Introduce downstreamConn.sendTargetBacklog

downstream.go

@@ -979,24 +979,32 @@ func (dc *downstreamConn) messageSupportsHistory(msg *irc.Message) bool {
 }
 
 func (dc *downstreamConn) sendNetworkBacklog(net *network) {
+	for target := range net.delivered {
+		dc.sendTargetBacklog(net, target)
+	}
+}
+
+func (dc *downstreamConn) sendTargetBacklog(net *network, target string) {
 	if dc.caps["draft/chathistory"] || dc.user.msgStore == nil {
 		return
 	}
-	for target, delivered := range net.delivered {
 	if ch, ok := net.channels[target]; ok && ch.Detached {
-			continue
+		return
+	}
+	delivered, ok := net.delivered[target]
+	if !ok {
+		return
 	}
-
 	lastDelivered, ok := delivered[dc.clientName]
 	if !ok {
-			continue
+		return
 	}
 
 	limit := 4000
 	history, err := dc.user.msgStore.LoadLatestID(net, target, lastDelivered, limit)
 	if err != nil {
 		dc.logger.Printf("failed to send implicit history for %q: %v", target, err)
-			continue
+		return
 	}
 
 	batchRef := "history"
@@ -1026,7 +1034,6 @@ func (dc *downstreamConn) sendNetworkBacklog(net *network) {
 			Params:  []string{"-" + batchRef},
 		})
 	}
-	}
 }
 
 func (dc *downstreamConn) runUntilRegistered() error {