after #6218 `Symbol` no longer confers a uniqueness invariant on the
string it wraps, it is now possible to create multiple symbols that
compare equal but whose string contents have different addresses. this
guarantee is now only provided by `SymbolIdx`, leaving `Symbol` only as
a string wrapper that knows about the intricacies of how symbols need to
be formatted for output.
this change renames `SymbolIdx` to `Symbol` to restore the previous
semantics of `Symbol` to that name. we also keep the wrapper type and
rename it to `SymbolStr` instead of returning plain strings from lookups
into the symbol table because symbols are formatted for output in many
places. theoretically we do not need `SymbolStr`, only a function that
formats a string for output as a symbol, but having to wrap every symbol
that appears in a message into eg `formatSymbol()` is error-prone and
inconvient.
this slightly increases the amount of memory used for any given symbol, but this
increase is more than made up for if the symbol is referenced more than once in
the EvalState that holds it. on average every symbol should be referenced at
least twice (once to introduce a binding, once to use it), so we expect no
increase in memory on average.
symbol tables are limited to 2³² entries like position tables, and similar
arguments apply to why overflow is not likely: 2³² symbols would require as many
string instances (at 24 bytes each) and map entries (at 24 bytes or more each,
assuming that the map holds on average at most one item per bucket as the docs
say). a full symbol table would require at least 192GB of memory just for
symbols, which is well out of reach. (an ofborg eval of nixpks today creates
less than a million symbols!)
Pos objects are somewhat wasteful as they duplicate the origin file name and
input type for each object. on files that produce more than one Pos when parsed
this a sizeable waste of memory (one pointer per Pos). the same goes for
ptr<Pos> on 64 bit machines: parsing enough source to require 8 bytes to locate
a position would need at least 8GB of input and 64GB of expression memory. it's
not likely that we'll hit that any time soon, so we can use a uint32_t index to
locate positions instead.
In particular, this means that 'nix eval` (which uses toValue()) no
longer auto-calls functions or functors (because
AttrCursor::findAlongAttrPath() doesn't).
Fixes#6152.
Also use ref<> in a few places, and don't return attrpaths from
getCursor() because cursors already have a getAttrPath() method.
This is useful whenever we want to evaluate something to a store path
(e.g. in get-drvs.cc).
Extracted from the lazy-trees branch (where we can require that a
store path must come from a store source tree accessor).
Rather than having them plain strings scattered through the whole
codebase, create an enum containing all the known experimental features.
This means that
- Nix can now `warn` when an unkwown experimental feature is passed
(making it much nicer to spot typos and spot deprecated features)
- It’s now easy to remove a feature altogether (once the feature isn’t
experimental anymore or is dropped) by just removing the field for the
enum and letting the compiler point us to all the now invalid usages
of it.
The boolean is only used to determine if the formals are set to a
non-null pointer in all our cases. We can get rid of that allocation and
instead just compare the pointer value with NULL. Saving up to
sizeof(bool) + platform specific alignment per ExprLambda instace.
Probably not a lot of memory but perhaps a few kilobyte with nixpkgs?
This also gets rid of a potential issue with dereferencing formals based on
the value of the boolean that didn't have to be aligned with the formals
pointer but was in all our cases.
It's now disabled by default for the following:
* 'nix search' (this was already implied by read-only mode)
* 'nix flake show'
* 'nix flake check', but only on the hydraJobs output
When the `keep-going` option is set to `true`, make `nix flake check`
continue as much as it can before failing.
The UI isn’t perfect as-it-is as all the lines currently start with a
mostly useless `error (ignored): error:` prefix, but I’m not sure what
the best output would be, so I’ll leave it as-it-is for the time being
(This is a bit hijacking the `keep-going` flag as it’s supposed to be a
build-time only thing. But I think it’s faire to reuse it here).
Fix https://github.com/NixOS/nix/issues/4450
This avoids an ambiguity where the `StorePathWithOutputs { drvPath, {}
}` could mean "build `brvPath`" or "substitute `drvPath`" depending on
context.
It also brings the internals closer in line to the new CLI, by
generalizing the `Buildable` type is used there and makes that
distinction already.
In doing so, relegate `StorePathWithOutputs` to being a type just for
backwards compatibility (CLI and RPC).
This is probably what most people expect it to do. Fixes#3781.
There is a new command 'nix flake lock' that has the old behaviour of
'nix flake update', i.e. it just adds missing lock file entries unless
overriden using --update-input.
