libstore: asyncify RemoteStore::openConnection

Change-Id: Icc7e705314b9a099687c37859700959139840631

lix/libstore/remote-store.cc

@@ -55,21 +55,23 @@ RemoteStore::RemoteStore(const RemoteStoreConfig & config)
 }
 
 
-ref<RemoteStore::Connection> RemoteStore::openConnectionWrapper()
-{
+kj::Promise<Result<ref<RemoteStore::Connection>>> RemoteStore::openConnectionWrapper()
+try {
     if (failed)
         throw Error("opening a connection to remote store '%s' previously failed", getUri());
     try {
-        return openConnection();
+        co_return TRY_AWAIT(openConnection());
     } catch (...) {
         failed = true;
         throw;
     }
+} catch (...) {
+    co_return result::current_exception();
 }
 
 kj::Promise<Result<ref<RemoteStore::Connection>>> RemoteStore::openAndInitConnection()
 try {
-    auto conn = openConnection();
+    auto conn = TRY_AWAIT(openConnection());
     try {
         TRY_AWAIT(initConnection(*conn));
         co_return conn;

lix/libstore/remote-store.hh

@@ -178,11 +178,11 @@ public:
 
     struct Connection;
 
-    ref<Connection> openConnectionWrapper();
+    kj::Promise<Result<ref<Connection>>> openConnectionWrapper();
 
 protected:
 
-    virtual ref<Connection> openConnection() = 0;
+    virtual kj::Promise<Result<ref<Connection>>> openConnection() = 0;
 
     kj::Promise<Result<ref<Connection>>> openAndInitConnection();
 

lix/libstore/ssh-store.cc

@@ -101,7 +101,7 @@ protected:
         }
     };
 
-    ref<RemoteStore::Connection> openConnection() override;
+    kj::Promise<Result<ref<RemoteStore::Connection>>> openConnection() override;
 
     std::string host;
 
@@ -119,8 +119,8 @@ protected:
     };
 };
 
-ref<RemoteStore::Connection> SSHStore::openConnection()
-{
+kj::Promise<Result<ref<RemoteStore::Connection>>> SSHStore::openConnection()
+try {
     auto conn = make_ref<Connection>();
 
     std::string command = config_.remoteProgram + " --stdio";
@@ -128,7 +128,9 @@ ref<RemoteStore::Connection> SSHStore::openConnection()
         command += " --store " + shellEscape(config_.remoteStore.get());
 
     conn->sshConn = ssh.startCommand(command);
-    return conn;
+    return {conn};
+} catch (...) {
+    return {result::current_exception()};
 }
 
 void registerSSHStore() {

lix/libstore/uds-remote-store.cc

@@ -78,8 +78,8 @@ static void connectToFirstAvailableSocket(AutoCloseFD & sockFD, const std::list<
     throw Error("could not connect to any lix socket (tried %s)", concatStringsSep(", ", paths));
 }
 
-ref<RemoteStore::Connection> UDSRemoteStore::openConnection()
-{
+kj::Promise<Result<ref<RemoteStore::Connection>>> UDSRemoteStore::openConnection()
+try {
     auto conn = make_ref<Connection>();
 
     /* Connect to a daemon that does the privileged work for us. */
@@ -109,7 +109,9 @@ ref<RemoteStore::Connection> UDSRemoteStore::openConnection()
 
     conn->startTime = std::chrono::steady_clock::now();
 
-    return conn;
+    co_return conn;
+} catch (...) {
+    co_return result::current_exception();
 }
 
 

lix/libstore/uds-remote-store.hh

@@ -101,7 +101,7 @@ private:
         }
     };
 
-    ref<RemoteStore::Connection> openConnection() override;
+    kj::Promise<Result<ref<RemoteStore::Connection>>> openConnection() override;
     std::optional<std::string> path;
 };
 

lix/nix/daemon.cc

@@ -531,7 +531,7 @@ daemonInstance(AsyncIoRoot & aio, std::optional<TrustedFlag> forceTrustClientOpt
  */
 static void forwardStdioConnection(AsyncIoRoot & aio, RemoteStore & store)
 {
-    auto conn = store.openConnectionWrapper();
+    auto conn = aio.blockOn(store.openConnectionWrapper());
     auto connSocket = AIO().lowLevelProvider.wrapSocketFd(conn->getFD());
     auto asyncStdin = AIO().lowLevelProvider.wrapInputFd(STDIN_FILENO);
     auto asyncStdout = AIO().lowLevelProvider.wrapOutputFd(STDOUT_FILENO);