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package worker_watcher //nolint:golint,stylecheck
import (
"context"
"sync"
"github.com/spiral/errors"
"github.com/spiral/roadrunner/v2/pkg/events"
"github.com/spiral/roadrunner/v2/pkg/worker"
)
// workerCreateFunc can be nil, but in that case, dead stack will not be replaced
func NewSyncWorkerWatcher(allocator worker.Allocator, numWorkers uint64, events events.Handler) Watcher {
ww := &workerWatcher{
stack: NewWorkersStack(numWorkers),
allocator: allocator,
events: events,
}
return ww
}
type workerWatcher struct {
mutex sync.RWMutex
stack *Stack
allocator worker.Allocator
events events.Handler
}
func (ww *workerWatcher) Watch(workers []worker.SyncWorker) error {
for i := 0; i < len(workers); i++ {
ww.stack.Push(workers[i])
go func(swc worker.SyncWorker) {
ww.wait(swc)
}(workers[i])
}
return nil
}
// Get is not a thread safe operation
func (ww *workerWatcher) Get(ctx context.Context) (worker.SyncWorker, error) {
const op = errors.Op("worker_watcher_get_free_worker")
// FAST PATH
// thread safe operation
w, stop := ww.stack.Pop()
if stop {
return nil, errors.E(op, errors.WatcherStopped)
}
// fast path, worker not nil and in the ReadyState
if w != nil && w.State().Value() == worker.StateReady {
return w, nil
}
// =========================================================
// SLOW PATH
// no free workers in the stack
// try to continuously get free one
for {
select {
default:
w, stop = ww.stack.Pop()
if stop {
return nil, errors.E(op, errors.WatcherStopped)
}
if w == nil {
continue
}
switch w.State().Value() {
case worker.StateRemove:
err := ww.Remove(w)
if err != nil {
return nil, errors.E(op, err)
}
// try to get next
continue
case
// all the possible wrong states
worker.StateInactive,
worker.StateDestroyed,
worker.StateErrored,
worker.StateStopped,
worker.StateInvalid,
worker.StateKilling,
worker.StateWorking, // ??? how
worker.StateStopping:
// worker doing no work because it in the stack
// so we can safely kill it (inconsistent state)
_ = w.Kill()
// try to get new worker
continue
// return only workers in the Ready state
case worker.StateReady:
return w, nil
}
case <-ctx.Done():
return nil, errors.E(op, errors.NoFreeWorkers, errors.Str("no free workers in the stack, timeout exceed"))
}
}
}
func (ww *workerWatcher) Allocate() error {
ww.stack.mutex.Lock()
const op = errors.Op("worker_watcher_allocate_new")
sw, err := ww.allocator()
if err != nil {
return errors.E(op, errors.WorkerAllocate, err)
}
ww.addToWatch(sw)
ww.stack.mutex.Unlock()
ww.Push(sw)
return nil
}
// Remove
func (ww *workerWatcher) Remove(wb worker.SyncWorker) error {
ww.mutex.Lock()
defer ww.mutex.Unlock()
const op = errors.Op("worker_watcher_remove_worker")
// set remove state
wb.State().Set(worker.StateRemove)
if ww.stack.FindAndRemoveByPid(wb.Pid()) {
err := wb.Kill()
if err != nil {
return errors.E(op, err)
}
return nil
}
return nil
}
// O(1) operation
func (ww *workerWatcher) Push(w worker.SyncWorker) {
ww.mutex.Lock()
defer ww.mutex.Unlock()
ww.stack.Push(w)
}
// Destroy all underlying stack (but let them to complete the task)
func (ww *workerWatcher) Destroy(ctx context.Context) {
// destroy stack, we don't use ww mutex here, since we should be able to push worker
ww.stack.Destroy(ctx)
}
// Warning, this is O(n) operation, and it will return copy of the actual workers
func (ww *workerWatcher) List() []worker.SyncWorker {
return ww.stack.Workers()
}
func (ww *workerWatcher) wait(w worker.BaseProcess) {
const op = errors.Op("worker_watcher_wait")
err := w.Wait()
if err != nil {
ww.events.Push(events.WorkerEvent{
Event: events.EventWorkerError,
Worker: w,
Payload: errors.E(op, err),
})
}
if w.State().Value() == worker.StateDestroyed {
// worker was manually destroyed, no need to replace
ww.events.Push(events.PoolEvent{Event: events.EventWorkerDestruct, Payload: w})
return
}
_ = ww.stack.FindAndRemoveByPid(w.Pid())
err = ww.Allocate()
if err != nil {
ww.events.Push(events.PoolEvent{
Event: events.EventPoolError,
Payload: errors.E(op, err),
})
}
}
func (ww *workerWatcher) addToWatch(wb worker.SyncWorker) {
go func() {
ww.wait(wb)
}()
}
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