tvl-depot/src/libstore/derivations.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

106 lines
2.6 KiB
C++

#pragma once
#include "types.hh"
#include "hash.hh"
#include <map>
namespace nix {
/* Extension of derivations in the Nix store. */
const string drvExtension = ".drv";
/* Abstract syntax of derivations. */
struct DerivationOutput
{
Path path;
string hashAlgo; /* hash used for expected hash computation */
string hash; /* expected hash, may be null */
DerivationOutput()
{
}
DerivationOutput(Path path, string hashAlgo, string hash)
{
this->path = path;
this->hashAlgo = hashAlgo;
this->hash = hash;
}
void parseHashInfo(bool & recursive, HashType & hashType, Hash & hash) const;
};
typedef std::map<string, DerivationOutput> DerivationOutputs;
/* For inputs that are sub-derivations, we specify exactly which
output IDs we are interested in. */
typedef std::map<Path, StringSet> DerivationInputs;
typedef std::map<string, string> StringPairs;
struct BasicDerivation
{
DerivationOutputs outputs; /* keyed on symbolic IDs */
PathSet inputSrcs; /* inputs that are sources */
string platform;
Path builder;
Strings args;
StringPairs env;
virtual ~BasicDerivation() { };
};
struct Derivation : BasicDerivation
{
DerivationInputs inputDrvs; /* inputs that are sub-derivations */
};
class StoreAPI;
/* Write a derivation to the Nix store, and return its path. */
Path writeDerivation(StoreAPI & store,
const Derivation & drv, const string & name, bool repair = false);
/* Read a derivation from a file. */
Derivation readDerivation(const Path & drvPath);
/* Print a derivation. */
string unparseDerivation(const Derivation & drv);
/* Check whether a file name ends with the extensions for
derivations. */
bool isDerivation(const string & fileName);
/* Return true iff this is a fixed-output derivation. */
bool isFixedOutputDrv(const Derivation & drv);
Hash hashDerivationModulo(StoreAPI & store, Derivation drv);
/* Memoisation of hashDerivationModulo(). */
typedef std::map<Path, Hash> DrvHashes;
extern DrvHashes drvHashes;
/* Split a string specifying a derivation and a set of outputs
(/nix/store/hash-foo!out1,out2,...) into the derivation path and
the outputs. */
typedef std::pair<string, std::set<string> > DrvPathWithOutputs;
DrvPathWithOutputs parseDrvPathWithOutputs(const string & s);
Path makeDrvPathWithOutputs(const Path & drvPath, const std::set<string> & outputs);
bool wantOutput(const string & output, const std::set<string> & wanted);
PathSet outputPaths(const BasicDerivation & drv);
struct Source;
struct Sink;
Source & operator >> (Source & in, BasicDerivation & drv);
Sink & operator << (Sink & out, const BasicDerivation & drv);
}