From 6fc60e2060be5958c2aad1c859ee60bae5e23980 Mon Sep 17 00:00:00 2001
From: Michael Raskin <7c6f434c@mail.ru>
Date: Thu, 15 Nov 2007 03:47:12 +0000
Subject: [PATCH] Added possibility to specify garbage collection levels for
 store paths; so packages can share intermediate results of compilation and GC
 will collect it automatically while never touching tarballs, for example.

---
 src/libstore/gc.cc | 19 +++++++++++++++----
 src/libstore/gc.hh |  6 ++++++
 2 files changed, 21 insertions(+), 4 deletions(-)
 create mode 100644 src/libstore/gc.hh

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index e2e6c23fd5..53ee100f96 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -4,6 +4,7 @@
 #include "local-store.hh"
 #include "db.hh"
 #include "util.hh"
+#include "gc.hh"
 
 #include <boost/shared_ptr.hpp>
 
@@ -445,6 +446,8 @@ void LocalStore::collectGarbage(GCAction action, const PathSet & pathsToDelete,
         queryBoolSetting("gc-keep-outputs", false);
     bool gcKeepDerivations =
         queryBoolSetting("gc-keep-derivations", true);
+    unsigned int gcKeepOutputsThreshold = 
+        queryIntSetting ("gc-keep-outputs-threshold", defaultGcLevel);
 
     /* Acquire the global GC root.  This prevents
        a) New roots from being added.
@@ -496,10 +499,18 @@ void LocalStore::collectGarbage(GCAction action, const PathSet & pathsToDelete,
              i != livePaths.end(); ++i)
             if (isDerivation(*i)) {
                 Derivation drv = derivationFromPath(*i);
-                for (DerivationOutputs::iterator j = drv.outputs.begin();
-                     j != drv.outputs.end(); ++j)
-                    if (store->isValidPath(j->second.path))
-                        computeFSClosure(j->second.path, livePaths);
+
+		string gcLevelStr = drv.env["__gcLevel"];
+		int gcLevel;
+		if (!string2Int(gcLevelStr,gcLevel)) {
+		    gcLevel = defaultGcLevel;
+		}
+		
+		if (gcLevel >= gcKeepOutputsThreshold)    
+		    for (DerivationOutputs::iterator j = drv.outputs.begin();
+		            j != drv.outputs.end(); ++j)
+			if (store->isValidPath(j->second.path))
+			    computeFSClosure(j->second.path, livePaths);
             }
     }
 
diff --git a/src/libstore/gc.hh b/src/libstore/gc.hh
new file mode 100644
index 0000000000..c86f7678b3
--- /dev/null
+++ b/src/libstore/gc.hh
@@ -0,0 +1,6 @@
+#ifndef  __GC_H_INCLUDED
+#define  __GC_H_INCLUDED
+
+const unsigned int defaultGcLevel = 1000;
+
+#endif //__GC_H_INCLUDED