libstore: asyncify RemoteStore connection setup

without this processStderr cannot be turned into a promise.

Change-Id: Ia8ee44e9e2344f61c2c63b787b42f867864c7119

lix/libstore/remote-store.cc

@@ -66,7 +66,7 @@ kj::Promise<Result<ref<RemoteStore::Connection>>> RemoteStore::openAndInitConnec
 try {
     auto conn = openConnection();
     try {
-        initConnection(*conn);
+        TRY_AWAIT(initConnection(*conn));
         co_return conn;
     } catch (...) {
         failed = true;
@@ -76,8 +76,8 @@ try {
     co_return result::current_exception();
 }
 
-void RemoteStore::initConnection(Connection & conn)
-{
+kj::Promise<Result<void>> RemoteStore::initConnection(Connection & conn)
+try {
     /* Send the magic greeting, check for the reply. */
     try {
         conn.store = this;
@@ -112,12 +112,14 @@ void RemoteStore::initConnection(Connection & conn)
         throw Error("cannot open connection to remote store '%s': %s", getUri(), e.what());
     }
 
-    setOptions(conn);
+    TRY_AWAIT(setOptions(conn));
+    co_return result::success();
+} catch (...) {
+    co_return result::current_exception();
 }
 
-
-void RemoteStore::setOptions(Connection & conn)
-{
+kj::Promise<Result<void>> RemoteStore::setOptions(Connection & conn)
+try {
     StringSink command;
 
     command << WorkerProto::Op::SetOptions
@@ -157,9 +159,11 @@ void RemoteStore::setOptions(Connection & conn)
     conn.to.flush();
     auto ex = conn.processStderr();
     if (ex) std::rethrow_exception(ex);
+    co_return result::success();
+} catch (...) {
+    co_return result::current_exception();
 }
 
-
 RemoteStore::ConnectionHandle::~ConnectionHandle()
 {
     if (!daemonException && std::uncaught_exceptions()) {
@@ -187,7 +191,7 @@ try {
 
 kj::Promise<Result<void>> RemoteStore::setOptions()
 try {
-    setOptions(*(TRY_AWAIT(getConnection()).handle));
+    TRY_AWAIT(setOptions(*(TRY_AWAIT(getConnection()).handle)));
     co_return result::success();
 } catch (...) {
     co_return result::current_exception();

lix/libstore/remote-store.hh

@@ -181,11 +181,11 @@ protected:
 
     kj::Promise<Result<ref<Connection>>> openAndInitConnection();
 
-    void initConnection(Connection & conn);
+    kj::Promise<Result<void>> initConnection(Connection & conn);
 
     ref<Pool<Connection>> connections;
 
-    virtual void setOptions(Connection & conn);
+    virtual kj::Promise<Result<void>> setOptions(Connection & conn);
 
     kj::Promise<Result<void>> setOptions() override;
 

lix/libstore/ssh-store.cc

@@ -5,6 +5,7 @@
 #include "lix/libstore/worker-protocol.hh"
 #include "lix/libutil/pool.hh"
 #include "lix/libstore/ssh.hh"
+#include "lix/libutil/result.hh"
 #include "lix/libutil/strings.hh"
 
 namespace nix {
@@ -77,7 +78,7 @@ protected:
 
     SSH ssh;
 
-    void setOptions(RemoteStore::Connection & conn) override
+    kj::Promise<Result<void>> setOptions(RemoteStore::Connection & conn) override
     {
         /* TODO Add a way to explicitly ask for some options to be
            forwarded. One option: A way to query the daemon for its
@@ -85,6 +86,7 @@ protected:
            forward-cores or forward-overridden-cores that only
            override the requested settings.
         */
+        return {result::success()};
     };
 };