Rewrite container for the workers

Update tests

6 files changed, 221 insertions, 101 deletions

diff --git a/pkg/worker_watcher/container/interface.go b/pkg/worker_watcher/container/interface.go
new file mode 100644
index 00000000..bb66897f
--- /dev/null
+++ b/pkg/worker_watcher/container/interface.go
@@ -0,0 +1,9 @@
+package container
+
+import "github.com/spiral/roadrunner/v2/pkg/worker"
+
+type Vector interface {
+	Enqueue(worker.BaseProcess)
+	Dequeue() (worker.BaseProcess, bool)
+	Destroy()
+}
diff --git a/pkg/worker_watcher/stack.go b/pkg/worker_watcher/container/stack.go
index 69e2024b..91c71b24 100644
--- a/pkg/worker_watcher/stack.go
+++ b/pkg/worker_watcher/container/stack.go
@@ -1,4 +1,4 @@
-package worker_watcher //nolint:golint,stylecheck
+package container //nolint:golint,stylecheck
 import (
 	"context"
 	"runtime"
@@ -32,8 +32,8 @@ func (stack *Stack) Reset() {
 	stack.workers = nil
 }
 
-// Push worker back to the stack
-// If stack in destroy state, Push will provide 100ms window to unlock the mutex
+// Push worker back to the vec
+// If vec in destroy state, Push will provide 100ms window to unlock the mutex
 func (stack *Stack) Push(w worker.BaseProcess) {
 	stack.Lock()
 	defer stack.Unlock()
@@ -51,7 +51,7 @@ func (stack *Stack) Pop() (worker.BaseProcess, bool) {
 	stack.Lock()
 	defer stack.Unlock()
 
-	// do not release new stack
+	// do not release new vec
 	if stack.destroy {
 		return nil, true
 	}
@@ -71,7 +71,7 @@ func (stack *Stack) FindAndRemoveByPid(pid int64) bool {
 	stack.Lock()
 	defer stack.Unlock()
 	for i := 0; i < len(stack.workers); i++ {
-		// worker in the stack, reallocating
+		// worker in the vec, reallocating
 		if stack.workers[i].Pid() == pid {
 			stack.workers = append(stack.workers[:i], stack.workers[i+1:]...)
 			stack.actualNumOfWorkers--
@@ -83,7 +83,7 @@ func (stack *Stack) FindAndRemoveByPid(pid int64) bool {
 	return false
 }
 
-// Workers return copy of the workers in the stack
+// Workers return copy of the workers in the vec
 func (stack *Stack) Workers() []worker.BaseProcess {
 	stack.Lock()
 	defer stack.Unlock()
@@ -124,11 +124,11 @@ func (stack *Stack) Destroy(_ context.Context) {
 			}
 			stack.Unlock()
 			// unnecessary mutex, but
-			// just to make sure. All stack at this moment are in the stack
+			// just to make sure. All vec at this moment are in the vec
 			// Pop operation is blocked, push can't be done, since it's not possible to pop
 			stack.Lock()
 			for i := 0; i < len(stack.workers); i++ {
-				// set state for the stack in the stack (unused at the moment)
+				// set state for the vec in the vec (unused at the moment)
 				stack.workers[i].State().Set(worker.StateDestroyed)
 				// kill the worker
 				_ = stack.workers[i].Kill()
diff --git a/pkg/worker_watcher/stack_test.go b/pkg/worker_watcher/container/stack_test.go
index 769419e4..59c15773 100644
--- a/pkg/worker_watcher/stack_test.go
+++ b/pkg/worker_watcher/container/stack_test.go
@@ -1,4 +1,4 @@
-package worker_watcher //nolint:golint,stylecheck
+package container //nolint:golint,stylecheck
 import (
 	"context"
 	"os/exec"
diff --git a/pkg/worker_watcher/container/vec.go b/pkg/worker_watcher/container/vec.go
new file mode 100644
index 00000000..da9822ef
--- /dev/null
+++ b/pkg/worker_watcher/container/vec.go
@@ -0,0 +1,45 @@
+package container //nolint:golint,stylecheck
+
+import (
+	"sync/atomic"
+
+	"github.com/spiral/roadrunner/v2/pkg/worker"
+)
+
+type Vec struct {
+	destroy uint64
+	workers chan worker.BaseProcess
+}
+
+func NewVector(initialNumOfWorkers uint64) Vector {
+	vec := &Vec{
+		destroy: 0,
+		workers: make(chan worker.BaseProcess, initialNumOfWorkers),
+	}
+
+	return vec
+}
+
+func (v *Vec) Enqueue(w worker.BaseProcess) {
+	v.workers <- w
+}
+
+func (v *Vec) Dequeue() (worker.BaseProcess, bool) {
+	/*
+		if *addr == old {
+			*addr = new
+			return true
+		}
+	*/
+	if atomic.CompareAndSwapUint64(&v.destroy, 1, 1) {
+		return nil, true
+	}
+
+	w := <-v.workers
+
+	return w, false
+}
+
+func (v *Vec) Destroy() {
+	atomic.StoreUint64(&v.destroy, 1)
+}
diff --git a/pkg/worker_watcher/interface.go b/pkg/worker_watcher/interface.go
index a3552e7e..4625b7a7 100644
--- a/pkg/worker_watcher/interface.go
+++ b/pkg/worker_watcher/interface.go
@@ -8,7 +8,7 @@ import (
 
