Commit graph

1595 commits

Author SHA1 Message Date
Eelco Dolstra 56e30e161c In the chroot, make all mounted filesystems private
This is required on systemd, which mounts filesystems as "shared"
subtrees.  Changes to shared trees in a private mount namespace are
propagated to the outside world, which is bad.
2012-08-20 15:27:30 -04:00
Eelco Dolstra f0eab0636b Don't bind-mount /proc since we mount our own 2012-08-20 15:27:00 -04:00
Eelco Dolstra 862c4c5ec5 Fix 1755 permission on temporary directories left behind by ‘-K’ 2012-08-19 16:32:42 -04:00
Eelco Dolstra 767101824a Avoid concatenating lists of one string 2012-08-13 15:10:29 -04:00
Eelco Dolstra e5c589d271 Don't allocate empty lists
This saves about 4 MB when evaluating a NixOS system configuration.
2012-08-13 15:02:09 -04:00
Eelco Dolstra 3e89ef597c Optimise concatenating a list to an empty list
More precisely, in concatLists, if all lists except one are empty,
then just return the non-empty list.  This reduces the number of list
element allocations by 32% when evaluating a NixOS system
configuration.
2012-08-13 14:58:54 -04:00
Eelco Dolstra 9c2d63084b Add a primop ‘elemAt’ to get an element from a list 2012-08-13 13:46:42 -04:00
Eelco Dolstra 198d0338be Add a primop ‘concatLists’
This can serve as a generic efficient list builder.  For instance, the
function ‘catAttrs’ in Nixpkgs can be rewritten from

  attr: l: fold (s: l: if hasAttr attr s then [(getAttr attr s)] ++ l else l) [] l

to

  attr: l: builtins.concatLists (map (s: if hasAttr attr s then [(getAttr attr s)] else []) l)

Statistics before:

  time elapsed: 1.08683
  size of a value: 24
  environments allocated: 1384376 (35809568 bytes)
  list elements: 6946783 (55574264 bytes)
  list concatenations: 37434
  values allocated: 1760440 (42250560 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18273
  number of thunks: 1297673
  number of thunks avoided: 1380759
  number of attr lookups: 430802
  number of primop calls: 628912
  number of function calls: 1333544

Statistics after (including new catAttrs):

  time elapsed: 0.959854
  size of a value: 24
  environments allocated: 1010198 (26829296 bytes)
  list elements: 1984878 (15879024 bytes)
  list concatenations: 30488
  values allocated: 1589760 (38154240 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18274
  number of thunks: 1040925
  number of thunks avoided: 1038428
  number of attr lookups: 438419
  number of primop calls: 474844
  number of function calls: 959366
2012-08-13 01:53:10 -04:00
Eelco Dolstra b9e5b908ed Provide an efficient implementation of ‘elem’
The one in Nixpkgs is O(n^2), this one is O(n).  Big reduction in the
number of list allocations.

Statistics before (on a NixOS system config):

  time elapsed: 1.17982
  size of a value: 24
  environments allocated: 1543334 (39624560 bytes)
  list elements: 9612638 (76901104 bytes)
  list concatenations: 37434
  values allocated: 1854933 (44518392 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18272
  number of thunks: 1392467
  number of thunks avoided: 1507311
  number of attr lookups: 430801
  number of primop calls: 691600
  number of function calls: 1492502

Statistics after:

  time elapsed: 1.08683
  size of a value: 24
  environments allocated: 1384376 (35809568 bytes)
  list elements: 6946783 (55574264 bytes)
  list concatenations: 37434
  values allocated: 1760440 (42250560 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18273
  number of thunks: 1297673
  number of thunks avoided: 1380759
  number of attr lookups: 430802
  number of primop calls: 628912
  number of function calls: 1333544
2012-08-13 01:05:35 -04:00
Eelco Dolstra 4ccd48ce24 Add a "filter" primop
Evaluation of a NixOS configuration spends quite a lot of time in the
"filter" function in Nixpkgs.  As implemented in Nixpkgs, this is a
O(n^2) operation, so it's a good candidate for providing a more
efficient (i.e. primop) implementation.  Using it gives a ~10% speed
increase and a significant reduction in the number of evaluations.

Statistics before (on a NixOS system config):

  time elapsed: 1.3258
  size of a value: 24
  environments allocated: 1980939 (50127080 bytes)
  list elements: 14679308 (117434464 bytes)
  list concatenations: 50828
  values allocated: 2098938 (50374512 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18271
  number of thunks: 1645752
  number of thunks avoided: 1921196
  number of attr lookups: 430798
  number of primop calls: 838807
  number of function calls: 1930107

Statistics after:

  time elapsed: 1.17982
  size of a value: 24
  environments allocated: 1543334 (39624560 bytes)
  list elements: 9612638 (76901104 bytes)
  list concatenations: 37434
  values allocated: 1854933 (44518392 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18272
  number of thunks: 1392467
  number of thunks avoided: 1507311
  number of attr lookups: 430801
  number of primop calls: 691600
  number of function calls: 1492502
2012-08-13 00:28:08 -04:00
Eelco Dolstra 62f72eb9e1 Add some more evaluations stats 2012-08-12 23:41:48 -04:00
Eelco Dolstra e82767910c Add some basic profiling support to the evaluator
Setting the environment variable NIX_COUNT_CALLS to 1 enables some
basic profiling in the evaluator.  It will count calls to functions
and primops as well as evaluations of attributes.

For example, to see where evaluation of a NixOS configuration spends
its time:

$ NIX_SHOW_STATS=1 NIX_COUNT_CALLS=1 ./src/nix-instantiate/nix-instantiate '<nixos>' -A system --readonly-mode
...
calls to 39 primops:
    239532 head
    233962 tail
    191252 hasAttr
...
calls to 1595 functions:
    224157 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:19'
    221767 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:14'
    221767 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:10'
...
evaluations of 7088 attributes:
    167377 undefined position
    132459 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/attrsets.nix:119:41'
     47322 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/attrsets.nix:13:21'
...
2012-08-12 23:29:28 -04:00
Eelco Dolstra 325d1cfebf Don't warn about maximum link count exceeded on 0-byte files 2012-08-07 16:22:54 -04:00
Eelco Dolstra d025142f52 Handle amount of disk space saved by hard linking being negative
Fixes bogus messages like "currently hard linking saves
17592186044416.00 MiB".
2012-08-05 21:45:27 -04:00
Eelco Dolstra b6c989b801 Fix race condition when two processes create a hard link to a file in .links
This is a problem because one process may set the immutable bit before
the second process has created its link.

Addressed random Hydra failures such as:

error: cannot rename `/nix/store/.tmp-link-17397-1804289383' to
`/nix/store/rsvzm574rlfip3830ac7kmaa028bzl6h-nixos-0.1pre-git/upstart-interface-version':
Operation not permitted
2012-08-05 21:41:44 -04:00
Eelco Dolstra 108e14bb18 Fix race condition when two processes create the same link in /nix/store/.links 2012-08-05 18:17:55 -04:00
Eelco Dolstra 6763084ae5 Count bytes freed deleting unused links 2012-08-01 22:43:03 -04:00
Eelco Dolstra 01d56c1eec Drop the block count in the garbage collector 2012-08-01 22:34:46 -04:00
Eelco Dolstra 967d066d8e nix-store --gc: Make ‘--max-freed 0’ do the right thing
That is, delete almost nothing (it will still remove unused links from
/nix/store/.links).
2012-08-01 19:14:58 -04:00
Eelco Dolstra 1df702d347 removeUnusedLinks(): Print stats on disk space saved by hard linking 2012-08-01 19:01:50 -04:00
Eelco Dolstra 234ce610e0 Doh 2012-08-01 16:09:47 -04:00
Eelco Dolstra 7b10562370 Make ‘nix-store --optimise’ interruptible 2012-08-01 16:06:49 -04:00
Eelco Dolstra 3a4623afbb Set permissions on temporary build directories to 0700
Fixes #39.
2012-07-26 15:04:40 -04:00
Shea Levy f5954e2d94 prim_import: When importing .drvs, allocate the intermediate attrset on the heap just in case it escapes the stack frame. 2012-07-25 09:30:17 -04:00
Shea Levy b1112bbef1 import: If the path is a valid .drv file, parse it and generate a derivation attrset.
The generated attrset has drvPath and outPath with the right string context, type 'derivation', outputName with
the right name, all with a list of outputs, and an attribute for each output.

