Make 'nix copy' to file:// binary caches run in constant memory

1 files changed, 8 insertions, 25 deletions

diff --git a/src/libstore/export-import.cc b/src/libstore/export-import.cc
index 57b7e9590..cfed8ccd8 100644
--- a/src/libstore/export-import.cc
+++ b/src/libstore/export-import.cc
@@ -7,24 +7,6 @@
 
 namespace nix {
 
-struct HashAndWriteSink : Sink
-{
-    Sink & writeSink;
-    HashSink hashSink;
-    HashAndWriteSink(Sink & writeSink) : writeSink(writeSink), hashSink(htSHA256)
-    {
-    }
-    virtual void operator () (const unsigned char * data, size_t len)
-    {
-        writeSink(data, len);
-        hashSink(data, len);
-    }
-    Hash currentHash()
-    {
-        return hashSink.currentHash().first;
-    }
-};
-
 void Store::exportPaths(const StorePathSet & paths, Sink & sink)
 {
     auto sorted = topoSortPaths(paths);
@@ -47,23 +29,24 @@ void Store::exportPath(const StorePath & path, Sink & sink)
 {
     auto info = queryPathInfo(path);
 
-    HashAndWriteSink hashAndWriteSink(sink);
+    HashSink hashSink(htSHA256);
+    TeeSink teeSink(sink, hashSink);
 
-    narFromPath(path, hashAndWriteSink);
+    narFromPath(path, teeSink);
 
     /* Refuse to export paths that have changed.  This prevents
        filesystem corruption from spreading to other machines.
        Don't complain if the stored hash is zero (unknown). */
-    Hash hash = hashAndWriteSink.currentHash();
+    Hash hash = hashSink.currentHash().first;
     if (hash != info->narHash && info->narHash != Hash(*info->narHash.type))
         throw Error("hash of path '%s' has changed from '%s' to '%s'!",
             printStorePath(path), info->narHash.to_string(Base32, true), hash.to_string(Base32, true));
 
-    hashAndWriteSink
+    teeSink
         << exportMagic
         << printStorePath(path);
-    writeStorePaths(*this, hashAndWriteSink, info->references);
-    hashAndWriteSink
+    writeStorePaths(*this, teeSink, info->references);
+    teeSink
         << (info->deriver ? printStorePath(*info->deriver) : "")
         << 0;
 }
@@ -77,7 +60,7 @@ StorePaths Store::importPaths(Source & source, std::shared_ptr<FSAccessor> acces
         if (n != 1) throw Error("input doesn't look like something created by 'nix-store --export'");
 
         /* Extract the NAR from the source. */
-        TeeSink tee(source);
+        TeeParseSink tee(source);
         parseDump(tee, tee.source);
 
         uint32_t magic = readInt(source);