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package centrifuge
import (
"sync"
"github.com/centrifugal/centrifuge/internal/queue"
)
type writerConfig struct {
WriteManyFn func(...[]byte) error
WriteFn func([]byte) error
MaxQueueSize int
MaxMessagesInFrame int
}
// writer helps to manage per-connection message byte queue.
type writer struct {
mu sync.Mutex
config writerConfig
messages queue.Queue
closed bool
}
func newWriter(config writerConfig) *writer {
w := &writer{
config: config,
messages: queue.New(),
}
return w
}
const (
defaultMaxMessagesInFrame = 4
)
func (w *writer) waitSendMessage(maxMessagesInFrame int) bool {
// Wait for message from queue.
ok := w.messages.Wait()
if !ok {
return false
}
w.mu.Lock()
defer w.mu.Unlock()
msg, ok := w.messages.Remove()
if !ok {
return !w.messages.Closed()
}
var writeErr error
messageCount := w.messages.Len()
if maxMessagesInFrame > 1 && messageCount > 0 {
// There are several more messages left in queue, try to send them in single frame,
// but no more than maxMessagesInFrame.
// Limit message count to get from queue with (maxMessagesInFrame - 1)
// (as we already have one message received from queue above).
messagesCap := messageCount + 1
if messagesCap > maxMessagesInFrame {
messagesCap = maxMessagesInFrame
}
messages := make([][]byte, 0, messagesCap)
messages = append(messages, msg)
for messageCount > 0 {
messageCount--
if len(messages) >= maxMessagesInFrame {
break
}
m, ok := w.messages.Remove()
if ok {
messages = append(messages, m)
} else {
if w.messages.Closed() {
return false
}
break
}
}
if len(messages) > 0 {
if len(messages) == 1 {
writeErr = w.config.WriteFn(messages[0])
} else {
writeErr = w.config.WriteManyFn(messages...)
}
}
} else {
// Write single message without allocating new [][]byte slice.
writeErr = w.config.WriteFn(msg)
}
if writeErr != nil {
// Write failed, transport must close itself, here we just return from routine.
return false
}
return true
}
// run supposed to be run in goroutine, this goroutine will be closed as
// soon as queue is closed.
func (w *writer) run() {
maxMessagesInFrame := w.config.MaxMessagesInFrame
if maxMessagesInFrame == 0 {
maxMessagesInFrame = defaultMaxMessagesInFrame
}
for {
ok := w.waitSendMessage(maxMessagesInFrame)
if !ok {
return
}
}
}
func (w *writer) enqueue(data []byte) *Disconnect {
ok := w.messages.Add(data)
if !ok {
return DisconnectNormal
}
if w.config.MaxQueueSize > 0 && w.messages.Size() > w.config.MaxQueueSize {
return DisconnectSlow
}
return nil
}
func (w *writer) close() error {
w.mu.Lock()
defer w.mu.Unlock()
if w.closed {
return nil
}
w.closed = true
remaining := w.messages.CloseRemaining()
if len(remaining) > 0 {
// TODO: make it respect MaxMessagesInFrame option.
_ = w.config.WriteManyFn(remaining...)
}
return nil
}
|
