From 05324b68610834b3e5af32be9245624e455ed041 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Mon, 4 Jan 2021 13:47:48 +0000
Subject: [PATCH] Send/state tweaks (#1681)

* Check missing event count

* Don't use request context for /send
---
 federationapi/routing/send.go | 139 +++++++++++++++++-----------------
 1 file changed, 71 insertions(+), 68 deletions(-)

diff --git a/federationapi/routing/send.go b/federationapi/routing/send.go
index f50b9c3d6..96b5355ea 100644
--- a/federationapi/routing/send.go
+++ b/federationapi/routing/send.go
@@ -84,7 +84,7 @@ func Send(
 
 	util.GetLogger(httpReq.Context()).Infof("Received transaction %q from %q containing %d PDUs, %d EDUs", txnID, request.Origin(), len(t.PDUs), len(t.EDUs))
 
-	resp, jsonErr := t.processTransaction(httpReq.Context())
+	resp, jsonErr := t.processTransaction(context.Background())
 	if jsonErr != nil {
 		util.GetLogger(httpReq.Context()).WithField("jsonErr", jsonErr).Error("t.processTransaction failed")
 		return *jsonErr
@@ -1005,79 +1005,82 @@ func (t *txnReq) lookupMissingStateViaStateIDs(ctx context.Context, roomID, even
 		return t.lookupMissingStateViaState(ctx, roomID, eventID, roomVersion)
 	}
 
-	util.GetLogger(ctx).WithFields(logrus.Fields{
-		"missing":             missingCount,
-		"event_id":            eventID,
-		"room_id":             roomID,
-		"total_state":         len(stateIDs.StateEventIDs),
-		"total_auth_events":   len(stateIDs.AuthEventIDs),
-		"concurrent_requests": concurrentRequests,
-	}).Info("Fetching missing state at event")
+	if missingCount > 0 {
+		util.GetLogger(ctx).WithFields(logrus.Fields{
+			"missing":             missingCount,
+			"event_id":            eventID,
+			"room_id":             roomID,
+			"total_state":         len(stateIDs.StateEventIDs),
+			"total_auth_events":   len(stateIDs.AuthEventIDs),
+			"concurrent_requests": concurrentRequests,
+		}).Info("Fetching missing state at event")
 
-	// Get a list of servers to fetch from.
-	servers := t.getServers(ctx, roomID)
-	if len(servers) > 5 {
-		servers = servers[:5]
-	}
-
-	// Create a queue containing all of the missing event IDs that we want
-	// to retrieve.
-	pending := make(chan string, missingCount)
-	for missingEventID := range missing {
-		pending <- missingEventID
-	}
-	close(pending)
-
-	// Define how many workers we should start to do this.
-	if missingCount < concurrentRequests {
-		concurrentRequests = missingCount
-	}
-
-	// Create the wait group.
-	var fetchgroup sync.WaitGroup
-	fetchgroup.Add(concurrentRequests)
-
-	// This is the only place where we'll write to t.haveEvents from
-	// multiple goroutines, and everywhere else is blocked on this
-	// synchronous function anyway.
-	var haveEventsMutex sync.Mutex
-
-	// Define what we'll do in order to fetch the missing event ID.
-	fetch := func(missingEventID string) {
-		var h *gomatrixserverlib.HeaderedEvent
-		h, err = t.lookupEvent(ctx, roomVersion, missingEventID, false, servers)
-		switch err.(type) {
-		case verifySigError:
-			return
-		case nil:
-			break
-		default:
-			util.GetLogger(ctx).WithFields(logrus.Fields{
-				"event_id": missingEventID,
-				"room_id":  roomID,
-			}).Info("Failed to fetch missing event")
-			return
+		// Get a list of servers to fetch from.
+		servers := t.getServers(ctx, roomID)
+		if len(servers) > 5 {
+			servers = servers[:5]
 		}
-		haveEventsMutex.Lock()
-		t.haveEvents[h.EventID()] = h
-		haveEventsMutex.Unlock()
-	}
 
-	// Create the worker.
-	worker := func(ch <-chan string) {
-		defer fetchgroup.Done()
-		for missingEventID := range ch {
-			fetch(missingEventID)
+		// Create a queue containing all of the missing event IDs that we want
+		// to retrieve.
+		pending := make(chan string, missingCount)
+		for missingEventID := range missing {
+			pending <- missingEventID
 		}
+		close(pending)
+
+		// Define how many workers we should start to do this.
+		if missingCount < concurrentRequests {
+			concurrentRequests = missingCount
+		}
+
+		// Create the wait group.
+		var fetchgroup sync.WaitGroup
+		fetchgroup.Add(concurrentRequests)
+
+		// This is the only place where we'll write to t.haveEvents from
+		// multiple goroutines, and everywhere else is blocked on this
+		// synchronous function anyway.
+		var haveEventsMutex sync.Mutex
+
+		// Define what we'll do in order to fetch the missing event ID.
+		fetch := func(missingEventID string) {
+			var h *gomatrixserverlib.HeaderedEvent
+			h, err = t.lookupEvent(ctx, roomVersion, missingEventID, false, servers)
+			switch err.(type) {
+			case verifySigError:
+				return
+			case nil:
+				break
+			default:
+				util.GetLogger(ctx).WithFields(logrus.Fields{
+					"event_id": missingEventID,
+					"room_id":  roomID,
+				}).Info("Failed to fetch missing event")
+				return
+			}
+			haveEventsMutex.Lock()
+			t.haveEvents[h.EventID()] = h
+			haveEventsMutex.Unlock()
+		}
+
+		// Create the worker.
+		worker := func(ch <-chan string) {
+			defer fetchgroup.Done()
+			for missingEventID := range ch {
+				fetch(missingEventID)
+			}
+		}
+
+		// Start the workers.
+		for i := 0; i < concurrentRequests; i++ {
+			go worker(pending)
+		}
+
+		// Wait for the workers to finish.
+		fetchgroup.Wait()
 	}
 
-	// Start the workers.
-	for i := 0; i < concurrentRequests; i++ {
-		go worker(pending)
-	}
-
-	// Wait for the workers to finish.
-	fetchgroup.Wait()
 	resp, err := t.createRespStateFromStateIDs(stateIDs)
 	return resp, err
 }