From 614a63b49abc5eff988bc95658160ddd6ab867e5 Mon Sep 17 00:00:00 2001
From: eldritch horrors <pennae@lix.systems>
Date: Wed, 5 Feb 2025 14:47:25 +0100
Subject: [PATCH] libstore: asyncify createGeneration

Change-Id: Iae47a0f732b2f0fe54525917c091169f4be2214e
---
 lix/legacy/nix-env.cc    |  4 ++--
 lix/legacy/user-env.cc   |  2 +-
 lix/libcmd/command.cc    |  2 +-
 lix/libstore/profiles.cc | 10 ++++++----
 lix/libstore/profiles.hh |  2 +-
 lix/nix/upgrade-nix.cc   |  3 ++-
 6 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/lix/legacy/nix-env.cc b/lix/legacy/nix-env.cc
index 48bdf98ca..77dba64c6 100644
--- a/lix/legacy/nix-env.cc
+++ b/lix/legacy/nix-env.cc
@@ -795,10 +795,10 @@ static void opSet(Globals & globals, Strings opFlags, Strings opArgs)
     );
 
     debug("switching to new user environment");
-    Path generation = createGeneration(
+    Path generation = globals.aio.blockOn(createGeneration(
         *store2,
         globals.profile,
-        drv.queryOutPath(*state));
+        drv.queryOutPath(*state)));
     switchLink(globals.profile, generation);
 }
 
diff --git a/lix/legacy/user-env.cc b/lix/legacy/user-env.cc
index 88cfec6fe..17e47ad99 100644
--- a/lix/legacy/user-env.cc
+++ b/lix/legacy/user-env.cc
@@ -142,7 +142,7 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
         }
 
         debug("switching to new user environment");
-        Path generation = createGeneration(*store2, profile, topLevelOut);
+        Path generation = state.aio.blockOn(createGeneration(*store2, profile, topLevelOut));
         switchLink(profile, generation);
     }
 
diff --git a/lix/libcmd/command.cc b/lix/libcmd/command.cc
index 9a5cba6c8..4cdb5517a 100644
--- a/lix/libcmd/command.cc
+++ b/lix/libcmd/command.cc
@@ -231,7 +231,7 @@ void MixProfile::updateProfile(const StorePath & storePath)
     if (!store) throw Error("'--profile' is not supported for this Nix store");
     auto profile2 = absPath(*profile);
     switchLink(profile2,
-        createGeneration(*store, profile2, storePath));
+        aio().blockOn(createGeneration(*store, profile2, storePath)));
 }
 
 void MixProfile::updateProfile(const BuiltPaths & buildables)
diff --git a/lix/libstore/profiles.cc b/lix/libstore/profiles.cc
index 95f146a4a..675b46bbf 100644
--- a/lix/libstore/profiles.cc
+++ b/lix/libstore/profiles.cc
@@ -70,8 +70,8 @@ static Path makeName(const Path & profile, GenerationNumber num)
 }
 
 
-Path createGeneration(LocalFSStore & store, Path profile, StorePath outPath)
-{
+kj::Promise<Result<Path>> createGeneration(LocalFSStore & store, Path profile, StorePath outPath)
+try {
     /* The new generation number should be higher than old the
        previous ones. */
     auto [gens, dummy] = findGenerations(profile);
@@ -87,7 +87,7 @@ Path createGeneration(LocalFSStore & store, Path profile, StorePath outPath)
                This helps keeping gratuitous installs/rebuilds from piling
                up uncontrolled numbers of generations, cluttering up the
                UI like grub. */
-            return last.path;
+            co_return last.path;
         }
 
         num = last.number;
@@ -104,7 +104,9 @@ Path createGeneration(LocalFSStore & store, Path profile, StorePath outPath)
     Path generation = makeName(profile, num + 1);
     store.addPermRoot(outPath, generation);
 
-    return generation;
+    co_return generation;
+} catch (...) {
+    co_return result::current_exception();
 }
 
 
diff --git a/lix/libstore/profiles.hh b/lix/libstore/profiles.hh
index bdf6d3b70..0dbe92fad 100644
--- a/lix/libstore/profiles.hh
+++ b/lix/libstore/profiles.hh
@@ -96,7 +96,7 @@ class LocalFSStore;
  * The behavior of reusing existing generations like this makes this
  * procedure idempotent. It also avoids clutter.
  */
-Path createGeneration(LocalFSStore & store, Path profile, StorePath outPath);
+kj::Promise<Result<Path>> createGeneration(LocalFSStore & store, Path profile, StorePath outPath);
 
 /**
  * Unconditionally delete a generation
diff --git a/lix/nix/upgrade-nix.cc b/lix/nix/upgrade-nix.cc
index ae01a50db..8875061f0 100644
--- a/lix/nix/upgrade-nix.cc
+++ b/lix/nix/upgrade-nix.cc
@@ -257,7 +257,8 @@ struct CmdUpgradeNix : MixDryRun, EvalCommand
         // Build the new profile, and switch to it.
         StorePath const newProfile = manifest.build(store);
         printTalkative("built new profile '%s'", store->printStorePath(newProfile));
-        auto const newGeneration = createGeneration(*fsStore, this->profileDir, newProfile);
+        auto const newGeneration =
+            aio().blockOn(createGeneration(*fsStore, this->profileDir, newProfile));
         printTalkative(
             "switching '%s' to newly created generation '%s'",
             this->profileDir,