From f5325d292d79f174f73b35ed886ae83bb80896cc Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 19 Nov 2008 10:59:36 +0000 Subject: [PATCH] * Release notes. --- doc/manual/release-notes.xml | 156 +++++++++++++++++++++++++++++++---- 1 file changed, 138 insertions(+), 18 deletions(-) diff --git a/doc/manual/release-notes.xml b/doc/manual/release-notes.xml index b64e2025c..c2eaa28bc 100644 --- a/doc/manual/release-notes.xml +++ b/doc/manual/release-notes.xml @@ -12,26 +12,85 @@ - TODO: Berkeley DB no longer needed. + + 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. - New substituter to copy from remotely mounted Nix - stores (TODO: document). + 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 + configure option + . - nix-store --dump-db / --load-db. + After the automatic conversion to the new schema, you can + delete the old Berkeley DB files: - New primops: - builtins.parseDrvName, - builtins.compareVersions, - builtins.length, - builtins.add, - builtins.sub, - builtins.genericClosure. - + +$ cd /nix/var/nix/db +$ rm __db* log.* derivers references referrers reserved validpaths DB_CONFIG - GC options: , - . + The new metadata is stored in the directories + /nix/var/nix/db/info and + /nix/var/nix/db/referrer. 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. - TODO: Optimistic profile locking. + 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 ext3 default nowadays) it + usually takes up much less space. + + + 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 sshfs. The environment + variable NIX_OTHER_STORES specifies the locations of + the remote Nix directories, + e.g. /mnt/remote-fs/nix. + + New nix-store operations + and to dump + and reload the Nix database. + + The garbage collector has a number of new options to + allow only some of the garbage to be deleted. The option + tells the + collector to stop after at least N bytes + have been deleted. The option tells it to stop after the + link count on /nix/store has dropped below + N. This is useful on very large Nix + stores on filesystems with a 32000 subdirectories limit (like + ext3). The 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 + specifies an upper limit to the last accessed time of paths that may + be deleted. For instance, + + + $ nix-store --gc -v --max-atime $(date +%s -d "2 months ago") + + deletes everything that hasn’t been accessed in two months. + + nix-env 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 nix-env -i / -u / -e + operations on the same profile in parallel. If a + nix-env operation sees at th 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. The option is now supported by nix-store -r and @@ -42,17 +101,78 @@ and which paths will be substituted) is now always shown by nix-env, nix-store -r and nix-build. The total download size of - substitutable paths is now also shown. + substitutable paths is now also shown. For instance, a build will + show something like + + +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 + ... + + + + Language features: + + + + @-patterns as in Haskell. For instance, in a + function definition + + f = args @ {x, y, z}: ...; + + args refers to the argument as a whole, which + is further pattern-matched against the attribute set pattern + {x, y, z}. + + “...” (ellipsis) patterns. + An attribute set pattern can now say ... at + the end of the attribute name list to specify that the function + takes at least the listed attributes, while + ignoring additional attributes. For instance, + + {stdenv, fetchurl, fuse, ...}: ... + + defines a function that accepts any attribute set that includes + at least the three listed attributes. + + New primops: + builtins.parseDrvName (split a package name + string like "nix-0.12pre12876" into its name + and version components, e.g. "nix" and + "0.12pre12876"), + builtins.compareVersions (compare two version + strings using the same algorithm that nix-env + uses), builtins.length (efficiently compute + the length of a list), builtins.mul (integer + multiplication), builtins.div (integer + division). + + + + + + nix-prefetch-url now supports - mirror:// URLs. + mirror:// URLs, provided that the environment + variable NIXPKGS_ALL points at a Nixpkgs + tree. Removed the commands nix-pack-closure and nix-unpack-closure. You can do almost the same thing but much more efficiently by doing nix-store --export $(nix-store -qR paths) > closure and - nix-store --import < closure. + nix-store --import < + closure. + + Lots of bugfixes, including a big performance bug in + the handling of with-expressions.