NewPool creates a Pool func NewPool(parentCtx context.Context) *Pool { baseCtx, baseCancel := context.WithCancel(parentCtx) ctx, cancel := context.WithCancel(baseCtx) return &Pool{ baseCtx: baseCtx, baseCancel: baseCancel, ctx: ctx, cancel: cancel, } } // Ctx returns main context func (p *Pool) Ctx() context.Context { return p.baseCtx } // AddGoCtx adds a recoverable goroutine with a context without starting it func (p *Pool) AddGoCtx(goroutine routineCtx) { p.lock.Lock() p.routinesCtx = append(p.routinesCtx, goroutine) p.lock.Unlock() } // GoCtx starts a recoverable goroutine with a context func (p *Pool) GoCtx(goroutine routineCtx) { p.lock.Lock() p.routinesCtx = append(p.routinesCtx, goroutine) p.waitGroup.Add(1) Go(func() { goroutine(p.ctx) p.waitGroup.Done() }) p.lock.Unlock() } // Go starts a recoverable goroutine, and can be stopped with stop chan func (p *Pool) Go(goroutine func(stop chan bool)) { p.lock.Lock() newRoutine := routine{ goroutine: goroutine, stop: make(chan bool, 1), } p.routines = append(p.routines, newRoutine) p.waitGroup.Add(1) Go(func() { goroutine(newRoutine.stop) p.waitGroup.Done() }) p.lock.Unlock() } // Stop stops all started routines, waiting for their termination func (p *Pool) Stop() { p.lock.Lock() defer p.lock.Unlock() p.cancel() for _, routine := range p.routines { routine.stop <- true } p.waitGroup.Wait() for _, routine := range p.routines { close(routine.stop) } } // Cleanup releases resources used by the pool, and should be called when the pool will no longer be used func (p *Pool) Cleanup() { p.Stop() p.lock.Lock() defer p.lock.Unlock() p.baseCancel() } // Start starts all stopped routines func (p *Pool) Start() { p.lock.Lock() defer p.lock.Unlock() p.ctx, p.cancel = context.WithCancel(p.baseCtx) for i := range p.routines { p.waitGroup.Add(1) p.routines[i].stop = make(chan bool, 1) Go(func() { p.routines[i].goroutine(p.routines[i].stop) p.waitGroup.Done() }) } for _, routine := range p.routinesCtx { p.waitGroup.Add(1) Go(func() { routine(p.ctx) p.waitGroup.Done() }) } } // Go starts a recoverable goroutine func Go(goroutine func()) { GoWithRecover(goroutine, defaultRecoverGoroutine) } // GoWithRecover starts a recoverable goroutine using given customRecover() function func GoWithRecover(goroutine func(), customRecover func(err interface{})) { go func() { defer func() { if err := recover(); err != nil { customRecover(err) } }() goroutine() }() } func defaultRecoverGoroutine(err interface{}) { log.Errorf("Error in Go routine: %s", err) log.Errorf("Stack: %s", debug.Stack()) } // OperationWithRecover wrap a backoff operation in a Recover func OperationWithRecover(operation backoff.Operation) backoff.Operation { return func() (err error) { defer func() { if res := recover(); res != nil { defaultRecoverGoroutine(res) err = fmt.Errorf("panic in operation: %s", err) } }() return operation() } }