lix/src/libstore/local-store.hh
Eelco Dolstra a8629de827 * New command `nix-store --optimise' to reduce Nix store disk space
usage by finding identical files in the store and hard-linking them
  to each other.  It typically reduces the size of the store by
  something like 25-35%.  This is what the optimise-store.pl script
  did, but the new command is faster and more correct (it's safe wrt
  garbage collection and concurrent builds).
2007-10-09 22:14:27 +00:00

177 lines
5 KiB
C++

#ifndef __LOCAL_STORE_H
#define __LOCAL_STORE_H
#include <string>
#include "store-api.hh"
namespace nix {
class Transaction;
/* 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. */
const int nixSchemaVersion = 4;
extern string drvsLogDir;
struct OptimiseStats
{
unsigned long totalFiles;
unsigned long sameContents;
unsigned long filesLinked;
unsigned long long bytesFreed;
OptimiseStats()
{
totalFiles = sameContents = filesLinked = 0;
bytesFreed = 0;
}
};
class LocalStore : public StoreAPI
{
private:
bool substitutablePathsLoaded;
PathSet substitutablePaths;
public:
/* Open the database environment. If `reserveSpace' is true, make
sure that a big empty file exists in /nix/var/nix/db/reserved.
If `reserveSpace' is false, delete this file if it exists. The
idea is that on normal operation, the file exists; but when we
run the garbage collector, it is deleted. This is to ensure
that the garbage collector has a small amount of disk space
available, which is required to open the Berkeley DB
environment. */
LocalStore(bool reserveSpace);
~LocalStore();
/* Implementations of abstract store API methods. */
bool isValidPath(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 querySubstitutablePaths();
bool hasSubstitutes(const Path & path);
Path addToStore(const Path & srcPath, bool fixed = false,
bool recursive = false, string hashAlgo = "",
PathFilter & filter = defaultPathFilter);
Path addTextToStore(const string & suffix, const string & s,
const PathSet & references);
void exportPath(const Path & path, bool sign,
Sink & sink);
Path importPath(bool requireSignature, Source & source);
void buildDerivations(const PathSet & drvPaths);
void ensurePath(const Path & path);
void addTempRoot(const Path & path);
void addIndirectRoot(const Path & path);
void syncWithGC();
Roots findRoots();
void collectGarbage(GCAction action, const PathSet & pathsToDelete,
bool ignoreLiveness, PathSet & result, unsigned long long & bytesFreed);
/* Optimise the disk space usage of the Nix store by hard-linking
files with the same contents. */
void optimiseStore(bool dryRun, OptimiseStats & stats);
};
/* Get a transaction object. */
void createStoreTransaction(Transaction & txn);
/* Copy a path recursively. */
void copyPath(const Path & src, const Path & dst);
/* 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 Transaction & txn,
const Path & path, const Hash & hash, const PathSet & references,
const Path & deriver);
typedef list<ValidPathInfo> ValidPathInfos;
void registerValidPaths(const Transaction & txn,
const ValidPathInfos & infos);
/* "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 0 (i.e.,
00:00:00 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);
/* Checks whether a path is valid. */
bool isValidPathTxn(const Transaction & txn, const Path & path);
/* Sets the set of outgoing FS references for a store path. Use with
care! */
void setReferences(const Transaction & txn, const Path & path,
const PathSet & references);
/* Sets the deriver of a store path. Use with care! */
void setDeriver(const Transaction & txn, const Path & path,
const Path & deriver);
/* Delete a value from the nixStore directory. */
void deleteFromStore(const Path & path, unsigned long long & bytesFreed);
MakeError(PathInUse, Error);
void verifyStore(bool checkContents);
/* Whether we are in build users mode. */
bool haveBuildUsers();
/* 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);
}
#endif /* !__LOCAL_STORE_H */