From 75989bdca773eedb8b8d1cc8a7675900358acd25 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Fri, 16 Sep 2016 18:54:14 +0200 Subject: 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.) --- src/libstore/store-api.hh | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'src/libstore/store-api.hh') 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 queryPathInfo(const Path & path); + /* Asynchronous version of queryPathInfo(). */ + void queryPathInfo(const Path & path, + std::function)> success, + std::function failure); + protected: - virtual std::shared_ptr queryPathInfoUncached(const Path & path) = 0; + virtual void queryPathInfoUncached(const Path & path, + std::function)> success, + std::function failure) = 0; public: -- cgit 1.4.1