Garbage-collect paths

src/libexpr/eval.cc

@@ -24,19 +24,6 @@ namespace nix {
 SymbolTable symbols;
 
 
-unsigned long stringBytes = 0;
-
-// FIXME
-static char * dupString(const char * s)
-{
-    char * t;
-    stringBytes += strlen(s) + 1;
-    t = strdup(s);
-    if (!t) throw std::bad_alloc();
-    return t;
-}
-
-
 static void printValue(std::ostream & str, std::set<const Value *> & active, const Value & v)
 {
     checkInterrupt();
@@ -67,7 +54,7 @@ static void printValue(std::ostream & str, std::set<const Value *> & active, con
         str << "\"";
         break;
     case tPath:
-        str << v.path; // !!! escaping?
+        str << v.path->s; // !!! escaping?
         break;
     case tNull:
         str << "null";
@@ -500,12 +487,6 @@ Value & mkString(Value & v, const string & s, const PathSet & context)
 }
 
 
-void mkPath(Value & v, const char * s)
-{
-    mkPathNoCopy(v, dupString(s));
-}
-
-
 inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
 {
     for (size_t l = var.level; l; --l, env = env->up) ;
@@ -1492,7 +1473,7 @@ string EvalState::coerceToString(const Pos & pos, Value & v, PathSet & context,
     }
 
     if (v.type == tPath) {
-        Path path(canonPath(v.path));
+        Path path(canonPath(v.path->s));
         return copyToStore ? copyPathToStore(context, path) : path;
     }
 
@@ -1603,7 +1584,7 @@ bool EvalState::eqValues(Value & v1, Value & v2)
             return v1.boolean == v2.boolean;
 
         case tPath:
-            return strcmp(v1.path, v2.path) == 0;
+            return strcmp(v1.path->s, v2.path->s) == 0;
 
         case tNull:
             return true;
@@ -1719,7 +1700,6 @@ void EvalState::printStats()
         topObj.attr("nrLookups", nrLookups);
         topObj.attr("nrPrimOpCalls", nrPrimOpCalls);
         topObj.attr("nrFunctionCalls", nrFunctionCalls);
-        topObj.attr("stringBytes", stringBytes);
 
         if (countCalls) {
             {
@@ -1770,12 +1750,6 @@ size_t valueSize(Value & v)
 {
     std::set<const void *> seen;
 
-    auto doString = [&](const char * s) -> size_t {
-        if (seen.find(s) != seen.end()) return 0;
-        seen.insert(s);
-        return strlen(s) + 1;
-    };
-
     std::function<size_t(Value & v)> doValue;
     std::function<size_t(Env & v)> doEnv;
 
@@ -1790,7 +1764,7 @@ size_t valueSize(Value & v)
             sz += v.string.s->words() * WORD_SIZE;
             break;
         case tPath:
-            sz += doString(v.path);
+            sz += v.path->words() * WORD_SIZE;
             break;
         case tAttrs:
             if (seen.find(v.attrs) == seen.end()) {

src/libexpr/gc.cc

@@ -167,7 +167,7 @@ void GC::gc()
         }
 
         case tPath:
-            // FIXME
+            push(((Value *) obj)->path);
             break;
 
         case tAttrs:

src/libexpr/nixexpr.cc

@@ -80,7 +80,7 @@ void ExprString::show(std::ostream & str) const
 
 void ExprPath::show(std::ostream & str) const
 {
-    str << s;
+    str << v->path->s;
 }
 
 void ExprVar::show(std::ostream & str) const

src/libexpr/nixexpr.hh

@@ -134,11 +134,10 @@ struct ExprIndStr : Expr
 
 struct ExprPath : Expr
 {
-    string s;
     Ptr<Value> v;
-    ExprPath(const string & s) : s(s) {
+    ExprPath(const string & s) {
         v = gc.alloc<Value>(Value::words());
-        mkPathNoCopy(v, this->s.c_str());
+        mkPath(v, s);
     };
     COMMON_METHODS
     Ptr<Value> maybeThunk(EvalState & state, Env & env) override;

src/libexpr/primops.cc

@@ -344,7 +344,7 @@ struct CompareValues
             case tFloat:
                 return v1->fpoint < v2->fpoint;
             case tPath:
-                return strcmp(v1->path, v2->path) < 0;
+                return strcmp(v1->path->s, v2->path->s) < 0;
             default:
                 throw EvalError(format("cannot compare %1% with %2%") % showType(*v1) % showType(*v2));
         }

src/libexpr/value-to-json.cc

@@ -34,7 +34,7 @@ void printValueAsJSON(EvalState & state, bool strict,
             break;
 
         case tPath:
-            out.write(state.copyPathToStore(context, v.path));
+            out.write(state.copyPathToStore(context, v.path->s));
             break;
 
         case tNull:

src/libexpr/value-to-xml.cc

@@ -77,7 +77,7 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
             break;
 
         case tPath:
-            doc.writeEmptyElement("path", singletonAttrs("value", v.path));
+            doc.writeEmptyElement("path", singletonAttrs("value", v.path->s));
             break;
 
         case tNull:

src/libexpr/value.hh

@@ -120,7 +120,7 @@ struct Value : Object
             Context * context;
         } string;
         const char * staticString;
-        const char * path;
+        String * path;
         Bindings * attrs;
         PtrList<Value> * bigList;
         Value * smallList[2];
@@ -288,16 +288,13 @@ static inline void mkString(Value & v, const Symbol & s)
 }
 
 
-static inline void mkPathNoCopy(Value & v, const char * s)
+static inline void mkPath(Value & v, const std::string & s)
 {
+    v.path = String::alloc(s.c_str());
     v.type = tPath;
-    v.path = s;
 }
 
 
-void mkPath(Value & v, const char * s);
-
-
 /* Compute the size in bytes of the given value, including all values
    and environments reachable from it. Static expressions (Exprs) are
    not included. */