Merge pull request #14203 from roberth/move-eval-cache-open-to-libflake

Move eval cache open to libflake

src/libcmd/include/nix/cmd/installable-flake.hh

@@ -69,7 +69,7 @@ struct InstallableFlake : InstallableValue
      */
     std::vector<ref<eval_cache::AttrCursor>> getCursors(EvalState & state) override;
 
-    std::shared_ptr<flake::LockedFlake> getLockedFlake() const;
+    ref<flake::LockedFlake> getLockedFlake() const;
 
     FlakeRef nixpkgsFlakeRef() const;
 };
@@ -87,6 +87,4 @@ static inline FlakeRef defaultNixpkgsFlakeRef()
     return FlakeRef::fromAttrs(fetchSettings, {{"type", "indirect"}, {"id", "nixpkgs"}});
 }
 
-ref<eval_cache::EvalCache> openEvalCache(EvalState & state, std::shared_ptr<flake::LockedFlake> lockedFlake);
-
 } // namespace nix

src/libcmd/installable-flake.cc

@@ -185,16 +185,16 @@ std::vector<ref<eval_cache::AttrCursor>> InstallableFlake::getCursors(EvalState
     return res;
 }
 
-std::shared_ptr<flake::LockedFlake> InstallableFlake::getLockedFlake() const
+ref<flake::LockedFlake> InstallableFlake::getLockedFlake() const
 {
     if (!_lockedFlake) {
         flake::LockFlags lockFlagsApplyConfig = lockFlags;
         // FIXME why this side effect?
         lockFlagsApplyConfig.applyNixConfig = true;
-        _lockedFlake =
+        _lockedFlake = make_ref<flake::LockedFlake>(lockFlake(flakeSettings, *state, flakeRef, lockFlagsApplyConfig));
-            std::make_shared<flake::LockedFlake>(lockFlake(flakeSettings, *state, flakeRef, lockFlagsApplyConfig));
     }
-    return _lockedFlake;
+    // _lockedFlake is now non-null but still just a shared_ptr
+    return ref<flake::LockedFlake>(_lockedFlake);
 }
 
 FlakeRef InstallableFlake::nixpkgsFlakeRef() const

src/libcmd/installables.cc

@@ -342,8 +342,7 @@ void completeFlakeRefWithFragment(
                 parseFlakeRef(fetchSettings, expandTilde(flakeRefS), std::filesystem::current_path().string());
 
             auto evalCache = openEvalCache(
-                *evalState,
+                *evalState, make_ref<flake::LockedFlake>(lockFlake(flakeSettings, *evalState, flakeRef, lockFlags)));
-                std::make_shared<flake::LockedFlake>(lockFlake(flakeSettings, *evalState, flakeRef, lockFlags)));
 
             auto root = evalCache->getRoot();
 
@@ -443,42 +442,6 @@ static StorePath getDeriver(ref<Store> store, const Installable & i, const Store
     return *derivers.begin();
 }
 
-ref<eval_cache::EvalCache> openEvalCache(EvalState & state, std::shared_ptr<flake::LockedFlake> lockedFlake)
-{
-    auto fingerprint = evalSettings.useEvalCache && evalSettings.pureEval
-                           ? lockedFlake->getFingerprint(state.store, state.fetchSettings)
-                           : std::nullopt;
-    auto rootLoader = [&state, lockedFlake]() {
-        /* For testing whether the evaluation cache is
-           complete. */
-        if (getEnv("NIX_ALLOW_EVAL").value_or("1") == "0")
-            throw Error("not everything is cached, but evaluation is not allowed");
-
-        auto vFlake = state.allocValue();
-        flake::callFlake(state, *lockedFlake, *vFlake);
-
-        state.forceAttrs(*vFlake, noPos, "while parsing cached flake data");
-
-        auto aOutputs = vFlake->attrs()->get(state.symbols.create("outputs"));
-        assert(aOutputs);
-
-        return aOutputs->value;
-    };
-
-    if (fingerprint) {
-        auto search = state.evalCaches.find(fingerprint.value());
-        if (search == state.evalCaches.end()) {
-            search =
-                state.evalCaches
-                    .emplace(fingerprint.value(), make_ref<nix::eval_cache::EvalCache>(fingerprint, state, rootLoader))
-                    .first;
-        }
-        return search->second;
-    } else {
-        return make_ref<nix::eval_cache::EvalCache>(std::nullopt, state, rootLoader);
-    }
-}
-
 Installables SourceExprCommand::parseInstallables(ref<Store> store, std::vector<std::string> ss)
 {
     Installables result;

