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
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
package roadrunner
import (
"fmt"
"os/exec"
"sync"
"sync/atomic"
"time"
)
const (
// ContextTerminate must be sent by worker in control payload if worker want to die.
ContextTerminate = "TERMINATE"
)
// Pool controls worker creation, destruction and task routing.
type Pool struct {
cfg Config // pool behaviour
cmd func() *exec.Cmd // worker command creator
factory Factory // creates and connects to workers
numWorkers uint64 // current number of tasks workers
tasks sync.WaitGroup // counts all tasks executions
mua sync.Mutex // protects worker allocation
muw sync.RWMutex // protects state of worker list
workers []*Worker // all registered workers
free chan *Worker // freed workers
}
// NewPool creates new worker pool and task multiplexer. Pool will initiate with one worker.
func NewPool(cmd func() *exec.Cmd, factory Factory, cfg Config) (*Pool, error) {
p := &Pool{
cfg: cfg,
cmd: cmd,
factory: factory,
workers: make([]*Worker, 0, cfg.MaxWorkers),
free: make(chan *Worker, cfg.MaxWorkers),
}
// to test if worker ready
w, err := p.createWorker()
if err != nil {
return nil, err
}
p.free <- w
return p, nil
}
// Execute one task with given payload and context, returns result and context or error. Must not be used once pool is
// being destroyed.
func (p *Pool) Execute(payload []byte, ctx interface{}) (resp []byte, rCtx []byte, err error) {
p.tasks.Add(1)
defer p.tasks.Done()
w, err := p.allocateWorker()
if err != nil {
return nil, nil, err
}
if resp, rCtx, err = w.Execute(payload, ctx); err != nil {
if !p.cfg.DestroyOnError {
if err, jobError := err.(JobError); jobError {
p.free <- w
return nil, nil, err
}
}
// worker level error
p.destroyWorker(w)
return nil, nil, err
}
// controlled destruction
if len(resp) == 0 && string(rCtx) == ContextTerminate {
p.destroyWorker(w)
go func() {
//immediate refill
if w, err := p.createWorker(); err != nil {
p.free <- w
}
}()
return p.Execute(payload, ctx)
}
if p.cfg.MaxExecutions != 0 && atomic.LoadUint64(&w.NumExecutions) > p.cfg.MaxExecutions {
p.destroyWorker(w)
} else {
p.free <- w
}
return resp, rCtx, nil
}
// Config returns associated pool configuration.
func (p *Pool) Config() Config {
return p.cfg
}
// Workers returns workers associated with the pool.
func (p *Pool) Workers() (workers []*Worker) {
p.muw.RLock()
defer p.muw.RUnlock()
for _, w := range p.workers {
workers = append(workers, w)
}
return workers
}
// Close all underlying workers (but let them to complete the task).
func (p *Pool) Close() {
p.tasks.Wait()
var wg sync.WaitGroup
for _, w := range p.Workers() {
wg.Add(1)
go func(w *Worker) {
defer wg.Done()
p.destroyWorker(w)
}(w)
}
wg.Wait()
}
// finds free worker in a given time interval or creates new if allowed.
func (p *Pool) allocateWorker() (*Worker, error) {
p.mua.Lock()
defer p.mua.Unlock()
select {
case w := <-p.free:
// we already have free worker
return w, nil
default:
if p.numWorkers < p.cfg.MaxWorkers {
return p.createWorker()
}
timeout := time.NewTimer(p.cfg.AllocateTimeout)
select {
case <-timeout.C:
return nil, fmt.Errorf("unable to allocate worker, timeout (%s)", p.cfg.AllocateTimeout)
case w := <-p.free:
timeout.Stop()
return w, nil
}
}
}
// destroy and remove worker from the pool.
func (p *Pool) destroyWorker(w *Worker) {
atomic.AddUint64(&p.numWorkers, ^uint64(0))
go func() {
w.Stop()
p.muw.Lock()
defer p.muw.Unlock()
for i, wc := range p.workers {
if wc == w {
p.workers = p.workers[:i+1]
break
}
}
}()
}
// creates new worker (must be called in a locked state).
func (p *Pool) createWorker() (*Worker, error) {
w, err := p.factory.NewWorker(p.cmd())
if err != nil {
return nil, err
}
atomic.AddUint64(&p.numWorkers, 1)
go func() {
p.muw.Lock()
defer p.muw.Unlock()
p.workers = append(p.workers, w)
}()
return w, nil
}
|
