feat(server): support long polling timeout.

server/middlewares.go

@@ -5,6 +5,8 @@ import (
 	"context"
 	"os"
 	"sync"
+	"sync/atomic"
+	"time"
 
 	"github.com/Mrs4s/go-cqhttp/coolq"
 	"github.com/Mrs4s/go-cqhttp/global"
@@ -73,11 +75,19 @@ func longPolling(bot *coolq.CQBot, maxSize int) handler {
 		if action != "get_updates" {
 			return nil
 		}
+		var (
+			ok      int32
+			ch      = make(chan []interface{}, 1)
+			timeout = time.Duration(p.Get("timeout").Int()) * time.Second
+		)
+		defer close(ch)
+		go func() {
 			mutex.Lock()
 			defer mutex.Unlock()
 			if queue.Len() == 0 {
 				cond.Wait()
 			}
+			if atomic.CompareAndSwapInt32(&ok, 0, 1) {
 				limit := int(p.Get("limit").Int())
 				if limit <= 0 || queue.Len() < limit {
 					limit = queue.Len()
@@ -86,6 +96,18 @@ func longPolling(bot *coolq.CQBot, maxSize int) handler {
 				for i := 0; i < limit; i++ {
 					ret[i] = queue.Remove(queue.Front())
 				}
+				ch <- ret
+			}
+		}()
+		if timeout != 0 {
+			select {
+			case <-time.After(timeout):
+				atomic.StoreInt32(&ok, 1)
+				return coolq.OK([]interface{}{})
+			case ret := <-ch:
 				return coolq.OK(ret)
 			}
 		}
+		return coolq.OK(<-ch)
+	}
+}