SERVER-21906 always use ReplicaSetMonitor when updating ShardRegistry lookup maps

(cherry picked from commit a05ba516fb340bd7a22480303c8d647b6d6c9874)

2 files changed, 28 insertions, 16 deletions

diff --git a/src/mongo/s/client/shard_registry.cpp b/src/mongo/s/client/shard_registry.cpp
index 55aa86def05..9b6814901b1 100644
--- a/src/mongo/s/client/shard_registry.cpp
+++ b/src/mongo/s/client/shard_registry.cpp
@@ -206,7 +206,7 @@ void ShardRegistry::reload(OperationContext* txn) {
             continue;
         }
 
-        _addShard_inlock(shardType);
+        _addShard_inlock(shardType, false);
     }
 }
 
@@ -326,10 +326,10 @@ void ShardRegistry::_addConfigShard_inlock() {
     ShardType configServerShard;
     configServerShard.setName("config");
     configServerShard.setHost(_configServerCS.toString());
-    _addShard_inlock(configServerShard);
+    _addShard_inlock(configServerShard, true);
 }
 
-void ShardRegistry::_addShard_inlock(const ShardType& shardType) {
+void ShardRegistry::_addShard_inlock(const ShardType& shardType, bool passHostName) {
     // This validation should ideally go inside the ShardType::validate call. However, doing
     // it there would prevent us from loading previously faulty shard hosts, which might have
     // been stored (i.e., the entire getAllShards call would fail).
@@ -347,27 +347,38 @@ void ShardRegistry::_addShard_inlock(const ShardType& shardType) {
         // mechanism and must only be reachable through CatalogManagerLegacy or legacy-style queries
         // and inserts. Do not create targeter for these connections. This code should go away after
         // 3.2 is released.
+        // Config server updates must pass the host name to avoid deadlock
         shard = std::make_shared<Shard>(shardType.getName(), shardHost, nullptr);
+        _updateLookupMapsForShard_inlock(std::move(shard), shardHost);
     } else {
         // Non-SYNC shards use targeter factory.
         shard = std::make_shared<Shard>(
             shardType.getName(), shardHost, _targeterFactory->create(shardHost));
+        if (passHostName) {
+            _updateLookupMapsForShard_inlock(std::move(shard), shardHost);
+        } else {
+            _updateLookupMapsForShard_inlock(std::move(shard),
+                                             boost::optional<const ConnectionString&>(boost::none));
+        }
     }
-
-    _updateLookupMapsForShard_inlock(std::move(shard), shardHost);
 }
 
-void ShardRegistry::updateLookupMapsForShard(shared_ptr<Shard> shard,
-                                             const ConnectionString& newConnString) {
-    log() << "Updating ShardRegistry connection string for shard " << shard->getId()
-          << " from: " << shard->getConnString().toString() << " to: " << newConnString.toString();
+void ShardRegistry::updateLookupMapsForShard(
+    shared_ptr<Shard> shard, boost::optional<const ConnectionString&> optConnString) {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
-    _updateLookupMapsForShard_inlock(std::move(shard), newConnString);
+    _updateLookupMapsForShard_inlock(std::move(shard), optConnString);
 }
 
-void ShardRegistry::_updateLookupMapsForShard_inlock(shared_ptr<Shard> shard,
-                                                     const ConnectionString& newConnString) {
+void ShardRegistry::_updateLookupMapsForShard_inlock(
+    shared_ptr<Shard> shard, boost::optional<const ConnectionString&> optConnString) {
     auto oldConnString = shard->getConnString();
+    auto newConnString = optConnString ? *optConnString : shard->getTargeter()->connectionString();
+
+    if (oldConnString.toString() != newConnString.toString()) {
+        log() << "Updating ShardRegistry connection string for shard " << shard->getId()
+              << " from: " << oldConnString.toString() << " to: " << newConnString.toString();
+    }
+
     for (const auto& host : oldConnString.getServers()) {
         _lookup.erase(host.toString());
         _hostLookup.erase(host);
diff --git a/src/mongo/s/client/shard_registry.h b/src/mongo/s/client/shard_registry.h
index e219cd26c7b..897b05809ec 100644
--- a/src/mongo/s/client/shard_registry.h
+++ b/src/mongo/s/client/shard_registry.h
@@ -149,12 +149,13 @@ public:
 
     /**
      * Updates _lookup and _rsLookup based on the given new version of the given Shard's
-     * ConnectionString.
+     * ConnectionString. If ConnectionString is not specified the maps are updated with hosts
+     * from the ReplicaSetMonitor.
      * Used to update the ShardRegistry when a change in replica set membership is detected by the
      * ReplicaSetMonitor.
      */
     void updateLookupMapsForShard(std::shared_ptr<Shard> shard,
-                                  const ConnectionString& newConnString);
+                                  boost::optional<const ConnectionString&> newConnString);
 
     /**
      * Returns a shared pointer to the shard object with the given shard id.
@@ -342,7 +343,7 @@ private:
     /**
      * Creates a shard based on the specified information and puts it into the lookup maps.
      */
-    void _addShard_inlock(const ShardType& shardType);
+    void _addShard_inlock(const ShardType& shardType, bool passHostName);
 
     /**
      * Adds the "config" shard (representing the config server) to the shard registry.
@@ -350,7 +351,7 @@ private:
     void _addConfigShard_inlock();
 
     void _updateLookupMapsForShard_inlock(std::shared_ptr<Shard> shard,
-                                          const ConnectionString& newConnString);
+                                          boost::optional<const ConnectionString&> newConnString);
 
     std::shared_ptr<Shard> _findUsingLookUp(const ShardId& shardId);