mirror of
https://github.com/NixOS/nix.git
synced 2024-12-13 00:52:32 +00:00
175 lines
7.6 KiB
XML
175 lines
7.6 KiB
XML
<section xmlns="http://docbook.org/ns/docbook"
|
||
xmlns:xlink="http://www.w3.org/1999/xlink"
|
||
xmlns:xi="http://www.w3.org/2001/XInclude"
|
||
version="5.0"
|
||
xml:id="ssec-relnotes-0.12">
|
||
|
||
<title>Release 0.12 (November 20, 2008)</title>
|
||
|
||
<itemizedlist>
|
||
|
||
<listitem>
|
||
<para>Nix no longer uses Berkeley DB to store Nix store metadata.
|
||
The principal advantages of the new storage scheme are: it works
|
||
properly over decent implementations of NFS (allowing Nix stores
|
||
to be shared between multiple machines); no recovery is needed
|
||
when a Nix process crashes; no write access is needed for
|
||
read-only operations; no more running out of Berkeley DB locks on
|
||
certain operations.</para>
|
||
|
||
<para>You still need to compile Nix with Berkeley DB support if
|
||
you want Nix to automatically convert your old Nix store to the
|
||
new schema. If you don’t need this, you can build Nix with the
|
||
<filename>configure</filename> option
|
||
<option>--disable-old-db-compat</option>.</para>
|
||
|
||
<para>After the automatic conversion to the new schema, you can
|
||
delete the old Berkeley DB files:
|
||
|
||
<screen>
|
||
$ cd /nix/var/nix/db
|
||
$ rm __db* log.* derivers references referrers reserved validpaths DB_CONFIG</screen>
|
||
|
||
The new metadata is stored in the directories
|
||
<filename>/nix/var/nix/db/info</filename> and
|
||
<filename>/nix/var/nix/db/referrer</filename>. Though the
|
||
metadata is stored in human-readable plain-text files, they are
|
||
not intended to be human-editable, as Nix is rather strict about
|
||
the format.</para>
|
||
|
||
<para>The new storage schema may or may not require less disk
|
||
space than the Berkeley DB environment, mostly depending on the
|
||
cluster size of your file system. With 1 KiB clusters (which
|
||
seems to be the <literal>ext3</literal> default nowadays) it
|
||
usually takes up much less space.</para>
|
||
</listitem>
|
||
|
||
<listitem><para>There is a new substituter that copies paths
|
||
directly from other (remote) Nix stores mounted somewhere in the
|
||
filesystem. For instance, you can speed up an installation by
|
||
mounting some remote Nix store that already has the packages in
|
||
question via NFS or <literal>sshfs</literal>. The environment
|
||
variable <envar>NIX_OTHER_STORES</envar> specifies the locations of
|
||
the remote Nix directories,
|
||
e.g. <literal>/mnt/remote-fs/nix</literal>.</para></listitem>
|
||
|
||
<listitem><para>New <command>nix-store</command> operations
|
||
<option>--dump-db</option> and <option>--load-db</option> to dump
|
||
and reload the Nix database.</para></listitem>
|
||
|
||
<listitem><para>The garbage collector has a number of new options to
|
||
allow only some of the garbage to be deleted. The option
|
||
<option>--max-freed <replaceable>N</replaceable></option> tells the
|
||
collector to stop after at least <replaceable>N</replaceable> bytes
|
||
have been deleted. The option <option>--max-links
|
||
<replaceable>N</replaceable></option> tells it to stop after the
|
||
link count on <filename>/nix/store</filename> has dropped below
|
||
<replaceable>N</replaceable>. This is useful for very large Nix
|
||
stores on filesystems with a 32000 subdirectories limit (like
|
||
<literal>ext3</literal>). The option <option>--use-atime</option>
|
||
causes store paths to be deleted in order of ascending last access
|
||
time. This allows non-recently used stuff to be deleted. The
|
||
option <option>--max-atime <replaceable>time</replaceable></option>
|
||
specifies an upper limit to the last accessed time of paths that may
|
||
be deleted. For instance,
|
||
|
||
<screen>
|
||
$ nix-store --gc -v --max-atime $(date +%s -d "2 months ago")</screen>
|
||
|
||
deletes everything that hasn’t been accessed in two months.</para></listitem>
|
||
|
||
<listitem><para><command>nix-env</command> now uses optimistic
|
||
profile locking when performing an operation like installing or
|
||
upgrading, instead of setting an exclusive lock on the profile.
