-
-
Notifications
You must be signed in to change notification settings - Fork 62
/
worker.go
62 lines (55 loc) · 1.45 KB
/
worker.go
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
package pond
import (
"context"
"sync"
)
// worker represents a worker goroutine
func worker(context context.Context, waitGroup *sync.WaitGroup, firstTask func(), tasks <-chan func(), taskExecutor func(func(), bool), taskWaitGroup *sync.WaitGroup) {
// If provided, execute the first task immediately, before listening to the tasks channel
if firstTask != nil {
taskExecutor(firstTask, true)
}
defer func() {
waitGroup.Done()
}()
for {
select {
case <-context.Done():
// Pool context was cancelled, empty tasks channel and exit
drainTasks(tasks, taskWaitGroup)
return
case task, ok := <-tasks:
// Prioritize context.Done statement (https://stackoverflow.com/questions/46200343/force-priority-of-go-select-statement)
select {
case <-context.Done():
if task != nil && ok {
// We have received a task, ignore it
taskWaitGroup.Done()
}
// Pool context was cancelled, empty tasks channel and exit
drainTasks(tasks, taskWaitGroup)
return
default:
if task == nil || !ok {
// We have received a signal to exit
return
}
// We have received a task, execute it
taskExecutor(task, false)
}
}
}
}
// drainPendingTasks discards queued tasks and decrements the corresponding wait group
func drainTasks(tasks <-chan func(), tasksWaitGroup *sync.WaitGroup) {
for {
select {
case task, ok := <-tasks:
if task != nil && ok {
tasksWaitGroup.Done()
}
default:
return
}
}
}