From 0dd9fdf9de71dc026b1e42624871ecd76f76afad Mon Sep 17 00:00:00 2001
From: "A.J. Beamon" <aj.beamon@snowflake.com>
Date: Thu, 11 Mar 2021 14:09:52 -0800
Subject: [PATCH] Throw an error if the local client is disabled and there are
 no external clients

---
 fdbclient/MultiVersionTransaction.actor.cpp | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/fdbclient/MultiVersionTransaction.actor.cpp b/fdbclient/MultiVersionTransaction.actor.cpp
index 504a2412db..54ddf4bd18 100644
--- a/fdbclient/MultiVersionTransaction.actor.cpp
+++ b/fdbclient/MultiVersionTransaction.actor.cpp
@@ -1333,6 +1333,18 @@ void MultiVersionApi::setupNetwork() {
 			}
 		}
 
+		if (externalClients.empty() && localClientDisabled) {
+			// SOMEDAY: this should be allowed when it's possible to add external clients after the
+			// network is setup.
+			//
+			// Typically we would create a more specific error for this case, but since we expect
+			// this case to go away soon, we can use a trace event and a generic error.
+			TraceEvent(SevWarn, "CannotSetupNetwork")
+			    .detail("Reason", "Local client is disabled and no external clients configured");
+
+			throw client_invalid_operation();
+		}
+
 		networkStartSetup = true;
 
 		if (externalClients.empty()) {
@@ -1453,8 +1465,7 @@ Reference<IDatabase> MultiVersionApi::createDatabase(const char* clusterFilePath
 	}
 	std::string clusterFile(clusterFilePath);
 
-	if (threadCount > 1 || localClientDisabled) {
-		ASSERT(localClientDisabled);
+	if (localClientDisabled) {
 		ASSERT(!bypassMultiClientApi);
 
 		int threadIdx = nextThread;
@@ -1470,6 +1481,8 @@ Reference<IDatabase> MultiVersionApi::createDatabase(const char* clusterFilePath
 
 	lock.leave();
 
+	ASSERT_LE(threadCount, 1);
+
 	auto db = localClient->api->createDatabase(clusterFilePath);
 	if (bypassMultiClientApi) {
 		return db;