lix/src/libstore/local-store.hh

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#pragma once
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#include "sqlite.hh"
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#include "pathlocks.hh"
#include "store-api.hh"
#include "sync.hh"
#include "util.hh"
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#include <chrono>
#include <future>
#include <string>
#include <unordered_set>
namespace nix {
/* Nix store and database schema version. Version 1 (or 0) was Nix <=
0.7. Version 2 was Nix 0.8 and 0.9. Version 3 is Nix 0.10.
Version 4 is Nix 0.11. Version 5 is Nix 0.12-0.16. Version 6 is
Nix 1.0. Version 7 is Nix 1.3. Version 10 is 2.0. */
const int nixSchemaVersion = 10;
struct Derivation;
struct OptimiseStats
{
unsigned long filesLinked = 0;
unsigned long long bytesFreed = 0;
unsigned long long blocksFreed = 0;
};
class LocalStore : public LocalFSStore
{
private:
/* Lock file used for upgrading. */
AutoCloseFD globalLock;
struct State
{
/* The SQLite database object. */
SQLite db;
/* Some precompiled SQLite statements. */
SQLiteStmt stmtRegisterValidPath;
SQLiteStmt stmtUpdatePathInfo;
SQLiteStmt stmtAddReference;
SQLiteStmt stmtQueryPathInfo;
SQLiteStmt stmtQueryReferences;
SQLiteStmt stmtQueryReferrers;
SQLiteStmt stmtInvalidatePath;
SQLiteStmt stmtAddDerivationOutput;
SQLiteStmt stmtQueryValidDerivers;
SQLiteStmt stmtQueryDerivationOutputs;
SQLiteStmt stmtQueryPathFromHashPart;
SQLiteStmt stmtQueryValidPaths;
/* The file to which we write our temporary roots. */
AutoCloseFD fdTempRoots;
/* The last time we checked whether to do an auto-GC, or an
auto-GC finished. */
std::chrono::time_point<std::chrono::steady_clock> lastGCCheck;
/* Whether auto-GC is running. If so, get gcFuture to wait for
the GC to finish. */
bool gcRunning = false;
std::shared_future<void> gcFuture;
/* How much disk space was available after the previous
auto-GC. If the current available disk space is below
minFree but not much below availAfterGC, then there is no
point in starting a new GC. */
uint64_t availAfterGC = std::numeric_limits<uint64_t>::max();
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std::unique_ptr<PublicKeys> publicKeys;
};
Sync<State, std::recursive_mutex> _state;
public:
PathSetting realStoreDir_;
const Path realStoreDir;
const Path dbDir;
const Path linksDir;
const Path reservedPath;
const Path schemaPath;
const Path trashDir;
const Path tempRootsDir;
const Path fnTempRoots;
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private:
Setting<bool> requireSigs{(Store*) this,
settings.requireSigs,
"require-sigs", "whether store paths should have a trusted signature on import"};
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const PublicKeys & getPublicKeys();
public:
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// Hack for build-remote.cc.
PathSet locksHeld = tokenizeString<PathSet>(getEnv("NIX_HELD_LOCKS"));
/* Initialise the local store, upgrading the schema if
necessary. */
LocalStore(const Params & params);
~LocalStore();
/* Implementations of abstract store API methods. */
std::string getUri() override;
bool isValidPathUncached(const Path & path) override;
PathSet queryValidPaths(const PathSet & paths,
SubstituteFlag maybeSubstitute = NoSubstitute) override;
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PathSet queryAllValidPaths() override;
void queryPathInfoUncached(const Path & path,
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Callback<std::shared_ptr<ValidPathInfo>> callback) override;
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void queryReferrers(const Path & path, PathSet & referrers) override;
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PathSet queryValidDerivers(const Path & path) override;
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PathSet queryDerivationOutputs(const Path & path) override;
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StringSet queryDerivationOutputNames(const Path & path) override;
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Path queryPathFromHashPart(const string & hashPart) override;
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PathSet querySubstitutablePaths(const PathSet & paths) override;
download-from-binary-cache: parallelise fetching of NAR info files Getting substitute information using the binary cache substituter has non-trivial latency overhead. A package or NixOS system configuration can have hundreds of dependencies, and in the worst case (when the local info cache is empty) we have to do a separate HTTP request for each of these. If the ping time to the server is t, getting N info files will take tN seconds; e.g., with a ping time of 0.1s to nixos.org, sequentially downloading 1000 info files (a typical NixOS config) will take at least 100 seconds. To fix this problem, the binary cache substituter can now perform requests in parallel. This required changing the substituter interface to support a function querySubstitutablePathInfos() that queries multiple paths at the same time, and rewriting queryMissing() to take advantage of parallelism. (Due to local caching, parallelising queryMissing() is sufficient for most use cases, since it's almost always called before building a derivation and thus fills the local info cache.) For example, parallelism speeds up querying all 1056 paths in a particular NixOS system configuration from 116s to 2.6s. It works so well because the eccentricity of the top-level derivation in the dependency graph is only 9. So we only need 10 round-trips (when using an unlimited number of parallel connections) to get everything. Currently we do a maximum of 150 parallel connections to the server. Thus it's important that the binary cache server (e.g. nixos.org) has a high connection limit. Alternatively we could use HTTP pipelining, but WWW::Curl doesn't support it and libcurl has a hard-coded limit of 5 requests per pipeline.