This adds a ‘nix export’ command which hooks into nix-bundle. It can
be used in a similar way as nix-bundle, with the benefit of hooking
into the new “app” functionality. For instance,
$ nix export nixpkgs#jq
$ ./jq --help
jq - commandline JSON processor [version 1.6]
...
$ scp jq machine-without-nix:
$ ssh machine-without-nix ./jq
jq - commandline JSON processor [version 1.6]
...
Note that nix-bundle currently requires Linux to run. Other exporters
might not have that requirement.
“exporters” are meant to be reusable, so that, other repos can
implement their own bundling.
Fixes#3705
'nix run' will try to run $out/bin/<name>, where <name> is the
derivation name (excluding the version). This often works well:
$ nix run nixpkgs#hello
Hello, world!
$ nix run nix -- --version
nix (Nix) 2.4pre20200626_adf2fbb
$ nix run patchelf -- --version
patchelf 0.11.20200623.e61654b
$ nix run nixpkgs#firefox -- --version
Mozilla Firefox 77.0.1
$ nix run nixpkgs#gimp -- --version
GNU Image Manipulation Program version 2.10.14
though not always:
$ nix run nixpkgs#git
error: unable to execute '/nix/store/kp7wp760l4gryq9s36x481b2x4rfklcy-git-2.25.4/bin/git-minimal': No such file or directory
This fixes an issue where lockfile generation was not idempotent:
after updating a lockfile, a "follows" node would end up pointing to a
new copy of the node, rather than to the original node.
The initial contents of the flake is specified by the
'templates.<name>' or 'defaultTemplate' output of another flake. E.g.
outputs = { self }: {
templates = {
nixos-container = {
path = ./nixos-container;
description = "An example of a NixOS container";
};
};
};
allows
$ nix flake init -t templates#nixos-container
Also add a command 'nix flake new', which is identical to 'nix flake
init' except that it initializes a specified directory rather than the
current directory.
The attributes previously stored in TreeInfo (narHash, revCount,
lastModified) are now stored in Input. This makes it less arbitrary
what attributes are stored where.
As a result, the lock file format has changed. An entry like
"info": {
"lastModified": 1585405475,
"narHash": "sha256-bESW0n4KgPmZ0luxvwJ+UyATrC6iIltVCsGdLiphVeE="
},
"locked": {
"owner": "NixOS",
"repo": "nixpkgs",
"rev": "b88ff468e9850410070d4e0ccd68c7011f15b2be",
"type": "github"
},
is now stored as
"locked": {
"owner": "NixOS",
"repo": "nixpkgs",
"rev": "b88ff468e9850410070d4e0ccd68c7011f15b2be",
"type": "github",
"lastModified": 1585405475,
"narHash": "sha256-bESW0n4KgPmZ0luxvwJ+UyATrC6iIltVCsGdLiphVeE="
},
The 'Input' class is now a dumb set of attributes. All the fetcher
implementations subclass InputScheme, not Input. This simplifies the
API.
Also, fix substitution of flake inputs. This was broken since lazy
flake fetching started using fetchTree internally.
This makes 'nix flake' less cluttered and more consistent (it's only
subcommands that operator on a flake). Also, the registry is not
inherently flake-related (e.g. fetchTree could also use it to remap
inputs).
In particular, doing 'nix build /path/to/dir' now works if
/path/to/dir is not a Git tree (it only has to contain a flake.nix
file).
Also, 'nix flake init' no longer requires a Git tree (but it will do a
'git add flake.nix' if it's a Git tree)
In particular, we store whether an attribute failed to evaluate (threw
an exception) or was an unsupported type. This is to ensure that a
repeated 'nix flake show' never has to evaluate anything, so it can
execute without fetching the flake.
With this, 'nix flake show nixpkgs/nixos-20.03 --legacy' executes in
0.6s (was 3.4s).
This speeds up the creation of the cache for the nixpkgs flake from
21.2s to 10.2s. Oddly, it also speeds up querying the cache
(i.e. running 'nix flake show nixpkgs/nixos-20.03 --legacy') from 4.2s
to 3.4s.
(For comparison, running with --no-eval-cache takes 9.5s, so the
overhead of building the SQLite cache is only 0.7s.)
In the fully cached case for the 'nixpkgs' flake, it went from 101s to
4.6s. Populating the cache went from 132s to 17.4s (which could
probably be improved further by combining INSERTs).
