little RAM. Even if the memory isn't actually used, it can cause
problems with the overcommit heuristics in the kernel. So use a VM
space of 25% of RAM, up to 384 MB.
because Berkeley DB needed it on some platforms, but we don't use
BDB anymore.
On FreeBSD, if you link against pthreads, then the main thread gets
a 2 MB stack which cannot be overriden (it ignores "ulimit -s"):
http://www.mail-archive.com/freebsd-hackers@freebsd.org/msg62445.html
This is not enough for Nix. For instance, the garbage collector can
fail if there is a pathologically deep chain of references
(http://hydra.nixos.org/build/556199). 2 MB is also not enough for
many Nix expressions.
Arguably the garbage collector shouldn't use recursion, because in
NixOS unprivileged users can DOS the garbage collector by creating a
sufficiently deeply nested chain of references. But getting rid of
recursion is a bit harder.
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.
externals directory. This is in particular useful because though
most systems have bzip2/bunzip2, they don't always have libbz2,
which we need for bsdiff/bspatch.
implementations of MD5, SHA-1 and SHA-256. The main benefit is that
we get assembler-optimised implementations of MD5 and SHA-1 (though
not SHA-256 (at least on x86), unfortunately). OpenSSL's SHA-1
implementation on Intel is twice as fast as ours.
http://www.daemonology.net/bsdiff/bsdiff-4.2.tar.gz) into the source
tree. The license is a bit peculiar, but it does allow verbatim
copying, which is what we do here (i.e., so don't make any changes
to the sources).