 // Watcher is an interface for the Sync workers lifecycle
 type Watcher interface {
-	// Watch used to add workers to the stack
+	// Watch used to add workers to the container
 	Watch(workers []worker.BaseProcess) error
 
 	// Get provide first free worker
@@ -20,12 +20,12 @@ type Watcher interface {
 	// Allocate - allocates new worker and put it into the WorkerWatcher
 	Allocate() error
 
-	// Destroy destroys the underlying stack
+	// Destroy destroys the underlying container
 	Destroy(ctx context.Context)
 
-	// WorkersList return all stack w/o removing it from internal storage
+	// WorkersList return all container w/o removing it from internal storage
 	List() []worker.BaseProcess
 
-	// RemoveWorker remove worker from the stack
-	Remove(wb worker.BaseProcess) error
+	// RemoveWorker remove worker from the container
+	Remove(wb worker.BaseProcess)
 }
diff --git a/pkg/worker_watcher/worker_watcher.go b/pkg/worker_watcher/worker_watcher.go
index 2380c190..3e0633a3 100755
--- a/pkg/worker_watcher/worker_watcher.go
+++ b/pkg/worker_watcher/worker_watcher.go
@@ -3,33 +3,42 @@ package worker_watcher //nolint:golint,stylecheck
 import (
 	"context"
 	"sync"
+	"time"
 
 	"github.com/spiral/errors"
 	"github.com/spiral/roadrunner/v2/pkg/events"
 	"github.com/spiral/roadrunner/v2/pkg/worker"
+	"github.com/spiral/roadrunner/v2/pkg/worker_watcher/container"
 )
 
-// workerCreateFunc can be nil, but in that case, dead stack will not be replaced
+// workerCreateFunc can be nil, but in that case, dead container will not be replaced
 func NewSyncWorkerWatcher(allocator worker.Allocator, numWorkers uint64, events events.Handler) Watcher {
 	ww := &workerWatcher{
-		stack:     NewWorkersStack(numWorkers),
-		allocator: allocator,
-		events:    events,
+		container:  container.NewVector(numWorkers),
+		numWorkers: numWorkers,
+		workers:    make([]worker.BaseProcess, 0, numWorkers),
+		allocator:  allocator,
+		events:     events,
 	}
 
 	return ww
 }
 
 type workerWatcher struct {
-	mutex     sync.RWMutex
-	stack     *Stack
-	allocator worker.Allocator
-	events    events.Handler
+	sync.RWMutex
+	container container.Vector
+	// used to control the Destroy stage (that all workers are in the container)
+	numWorkers uint64
+	workers    []worker.BaseProcess
+	allocator  worker.Allocator
+	events     events.Handler
 }
 
 func (ww *workerWatcher) Watch(workers []worker.BaseProcess) error {
 	for i := 0; i < len(workers); i++ {
-		ww.stack.Push(workers[i])
+		ww.container.Enqueue(workers[i])
+		// add worker to watch slice
+		ww.workers = append(ww.workers, workers[i])
 
 		go func(swc worker.BaseProcess) {
 			ww.wait(swc)
@@ -38,75 +47,96 @@ func (ww *workerWatcher) Watch(workers []worker.BaseProcess) error {
 	return nil
 }
 
+// return value from Get
+type get struct {
+	w   worker.BaseProcess
+	err error
+}
+
 // Get is not a thread safe operation
 func (ww *workerWatcher) Get(ctx context.Context) (worker.BaseProcess, error) {
+	c := make(chan get, 1)
 	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
-	// Put worker back (no matter it's state, it will be killed next)
-	if w != nil {
-		ww.stack.Push(w)
-	}
-	// 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)
+	go func() {
+		// FAST PATH
+		// thread safe operation
+		w, stop := ww.container.Dequeue()
+		if stop {
+			c <- get{
+				nil,
+				errors.E(op, errors.WatcherStopped),
 			}
-			if w == nil {
-				continue
+			return
+		}
+
+		// fast path, worker not nil and in the ReadyState
+		if w.State().Value() == worker.StateReady {
+			c <- get{
+				w,
+				nil,
 			}
+			return
+		}
+		// =========================================================
+		// SLOW PATH
+		_ = w.Kill()
+		// no free workers in the container
+		// try to continuously get free one
+		for {
+			select {
+			default:
+				w, stop = ww.container.Dequeue()
+				if stop {
+					c <- get{
+						nil,
+						errors.E(op, errors.WatcherStopped),
+					}
+				}
 
