Move getTarballCache() into fetchers::Settings

This keeps the tarball cache open across calls.

Author: edolstra

src/libfetchers/git-utils.cc

@@ -1304,13 +1304,18 @@ std::vector<std::tuple<GitRepoImpl::Submodule, Hash>> GitRepoImpl::getSubmodules
     return result;
 }
 
-ref<GitRepo> getTarballCache()
-{
-    static auto repoDir = std::filesystem::path(getCacheDir()) / "tarball-cache";
+namespace fetchers {
 
-    return GitRepo::openRepo(repoDir, true, true);
+ref<GitRepo> Settings::getTarballCache() const
+{
+    auto tarballCache(_tarballCache.lock());
+    if (!*tarballCache)
+        *tarballCache = GitRepo::openRepo(std::filesystem::path(getCacheDir()) / "tarball-cache", true, true);
+    return ref<GitRepo>(*tarballCache);
 }
 
+} // namespace fetchers
+
 GitRepo::WorkdirInfo GitRepo::getCachedWorkdirInfo(const std::filesystem::path & path)
 {
     static Sync<std::map<std::filesystem::path, WorkdirInfo>> _cache;

src/libfetchers/github.cc

@@ -270,7 +270,7 @@ struct GitArchiveInputScheme : InputScheme
             if (auto lastModifiedAttrs = cache->lookup(lastModifiedKey)) {
                 auto treeHash = getRevAttr(*treeHashAttrs, "treeHash");
                 auto lastModified = getIntAttr(*lastModifiedAttrs, "lastModified");
-                if (getTarballCache()->hasObject(treeHash))
+                if (input.settings->getTarballCache()->hasObject(treeHash))
                     return {std::move(input), TarballInfo{.treeHash = treeHash, .lastModified = (time_t) lastModified}};
                 else
                     debug("Git tree with hash '%s' has disappeared from the cache, refetching...", treeHash.gitRev());
@@ -290,7 +290,7 @@ struct GitArchiveInputScheme : InputScheme
             *logger, lvlInfo, actUnknown, fmt("unpacking '%s' into the Git cache", input.to_string()));
 
         TarArchive archive{*source};
-        auto tarballCache = getTarballCache();
+        auto tarballCache = input.settings->getTarballCache();
         auto parseSink = tarballCache->getFileSystemObjectSink();
         auto lastModified = unpackTarfileToSink(archive, *parseSink);
         auto tree = parseSink->flush();
@@ -324,7 +324,8 @@ struct GitArchiveInputScheme : InputScheme
 #endif
         input.attrs.insert_or_assign("lastModified", uint64_t(tarballInfo.lastModified));
 
-        auto accessor = getTarballCache()->getAccessor(tarballInfo.treeHash, false, "«" + input.to_string() + "»");
+        auto accessor =
+            input.settings->getTarballCache()->getAccessor(tarballInfo.treeHash, false, "«" + input.to_string() + "»");
 
         return {accessor, input};
     }

src/libfetchers/include/nix/fetchers/fetch-settings.hh

@@ -11,6 +11,12 @@
 
 #include <sys/types.h>
 
+namespace nix {
+
+struct GitRepo;
+
+}
+
 namespace nix::fetchers {
 
 struct Cache;
@@ -125,8 +131,12 @@ struct Settings : public Config
 
     ref<Cache> getCache() const;
 
+    ref<GitRepo> getTarballCache() const;
+
 private:
     mutable Sync<std::shared_ptr<Cache>> _cache;
+
+    mutable Sync<std::shared_ptr<GitRepo>> _tarballCache;
 };
 
 } // namespace nix::fetchers

src/libfetchers/include/nix/fetchers/git-utils.hh

@@ -120,8 +120,6 @@ struct GitRepo
     virtual Hash dereferenceSingletonDirectory(const Hash & oid) = 0;
 };
 
-ref<GitRepo> getTarballCache();
-
 // A helper to ensure that the `git_*_free` functions get called.
 template<auto del>
 struct Deleter

src/libfetchers/tarball.cc

@@ -136,11 +136,11 @@ static DownloadTarballResult downloadTarball_(
             .treeHash = treeHash,
             .lastModified = (time_t) getIntAttr(infoAttrs, "lastModified"),
             .immutableUrl = maybeGetStrAttr(infoAttrs, "immutableUrl"),
-            .accessor = getTarballCache()->getAccessor(treeHash, false, displayPrefix),
+            .accessor = settings.getTarballCache()->getAccessor(treeHash, false, displayPrefix),
         };
     };
 
-    if (cached && !getTarballCache()->hasObject(getRevAttr(cached->value, "treeHash")))
+    if (cached && !settings.getTarballCache()->hasObject(getRevAttr(cached->value, "treeHash")))
         cached.reset();
 
     if (cached && !cached->expired)
@@ -179,7 +179,7 @@ static DownloadTarballResult downloadTarball_(
         TarArchive{path};
     })
                                                                                     : TarArchive{*source};
-    auto tarballCache = getTarballCache();
+    auto tarballCache = settings.getTarballCache();
     auto parseSink = tarballCache->getFileSystemObjectSink();
     auto lastModified = unpackTarfileToSink(archive, *parseSink);
     auto tree = parseSink->flush();
@@ -398,7 +398,9 @@ struct TarballInputScheme : CurlInputScheme
 
         input.attrs.insert_or_assign(
             "narHash",
-            getTarballCache()->treeHashToNarHash(*input.settings, result.treeHash).to_string(HashFormat::SRI, true));
+            input.settings->getTarballCache()
+                ->treeHashToNarHash(*input.settings, result.treeHash)
+                .to_string(HashFormat::SRI, true));
 
         return {result.accessor, input};
     }