It was made transactional in a4678c6ba1, with
the reasoning to prevent broken intermediate states from being visible. I
think this means something like an entry being in ValidPaths, but the Refs not
being inserted.
Using a transaction for this makes sense, but I think using one single
transaction for the whole register-items call is unnecessary to avoid broken
states from being visible, and could block other writes to the store database
while register-items is running. Because the deduplication and resetting
timestamps happens within the transaction as well, even though these things
don't involve the database, writes to the database will still be blocked while
this is happening.
To reduce the potential for register-items to block other writers to the
database for extended periods, this commit moves the transaction to just wrap
the call to sqlite-register. This is the one place where writes occur, so that
should prevent the broken intermediate states issue above. The one difference
this will make is some of the registered items will be visible to other
connections while others may be still being added. I think this is OK, as it's
equivalent to just registering different items.
* guix/store/database.scm (register-items): Reduce transaction scope.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
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-*- mode: org -*-
[[https://www.gnu.org/software/guix/][GNU Guix]] (IPA: /ɡiːks/) is a purely functional package manager, and
associated free software distribution, for the [[https://www.gnu.org/gnu/gnu.html][GNU system]]. In addition
to standard package management features, Guix supports transactional
upgrades and roll-backs, unprivileged package management, per-user
profiles, and garbage collection.
It provides [[https://www.gnu.org/software/guile/][Guile]] Scheme APIs, including a high-level embedded
domain-specific languages (EDSLs) to describe how packages are to be
built and composed.
GNUGuix can be used on top of an already-installed GNU/Linux distribution, or
it can be used standalone (we call that “Guix System”).
Guix is based on the [[https://nixos.org/nix/][Nix]] package manager.
* Requirements
If you are building Guix from source, please see the manual for build
instructions and requirements, either by running:
info -f doc/guix.info "Requirements"
or by checking the [[https://guix.gnu.org/manual/en/html_node/Requirements.html][web copy of the manual]].
* Installation
See the manual for the installation instructions, either by running
info -f doc/guix.info "Installation"
or by checking the [[https://guix.gnu.org/manual/en/html_node/Installation.html][web copy of the manual]].
For information on installation from a Git checkout, please see the section
"Building from Git" in the manual.
* Installing Guix from Guix
You can re-build and re-install Guix using a system that already runs Guix.
To do so:
- Start a shell with the development environment for Guix:
guix environment guix
- Re-run the 'configure' script passing it the option
'--localstatedir=/somewhere', where '/somewhere' is the 'localstatedir'
value of the currently installed Guix (failing to do that would lead the
new Guix to consider the store to be empty!). We recommend to use the
value '/var'.
- Run "make", "make check", and "make install".
* How It Works
Guix does the high-level preparation of a /derivation/. A derivation is
the promise of a build; it is stored as a text file under
=/gnu/store/xxx.drv=. The (guix derivations) module provides the
`derivation' primitive, as well as higher-level wrappers such as
`build-expression->derivation'.
Guix does remote procedure calls (RPCs) to the build daemon (the =guix-daemon=
command), which in turn performs builds and accesses to the store on its
behalf. The RPCs are implemented in the (guix store) module.
* Contact
GNU Guix is hosted at https://savannah.gnu.org/projects/guix/.
Please email <help-guix@gnu.org> for questions and <bug-guix@gnu.org> for bug
reports; email <gnu-system-discuss@gnu.org> for general issues regarding the
GNU system.
Join #guix on irc.freenode.net.
* Guix & Nix
GNU Guix is based on [[https://nixos.org/nix/][the Nix package manager]]. It implements the same
package deployment paradigm, and in fact it reuses some of its code.
Yet, different engineering decisions were made for Guix, as described
below.
Nix is really two things: a package build tool, implemented by a library
and daemon, and a special-purpose programming language. GNU Guix relies
on the former, but uses Scheme as a replacement for the latter.
Using Scheme instead of a specific language allows us to get all the
features and tooling that come with Guile (compiler, debugger, REPL,
Unicode, libraries, etc.) And it means that we have a general-purpose
language, on top of which we can have embedded domain-specific languages
(EDSLs), such as the one used to define packages. This broadens what
can be done in package recipes themselves, and what can be done around them.
Technically, Guix makes remote procedure calls to the ‘nix-worker’
daemon to perform operations on the store. At the lowest level, Nix
“derivations” represent promises of a build, stored in ‘.drv’ files in
the store. Guix produces such derivations, which are then interpreted
by the daemon to perform the build. Thus, Guix derivations can use
derivations produced by Nix (and vice versa).
With Nix and the [[https://nixos.org/nixpkgs][Nixpkgs]] distribution, package composition happens at
the Nix language level, but builders are usually written in Bash.
Conversely, Guix encourages the use of Scheme for both package
composition and builders. Likewise, the core functionality of Nix is
written in C++ and Perl; Guix relies on some of the original C++ code,
but exposes all the API as Scheme.
* Related software
- [[https://nixos.org][Nix, Nixpkgs, and NixOS]], functional package manager and associated
software distribution, are the inspiration of Guix
- [[https://www.gnu.org/software/stow/][GNU Stow]] builds around the idea of one directory per prefix, and a
symlink tree to create user environments
- [[https://www.pvv.ntnu.no/~arnej/store/storedoc_6.html][STORE]] shares the same idea
- [[https://live.gnome.org/OSTree/][GNOME's OSTree]] allows bootable system images to be built from a
specified set of packages
- The [[https://www.gnu.org/s/gsrc/][GNU Source Release Collection]] (GSRC) is a user-land software
distribution; unlike Guix, it relies on core tools available on the
host system
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