summaryrefslogtreecommitdiff
path: root/pkg/worker_watcher/worker_watcher.go
blob: cf2e1eb7780c5afe09c3289d92c30badfd61ed1d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
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/states"
	"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) AddToWatch(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
}

func (ww *workerWatcher) GetFreeWorker(ctx context.Context) (worker.SyncWorker, error) {
	const op = errors.Op("worker_watcher_get_free_worker")
	// thread safe operation
	w, stop := ww.stack.Pop()
	if stop {
		return nil, errors.E(op, errors.WatcherStopped)
	}

	// handle worker remove state
	// in this state worker is destroyed by supervisor
	if w != nil && w.State().Value() == states.StateRemove {
		err := ww.RemoveWorker(w)
		if err != nil {
			return nil, err
		}
		// try to get next
		return ww.GetFreeWorker(ctx)
	}
	// no free stack
	if w == nil {
		for {
			select {
			default:
				w, stop = ww.stack.Pop()
				if stop {
					return nil, errors.E(op, errors.WatcherStopped)
				}
				if w == nil {
					continue
				}
				return w, nil
			case <-ctx.Done():
				return nil, errors.E(op, errors.NoFreeWorkers, errors.Str("no free workers in the stack, timeout exceed"))
			}
		}
	}

	return w, nil
}

func (ww *workerWatcher) AllocateNew() 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.PushWorker(sw)

	return nil
}

func (ww *workerWatcher) RemoveWorker(wb worker.SyncWorker) error {
	ww.mutex.Lock()
	defer ww.mutex.Unlock()

	const op = errors.Op("worker_watcher_remove_worker")
	pid := wb.Pid()

	if ww.stack.FindAndRemoveByPid(pid) {
		wb.State().Set(states.StateRemove)
		err := wb.Kill()
		if err != nil {
			return errors.E(op, err)
		}
		return nil
	}

	return nil
}

// O(1) operation
func (ww *workerWatcher) PushWorker(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) WorkersList() []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() == states.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.AllocateNew()
	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)
	}()
}