From d842f320f0ee911d7d219bba7baa45240edcbe6d Mon Sep 17 00:00:00 2001
From: Roel Janssen <roel@gnu.org>
Date: Tue, 3 Apr 2018 11:22:16 +0200
Subject: [PATCH] guix-daemon: Add option to disable garbage collection.

* nix/libstore/gc.cc: Return early on deleterious functions.
* nix/libstore/globals.hh (disableGarbageCollection): New settings variable.
* nix/nix-daemon/guix-daemon.cc: Implement new settings variable.
* nix/nix-daemon/nix-daemon.cc: Show appropriate message.
---
 nix/libstore/gc.cc            | 20 ++++++++++++++++++++
 nix/libstore/globals.hh       |  3 +++
 nix/nix-daemon/guix-daemon.cc |  6 ++++++
 nix/nix-daemon/nix-daemon.cc  |  5 +++++
 4 files changed, 34 insertions(+)

diff --git a/nix/libstore/gc.cc b/nix/libstore/gc.cc
index 72eff5242..b811cacd1 100644
--- a/nix/libstore/gc.cc
+++ b/nix/libstore/gc.cc
@@ -393,6 +393,10 @@ bool LocalStore::isActiveTempFile(const GCState & state,
 
 void LocalStore::deleteGarbage(GCState & state, const Path & path)
 {
+    if (settings.disableGarbageCollection) {
+        return;
+    }
+
     unsigned long long bytesFreed;
     deletePath(path, bytesFreed);
     state.results.bytesFreed += bytesFreed;
@@ -401,6 +405,10 @@ void LocalStore::deleteGarbage(GCState & state, const Path & path)
 
 void LocalStore::deletePathRecursive(GCState & state, const Path & path)
 {
+    if (settings.disableGarbageCollection) {
+        return;
+    }
+
     checkInterrupt();
 
     unsigned long long size = 0;
@@ -513,6 +521,10 @@ bool LocalStore::canReachRoot(GCState & state, PathSet & visited, const Path & p
 
 void LocalStore::tryToDelete(GCState & state, const Path & path)
 {
+    if (settings.disableGarbageCollection) {
+        return;
+    }
+
     checkInterrupt();
 
     if (path == linksDir || path == state.trashDir) return;
@@ -552,6 +564,10 @@ void LocalStore::tryToDelete(GCState & state, const Path & path)
    the link count. */
 void LocalStore::removeUnusedLinks(const GCState & state)
 {
+    if (settings.disableGarbageCollection) {
+        return;
+    }
+
     AutoCloseDir dir = opendir(linksDir.c_str());
     if (!dir) throw SysError(format("opening directory `%1%'") % linksDir);
 
@@ -595,6 +611,10 @@ void LocalStore::removeUnusedLinks(const GCState & state)
 
 void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 {
+    if (settings.disableGarbageCollection) {
+        return;
+    }
+
     GCState state(results);
     state.options = options;
     state.trashDir = settings.nixStore + "/trash";
diff --git a/nix/libstore/globals.hh b/nix/libstore/globals.hh
index 1293625e1..54e04f218 100644
--- a/nix/libstore/globals.hh
+++ b/nix/libstore/globals.hh
@@ -218,6 +218,9 @@ struct Settings {
     /* Whether the importNative primop should be enabled */
     bool enableImportNative;
 
+    /* Whether the disable garbage collection. */
+    bool disableGarbageCollection;
+
 private:
     SettingsMap settings, overrides;
 
diff --git a/nix/nix-daemon/guix-daemon.cc b/nix/nix-daemon/guix-daemon.cc
index b71b100f6..13811cd99 100644
--- a/nix/nix-daemon/guix-daemon.cc
+++ b/nix/nix-daemon/guix-daemon.cc
@@ -89,6 +89,7 @@ builds derivations on behalf of its clients.");
 #define GUIX_OPT_TIMEOUT 18
 #define GUIX_OPT_MAX_SILENT_TIME 19
 #define GUIX_OPT_LOG_COMPRESSION 20
+#define GUIX_OPT_DISABLE_GC 21
 
 static const struct argp_option options[] =
   {
@@ -133,6 +134,8 @@ static const struct argp_option options[] =
       n_("disable automatic file \"deduplication\" in the store") },
     { "disable-store-optimization", GUIX_OPT_DISABLE_DEDUPLICATION, 0,
       OPTION_ALIAS | OPTION_HIDDEN, NULL },
+    { "disable-gc", GUIX_OPT_DISABLE_GC, 0, 0,
+      n_("disable garbage collection.") },
 
     { "impersonate-linux-2.6", GUIX_OPT_IMPERSONATE_LINUX_26, 0,
 #ifdef HAVE_SYS_PERSONALITY_H
@@ -225,6 +228,9 @@ parse_opt (int key, char *arg, struct argp_state *state)
     case GUIX_OPT_DISABLE_DEDUPLICATION:
       settings.autoOptimiseStore = false;
       break;
+    case GUIX_OPT_DISABLE_GC:
+      settings.disableGarbageCollection = true;
+      break;
     case GUIX_OPT_CACHE_FAILURES:
       settings.cacheFailure = true;
       break;
diff --git a/nix/nix-daemon/nix-daemon.cc b/nix/nix-daemon/nix-daemon.cc
index deb7003d7..5af8ec796 100644
--- a/nix/nix-daemon/nix-daemon.cc
+++ b/nix/nix-daemon/nix-daemon.cc
@@ -529,6 +529,11 @@ static void performOp(bool trusted, unsigned int clientVersion,
     }
 
     case wopCollectGarbage: {
+        if (settings.disableGarbageCollection) {
+            throw Error("Garbage collection is disabled.");
+            break;
+        }
+
         GCOptions options;
         options.action = (GCOptions::GCAction) readInt(from);
         options.pathsToDelete = readStorePaths<PathSet>(from);
-- 
2.16.1