lix/src/libstore/local-store.hh

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#pragma once
#include <string>
#include "store-api.hh"
#include "util.hh"
#include "pathlocks.hh"
class sqlite3;
class sqlite3_stmt;
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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. */
const int nixSchemaVersion = 7;
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extern string drvsLogDir;
struct Derivation;
struct OptimiseStats
{
unsigned long totalFiles;
unsigned long sameContents;
unsigned long filesLinked;
unsigned long long bytesFreed;
unsigned long long blocksFreed;
OptimiseStats()
{
totalFiles = sameContents = filesLinked = 0;
bytesFreed = blocksFreed = 0;
}
};
struct RunningSubstituter
{
Pid pid;
AutoCloseFD to, from, error;
FdSource fromBuf;
};
/* Wrapper object to close the SQLite database automatically. */
struct SQLite
{
sqlite3 * db;
SQLite() { db = 0; }
~SQLite();
operator sqlite3 * () { return db; }
};
/* Wrapper object to create and destroy SQLite prepared statements. */
struct SQLiteStmt
{
sqlite3 * db;
sqlite3_stmt * stmt;
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unsigned int curArg;
SQLiteStmt() { stmt = 0; }
void create(sqlite3 * db, const string & s);
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void reset();
~SQLiteStmt();
operator sqlite3_stmt * () { return stmt; }
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void bind(const string & value);
void bind(int value);
void bind64(long long value);
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void bind();
};
class LocalStore : public StoreAPI
{
private:
typedef std::map<Path, RunningSubstituter> RunningSubstituters;
RunningSubstituters runningSubstituters;
Path linksDir;
public:
/* Initialise the local store, upgrading the schema if
necessary. */
LocalStore(bool reserveSpace = true);
~LocalStore();
/* Implementations of abstract store API methods. */
bool isValidPath(const Path & path);
PathSet queryValidPaths(const PathSet & paths);
PathSet queryAllValidPaths();
ValidPathInfo queryPathInfo(const Path & path);
Hash queryPathHash(const Path & path);
void queryReferences(const Path & path, PathSet & references);
void queryReferrers(const Path & path, PathSet & referrers);
Path queryDeriver(const Path & path);
PathSet queryValidDerivers(const Path & path);
PathSet queryDerivationOutputs(const Path & path);
StringSet queryDerivationOutputNames(const Path & path);
Path queryPathFromHashPart(const string & hashPart);
PathSet querySubstitutablePaths(const PathSet & paths);
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 Path & substituter,
PathSet & paths, SubstitutablePathInfos & infos);
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,
SubstitutablePathInfos & infos);
Path addToStore(const Path & srcPath,
bool recursive = true, HashType hashAlgo = htSHA256,
PathFilter & filter = defaultPathFilter, bool repair = false);
/* 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, bool repair = false);
Path addTextToStore(const string & name, const string & s,
const PathSet & references, bool repair = false);
void exportPath(const Path & path, bool sign,
Sink & sink);
Paths importPaths(bool requireSignature, Source & source);
void buildPaths(const PathSet & paths, bool repair = false);
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void ensurePath(const Path & path);
void addTempRoot(const Path & path);
void addIndirectRoot(const Path & path);
void syncWithGC();
Roots findRoots();
void collectGarbage(const GCOptions & options, GCResults & results);
/* Optimise the disk space usage of the Nix store by hard-linking
files with the same contents. */
void optimiseStore(OptimiseStats & stats);
/* Optimise a single store path. */
void optimisePath(const Path & path);
/* Check the integrity of the Nix store. Returns true if errors
remain. */
bool verifyStore(bool checkContents, bool repair);
/* 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 succesful
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);
/* Register that the build of a derivation with output `path' has
failed. */
void registerFailedPath(const Path & path);
/* Query whether `path' previously failed to build. */
bool hasPathFailed(const Path & path);
PathSet queryFailedPaths();
void clearFailedPaths(const PathSet & paths);
void vacuumDB();
/* Repair the contents of the given path by redownloading it using
a substituter (if available). */
void repairPath(const Path & path);
/* Check whether the given valid path exists and has the right
contents. */
bool pathContentsGood(const Path & path);
void markContentsGood(const Path & path);
void setSubstituterEnv();
private:
Path schemaPath;
/* Lock file used for upgrading. */
AutoCloseFD globalLock;
/* The SQLite database object. */
SQLite db;
/* Some precompiled SQLite statements. */
SQLiteStmt stmtRegisterValidPath;
SQLiteStmt stmtUpdatePathInfo;
SQLiteStmt stmtAddReference;
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SQLiteStmt stmtQueryPathInfo;
SQLiteStmt stmtQueryReferences;
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SQLiteStmt stmtQueryReferrers;
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SQLiteStmt stmtInvalidatePath;
SQLiteStmt stmtRegisterFailedPath;
SQLiteStmt stmtHasPathFailed;
SQLiteStmt stmtQueryFailedPaths;
SQLiteStmt stmtClearFailedPath;
SQLiteStmt stmtAddDerivationOutput;
SQLiteStmt stmtQueryValidDerivers;
SQLiteStmt stmtQueryDerivationOutputs;
SQLiteStmt stmtQueryPathFromHashPart;
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/* Cache for pathContentsGood(). */
std::map<Path, bool> pathContentsGoodCache;
bool didSetSubstituterEnv;
int getSchema();
void openDB(bool create);
void makeStoreWritable();
unsigned long long queryValidPathId(const Path & path);
unsigned long long addValidPath(const ValidPathInfo & info, bool checkOutputs = true);
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void addReference(unsigned long long referrer, unsigned long long reference);
void appendReferrer(const Path & from, const Path & to, bool lock);
void rewriteReferrers(const Path & path, bool purge, PathSet referrers);
void invalidatePath(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, bool repair, bool & errors);
void updatePathInfo(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 removeUnusedLinks(const GCState & state);
void startSubstituter(const Path & substituter,
RunningSubstituter & runningSubstituter);
string getLineFromSubstituter(RunningSubstituter & run);
template<class T> T getIntLineFromSubstituter(RunningSubstituter & run);
Path createTempDirInStore();
Path importPath(bool requireSignature, Source & source);
void checkDerivationOutputs(const Path & drvPath, const Derivation & drv);
void optimisePath_(OptimiseStats & stats, const Path & path);
};
/* "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
in a setuid Nix installation. */
void canonicalisePathMetaData(const Path & path, uid_t fromUid);
void canonicaliseTimestampAndPermissions(const Path & path);
MakeError(PathInUse, Error);
/* Whether we are root. */
bool amPrivileged();
/* Recursively change the ownership of `path' to the current uid. */
void getOwnership(const Path & path);
/* Like deletePath(), but changes the ownership of `path' using the
setuid wrapper if necessary (and possible). */
void deletePathWrapped(const Path & path, unsigned long long & bytesFreed);
void deletePathWrapped(const Path & path);
}