I see three uses for this (though certainly there may be more):

* Using derivations generated by something besides nix-instantiate (e.g. guix)

* Allowing packages provided by channels to be used in nix expressions. If a channel installed a valid deriver
  for each package it provides into the store, then those could be imported and used as dependencies or installed
  in environment.systemPackages, for example.

* Enable hydra to be consistent in how it treats inputs that are outputs of another build. Right now, if an
  input is passed as an argument to the job, it is passed as a derivation, but if it is accessed via NIX_PATH
  (i.e. through the <> syntax), then it is a path that can be imported. This is problematic because the build
  being depended upon may have been built with non-obvious arguments passed to its jobset file. With this
  feature, hydra can just set the name of that input to the path to its drv file in NIX_PATH
2012-07-25 09:30:17 -04:00
Eelco Dolstra e98c029717 Handle platforms that don't support linking to a symlink
E.g. Darwin doesn't allow this.
2012-07-23 18:42:18 -04:00
Eelco Dolstra fd63c8bfcd Unlink the right file 2012-07-23 18:06:37 -04:00
Eelco Dolstra 680ab6f83d Garbage collect unused links in /nix/store/.links
Incremental optimisation requires creating links in /nix/store/.links
to all files in the store.  However, this means that if we delete a
store path, no files are actually deleted because links in
/nix/store/.links still exists.  So we need to check /nix/store/.links
for files with a link count of 1 and delete them.
2012-07-23 17:14:16 -04:00
Eelco Dolstra 6193105710 Automatically optimise the Nix store when a new path is added
Auto-optimisation is enabled by default.  It can be turned off by
setting auto-optimise-store to false in nix.conf.
2012-07-23 17:14:15 -04:00
Eelco Dolstra 564fb7d9fa optimiseStore(): Use a content-addressed file store in /nix/store/.links
optimiseStore() now creates persistent, content-addressed hard links
in /nix/store/.links.  For instance, if it encounters a file P with
hash H, it will create a hard link

  P' = /nix/store/.link/<H>

to P if P' doesn't already exist; if P' exist, then P is replaced by a
hard link to P'.  This is better than the previous in-memory map,
because it had the tendency to unnecessarily replace hard links with a
hard link to whatever happened to be the first file with a given hash
it encountered.  It also allows on-the-fly, incremental optimisation.
2012-07-23 17:14:15 -04:00
Eelco Dolstra 6852289c46 Use lutimes() if available to canonicalise the timestamp of symlinks
Also use utimes() instead of utime() if lutimes() is not available.
2012-07-23 16:52:25 -04:00
Eelco Dolstra b7fd2c2822 Use "#pragma once" to prevent repeated header file inclusion 2012-07-18 14:59:03 -04:00
Eelco Dolstra ccc52adfb2 Add function queryPathFromHashPart()
To implement binary caches efficiently, Hydra needs to be able to map
the hash part of a store path (e.g. "gbg...zr7") to the full store
path (e.g. "/nix/store/gbg...kzr7-subversion-1.7.5").  (The binary
cache mechanism uses hash parts as a key for looking up store paths to
ensure privacy.)  However, doing a search in the Nix store for
/nix/store/<hash>* is expensive since it requires reading the entire
directory.  queryPathFromHashPart() prevents this by doing a cheap
database lookup.
2012-07-17 18:55:39 -04:00
Eelco Dolstra 3a9fdf2747 Return an exit code of 100 for cached failed builds
Exit code 100 should be returned for all permanent failures.  This
includes cached failures.

Fixes #34.
2012-07-17 15:55:30 -04:00
Eelco Dolstra 1217204c81 Remove dead code 2012-07-17 14:07:52 -04:00
Eelco Dolstra 6c01fb4d68 Update Nix 1.1 release notes 2012-07-17 10:06:20 -04:00
Eelco Dolstra 53b24f3518 Allow disabling log compression 2012-07-17 09:40:12 -04:00
Eelco Dolstra a7a43adb79 builtins.storePath: resolve symlinks
Needed for Charon/Hydra interaction.
2012-07-12 18:25:01 -04:00
Eelco Dolstra 1aba0bf0fa nix-store -r: do substitutions in parallel
I.e. when multiple non-derivation arguments are passed to ‘nix-store
-r’ to be substituted, do them in parallel.
2012-06-27 16:58:15 -04:00
Eelco Dolstra 42f5a2fc29 Mount an empty /dev/shm tmpfs in the chroot
This ensures that whatever the builder writes in /dev/shm is
automatically cleaned up.
2012-06-27 09:52:27 -04:00
Eelco Dolstra 3ee208516f Check the return code of the clone() call 2012-06-27 09:52:06 -04:00
Eelco Dolstra 1db38ae81b When using chroots, use a private PID namespace
In a private PID namespace, processes have PIDs that are separate from
the rest of the system.  The initial child gets PID 1.  Processes in
the chroot cannot see processes outside of the chroot.  This improves
isolation between builds.  However, processes on the outside can see
processes in the chroot and send signals to them (if they have
appropriate rights).

Since the builder gets PID 1, it serves as the reaper for zombies in
the chroot.  This might turn out to be a problem.  In that case we'll
need to have a small PID 1 process that sits in a loop calling wait().
2012-06-25 15:45:16 -04:00
Eelco Dolstra 5489086456 Use a private UTS namespace to provide a deterministic host/domain name to builders
In chroot builds, set the host name to "localhost" and the domain name
to "(none)" (the latter being the kernel's default).  This improves
determinism a bit further.

P.S. I have to idea what UTS stands for.
2012-06-25 14:12:17 -04:00
Eelco Dolstra 723a68c826 Improve error message 2012-06-23 00:57:14 -04:00
Eelco Dolstra 7ffa523fd1 In chroot builds, use a private SysV IPC namespace
This improves isolation a bit further, and it's just one extra flag in
the unshare() call.

P.S. It would be very cool to use CLONE_NEWPID (to put the builder in
a private PID namespace) as well, but that's slightly more risky since
having a builder start as PID 1 may cause problems.
2012-06-23 00:51:40 -04:00
Eelco Dolstra df716c98d2 In chroot builds, use a private network namespace
On Linux it's possible to run a process in its own network namespace,
meaning that it gets its own set of network interfaces, disjunct from
the rest of the system.  We use this to completely remove network
access to chroot builds, except that they get a private loopback
interface.  This means that:

- Builders cannot connect to the outside network or to other processes
  on the same machine, except processes within the same build.

- Vice versa, other processes cannot connect to processes in a chroot
  build, and open ports/connections do not show up in "netstat".

- If two concurrent builders try to listen on the same port (e.g. as
  part of a test), they no longer conflict with each other.

This was inspired by the "PrivateNetwork" flag in systemd.
2012-06-23 00:28:35 -04:00
Eelco Dolstra 2f3f413e91 Support socket-based, on-demand activation of the Nix daemon with systemd
Systemd can start the Nix daemon on demand when the Nix daemon socket
is first accessed.  This is signalled through the LISTEN_FDS
environment variable, so all we need to do is check for that and then
use file descriptor 3 as the listen socket instead of creating one
ourselves.
2012-06-18 23:01:46 -04:00
Eelco Dolstra f5398d374b Compress build logs on the fly using bzip2 2012-05-30 10:12:29 -04:00
Eelco Dolstra 881beb170d "nix-store -l": support compressed logs 2012-05-30 00:00:02 -04:00
Eelco Dolstra 4bc4da331a Reserve some disk space for the garbage collector
We can't open a SQLite database if the disk is full.  Since this
prevents the garbage collector from running when it's most needed, we
reserve some dummy space that we can free just before doing a garbage
collection.  This actually revives some old code from the Berkeley DB
days.

Fixes #27.
2012-05-29 22:59:12 -04:00