about summary refs log tree commit diff
path: root/src/libstore/store-api.hh
diff options
context:
space:
mode:
authorEelco Dolstra <eelco.dolstra@logicblox.com>2016-09-16T16·54+0200
committerEelco Dolstra <eelco.dolstra@logicblox.com>2016-09-16T16·54+0200
commit75989bdca773eedb8b8d1cc8a7675900358acd25 (patch)
tree2d1dce1431662f441cead67d8754e96eb4db6807 /src/libstore/store-api.hh
parent054be5025762c5e1c7e853c4fa5d7eed8da1727f (diff)
Make computeFSClosure() single-threaded again
The fact that queryPathInfo() is synchronous meant that we needed a
thread for every concurrent binary cache lookup, even though they end
up being handled by the same download thread. Requiring hundreds of
threads is not a good idea. So now there is an asynchronous version of
queryPathInfo() that takes a callback function to process the
result. Similarly, enqueueDownload() now takes a callback rather than
returning a future.

Thus, a command like

  nix path-info --store https://cache.nixos.org/ -r /nix/store/slljrzwmpygy1daay14kjszsr9xix063-nixos-16.09beta231.dccf8c5

that returns 4941 paths now takes 1.87s using only 2 threads (the main
thread and the downloader thread). (This is with a prewarmed
CloudFront.)
Diffstat (limited to 'src/libstore/store-api.hh')
-rw-r--r--src/libstore/store-api.hh9
1 files changed, 8 insertions, 1 deletions
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 41fc58fc48e2..cba4deaad5d7 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -319,9 +319,16 @@ public:
        the name part of the store path. */
     ref<const ValidPathInfo> queryPathInfo(const Path & path);
 
+    /* Asynchronous version of queryPathInfo(). */
+    void queryPathInfo(const Path & path,
+        std::function<void(ref<ValidPathInfo>)> success,
+        std::function<void(std::exception_ptr exc)> failure);
+
 protected:
 
-    virtual std::shared_ptr<ValidPathInfo> queryPathInfoUncached(const Path & path) = 0;
+    virtual void queryPathInfoUncached(const Path & path,
+        std::function<void(std::shared_ptr<ValidPathInfo>)> success,
+        std::function<void(std::exception_ptr exc)> failure) = 0;
 
 public: