Commit graph

246 commits

Author SHA1 Message Date
Eelco Dolstra 6b83174fff std::uncaught_exception() -> std::uncaught_exceptions()
The former is deprecated in C++17. Fixes a clang warning.
2019-09-13 20:05:44 +02:00
Eelco Dolstra f186000367
Add some noexcepts
This is to assert that callback functions should never throw (since
the context in which they're called may not be able to handle the
exception).
2019-09-03 13:45:35 +02:00
Eelco Dolstra 7298a38a07
Don't send certain setting overrides to the daemon
These are already handled separately. This fixes warnings like

  warning: ignoring the user-specified setting 'max-jobs', because it is a restricted setting and you are not a trusted user

when using the -j flag.
2019-08-28 16:29:44 +02:00
Eelco Dolstra 53522cb6ac
findRoots(): Add 'censor' parameter
This is less brittle than filtering paths after the fact in
nix-daemon.
2019-03-14 13:53:34 +01:00
Guillaume Maudoux ebc86550f9 Make roots a map of store paths to pinning links
This new structure makes more sense as there may be many sources rooting
the same store path. Many profiles can reference the same path but this
is even more true with /proc/<pid>/maps where distinct pids can and
often do map the same store path.
This implementation is also more efficient as the `Roots` map contains
only one entry per rooted store path.
2019-03-10 00:56:09 +01:00
Eelco Dolstra 63575ffa38
Merge branch 'nix-doctor' of https://github.com/LnL7/nix 2018-10-27 12:54:22 +02:00
Eelco Dolstra 79e358ce6d RemoteStore: Close connection if an exception occurs
Fixes #2075.
2018-10-16 23:36:15 +02:00
Daiderd Jordan 070823baa4
Store: expose the protocol version used by a store 2018-09-02 12:54:29 +02:00
Eelco Dolstra 3c2de9830d
RemoteStore::addToStore(): Ensure capacity is decreased on exceptions 2018-05-30 13:48:31 +02:00
Eelco Dolstra a4c1618876
Fix deadlock in RemoteStore::queryPathInfoUncached() 2018-05-30 13:46:14 +02:00
Eelco Dolstra 81ea8bd5ce
Simplify the callback mechanism 2018-05-30 13:34:37 +02:00
Eelco Dolstra 737ed88f35
Modularize config settings
Allow global config settings to be defined in multiple Config
classes. For example, this means that libutil can have settings and
evaluator settings can be moved out of libstore. The Config classes
are registered in a new GlobalConfig class to which config files
etc. are applied.

Relevant to https://github.com/NixOS/nix/issues/2009 in that it
removes the need for ad hoc handling of useCaseHack, which was the
underlying cause of that issue.
2018-05-30 13:28:01 +02:00
Eelco Dolstra 6185d25e52
Make 'nix copy --to daemon' run in constant memory (daemon side)
Continuation of 97002b684c. This makes
the daemon use constant memory. For example, it reduces the daemon's
maximum RSS on

  $ nix copy --from ~/my-nix --to daemon /nix/store/1n7x0yv8vq6zi90hfmian84vdhd04bgp-blender-2.79a

from 264 MiB to 7 MiB.

We now use a TunnelSource to prevent the connection from ending up in
an undefined state if an exception is thrown while the NAR is being
sent.

Issue https://github.com/NixOS/nix/issues/1681.
2018-05-30 13:26:48 +02:00
Eelco Dolstra ec91840e70 Also make the backwards compatible case of RemoteStore::addToStore run in constant memory
Just because we can.
2018-03-21 23:46:03 +01:00
Eelco Dolstra 97002b684c Make 'nix copy --to daemon' run in constant memory 2018-03-21 23:42:52 +01:00
Spencer Baugh 746f8aed86 remote_store: register for NIX_REMOTE=unix://path
This allows overriding the socket path so the daemon may be listening at
an arbitrary Unix domain socket location.

Fixes #1800
2018-01-26 22:05:16 +00:00
Eelco Dolstra 25f32625e2
Remove the remote-builds option
This is superfluous since you can now just set "builders" to empty,
e.g. "--builders ''".
2017-10-24 11:00:16 +02:00
Eelco Dolstra 89dc62c174
RemoteStore: Add option to drop old connections from the pool
This is a hack to make hydra-queue-runner free its temproots
periodically, thereby ensuring that garbage collection of the
corresponding paths is not blocked until the queue runner is
restarted.

