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/libutil/util.cc | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'src/libutil/util.cc') diff --git a/src/libutil/util.cc b/src/libutil/util.cc index 8e029fb4874a..1750e03737b7 100644 --- a/src/libutil/util.cc +++ b/src/libutil/util.cc @@ -1215,4 +1215,15 @@ string base64Decode(const string & s) } +void callFailure(const std::function & failure) +{ + try { + failure(std::current_exception()); + } catch (std::exception & e) { + printMsg(lvlError, format("uncaught exception: %s") % e.what()); + abort(); + } +} + + } -- cgit 1.4.1