mirror of
https://github.com/matrix-org/dendrite
synced 2024-09-10 21:21:51 +02:00
* Use a FIFO queue instead of a channel to reduce backpressure * Make sure someone wakes up * Tweaks * Add comments
64 lines
1.3 KiB
Go
64 lines
1.3 KiB
Go
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
|
|
}
|