It would be better if temproots could be released earlier than at
process exit. I started working on a RAII object returned by functions
like addToStore() that releases temproots. However, this would be a
pretty massive change so I gave up on it for now.
2017-09-14 18:10:38 +02:00
Eelco Dolstra 2cc345b95f
Give activities a verbosity level again
And print them (separately from the progress bar) given sufficient -v
flags.
2017-08-28 19:13:24 +02:00
Eelco Dolstra fe34b91289
Tunnel progress messages from the daemon to the client
This makes the progress bar work for non-root users.
2017-08-28 18:49:42 +02:00
Jörg Thalheim 2fd8f8bb99 Replace Unicode quotes in user-facing strings by ASCII
Relevant RFC: NixOS/rfcs#4

$ ag -l | xargs sed -i -e "/\"/s/’/'/g;/\"/s/‘/'/g"
2017-07-30 12:32:45 +01:00
Eelco Dolstra c0015e87af
Support base-64 hashes
Also simplify the Hash API.

Fixes #1437.
2017-07-04 15:07:41 +02:00
Eelco Dolstra fcca702a96
Replace a few bool flags with enums
Functions like copyClosure() had 3 bool arguments, which creates a
severe risk of mixing up arguments.

Also, implement copyClosure() using copyPaths().
2017-07-03 11:38:08 +02:00
Eelco Dolstra cd4d2705ec
build-remote: Fix fallback to other machines when connecting fails
Opening an SSHStore or LegacySSHStore does not actually establish a
connection, so the try/catch block here did nothing. Added a
Store::connect() method to test whether a connection can be
established.
2017-05-02 15:46:09 +02:00
Shea Levy 4bc00760f9 Add Store nesting to fix import-from-derivation within filterSource 2017-04-26 14:15:47 -04:00
Eelco Dolstra f05d5f89ff
Read per-user settings from ~/.config/nix/nix.conf 2017-04-20 14:58:16 +02:00
Eelco Dolstra ba9ad29fdb
Convert Settings to the new config system
This makes all config options self-documenting.

Unknown or unparseable config settings and --option flags now cause a
warning.
2017-04-13 20:53:23 +02:00
Eelco Dolstra 2040240e23
Add a Config class to simplify adding configuration settings
The typical use is to inherit Config and add Setting<T> members:

  class MyClass : private Config
  {
    Setting<int> foo{this, 123, "foo", "the number of foos to use"};
    Setting<std::string> bar{this, "blabla", "bar", "the name of the bar"};

    MyClass() : Config(readConfigFile("/etc/my-app.conf"))
    {
      std::cout << foo << "\n"; // will print 123 unless overriden
    }
  };

Currently, this is used by Store and its subclasses for store
parameters. You now get a warning if you specify a non-existant store
parameter in a store URI.
2017-04-13 16:03:31 +02:00
Eelco Dolstra ba20730b3f
Implement RemoteStore::queryMissing()
This provides a significant speedup, e.g. 64 s -> 12 s for

  nix-build --dry-run -I nixpkgs=channel:nixos-16.03 '<nixpkgs/nixos/tests/misc.nix>' -A test

on a cold local and CloudFront cache.

The alternative is to use lots of concurrent daemon connections but
that seems wasteful.
2017-04-06 18:40:19 +02:00
Eelco Dolstra c5b83d8913
copyPaths(): Use queryValidPaths() to reduce SSH latency 2017-03-16 13:50:01 +01:00
Eelco Dolstra d1158bb816
Cache connection failures 2017-03-03 19:36:01 +01:00
Eelco Dolstra 577ebeaefb
Improve SSH handling
* Unify SSH code in SSHStore and LegacySSHStore.

* Fix a race starting the SSH master. We now wait synchronously for
  the SSH master to finish starting. This prevents the SSH clients
  from starting their own connections.

* Don't use a master if max-connections == 1.

* Add a "max-connections" store parameter.

