BinaryCacheStore: Optionally write a NAR listing

The store parameter "write-nar-listing=1" will cause BinaryCacheStore
to write a file ‘<store-hash>.ls.xz’ for each ‘<store-hash>.narinfo’
added to the binary cache. This file contains an XZ-compressed JSON
file describing the contents of the NAR, excluding the contents of
regular files.

E.g.

  {
    "version": 1,
    "root": {
      "type": "directory",
      "entries": {
        "lib": {
          "type": "directory",
          "entries": {
            "Mcrt1.o": {
              "type": "regular",
              "size": 1288
            },
            "Scrt1.o": {
              "type": "regular",
              "size": 3920
            },
          }
        }
      }
      ...
    }
  }

(The actual file has no indentation.)

This is intended to speed up the NixOS channels programs index
generator [1], since fetching gazillions of large NARs from
cache.nixos.org is currently a bottleneck for updating the regular
(non-small) channel.

[1] https://github.com/NixOS/nixos-channel-scripts/blob/master/generate-programs-index.cc

1 files changed, 3 insertions, 3 deletions

diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index ed5747f313..2c2475afc5 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -909,10 +909,10 @@ void LocalStore::invalidatePath(State & state, const Path & path)
 }
 
 
-void LocalStore::addToStore(const ValidPathInfo & info, const std::string & nar,
+void LocalStore::addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
     bool repair, bool dontCheckSigs)
 {
-    Hash h = hashString(htSHA256, nar);
+    Hash h = hashString(htSHA256, *nar);
     if (h != info.narHash)
         throw Error(format("hash mismatch importing path ‘%s’; expected hash ‘%s’, got ‘%s’") %
             info.path % info.narHash.to_string() % h.to_string());
@@ -939,7 +939,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, const std::string & nar,
 
             deletePath(realPath);
 
-            StringSource source(nar);
+            StringSource source(*nar);
             restorePath(realPath, source);
 
             canonicalisePathMetaData(realPath, -1);