|
||
This allows multiple <command>nix-env -i / -u / -e</command>
|
||
operations on the same profile in parallel. If a
|
||
<command>nix-env</command> operation sees at the end that the profile
|
||
was changed in the meantime by another process, it will just
|
||
restart. This is generally cheap because the build results are
|
||
still in the Nix store.</para></listitem>
|
||
|
||
<listitem><para>The option <option>--dry-run</option> is now
|
||
supported by <command>nix-store -r</command> and
|
||
<command>nix-build</command>.</para></listitem>
|
||
|
||
<listitem><para>The information previously shown by
|
||
<option>--dry-run</option> (i.e., which derivations will be built
|
||
and which paths will be substituted) is now always shown by
|
||
<command>nix-env</command>, <command>nix-store -r</command> and
|
||
<command>nix-build</command>. The total download size of
|
||
substitutable paths is now also shown. For instance, a build will
|
||
show something like
|
||
|
||
<screen>
|
||
the following derivations will be built:
|
||
/nix/store/129sbxnk5n466zg6r1qmq1xjv9zymyy7-activate-configuration.sh.drv
|
||
/nix/store/7mzy971rdm8l566ch8hgxaf89x7lr7ik-upstart-jobs.drv
|
||
...
|
||
the following paths will be downloaded/copied (30.02 MiB):
|
||
/nix/store/4m8pvgy2dcjgppf5b4cj5l6wyshjhalj-samba-3.2.4
|
||
/nix/store/7h1kwcj29ip8vk26rhmx6bfjraxp0g4l-libunwind-0.98.6
|
||
...</screen>
|
||
|
||
</para></listitem>
|
||
|
||
<listitem><para>Language features:
|
||
|
||
<itemizedlist>
|
||
|
||
<listitem><para>@-patterns as in Haskell. For instance, in a
|
||
function definition
|
||
|
||
<programlisting>f = args @ {x, y, z}: <replaceable>...</replaceable>;</programlisting>
|
||
|
||
<varname>args</varname> refers to the argument as a whole, which
|
||
is further pattern-matched against the attribute set pattern
|
||
<literal>{x, y, z}</literal>.</para></listitem>
|
||
|
||
<listitem><para>“<literal>...</literal>” (ellipsis) patterns.
|
||
An attribute set pattern can now say <literal>...</literal> at
|
||
the end of the attribute name list to specify that the function
|
||
takes <emphasis>at least</emphasis> the listed attributes, while
|
||
ignoring additional attributes. For instance,
|
||
|
||
<programlisting>{stdenv, fetchurl, fuse, ...}: <replaceable>...</replaceable></programlisting>
|
||
|
||
defines a function that accepts any attribute set that includes
|
||
at least the three listed attributes.</para></listitem>
|
||
|
||
<listitem><para>New primops:
|
||
<varname>builtins.parseDrvName</varname> (split a package name
|
||
string like <literal>"nix-0.12pre12876"</literal> into its name
|
||
and version components, e.g. <literal>"nix"</literal> and
|
||
<literal>"0.12pre12876"</literal>),
|
||
<varname>builtins.compareVersions</varname> (compare two version
|
||
strings using the same algorithm that <command>nix-env</command>
|
||
uses), <varname>builtins.length</varname> (efficiently compute
|
||
the length of a list), <varname>builtins.mul</varname> (integer
|
||
multiplication), <varname>builtins.div</varname> (integer
|
||
division).
|
||
<!-- <varname>builtins.genericClosure</varname> -->
|
||
</para></listitem>
|
||
|
||
</itemizedlist>
|
||
|
||
</para></listitem>
|
||
|
||
<listitem><para><command>nix-prefetch-url</command> now supports
|
||
<literal>mirror://</literal> URLs, provided that the environment
|
||
variable <envar>NIXPKGS_ALL</envar> points at a Nixpkgs
|
||
tree.</para></listitem>
|
||
|
||
<listitem><para>Removed the commands
|
||
<command>nix-pack-closure</command> and
|
||
<command>nix-unpack-closure</command>. You can do almost the same
|
||
thing but much more efficiently by doing <literal>nix-store --export
|
||
$(nix-store -qR <replaceable>paths</replaceable>) > closure</literal> and
|
||
<literal>nix-store --import <
|
||
closure</literal>.</para></listitem>
|
||
|
||
<listitem><para>Lots of bug fixes, including a big performance bug in
|
||
the handling of <literal>with</literal>-expressions.</para></listitem>
|
||
|
||
</itemizedlist>
|
||
|
||
</section> |