* Add a "compress" store parameter.
2017-03-03 19:05:50 +01:00
Eelco Dolstra f61f67ddee
RemoteStore::addToStore(): Send NAR rather than string containing NAR
This allows the NAR to be streamed in the future (though we're not
doing that yet).
2017-03-01 16:07:15 +01:00
Eelco Dolstra c4a40949d9
Handle importing NARs containing files greater than 4 GiB
Also templatize readInt() to work for various integer types.
2017-03-01 13:52:54 +01:00
Eelco Dolstra f023f64f40
RemoteStore::addToStore(): Pass content-addressability assertion
... and use this in Downloader::downloadCached(). This fixes

  $ nix-build https://nixos.org/channels/nixos-16.09-small/nixexprs.tar.xz -A hello
  error: cannot import path ‘/nix/store/csfbp1s60dkgmk9f8g0zk0mwb7hzgabd-nixexprs.tar.xz’ because it lacks a valid signature
2017-02-22 16:58:00 +01:00
Eelco Dolstra caa5793b4a
Add a LegacySSHStore that uses nix-store --serve
This is useful for nix-copy-closure.
2017-02-07 19:29:21 +01:00
Eelco Dolstra 2b9d0a99cb AutoDeleteArray -> std::unique_ptr
Also, switch to C++14 for std::make_unique.
2017-01-16 22:24:49 +01:00
Eelco Dolstra 215b70f51e
Revert "Get rid of unicode quotes (#1140)"
This reverts commit f78126bfd6. There
really is no need for such a massive change...
2016-11-26 00:38:01 +01:00
Guillaume Maudoux f78126bfd6 Get rid of unicode quotes (#1140) 2016-11-25 15:48:27 +01:00
Eelco Dolstra 4b8f1b0ec0 Merge branch 'ssh-store' of https://github.com/shlevy/nix 2016-11-09 18:57:22 +01:00
Eelco Dolstra 21c55ab3b5 Implement backwards-compatible RemoteStore::addToStore()
The SSHStore PR adds this functionality to the daemon, but we have to
handle the case where the Nix daemon is 1.11.

Also, don't require signatures for trusted users. This restores 1.11
behaviour.

Fixes https://github.com/NixOS/hydra/issues/398.
2016-11-09 18:45:06 +01:00
Eelco Dolstra fdbbcc4492 Remove addPathToAccessor 2016-10-21 18:09:30 +02:00
Eelco Dolstra 542ae5c8f8 BinaryCacheStore: Optionally write a NAR listing
The store parameter "write-nar-listing=1" will cause BinaryCacheStore
to write a file ‘<store-hash>.ls.xz’ for each ‘<store-hash>.narinfo’
added to the binary cache. This file contains an XZ-compressed JSON
file describing the contents of the NAR, excluding the contents of
regular files.

E.g.

  {
    "version": 1,
    "root": {
      "type": "directory",
      "entries": {
        "lib": {
          "type": "directory",
          "entries": {
            "Mcrt1.o": {
              "type": "regular",
              "size": 1288
            },
            "Scrt1.o": {
              "type": "regular",
              "size": 3920
            },
          }
        }
      }
      ...
    }
  }

(The actual file has no indentation.)

This is intended to speed up the NixOS channels programs index
generator [1], since fetching gazillions of large NARs from
cache.nixos.org is currently a bottleneck for updating the regular
(non-small) channel.

[1] https://github.com/NixOS/nixos-channel-scripts/blob/master/generate-programs-index.cc
2016-10-21 16:50:28 +02:00
Eelco Dolstra c55bf085eb printMsg(lvlError, ...) -> printError(...) etc. 2016-09-21 16:54:53 +02:00
Eelco Dolstra 4036185cb4 Some notational convenience for formatting strings
We can now write

  throw Error("file '%s' not found", path);

instead of

  throw Error(format("file '%s' not found") % path);

and similarly

  printError("file '%s' not found", path);

