lix/src/libstore/binary-cache-store.hh
Eelco Dolstra ca580bec35 BinaryCacheStore: Support local caching of NARs
This speeds up commands like "nix cat-store". For example:

  $ time nix cat-store --store https://cache.nixos.org?local-nar-cache=/tmp/nar-cache /nix/store/i60yncmq6w9dyv37zd2k454g0fkl3arl-systemd-234/etc/udev/udev.conf
  real    0m4.336s

  $ time nix cat-store --store https://cache.nixos.org?local-nar-cache=/tmp/nar-cache /nix/store/i60yncmq6w9dyv37zd2k454g0fkl3arl-systemd-234/etc/udev/udev.conf
  real    0m0.045s

The primary motivation is to allow hydra-server to serve files from S3
binary caches. Previously Hydra had a hack to do "nix-store -r
<path>", but that fetches the entire closure so is prohibitively
expensive.

There is no garbage collection of the NAR cache yet. Also, the entire
NAR is read when accessing a single member file. We could generate the
NAR listing to provide random access.

Note: the NAR cache is indexed by the store path hash, not the content
hash, so NAR caches should not be shared between binary caches, unless
you're sure that all your builds are binary-reproducible.
2017-10-17 21:15:33 +02:00

132 lines
3.5 KiB
C++

#pragma once
#include "crypto.hh"
#include "store-api.hh"
#include "pool.hh"
#include <atomic>
namespace nix {
struct NarInfo;
class BinaryCacheStore : public Store
{
public:
const Setting<std::string> compression{this, "xz", "compression", "NAR compression method ('xz', 'bzip2', or 'none')"};
const Setting<bool> writeNARListing{this, false, "write-nar-listing", "whether to write a JSON file listing the files in each NAR"};
const Setting<Path> secretKeyFile{this, "", "secret-key", "path to secret key used to sign the binary cache"};
const Setting<Path> localNarCache{this, "", "local-nar-cache", "path to a local cache of NARs"};
private:
std::unique_ptr<SecretKey> secretKey;
protected:
BinaryCacheStore(const Params & params);
public:
virtual bool fileExists(const std::string & path) = 0;
virtual void upsertFile(const std::string & path,
const std::string & data,
const std::string & mimeType) = 0;
/* Return the contents of the specified file, or null if it
doesn't exist. */
virtual void getFile(const std::string & path,
std::function<void(std::shared_ptr<std::string>)> success,
std::function<void(std::exception_ptr exc)> failure) = 0;
std::shared_ptr<std::string> getFile(const std::string & path);
protected:
bool wantMassQuery_ = false;
int priority = 50;
public:
virtual void init();
private:
std::string narMagic;
std::string narInfoFileFor(const Path & storePath);
public:
bool isValidPathUncached(const Path & path) override;
PathSet queryAllValidPaths() override
{ unsupported(); }
void queryPathInfoUncached(const Path & path,
std::function<void(std::shared_ptr<ValidPathInfo>)> success,
std::function<void(std::exception_ptr exc)> failure) override;
void queryReferrers(const Path & path,
PathSet & referrers) override
{ unsupported(); }
PathSet queryDerivationOutputs(const Path & path) override
{ unsupported(); }
StringSet queryDerivationOutputNames(const Path & path) override
{ unsupported(); }
Path queryPathFromHashPart(const string & hashPart) override
{ unsupported(); }
bool wantMassQuery() override { return wantMassQuery_; }
void addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
RepairFlag repair, CheckSigsFlag checkSigs,
std::shared_ptr<FSAccessor> accessor) override;
Path addToStore(const string & name, const Path & srcPath,
bool recursive, HashType hashAlgo,
PathFilter & filter, RepairFlag repair) override;
Path addTextToStore(const string & name, const string & s,
const PathSet & references, RepairFlag repair) override;
void narFromPath(const Path & path, Sink & sink) override;
BuildResult buildDerivation(const Path & drvPath, const BasicDerivation & drv,
BuildMode buildMode) override
{ unsupported(); }
void ensurePath(const Path & path) override
{ unsupported(); }
void addTempRoot(const Path & path) override
{ unsupported(); }
void addIndirectRoot(const Path & path) override
{ unsupported(); }
Roots findRoots() override
{ unsupported(); }
void collectGarbage(const GCOptions & options, GCResults & results) override
{ unsupported(); }
ref<FSAccessor> getFSAccessor() override;
void addSignatures(const Path & storePath, const StringSet & sigs) override
{ unsupported(); }
std::shared_ptr<std::string> getBuildLog(const Path & path) override;
int getPriority() override { return priority; }
};
}