* Some refactoring: put the GC options / results in separate structs.

* The garbage collector now also prints the number of blocks freed.

src/libstore/worker-protocol.hh

@@ -15,24 +15,24 @@ namespace nix {
 
 typedef enum {
     wopQuit = 0,
-    wopIsValidPath,
+    wopIsValidPath = 1,
     wopHasSubstitutes = 3,
-    wopQueryPathHash,
-    wopQueryReferences,
-    wopQueryReferrers,
-    wopAddToStore,
-    wopAddTextToStore,
-    wopBuildDerivations,
-    wopEnsurePath,
-    wopAddTempRoot,
-    wopAddIndirectRoot,
-    wopSyncWithGC,
-    wopFindRoots,
-    wopCollectGarbage,
-    wopExportPath,
-    wopImportPath,
-    wopQueryDeriver,
-    wopSetOptions,
+    wopQueryPathHash = 4,
+    wopQueryReferences = 5,
+    wopQueryReferrers = 6,
+    wopAddToStore = 7,
+    wopAddTextToStore = 8,
+    wopBuildDerivations = 9,
+    wopEnsurePath = 10,
+    wopAddTempRoot = 11,
+    wopAddIndirectRoot = 12,
+    wopSyncWithGC = 13,
+    wopFindRoots = 14,
+    wopExportPath = 16,
+    wopImportPath = 17,
+    wopQueryDeriver = 18,
+    wopSetOptions = 19,
+    wopCollectGarbage = 20,
 } WorkerOp;