* Huge reduction in memory use (2/3 or so on large nix-env -qas

  operations): share ATermMaps between DrvInfos.

3 files changed, 12 insertions, 9 deletions

diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index bc2302a0b2fb..78ccab7f32a7 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -5,7 +5,7 @@
 string DrvInfo::queryDrvPath(EvalState & state) const
 {
     if (drvPath == "") {
-        Expr a = attrs.get("drvPath");
+        Expr a = attrs->get("drvPath");
         (string &) drvPath = a ? evalPath(state, a) : "";
     }
     return drvPath;
@@ -15,7 +15,7 @@ string DrvInfo::queryDrvPath(EvalState & state) const
 string DrvInfo::queryOutPath(EvalState & state) const
 {
     if (outPath == "") {
-        Expr a = attrs.get("outPath");
+        Expr a = attrs->get("outPath");
         if (!a) throw Error("output path missing");
         (string &) outPath = evalPath(state, a);
     }
@@ -27,7 +27,7 @@ MetaInfo DrvInfo::queryMetaInfo(EvalState & state) const
 {
     MetaInfo meta;
     
-    Expr a = attrs.get("meta");
+    Expr a = attrs->get("meta");
     if (!a) return meta; /* fine, empty meta information */
 
     ATermMap attrs2;
@@ -66,10 +66,10 @@ static bool getDerivation(EvalState & state, Expr e,
         e = evalExpr(state, e);
         if (!matchAttrs(e, es)) return true;
 
-        ATermMap attrs;
-        queryAllAttrs(e, attrs, false);
+        shared_ptr<ATermMap> attrs(new ATermMap());
+        queryAllAttrs(e, *attrs, false);
     
-        Expr a = attrs.get("type");
+        Expr a = attrs->get("type");
         if (!a || evalString(state, a) != "derivation") return true;
 
         /* Remove spurious duplicates (e.g., an attribute set like
@@ -79,11 +79,11 @@ static bool getDerivation(EvalState & state, Expr e,
 
         DrvInfo drv;
     
-        a = attrs.get("name");
+        a = attrs->get("name");
         if (!a) throw badTerm("derivation name missing", e);
         drv.name = evalString(state, a);
 
-        a = attrs.get("system");
+        a = attrs->get("system");
         if (!a)
             drv.system = "unknown";
         else
diff --git a/src/libexpr/get-drvs.hh b/src/libexpr/get-drvs.hh
index e692a5c660e1..2b88111b2c84 100644
--- a/src/libexpr/get-drvs.hh
+++ b/src/libexpr/get-drvs.hh
@@ -4,6 +4,8 @@
 #include <string>
 #include <map>
 
+#include <boost/shared_ptr.hpp>
+
 #include "eval.hh"
 
 
@@ -20,7 +22,7 @@ public:
     string name;
     string system;
 
-    ATermMap attrs;
+    shared_ptr<ATermMap> attrs;
 
     string queryDrvPath(EvalState & state) const;
     string queryOutPath(EvalState & state) const;
diff --git a/src/nix-env/main.cc b/src/nix-env/main.cc
index f9a0c19a9b63..ad3c1b5ce329 100644
--- a/src/nix-env/main.cc
+++ b/src/nix-env/main.cc
@@ -348,6 +348,7 @@ static void queryInstSources(EvalState & state,
                 assertStorePath(*i);
 
                 DrvInfo elem;
+                elem.attrs = shared_ptr<ATermMap>(new ATermMap()); /* ugh... */
                 string name = baseNameOf(*i);
                 unsigned int dash = name.find('-');
                 if (dash != string::npos)