Commit graph

68 commits

Author SHA1 Message Date
Eelco Dolstra aa115e22df download-from-binary-cache: Print correct URL 2012-07-18 11:01:17 -04:00
Eelco Dolstra a6f348599c Print some debug output 2012-07-17 16:19:40 -04:00
Eelco Dolstra d287b62b64 Set the User-Agent header to "Nix/<version>" 2012-07-11 18:05:30 -04:00
Eelco Dolstra b74d92755d download-from-binary-cache: Use HEAD requests if possible
In "nix-env -qas", we don't need the substitute info, we just need to
know if it exists.  This can be done using a HTTP HEAD request, which
saves bandwidth.

Note however that curl currently has a bug that prevents it from
reusing HTTP connections if HEAD requests return a 404:

https://sourceforge.net/tracker/?func=detail&aid=3542731&group_id=976&atid=100976

Without the patch attached to the issue, using HEAD is actually quite
a bit slower than GET.
2012-07-11 17:53:20 -04:00
Eelco Dolstra 5ee8944155 Cleanup 2012-07-11 10:13:16 -04:00
Eelco Dolstra 099125435f download-from-binary-cache: add nix.conf options 2012-07-09 10:57:28 -04:00
Eelco Dolstra 400e556b34 Cleanup 2012-07-08 18:39:07 -04:00
Eelco Dolstra 11800e6198 download-from-binary-cache: parallelise fetching of NAR info files
Getting substitute information using the binary cache substituter has
non-trivial latency overhead.  A package or NixOS system configuration
can have hundreds of dependencies, and in the worst case (when the
local info cache is empty) we have to do a separate HTTP request for
each of these.  If the ping time to the server is t, getting N info
files will take tN seconds; e.g., with a ping time of 0.1s to
nixos.org, sequentially downloading 1000 info files (a typical NixOS
config) will take at least 100 seconds.

To fix this problem, the binary cache substituter can now perform
requests in parallel.  This required changing the substituter
interface to support a function querySubstitutablePathInfos() that
queries multiple paths at the same time, and rewriting queryMissing()
to take advantage of parallelism.  (Due to local caching,
parallelising queryMissing() is sufficient for most use cases, since
it's almost always called before building a derivation and thus fills
the local info cache.)

For example, parallelism speeds up querying all 1056 paths in a
particular NixOS system configuration from 116s to 2.6s.  It works so
well because the eccentricity of the top-level derivation in the
dependency graph is only 9.  So we only need 10 round-trips (when
using an unlimited number of parallel connections) to get everything.

Currently we do a maximum of 150 parallel connections to the server.
Thus it's important that the binary cache server (e.g. nixos.org) has
a high connection limit.  Alternatively we could use HTTP pipelining,
but WWW::Curl doesn't support it and libcurl has a hard-coded limit of
5 requests per pipeline.
2012-07-06 19:08:20 -04:00
Eelco Dolstra cd94665f38 download-from-binary-cache: use WWW::Curl
Using WWW::Curl rather than running an external curl process for every
NAR info file halves the time it takes to get info thanks to libcurl's
support for persistent HTTP connections.  (We save a roundtrip per
file.)  But the real gain will come from using parallel and/or
pipelined requests.
2012-07-06 00:30:40 -04:00
Eelco Dolstra ae60643c15 download-from-binary-cache: do negative NAR info caching
I.e. if a NAR info file does *not* exist, we record it in the cache DB
so that we don't retry it later.
2012-07-03 18:54:46 -04:00
Eelco Dolstra 89380c03e9 download-from-binary-cache: in queries, preferred cached info 2012-07-03 18:35:39 -04:00
Eelco Dolstra 2a8e5c8b11 download-from-binary-cache: strip trailing / from URLs 2012-07-03 17:47:01 -04:00
Eelco Dolstra d694c599e2 download-from-binary-cache: cache binary cache info in a SQLite DB 2012-07-03 17:29:33 -04:00
Eelco Dolstra 8319b1ab9f download-from-binary-cache: Verify NAR hashes 2012-07-02 18:53:04 -04:00
Eelco Dolstra 6ec7460af1 Binary caches: use a better key
Use the hash part of the store path as a key rather than a hash of the
store path.  This is enough to get the desired privacy property.
2012-07-02 12:42:58 -04:00
Eelco Dolstra 440adfbdd1 Add an environment variable $NIX_BINARY_CACHES specifying URLs of binary caches 2012-07-01 21:55:36 -04:00
Eelco Dolstra f4190c38ba Allow both bzip2 and xz compression 2012-07-01 18:46:38 -04:00
Eelco Dolstra 37f7098464 First attempt at the manifest-less substituter 2012-06-29 18:28:52 -04:00