run patch server on main thread on windows

src/Main.cc

@@ -2361,7 +2361,7 @@ Action a_run_server_replay_log(
       }
 
       if (evthread_use_pthreads()) {
-        throw runtime_error("failed to setup libevent threads");
+        throw runtime_error("failed to set up libevent threads");
       }
 
       if (!isdir("system/players")) {

src/PatchServer.cc

@@ -395,17 +395,31 @@ void PatchServer::on_client_error(Channel& ch, short events) {
 }
 
 PatchServer::PatchServer(shared_ptr<const Config> config)
-    : base(event_base_new(), event_base_free),
-      config(config),
-      destroy_clients_ev(event_new(this->base.get(), -1, EV_TIMEOUT, &PatchServer::dispatch_destroy_clients, this), event_free),
-      th(&PatchServer::thread_fn, this) {}
+    : config(config) {
+  if (config->shared_base) {
+    this->base = config->shared_base;
+    this->base_is_shared = true;
+  } else {
+    this->base.reset(event_base_new(), event_base_free);
+    this->base_is_shared = false;
+  }
+  this->destroy_clients_ev.reset(
+      event_new(this->base.get(), -1, EV_TIMEOUT, &PatchServer::dispatch_destroy_clients, this), event_free);
+  if (!this->base_is_shared) {
+    this->th = thread(&PatchServer::thread_fn, this);
+  }
+}
 
 void PatchServer::schedule_stop() {
-  event_base_loopexit(this->base.get(), nullptr);
+  if (!this->base_is_shared) {
+    event_base_loopexit(this->base.get(), nullptr);
+  }
 }
 
 void PatchServer::wait_for_stop() {
-  this->th.join();
+  if (!this->base_is_shared) {
+    this->th.join();
+  }
 }
 
 void PatchServer::listen(const std::string& addr_str, const string& socket_path, Version version) {

src/PatchServer.hh

@@ -22,6 +22,7 @@ public:
     std::string message;
     std::shared_ptr<const LicenseIndex> license_index;
     std::shared_ptr<const PatchFileIndex> patch_file_index;
+    std::shared_ptr<struct event_base> shared_base;
   };
 
   PatchServer() = delete;
@@ -86,6 +87,7 @@ private:
   };
 
   std::shared_ptr<struct event_base> base;
+  bool base_is_shared;
   std::shared_ptr<const Config> config;
 
   std::unordered_set<std::shared_ptr<Client>> clients_to_destroy;

src/ServerState.cc

@@ -1787,6 +1787,14 @@ void ServerState::load_all() {
 
 shared_ptr<PatchServer::Config> ServerState::generate_patch_server_config(bool is_bb) const {
   auto ret = make_shared<PatchServer::Config>();
+#ifdef PHOSG_WINDOWS
+  // libevent doesn't play nice with Cygwin, so we run the patch server on the
+  // main thread there. The problem seems to be that the locking structures are
+  // never set up, presumably since we call event_use_pthreads() since
+  // event_use_windows_threads() doesn't exist. (Does literally no one else use
+  // libevent with Cygwin??)
+  ret->shared_base = this->base;
+#endif
   ret->allow_unregistered_users = this->allow_unregistered_users;
   ret->hide_data_from_logs = this->hide_download_commands;
   ret->idle_timeout_usecs = this->patch_client_idle_timeout_usecs;