-			switch w.State().Value() {
-			// return only workers in the Ready state
-			// check first
-			case worker.StateReady:
-				return w, nil
-			case worker.StateRemove:
-				err := ww.Remove(w)
-				if err != nil {
-					return nil, errors.E(op, err)
+				switch w.State().Value() {
+				// return only workers in the Ready state
+				// check first
+				case worker.StateReady:
+					c <- get{
+						w,
+						nil,
+					}
+					return
+				case worker.StateWorking: // how??
+					ww.container.Enqueue(w)
+					continue
+				case
+					// all the possible wrong states
+					worker.StateInactive,
+					worker.StateDestroyed,
+					worker.StateErrored,
+					worker.StateStopped,
+					worker.StateInvalid,
+					worker.StateKilling,
+					worker.StateStopping:
+					// worker doing no work because it in the container
+					// so we can safely kill it (inconsistent state)
+					_ = w.Kill()
+					// try to get new worker
+					continue
 				}
-				// 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
 			}
-		case <-ctx.Done():
-			return nil, errors.E(op, errors.NoFreeWorkers, errors.Str("no free workers in the stack, timeout exceed"))
 		}
+	}()
+
+	select {
+	case r := <-c:
+		if r.err != nil {
+			return nil, r.err
+		}
+		return r.w, nil
+	case <-ctx.Done():
+		return nil, errors.E(op, errors.NoFreeWorkers, errors.Str("no free workers in the container, timeout exceed"))
 	}
 }
 
 func (ww *workerWatcher) Allocate() error {
-	ww.mutex.Lock()
+	ww.Lock()
 	const op = errors.Op("worker_watcher_allocate_new")
 	sw, err := ww.allocator()
 	if err != nil {
@@ -114,47 +144,83 @@ func (ww *workerWatcher) Allocate() error {
 	}
 
 	ww.addToWatch(sw)
-	ww.mutex.Unlock()
-	ww.Push(sw)
 
+	ww.workers = append(ww.workers, sw)
+
+	ww.Unlock()
+	ww.Push(sw)
 	return nil
 }
 
 // Remove
-func (ww *workerWatcher) Remove(wb worker.BaseProcess) error {
-	ww.mutex.Lock()
-	defer ww.mutex.Unlock()
+func (ww *workerWatcher) Remove(wb worker.BaseProcess) {
+	ww.Lock()
+	defer ww.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)
+	pid := wb.Pid()
+
+	// worker will be removed on the Get operation
+	for i := 0; i < len(ww.workers); i++ {
+		if ww.workers[i].Pid() == pid {
+			ww.workers = append(ww.workers[:i], ww.workers[i+1:]...)
+			// kill worker
+			_ = wb.Kill()
+			return
 		}
-		return nil
 	}
-
-	return nil
 }
 
 // O(1) operation
 func (ww *workerWatcher) Push(w worker.BaseProcess) {
-	ww.mutex.Lock()
-	defer ww.mutex.Unlock()
-	ww.stack.Push(w)
+	ww.container.Enqueue(w)
 }
 
-// Destroy all underlying stack (but let them to complete the task)
+// Destroy all underlying container (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)
+	// destroy container, we don't use ww mutex here, since we should be able to push worker
+	ww.Lock()
+	// do not release new workers
+	ww.container.Destroy()
+	ww.Unlock()
+
+	tt := time.NewTicker(time.Millisecond * 500)
+	defer tt.Stop()
+	for {
+		select {
+		case <-tt.C:
+			ww.Lock()
+			// that might be one of the workers is working
+			if ww.numWorkers != uint64(len(ww.workers)) {
+				ww.Unlock()
+				continue
+			}
+			ww.Unlock()
+			// unnecessary mutex, but
+			// just to make sure. All container at this moment are in the container
+			// Pop operation is blocked, push can't be done, since it's not possible to pop
+			ww.Lock()
+			for i := 0; i < len(ww.workers); i++ {
+				ww.workers[i].State().Set(worker.StateDestroyed)
+				// kill the worker
+				_ = ww.workers[i].Kill()
+			}
+			return
+		}
+	}
 }
 
 // Warning, this is O(n) operation, and it will return copy of the actual workers
 func (ww *workerWatcher) List() []worker.BaseProcess {
-	return ww.stack.Workers()
+	ww.Lock()
+	defer ww.Unlock()
+
+	base := make([]worker.BaseProcess, 0, len(ww.workers))
+	for i := 0; i < len(ww.workers); i++ {
+		base = append(base, ww.workers[i])
+	}
+
+	return base
 }
 
 func (ww *workerWatcher) wait(w worker.BaseProcess) {
@@ -174,7 +240,7 @@ func (ww *workerWatcher) wait(w worker.BaseProcess) {
 		return
 	}
 
-	_ = ww.stack.FindAndRemoveByPid(w.Pid())
+	ww.Remove(w)
 	err = ww.Allocate()
 	if err != nil {
 		ww.events.Push(events.PoolEvent{