instead of

  printMsg(lvlError, format("file '%s' not found") % path);
2016-09-21 16:54:53 +02:00
Eelco Dolstra 75989bdca7 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.)
2016-09-16 18:54:14 +02:00
Shea Levy 584f8a62de Implement nar-based addToStore for remote-store 2016-09-02 14:33:58 -04:00
Shea Levy 0f39633290 Factor out the unix domain socket-specific code from RemoteStore 2016-09-02 14:15:04 -04:00
Eelco Dolstra d961c29c9c Mark content-addressed paths in the Nix database and in .narinfo
This allows such paths to be imported without signatures.
2016-08-10 18:05:35 +02:00
Eelco Dolstra be64fbb501 RemoteStore / nix-daemon: Drop support for Nix < 1.0 2016-08-10 18:05:35 +02:00
Shea Levy cb5e7254b6 Modernize AutoCloseFD 2016-07-11 15:44:44 -04:00
Eelco Dolstra 202683a4fc Use O_CLOEXEC in most places 2016-06-09 16:37:08 +02:00
Eelco Dolstra 7850d3d279 Make the store directory a member variable of Store 2016-06-01 16:24:17 +02:00
Eelco Dolstra c2d27d30cf nix-copy-closure / build-remote.pl: Disable signature checking
This restores the Nix 1.11 behaviour.
2016-05-31 11:48:05 +02:00
Eelco Dolstra 0d4a10e910 Do compression in a sink 2016-05-04 16:16:53 +02:00
Eelco Dolstra 538a64e8c3 Add a Store::addToStore() variant that accepts a NAR
As a side effect, this ensures that signatures are propagated when
copying paths between stores.

Also refactored import/export to make use of this.
2016-05-04 16:15:54 +02:00
Eelco Dolstra f435f82475 Remove OpenSSL-based signing 2016-05-04 11:01:48 +02:00
Eelco Dolstra 95d20dfde9 Allow parameters in store URIs
This is to allow store-specific configuration,
e.g. s3://my-cache?compression=bzip2&secret-key=/path/to/key.
2016-04-29 16:26:16 +02:00
Eelco Dolstra 5761827d5b Show the log tail when a build fails
If --no-build-output is given (which will become the default for the
"nix" command at least), show the last 10 lines of the build output if
the build fails.
2016-04-25 19:18:45 +02:00
Eelco Dolstra 6e1b099279 Remove --print-build-trace
This was added to support Hydra, but Hydra no longer uses it.
2016-04-25 19:18:45 +02:00
Eelco Dolstra 41633f9f73 Improved logging abstraction
This also gets rid of --log-type, since the nested log type isn't
useful in a multi-threaded situation, and nobody cares about the
"pretty" log type.
2016-04-25 19:18:45 +02:00
Eelco Dolstra ddea253ff8 RemoteStore: Propagate InvalidPath exceptions from the daemon 2016-04-20 15:28:07 +02:00
Eelco Dolstra 451ebf24ce Cache path info lookups in SQLite
This re-implements the binary cache database in C++, allowing it to be
used by other Store backends, in particular the S3 backend.
2016-04-20 14:12:38 +02:00
Eelco Dolstra e0204f8d46 Move path info caching from BinaryCacheStore to Store
Caching path info is generally useful. For instance, it speeds up "nix
path-info -rS /run/current-system" (i.e. showing the closure sizes of
all paths in the closure of the current system) from 5.6s to 0.15s.

This also eliminates some APIs like Store::queryDeriver() and
Store::queryReferences().
2016-04-19 18:52:53 +02:00
Eelco Dolstra 8cffec8485 Remove failed build caching
This feature was implemented for Hydra, but Hydra no longer uses it.
2016-04-08 18:19:04 +02:00
Eelco Dolstra d0f5719c2a Add "nix copy-sigs" command
This imports signatures from one store into another. E.g.

  $ nix copy-sigs -r /run/current-system -s https://cache.nixos.org/
  imported 595 signatures
2016-04-05 16:39:23 +02:00
Eelco Dolstra 9cee600c88 LocalStore: Keep track of ultimately trusted paths
These are content-addressed paths or outputs of locally performed
builds. They are trusted even if they don't have signatures, so "nix
verify-paths" won't complain about them.
2016-03-30 17:35:48 +02:00
Eelco Dolstra c7d44bad00 Drop support for daemon socket path >= 108 characters
Doing a chdir() is a bad idea in multi-threaded programs, leading to
failures such as

  error: cannot connect to daemon at ‘/nix/var/nix/daemon-socket/socket’: No such file or directory

Since Linux doesn't have a connectat() syscall like FreeBSD, there is
no way we can support this in a race-free way.
2016-03-23 17:16:16 +01:00
Eelco Dolstra bb1034316d Don't overload dumpPath() 2016-03-22 14:21:45 +01:00
Eelco Dolstra 1c5f73f529 Add Store::dumpPath() method
This allows applying nix-store --verify-path to binary cache stores:

  NIX_REMOTE=https://cache.nixos.org nix-store --verify-path /nix/store/s5c7...
2016-03-21 17:55:57 +01:00
Eelco Dolstra bcc9943cee importPaths(): Optionally add NARs to binary cache accessor
This enables an optimisation in hydra-queue-runner, preventing a
download of a NAR it just uploaded to the cache when reading files
like hydra-build-products.
2016-02-26 15:20:10 +01:00
Eelco Dolstra 28e7e29abd Eliminate reserveSpace flag 2016-02-24 17:44:55 +01:00
Eelco Dolstra 5f862658c3 Remove bad daemon connections from the pool
This is necessary for long-running processes like hydra-queue-runner:
if a nix-daemon worker is killed, we need to stop reusing that
connection.
2016-02-24 11:39:56 +01:00
Eelco Dolstra d5626bf4c1 Pool<T>: Allow a maximum pool size 2016-02-23 16:40:16 +01:00
Eelco Dolstra e292144d46 RemoteStore: Make thread-safe
This allows a RemoteStore object to be used safely from multiple
threads concurrently. It will make multiple daemon connections if
necessary.

Note: pool.hh and sync.hh have been copied from the Hydra source tree.
2016-02-23 15:00:59 +01:00
Eelco Dolstra 5ac27053e9 Rename ValidPathInfo::hash -> narHash for consistency 2016-02-16 11:49:12 +01:00
Eelco Dolstra 9e7c1a4bbd Use the daemon when we don't have write access to the Nix database 2016-01-31 10:28:48 +01:00
Ludovic Courtès d1e3bf01bc daemon: Add 'buildMode' parameter to 'buildPaths' RPC 2015-12-02 18:14:49 +01:00
Eelco Dolstra 71a5161365 Implement buildDerivation() via the daemon 2015-09-03 12:56:59 +02:00
Eelco Dolstra b3491c781c More cleanup 2015-07-20 01:16:16 +02:00
Eelco Dolstra 6bd2c7bb38 OCD: foreach -> C++11 ranged for 2015-07-17 20:13:56 +02:00
Eelco Dolstra 1511aa9f48 Allow remote builds without sending the derivation closure
Previously, to build a derivation remotely, we had to copy the entire
closure of the .drv file to the remote machine, even though we only
need the top-level derivation. This is very wasteful: the closure can
contain thousands of store paths, and in some Hydra use cases, include
source paths that are very large (e.g. Git/Mercurial checkouts).

So now there is a new operation, StoreAPI::buildDerivation(), that
performs a build from an in-memory representation of a derivation
(BasicDerivation) rather than from a on-disk .drv file. The only files
that need to be in the Nix store are the sources of the derivation
(drv.inputSrcs), and the needed output paths of the dependencies (as
described by drv.inputDrvs). "nix-store --serve" exposes this
interface.

Note that this is a privileged operation, because you can construct a
derivation that builds any store path whatsoever. Fixing this will
require changing the hashing scheme (i.e., the output paths should be
computed from the other fields in BasicDerivation, allowing them to be
verified without access to other derivations). However, this would be
quite nice because it would allow .drv-free building (e.g. "nix-env
-i" wouldn't have to write any .drv files to disk).

Fixes #173.
2015-07-17 17:57:40 +02:00
Ludovic Courtès b755752f76 Add a ‘verifyStore’ RPC
Hello!

The patch below adds a ‘verifyStore’ RPC with the same signature as the
current LocalStore::verifyStore method.

Thanks,
Ludo’.

>From aef46c03ca77eb6344f4892672eb6d9d06432041 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Mon, 1 Jun 2015 23:17:10 +0200
Subject: [PATCH] Add a 'verifyStore' remote procedure call.
2015-06-02 02:14:24 +02:00
Eelco Dolstra 7ea6ecf855 addToStore(): Take explicit name argument 2015-03-25 17:06:12 +01:00
Eelco Dolstra 8bdff8c100 Merge branch 'cygwin-master' of https://github.com/ternaris/nix 2014-12-14 01:49:14 +01:00
Eelco Dolstra fa2063ca35 Better error message 2014-12-13 16:54:40 +01:00
Eelco Dolstra b77037b8fd Silence some warnings on GCC 4.9 2014-12-12 17:14:28 +01:00
Marko Durkovic 629e8da3aa Explicitly include required C headers 2014-12-09 13:00:59 +01:00
Eelco Dolstra e389f4ea55 Improve error message if the daemon worker fails to start 2014-10-31 09:36:09 +01:00
Ludovic Courtès 8fb8c26b6d Add an 'optimiseStore' remote procedure call. 2014-09-01 23:53:26 +02:00
Eelco Dolstra 11849a320e Use proper quotes everywhere 2014-08-20 18:03:48 +02:00
Eelco Dolstra 67937907ca nix-daemon: Pass on the user's $SSH_AUTH_SOCK to the SSH substituter 2014-07-25 18:02:48 +02:00
Eelco Dolstra 5989966ed3 Remove dead code 2014-07-23 14:46:28 +02:00
Eelco Dolstra fa13d3f4f3 build-remote.pl: Fix building multiple output derivations
We were importing paths without sorting them topologically, leading to
"path is not valid" errors.

