faster than the old mode when fsyncs are enabled, because it only
performs an fsync() when doing a checkpoint, rather than at every
commit. Some timings for doing a "nix-instantiate /etc/nixos/nixos
-A system" after modifying the stdenv setup script:
42.5s - SQLite 3.6.23 with truncate mode and fsync
3.4s - SQLite 3.6.23 with truncate mode and no fsync
32.1s - SQLite 3.7.0 with truncate mode and fsync
16.8s - SQLite 3.7.0 with WAL mode and fsync, auto-checkpoint
every 1000 pages
8.3s - SQLite 3.7.0 with WAL mode and fsync, auto-checkpoint
every 8192 pages
1.7s - SQLite 3.7.0 with WAL mode and no fsync
The default is now to use WAL mode with fsyncs. Because WAL doesn't
work on remote filesystems such as NFS (as it uses shared memory),
truncate mode can be re-enabled by setting the "use-sqlite-wal"
option to false.
Defining -D_FILE_OFFSET_BITS=64 works on most platforms, but not on all (i.e.
Solaris). Also, the Autoconf macro offers the user a switch to disable the
functionality in case of problems.
would just silently store only (fileSize % 2^32) bytes.
* Use posix_fallocate if available when unpacking archives.
* Provide a better error message when trying to unpack something that
isn't a NAR archive.
bind-mounts we do are only visible to the builder process and its
children. So accidentally doing "rm -rf" on the chroot directory
won't wipe out /nix/store and other bind-mounted directories
anymore. Also, the bind-mounts in the private namespace disappear
automatically when the builder exits.
get the basename of the channel URL (e.g., nixpkgs-unstable). The
top-level Nix expression of the channel is now an attribute set, the
attributes of which are the individual channels (e.g.,
{nixpkgs_unstable = ...; strategoxt_unstable = ...}). This makes
attribute paths ("nix-env -qaA" and "nix-env -iA") more sensible,
e.g., "nix-env -iA nixpkgs_unstable.subversion".
that have to be done as root: running builders under different uids,
changing ownership of build results, and deleting paths in the store
with the wrong ownership).
* Some refactoring: put the NAR archive integer/string serialisation
code in a separate file so it can be reused by the worker protocol
implementation.
Rather, setuid support is now always compiled in (at least on
platforms that have the setresuid system call, e.g., Linux and
FreeBSD), but it must enabled by chowning/chmodding the Nix
binaries.
