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authorGraham Christensen <graham.christensen@target.com>2018-08-17T14·29-0400
committerGraham Christensen <graham.christensen@target.com>2018-08-17T15·27-0400
commit02098d2073e2f7c06b6d05c6749ae2b76b7f57d5 (patch)
treeb5e37e17af5e63f484d44259efbcbcbc30dd10af /src/libexpr/primops
parentd277442df53a01343ba7c1df0bbd2a294058dcba (diff)
fetchGit: use a better caching scheme
The current usage technically works by putting multiple different
repos in to the same git directory. However, it is very slow as
Git tries very hard to find common commits between the two
repositories. If the two repositories are large (like Nixpkgs and
another long-running project,) it is maddeningly slow.

This change busts the cache for existing deployments, but users
will be promptly repaid in per-repository performance.
Diffstat (limited to 'src/libexpr/primops')
-rw-r--r--src/libexpr/primops/fetchGit.cc4
1 files changed, 3 insertions, 1 deletions
diff --git a/src/libexpr/primops/fetchGit.cc b/src/libexpr/primops/fetchGit.cc
index 7aa98e0bfab3..aeb2df5f8aee 100644
--- a/src/libexpr/primops/fetchGit.cc
+++ b/src/libexpr/primops/fetchGit.cc
@@ -3,6 +3,7 @@
 #include "download.hh"
 #include "store-api.hh"
 #include "pathlocks.hh"
+#include "hash.hh"
 
 #include <sys/time.h>
 
@@ -84,9 +85,10 @@ GitInfo exportGit(ref<Store> store, const std::string & uri,
     if (rev != "" && !std::regex_match(rev, revRegex))
         throw Error("invalid Git revision '%s'", rev);
 
-    Path cacheDir = getCacheDir() + "/nix/git";
+    Path cacheDir = getCacheDir() + "/nix/gitv2/" + hashString(htSHA256, uri).to_string(Base32, false);
 
     if (!pathExists(cacheDir)) {
+        createDirs(dirOf(cacheDir));
         runProgram("git", true, { "init", "--bare", cacheDir });
     }