lix/src/libstore/misc.hh
Eelco Dolstra 1511aa9f48 Allow remote builds without sending the derivation closure
Previously, to build a derivation remotely, we had to copy the entire
closure of the .drv file to the remote machine, even though we only
need the top-level derivation. This is very wasteful: the closure can
contain thousands of store paths, and in some Hydra use cases, include
source paths that are very large (e.g. Git/Mercurial checkouts).

So now there is a new operation, StoreAPI::buildDerivation(), that
performs a build from an in-memory representation of a derivation
(BasicDerivation) rather than from a on-disk .drv file. The only files
that need to be in the Nix store are the sources of the derivation
(drv.inputSrcs), and the needed output paths of the dependencies (as
described by drv.inputDrvs). "nix-store --serve" exposes this
interface.

Note that this is a privileged operation, because you can construct a
derivation that builds any store path whatsoever. Fixing this will
require changing the hashing scheme (i.e., the output paths should be
computed from the other fields in BasicDerivation, allowing them to be
verified without access to other derivations). However, this would be
quite nice because it would allow .drv-free building (e.g. "nix-env
-i" wouldn't have to write any .drv files to disk).

Fixes #173.
2015-07-17 17:57:40 +02:00

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1.4 KiB
C++

#pragma once
#include "derivations.hh"
namespace nix {
/* Read a derivation, after ensuring its existence through
ensurePath(). */
Derivation derivationFromPath(StoreAPI & store, const Path & drvPath);
/* Place in `paths' the set of all store paths in the file system
closure of `storePath'; that is, all paths than can be directly or
indirectly reached from it. `paths' is not cleared. If
`flipDirection' is true, the set of paths that can reach
`storePath' is returned; that is, the closures under the
`referrers' relation instead of the `references' relation is
returned. */
void computeFSClosure(StoreAPI & store, const Path & path,
PathSet & paths, bool flipDirection = false,
bool includeOutputs = false, bool includeDerivers = false);
/* Return the path corresponding to the output identifier `id' in the
given derivation. */
Path findOutput(const Derivation & drv, string id);
/* Given a set of paths that are to be built, return the set of
derivations that will be built, and the set of output paths that
will be substituted. */
void queryMissing(StoreAPI & store, const PathSet & targets,
PathSet & willBuild, PathSet & willSubstitute, PathSet & unknown,
unsigned long long & downloadSize, unsigned long long & narSize);
bool willBuildLocally(const BasicDerivation & drv);
bool substitutesAllowed(const BasicDerivation & drv);
}