Merge pull request #26 from StackVista/stac-21470-fix-panic

STAC-21470: Forward request even on panic

internal/mirror/reflector.go

@@ -68,7 +68,7 @@ func (r *Reflector) sendToMirrors(req *Request) {
 	defer r.RUnlock()
 
 	for _, mirror := range r.mirrors {
-		go mirror.Reflect(req)
+		mirror.Reflect(req)
 	}
 }
 

internal/mirror/sendqueue.go

@@ -66,12 +66,12 @@ func (s *SendQueue) AddToQueue(req *Request, targetURL string) {
 }
 
 func (s *SendQueue) NextExecuteItems() []*Request {
-	var result []*Request
-	var newQueue []*Request
-
 	s.Lock()
 	defer s.Unlock()
 
+	var result []*Request
+	var newQueue []*Request = make([]*Request, 0, len(s.requestsQueued))
+
 	// Try to find the next request that can execute, assumes
 	for _, request := range s.requestsQueued {
 		// Try to figure out whether the completed epoch have advanced enough for the request to be picked up.

internal/proxy/handler.go

@@ -33,6 +33,18 @@ func ReverseProxyHandler(reflector *mirror.Reflector, url *url.URL) func(res htt
 		requestEpoch := epoch.Add(1)
 		activeRequests.Set(requestEpoch, nil)
 
+		// Catch panic in serving HTTP
+		defer func() {
+			if p := recover(); p != nil {
+				// At this point the request has been served to the main target, so we remove this as active request
+				activeRequests.Remove(requestEpoch)
+
+				reflector.IncomingCh <- mirror.NewRequest(req, body, requestEpoch, activeSnapshot)
+
+				panic(p)
+			}
+		}()
+
 		// Server the request to main target
 		proxyTo.ServeHTTP(res, req)