forked from lix-project/lix
* Manual updates.
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</para>
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</para>
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</listitem>
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<listitem>
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<para>
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Unify the concepts of successors and substitutes into a
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general notion of <emphasis>equivalent expressions</emphasis>.
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Expressions are equivalent if they have the same target paths
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with the same identifiers. However, even though they are
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functionally equivalent, they may differ stronly with respect
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to their <emphasis>performance characteristics</emphasis>.
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For example, realising a closure expression is more efficient
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that realising the derivation expression from which it was
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produced. On the other hand, distributing sources may be more
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efficient (storage- or bandwidth-wise) than distributing
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binaries. So we need to be able to attach weigths or
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priorities or performance annotations to expressions; Nix can
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then choose the most efficient expression dependent on the
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context.
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</para>
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</listitem>
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<listitem>
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<listitem>
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<para>
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<para>
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<emphasis>Build management.</emphasis> In principle it is already
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<emphasis>Build management.</emphasis> In principle it is already
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@ -52,41 +33,6 @@
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</para>
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</para>
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</listitem>
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</listitem>
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<listitem>
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<para>
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There are race conditions between the garbage collector and
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other Nix tools. For instance, when we run
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<command>nix-env</command> to build and install a derivation
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and run the garbage collector at the same time, the garbage
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collector may kick in exactly between the build and
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installation steps, i.e., before the newly built derivation
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has become reachable from a root of the garbage collector.
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</para>
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<para>
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One solution would be for these programs to properly register
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temporary roots for the collector. Another would be to use
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stop-the-world garbage collection: if any tool is running, the
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garbage collector blocks, and vice versa. These solutions do
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not solve the situation where multiple tools are involved,
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e.g.,
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<screen>
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$ nix-store -r $(nix-instantiate foo.nix)</screen>
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since even if <command>nix-instantiate</command> where to
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register a temporary root, it would be released by the time
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<command>nix-store</command> is started. A solution would be
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to write the intermediate value to a file that is used as a
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root to the collector, e.g.,
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<screen>
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$ nix-instantiate foo.nix > /nix/var/nix/roots/bla
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$ nix-store -r $(cat /nix/var/nix/roots/bla)</screen>
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</para>
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</listitem>
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<listitem><para>For security, <command>nix-push</command> manifests
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<listitem><para>For security, <command>nix-push</command> manifests
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should be digitally signed, and <command>nix-pull</command> should
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should be digitally signed, and <command>nix-pull</command> should
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verify the signatures. The actual NAR archives in the cache do not
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verify the signatures. The actual NAR archives in the cache do not
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@ -94,11 +40,6 @@ need to be signed, since the manifest contains cryptographic hashes of
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these files (and <filename>fetchurl.nix</filename> checks
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these files (and <filename>fetchurl.nix</filename> checks
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them).</para></listitem>
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them).</para></listitem>
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<listitem><para>We should switch away from MD5, since it has been
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more-or-less cracked. We don't currently depend very much on the
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collision-resistance of MD5, but we will once we start sharing build
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results between users.</para></listitem>
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<listitem><para>It would be useful to have an option in
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<listitem><para>It would be useful to have an option in
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<command>nix-env --delete-generations</command> to remove non-current
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<command>nix-env --delete-generations</command> to remove non-current
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generations older than a certain age.</para></listitem>
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generations older than a certain age.</para></listitem>
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@ -130,11 +130,7 @@ collection. It also discusses some advanced topics, such as setting
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up a Nix-based build farm, and doing service deployment using
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up a Nix-based build farm, and doing service deployment using
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Nix.</para>
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Nix.</para>
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<warning><para>This manual is a work in progress. It's quite likely
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<note><para>Some background information on Nix can be found in three
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to be incomplete, inconsistent with the current implementation, or
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simply wrong.</para></warning>
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<note><para>Some background information on Nix can be found in two
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papers. The ICSE 2004 paper <ulink
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papers. The ICSE 2004 paper <ulink
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url='http://www.cs.uu.nl/~eelco/pubs/immdsd-icse2004-final.pdf'><citetitle>Imposing
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url='http://www.cs.uu.nl/~eelco/pubs/immdsd-icse2004-final.pdf'><citetitle>Imposing
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a Memory Management Discipline on Software
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a Memory Management Discipline on Software
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@ -145,6 +141,10 @@ different versions and variants of packages. The LISA 2004 paper
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url='http://www.cs.uu.nl/~eelco/pubs/nspfssd-lisa2004-final.pdf'><citetitle>Nix:
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url='http://www.cs.uu.nl/~eelco/pubs/nspfssd-lisa2004-final.pdf'><citetitle>Nix:
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A Safe and Policy-Free System for Software
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A Safe and Policy-Free System for Software
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Deployment</citetitle></ulink> gives a more general discussion of Nix
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Deployment</citetitle></ulink> gives a more general discussion of Nix
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from a system-administration perspective.</para></note>
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from a system-administration perspective. The CBSE 2005 paper <ulink
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url='http://www.cs.uu.nl/~eelco/pubs/eupfcdm-cbse2005-final.pdf'><citetitle>Efficient
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Upgrading in a Purely Functional Component Deployment Model
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</citetitle></ulink> is about transparent patch deployment in
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Nix.</para></note>
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</chapter>
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</chapter>
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@ -36,6 +36,7 @@
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</author>
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</author>
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<copyright>
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<copyright>
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<year>2004</year>
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<year>2004</year>
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<year>2005</year>
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<holder>Eelco Dolstra</holder>
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<holder>Eelco Dolstra</holder>
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</copyright>
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</copyright>
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</bookinfo>
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</bookinfo>
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@ -189,12 +189,12 @@ of the Subversion component might be stored in a directory
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while another version might be stored in
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while another version might be stored in
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<filename>/nix/store/58823d558a6a...-subversion-0.34/</filename>. The
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<filename>/nix/store/58823d558a6a...-subversion-0.34/</filename>. The
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long hexadecimal numbers prefixed to the directory names are
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long hexadecimal numbers prefixed to the directory names are
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cryptographic hashes<footnote><para>128 bit MD5 hashes, to be
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cryptographic hashes<footnote><para>160-bit truncations of SHA-256
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precise.</para></footnote> of <emphasis>all</emphasis> inputs involved
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hashes, to be precise.</para></footnote> of <emphasis>all</emphasis>
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in building the component — sources, dependencies, compiler flags, and
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inputs involved in building the component — sources, dependencies,
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so on. So if two components differ in any way, they end up in
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compiler flags, and so on. So if two components differ in any way,
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different locations in the file system, so they don't interfere with
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they end up in different locations in the file system, so they don't
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each other. <xref linkend='fig-user-environments'
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interfere with each other. <xref linkend='fig-user-environments'
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/><footnote><para>TODO: the figure isn't entirely up to date. It
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/><footnote><para>TODO: the figure isn't entirely up to date. It
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should show multiple profiles and
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should show multiple profiles and
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<filename>~/.nix-profile</filename>.</para></footnote> shows a part of
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<filename>~/.nix-profile</filename>.</para></footnote> shows a part of
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