libstore: asyncify Store::connect

Change-Id: I6668295e228092754304ef63cda0b889bd82b198

lix/legacy/build-remote.cc

@@ -244,7 +244,7 @@ static int main_build_remote(AsyncIoRoot & aio, std::string programName, Strings
                     Activity act(*logger, lvlTalkative, actUnknown, fmt("connecting to '%s'", bestMachine->storeUri));
 
                     sshStore = aio.blockOn(bestMachine->openStore());
-                    sshStore->connect();
+                    aio.blockOn(sshStore->connect());
                     storeUri = bestMachine->storeUri;
 
                 } catch (std::exception & e) {

lix/libstore/legacy-ssh-store.cc

@@ -431,9 +431,12 @@ public:
         co_return result::current_exception();
     }
 
-    void connect() override
-    {
+    kj::Promise<Result<void>> connect() override
+    try {
         auto conn(connections->get());
+        co_return result::success();
+    } catch (...) {
+        co_return result::current_exception();
     }
 
     unsigned int getProtocol() override

lix/libstore/remote-store.cc

@@ -935,9 +935,12 @@ std::optional<std::string> RemoteStore::getVersion()
 }
 
 
-void RemoteStore::connect()
-{
+kj::Promise<Result<void>> RemoteStore::connect()
+try {
     auto conn(getConnection());
+    co_return result::success();
+} catch (...) {
+    co_return result::current_exception();
 }
 
 

lix/libstore/remote-store.hh

@@ -165,7 +165,7 @@ public:
 
     std::optional<std::string> getVersion() override;
 
-    void connect() override;
+    kj::Promise<Result<void>> connect() override;
 
     unsigned int getProtocol() override;
 

lix/libstore/store-api.hh

@@ -862,7 +862,7 @@ public:
      * Establish a connection to the store, for store types that have
      * a notion of connection. Otherwise this is a no-op.
      */
-    virtual void connect() { };
+    virtual kj::Promise<Result<void>> connect() { return {result::success()}; }
 
     /**
      * Get the protocol version of this store or it's connection.

lix/nix/ping-store.cc

@@ -25,7 +25,7 @@ struct CmdPingStore : StoreCommand, MixJSON
     {
         if (!json) {
             notice("Store URL: %s", store->getUri());
-            store->connect();
+            aio().blockOn(store->connect());
             if (auto version = store->getVersion())
                 notice("Version: %s", *version);
             if (auto trusted = store->isTrustedClient())
@@ -37,7 +37,7 @@ struct CmdPingStore : StoreCommand, MixJSON
             });
 
             res["url"] = store->getUri();
-            store->connect();
+            aio().blockOn(store->connect());
             if (auto version = store->getVersion())
                 res["version"] = *version;
             if (auto trusted = store->isTrustedClient())