X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/2f59cb8dd12e80a6a82f834a6599fd9d8bb0f586..1fd838ddcc3274448908227c285d1b7f233207d9:/sdk/go/httpserver/request_limiter.go

diff --git a/sdk/go/httpserver/request_limiter.go b/sdk/go/httpserver/request_limiter.go
index 33a2eb6146..9d501ab0eb 100644
--- a/sdk/go/httpserver/request_limiter.go
+++ b/sdk/go/httpserver/request_limiter.go
@@ -15,7 +15,7 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-const IneligibleForQueuePriority = math.MinInt64
+const MinPriority = math.MinInt64
 
 // Prometheus typically polls every 10 seconds, but it doesn't cost us
 // much to also accommodate higher frequency collection by updating
@@ -48,6 +48,11 @@ type RequestLimiter struct {
 	// handled FIFO.
 	Priority func(req *http.Request, queued time.Time) int64
 
+	// Return 503 for any request for which Priority() returns
+	// MinPriority if it spends longer than this in the queue
+	// before starting processing.
+	MaxQueueTimeForMinPriority time.Duration
+
 	// "concurrent_requests", "max_concurrent_requests",
 	// "queued_requests", and "max_queued_requests" metrics are
 	// registered with Registry, if it is not nil.
@@ -233,14 +238,6 @@ func (rl *RequestLimiter) enqueue(req *http.Request) *qent {
 		ent.ready <- true
 		return ent
 	}
-	if priority == IneligibleForQueuePriority {
-		// Priority func is telling us to return 503
-		// immediately instead of queueing, regardless of
-		// queue size, if we can't handle the request
-		// immediately.
-		ent.ready <- false
-		return ent
-	}
 	rl.queue.add(ent)
 	rl.trimqueue()
 	return ent
@@ -259,6 +256,16 @@ func (rl *RequestLimiter) ServeHTTP(resp http.ResponseWriter, req *http.Request)
 	rl.setupOnce.Do(rl.setup)
 	ent := rl.enqueue(req)
 	SetResponseLogFields(req.Context(), logrus.Fields{"priority": ent.priority})
+	if ent.priority == MinPriority {
+		// Note that MaxQueueTime==0 does not cancel a req
+		// that skips the queue, because in that case
+		// rl.enqueue() has already fired ready<-true and
+		// rl.remove() is a no-op.
+		go func() {
+			time.Sleep(rl.MaxQueueTimeForMinPriority)
+			rl.remove(ent)
+		}()
+	}
 	var ok bool
 	select {
 	case <-req.Context().Done():