From 90ad02bf626b885a5dd8967894e2eafc953bdf92 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 14 Sep 2016 16:00:40 +0200 Subject: Enable HTTP/2 support The binary cache store can now use HTTP/2 to do lookups. This is much more efficient than HTTP/1.1 due to multiplexing: we can issue many requests in parallel over a single TCP connection. Thus it's no longer necessary to use a bunch of concurrent TCP connections (25 by default). For example, downloading 802 .narinfo files from https://cache.nixos.org/, using a single TCP connection, takes 11.8s with HTTP/1.1, but only 0.61s with HTTP/2. This did require a fairly substantial rewrite of the Downloader class to use the curl multi interface, because otherwise curl wouldn't be able to do multiplexing for us. As a bonus, we get connection reuse even with HTTP/1.1. All downloads are now handled by a single worker thread. Clients call Downloader::enqueueDownload() to tell the worker thread to start the download, getting a std::future to the result. --- src/libexpr/primops.cc | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/libexpr/primops.cc') diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc index 3b965f209bb2..e460000841ac 100644 --- a/src/libexpr/primops.cc +++ b/src/libexpr/primops.cc @@ -1769,7 +1769,7 @@ void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v, if (state.restricted && !expectedHash) throw Error(format("‘%1%’ is not allowed in restricted mode") % who); - Path res = makeDownloader()->downloadCached(state.store, url, unpack, name, expectedHash); + Path res = getDownloader()->downloadCached(state.store, url, unpack, name, expectedHash); mkString(v, res, PathSet({res})); } -- cgit 1.4.1