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void querySubstitutablePathInfos(const PathSet & paths,
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SubstitutablePathInfos & infos) override;
void addToStore(const ValidPathInfo & info, Source & source,
RepairFlag repair, CheckSigsFlag checkSigs,
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std::shared_ptr<FSAccessor> accessor) override;
Path addToStore(const string & name, const Path & srcPath,
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bool recursive, HashType hashAlgo,
PathFilter & filter, RepairFlag repair) override;
/* Like addToStore(), but the contents of the path are contained
in `dump', which is either a NAR serialisation (if recursive ==
true) or simply the contents of a regular file (if recursive ==
false). */
Path addToStoreFromDump(const string & dump, const string & name,
bool recursive = true, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair);
Path addTextToStore(const string & name, const string & s,
const PathSet & references, RepairFlag repair) override;
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void buildPaths(const PathSet & paths, BuildMode buildMode) override;
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BuildResult buildDerivation(const Path & drvPath, const BasicDerivation & drv,
BuildMode buildMode) override;
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void ensurePath(const Path & path) override;
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void addTempRoot(const Path & path) override;
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void addIndirectRoot(const Path & path) override;
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void syncWithGC() override;
private:
typedef std::shared_ptr<AutoCloseFD> FDPtr;
typedef list<FDPtr> FDs;
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std::set<std::pair<pid_t, Path>> readTempRoots(FDs & fds);
public:
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Roots findRoots() override;
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void collectGarbage(const GCOptions & options, GCResults & results) override;
/* Optimise the disk space usage of the Nix store by hard-linking
files with the same contents. */
void optimiseStore(OptimiseStats & stats);
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void optimiseStore() override;
/* Optimise a single store path. */
void optimisePath(const Path & path);
bool verifyStore(bool checkContents, RepairFlag repair) override;
/* Register the validity of a path, i.e., that `path' exists, that
the paths referenced by it exists, and in the case of an output
path of a derivation, that it has been produced by a successful
execution of the derivation (or something equivalent). Also
register the hash of the file system contents of the path. The
hash must be a SHA-256 hash. */
void registerValidPath(const ValidPathInfo & info);
void registerValidPaths(const ValidPathInfos & infos);
unsigned int getProtocol() override;
void vacuumDB();
/* Repair the contents of the given path by redownloading it using
a substituter (if available). */
void repairPath(const Path & path);
void addSignatures(const Path & storePath, const StringSet & sigs) override;
/* If free disk space in /nix/store if below minFree, delete
garbage until it exceeds maxFree. */
void autoGC(bool sync = true);
private:
int getSchema();
void openDB(State & state, bool create);
void makeStoreWritable();
uint64_t queryValidPathId(State & state, const Path & path);
uint64_t addValidPath(State & state, const ValidPathInfo & info, bool checkOutputs = true);
void invalidatePath(State & state, const Path & path);
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/* Delete a path from the Nix store. */
void invalidatePathChecked(const Path & path);
void verifyPath(const Path & path, const PathSet & store,
PathSet & done, PathSet & validPaths, RepairFlag repair, bool & errors);
void updatePathInfo(State & state, const ValidPathInfo & info);
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void upgradeStore6();
void upgradeStore7();
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PathSet queryValidPathsOld();
ValidPathInfo queryPathInfoOld(const Path & path);
struct GCState;
void deleteGarbage(GCState & state, const Path & path);
void tryToDelete(GCState & state, const Path & path);
bool canReachRoot(GCState & state, PathSet & visited, const Path & path);
void deletePathRecursive(GCState & state, const Path & path);
bool isActiveTempFile(const GCState & state,
const Path & path, const string & suffix);
int openGCLock(LockType lockType);
void findRoots(const Path & path, unsigned char type, Roots & roots);
Roots findRootsNoTemp();
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void findRuntimeRoots(Roots & roots);
void removeUnusedLinks(const GCState & state);
Path createTempDirInStore();
void checkDerivationOutputs(const Path & drvPath, const Derivation & drv);
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typedef std::unordered_set<ino_t> InodeHash;
InodeHash loadInodeHash();
Strings readDirectoryIgnoringInodes(const Path & path, const InodeHash & inodeHash);
void optimisePath_(Activity * act, OptimiseStats & stats, const Path & path, InodeHash & inodeHash);
// Internal versions that are not wrapped in retry_sqlite.
bool isValidPath_(State & state, const Path & path);
void queryReferrers(State & state, const Path & path, PathSet & referrers);
/* Add signatures to a ValidPathInfo using the secret keys
specified by the secret-key-files option. */
void signPathInfo(ValidPathInfo & info);
Path getRealStoreDir() override { return realStoreDir; }
friend class DerivationGoal;
friend class SubstitutionGoal;
};
typedef std::pair<dev_t, ino_t> Inode;
typedef set<Inode> InodesSeen;
/* "Fix", or canonicalise, the meta-data of the files in a store path
after it has been built. In particular:
- the last modification date on each file is set to 1 (i.e.,
00:00:01 1/1/1970 UTC)
- the permissions are set of 444 or 555 (i.e., read-only with or
without execute permission; setuid bits etc. are cleared)
- the owner and group are set to the Nix user and group, if we're
running as root. */
void canonicalisePathMetaData(const Path & path, uid_t fromUid, InodesSeen & inodesSeen);
void canonicalisePathMetaData(const Path & path, uid_t fromUid);
void canonicaliseTimestampAndPermissions(const Path & path);
MakeError(PathInUse, Error);
}