See e.g. http://hydra.nixos.org/build/12451761
2014-07-14 12:19:27 +02:00
Eelco Dolstra a5c6347ff0 build-remote.pl: Use ‘nix-store --serve’ on the remote side
This makes things more efficient (we don't need to use an SSH master
connection, and we only start a single remote process) and gets rid of
locking issues (the remote nix-store process will keep inputs and
outputs locked as long as they're needed).

It also makes it more or less secure to connect directly to the root
account on the build machine, using a forced command
(e.g. ‘command="nix-store --serve --write"’). This bypasses the Nix
daemon and is therefore more efficient.

Also, don't call nix-store to import the output paths.
2014-07-11 16:22:24 +02:00
Eelco Dolstra b1beed97a0 Report daemon OOM better
When copying a large path causes the daemon to run out of memory, you
now get:

  error: Nix daemon out of memory

instead of:

  error: writing to file: Broken pipe
2014-06-10 13:45:50 +02:00
Eelco Dolstra 829af22759 Print a warning when loading a large path into memory
I.e. if you have a derivation with

  src = ./huge-directory;

you'll get a warning that this is not a good idea.
2014-06-10 13:30:09 +02:00
Eelco Dolstra 1aa19b24b2 Add a flag ‘--check’ to verify build determinism
The flag ‘--check’ to ‘nix-store -r’ or ‘nix-build’ will cause Nix to
redo the build of a derivation whose output paths are already valid.
If the new output differs from the original output, an error is
printed.  This makes it easier to test if a build is deterministic.
(Obviously this cannot catch all sources of non-determinism, but it
catches the most common one, namely the current time.)

For example:

  $ nix-build '<nixpkgs>' -A patchelf
  ...
  $ nix-build '<nixpkgs>' -A patchelf --check
  error: derivation `/nix/store/1ipvxsdnbhl1rw6siz6x92s7sc8nwkkb-patchelf-0.6' may not be deterministic: hash mismatch in output `/nix/store/4pc1dmw5xkwmc6q3gdc9i5nbjl4dkjpp-patchelf-0.6.drv'

The --check build fails if not all outputs are valid.  Thus the first
call to nix-build is necessary to ensure that all outputs are valid.

The current outputs are left untouched: the new outputs are either put
in a chroot or diverted to a different location in the store using
hash rewriting.
2014-02-18 01:01:14 +01:00
Eelco Dolstra 936f9d45ba Don't apply the CPU affinity hack to nix-shell (and other Perl programs)
As discovered by Todd Veldhuizen, the shell started by nix-shell has
its affinity set to a single CPU.  This is because nix-shell connects
to the Nix daemon, which causes the affinity hack to be applied.  So
we turn this off for Perl programs.
2013-09-06 16:36:56 +02:00
Eelco Dolstra a583a2bc59 Run the daemon worker on the same CPU as the client
On a system with multiple CPUs, running Nix operations through the
daemon is significantly slower than "direct" mode:

$ NIX_REMOTE= nix-instantiate '<nixos>' -A system
real    0m0.974s
user    0m0.875s
sys     0m0.088s

$ NIX_REMOTE=daemon nix-instantiate '<nixos>' -A system
real    0m2.118s
user    0m1.463s
sys     0m0.218s

The main reason seems to be that the client and the worker get moved
to a different CPU after every call to the worker.  This patch adds a
hack to lock them to the same CPU.  With this, the overhead of going
through the daemon is very small:

$ NIX_REMOTE=daemon nix-instantiate '<nixos>' -A system
real    0m1.074s
user    0m0.809s
sys     0m0.098s
2013-08-07 14:02:04 +02:00