blob: 694b172455f3d5ead30a35756e3b14a7c2fe3cf7 (
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
|
package input
import (
"sync"
)
type fifoQueue struct {
tasks []*inputTask
count int
mutex sync.Mutex
notifs chan struct{}
}
func newFIFOQueue() *fifoQueue {
q := &fifoQueue{
notifs: make(chan struct{}, 1),
}
return q
}
func (q *fifoQueue) push(frame *inputTask) {
q.mutex.Lock()
defer q.mutex.Unlock()
q.tasks = append(q.tasks, frame)
q.count++
select {
case q.notifs <- struct{}{}:
default:
}
}
// pop returns the first item of the queue, if there is one.
// The second return value will indicate if a task was returned.
// You must check this value, even after calling wait().
func (q *fifoQueue) pop() (*inputTask, bool) {
q.mutex.Lock()
defer q.mutex.Unlock()
if q.count == 0 {
return nil, false
}
frame := q.tasks[0]
q.tasks[0] = nil
q.tasks = q.tasks[1:]
q.count--
if q.count == 0 {
// Force a GC of the underlying array, since it might have
// grown significantly if the queue was hammered for some reason
q.tasks = nil
}
return frame, true
}
// wait returns a channel which can be used to detect when an
// item is waiting in the queue.
func (q *fifoQueue) wait() <-chan struct{} {
q.mutex.Lock()
defer q.mutex.Unlock()
if q.count > 0 && len(q.notifs) == 0 {
ch := make(chan struct{})
close(ch)
return ch
}
return q.notifs
}
|