src/libflake/flake.cc

@@ -1,6 +1,9 @@
 #include "nix/util/terminal.hh"
+#include "nix/util/ref.hh"
+#include "nix/util/environment-variables.hh"
 #include "nix/flake/flake.hh"
 #include "nix/expr/eval.hh"
+#include "nix/expr/eval-cache.hh"
 #include "nix/expr/eval-settings.hh"
 #include "nix/flake/lockfile.hh"
 #include "nix/expr/primops.hh"
@@ -924,8 +927,6 @@ void callFlake(EvalState & state, const LockedFlake & lockedFlake, Value & vRes)
     state.callFunction(*vCallFlake, args, vRes, noPos);
 }
 
-} // namespace flake
-
 std::optional<Fingerprint> LockedFlake::getFingerprint(ref<Store> store, const fetchers::Settings & fetchSettings) const
 {
     if (lockFile.isUnlocked(fetchSettings))
@@ -953,4 +954,41 @@ std::optional<Fingerprint> LockedFlake::getFingerprint(ref<Store> store, const f
 
 Flake::~Flake() {}
 
+ref<eval_cache::EvalCache> openEvalCache(EvalState & state, ref<const LockedFlake> lockedFlake)
+{
+    auto fingerprint = state.settings.useEvalCache && state.settings.pureEval
+                           ? lockedFlake->getFingerprint(state.store, state.fetchSettings)
+                           : std::nullopt;
+    auto rootLoader = [&state, lockedFlake]() {
+        /* For testing whether the evaluation cache is
+           complete. */
+        if (getEnv("NIX_ALLOW_EVAL").value_or("1") == "0")
+            throw Error("not everything is cached, but evaluation is not allowed");
+
+        auto vFlake = state.allocValue();
+        callFlake(state, *lockedFlake, *vFlake);
+
+        state.forceAttrs(*vFlake, noPos, "while parsing cached flake data");
+
+        auto aOutputs = vFlake->attrs()->get(state.symbols.create("outputs"));
+        assert(aOutputs);
+
+        return aOutputs->value;
+    };
+
+    if (fingerprint) {
+        auto search = state.evalCaches.find(fingerprint.value());
+        if (search == state.evalCaches.end()) {
+            search = state.evalCaches
+                         .emplace(fingerprint.value(), make_ref<eval_cache::EvalCache>(fingerprint, state, rootLoader))
+                         .first;
+        }
+        return search->second;
+    } else {
+        return make_ref<eval_cache::EvalCache>(std::nullopt, state, rootLoader);
+    }
+}
+
+} // namespace flake
+
 } // namespace nix

src/libflake/include/nix/flake/flake.hh

@@ -5,6 +5,7 @@
 #include "nix/flake/flakeref.hh"
 #include "nix/flake/lockfile.hh"
 #include "nix/expr/value.hh"
+#include "nix/expr/eval-cache.hh"
 
 namespace nix {
 
@@ -218,6 +219,11 @@ lockFlake(const Settings & settings, EvalState & state, const FlakeRef & flakeRe
 
 void callFlake(EvalState & state, const LockedFlake & lockedFlake, Value & v);
 
+/**
+ * Open an evaluation cache for a flake.
+ */
+ref<eval_cache::EvalCache> openEvalCache(EvalState & state, ref<const LockedFlake> lockedFlake);
+
 } // namespace flake
 
 void emitTreeAttrs(

src/nix/flake.cc

@@ -1155,7 +1155,7 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
         evalSettings.enableImportFromDerivation.setDefault(false);
 
         auto state = getEvalState();
-        auto flake = std::make_shared<LockedFlake>(lockFlake());
+        auto flake = make_ref<LockedFlake>(lockFlake());
         auto localSystem = std::string(settings.thisSystem.get());
 
         std::function<bool(eval_cache::AttrCursor & visitor, const std::vector<Symbol> & attrPath, const Symbol & attr)>
@@ -1443,7 +1443,7 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
             return j;
         };
 
-        auto cache = openEvalCache(*state, flake);
+        auto cache = openEvalCache(*state, ref<flake::LockedFlake>(flake));
 
         auto j = visit(*cache->getRoot(), {}, fmt(ANSI_BOLD "%s" ANSI_NORMAL, flake->flake.lockedRef), "");
         if (json)