Get rid of the old eval cache

src/libexpr/flake/eval-cache.hh

@@ -1,40 +1,103 @@
 #pragma once
 
 #include "sync.hh"
-#include "flake.hh"
-#include "path.hh"
+#include "hash.hh"
+#include "eval.hh"
 
-namespace nix { struct SQLite; struct SQLiteStmt; }
+#include <variant>
 
-namespace nix::flake {
+namespace nix::eval_cache {
 
-class EvalCache
+class AttrDb;
+class AttrCursor;
+
+class EvalCache : public std::enable_shared_from_this<EvalCache>
 {
-    struct State;
+    friend class AttrCursor;
 
-    std::unique_ptr<Sync<State>> _state;
+    std::shared_ptr<AttrDb> db;
+    EvalState & state;
+    typedef std::function<Value *()> RootLoader;
+    RootLoader rootLoader;
+    RootValue value;
 
-    EvalCache();
+    Value * getRootValue();
 
 public:
 
-    struct Derivation
-    {
-        StorePath drvPath;
-        StorePath outPath;
-        std::string outputName;
-    };
+    EvalCache(
+        bool useCache,
+        const Hash & fingerprint,
+        EvalState & state,
+        RootLoader rootLoader);
 
-    void addDerivation(
-        const Fingerprint & fingerprint,
-        const std::string & attrPath,
-        const Derivation & drv);
+    std::shared_ptr<AttrCursor> getRoot();
+};
 
-    std::optional<Derivation> getDerivation(
-        const Fingerprint & fingerprint,
-        const std::string & attrPath);
+enum AttrType {
+    Placeholder = 0,
+    FullAttrs = 1,
+    String = 2,
+    Missing = 3,
+    Misc = 4,
+    Failed = 5,
+};
 
-    static EvalCache & singleton();
+struct placeholder_t {};
+struct missing_t {};
+struct misc_t {};
+struct failed_t {};
+typedef uint64_t AttrId;
+typedef std::pair<AttrId, Symbol> AttrKey;
+typedef std::variant<std::vector<Symbol>, std::string, placeholder_t, missing_t, misc_t, failed_t> AttrValue;
+
+class AttrCursor : public std::enable_shared_from_this<AttrCursor>
+{
+    friend class EvalCache;
+
+    ref<EvalCache> root;
+    typedef std::optional<std::pair<std::shared_ptr<AttrCursor>, Symbol>> Parent;
+    Parent parent;
+    RootValue _value;
+    std::optional<std::pair<AttrId, AttrValue>> cachedValue;
+
+    AttrKey getKey();
+
+    Value & getValue();
+
+public:
+
+    AttrCursor(
+        ref<EvalCache> root,
+        Parent parent,
+        Value * value = nullptr,
+        std::optional<std::pair<AttrId, AttrValue>> && cachedValue = {});
+
+    std::vector<Symbol> getAttrPath() const;
+
+    std::vector<Symbol> getAttrPath(Symbol name) const;
+
+    std::string getAttrPathStr() const;
+
+    std::string getAttrPathStr(Symbol name) const;
+
+    std::shared_ptr<AttrCursor> maybeGetAttr(Symbol name);
+
+    std::shared_ptr<AttrCursor> maybeGetAttr(std::string_view name);
+
+    std::shared_ptr<AttrCursor> getAttr(Symbol name);
+
+    std::shared_ptr<AttrCursor> getAttr(std::string_view name);
+
+    std::shared_ptr<AttrCursor> findAlongAttrPath(const std::vector<Symbol> & attrPath);
+
+    std::string getString();
+
+    std::vector<Symbol> getAttrs();
+
+    bool isDerivation();
+
+    Value & forceValue();
 };
 
 }