forked from lix-project/lix
d3aa183beb
bytes have been freed, `--max-links' to stop when the Nix store directory has fewer than N hard links (the latter being important for very large Nix stores on filesystems with a 32000 subdirectories limit).
320 lines
10 KiB
C++
320 lines
10 KiB
C++
#ifndef __STOREAPI_H
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#define __STOREAPI_H
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#include <string>
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#include <map>
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#include <boost/shared_ptr.hpp>
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#include "hash.hh"
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#include "serialise.hh"
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namespace nix {
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typedef std::map<Path, Path> Roots;
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struct GCOptions
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{
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/* Garbage collector operation:
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- `gcReturnRoots': find and return the set of roots for the
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garbage collector. These are the store paths symlinked to in
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the `gcroots' directory.
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- `gcReturnLive': return the set of paths reachable from
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(i.e. in the closure of) the roots.
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- `gcReturnDead': return the set of paths not reachable from
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the roots.
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- `gcDeleteDead': actually delete the latter set.
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- `gcDeleteSpecific': delete the paths listed in
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`pathsToDelete', insofar as they are not reachable.
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*/
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typedef enum {
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gcReturnRoots,
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gcReturnLive,
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gcReturnDead,
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gcDeleteDead,
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gcDeleteSpecific,
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} GCAction;
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GCAction action;
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/* If `ignoreLiveness' is set, then reachability from the roots is
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ignored (dangerous!). However, the paths must still be
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unreferenced *within* the store (i.e., there can be no other
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store paths that depend on them). */
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bool ignoreLiveness;
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/* For `gcDeleteSpecific', the paths to delete. */
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PathSet pathsToDelete;
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/* Stop after at least `maxFreed' bytes have been freed. */
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unsigned long long maxFreed;
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/* Stop after the number of hard links to the Nix store directory
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has dropped below `maxLinks'. */
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unsigned int maxLinks;
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GCOptions();
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};
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struct GCResults
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{
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/* Depending on the action, the GC roots, or the paths that would
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be or have been deleted. */
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PathSet paths;
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/* For `gcReturnDead', `gcDeleteDead' and `gcDeleteSpecific', the
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number of bytes that would be or was freed. */
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unsigned long long bytesFreed;
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/* The number of file system blocks that would be or was freed. */
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unsigned long long blocksFreed;
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GCResults()
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{
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bytesFreed = 0;
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blocksFreed = 0;
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}
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};
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class StoreAPI
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{
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public:
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virtual ~StoreAPI() { }
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/* Checks whether a path is valid. */
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virtual bool isValidPath(const Path & path) = 0;
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/* Query the set of valid paths. */
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virtual PathSet queryValidPaths() = 0;
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/* Queries the hash of a valid path. */
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virtual Hash queryPathHash(const Path & path) = 0;
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/* Queries the set of outgoing FS references for a store path.
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The result is not cleared. */
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virtual void queryReferences(const Path & path,
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PathSet & references) = 0;
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/* Queries the set of incoming FS references for a store path.
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The result is not cleared. */
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virtual void queryReferrers(const Path & path,
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PathSet & referrers) = 0;
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/* Query the deriver of a store path. Return the empty string if
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no deriver has been set. */
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virtual Path queryDeriver(const Path & path) = 0;
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/* Query the set of substitutable paths. */
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virtual PathSet querySubstitutablePaths() = 0;
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/* More efficient variant if we just want to know if a path has
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substitutes. */
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virtual bool hasSubstitutes(const Path & path);
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/* Copy the contents of a path to the store and register the
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validity the resulting path. The resulting path is returned.
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If `fixed' is true, then the output of a fixed-output
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derivation is pre-loaded into the Nix store. The function
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object `filter' can be used to exclude files (see
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libutil/archive.hh). */
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virtual Path addToStore(const Path & srcPath, bool fixed = false,
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bool recursive = false, string hashAlgo = "",
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PathFilter & filter = defaultPathFilter) = 0;
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/* Like addToStore, but the contents written to the output path is
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a regular file containing the given string. */
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virtual Path addTextToStore(const string & suffix, const string & s,
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const PathSet & references) = 0;
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/* Export a store path, that is, create a NAR dump of the store
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path and append its references and its deriver. Optionally, a
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cryptographic signature (created by OpenSSL) of the preceding
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data is attached. */
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virtual void exportPath(const Path & path, bool sign,
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Sink & sink) = 0;
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/* Import a NAR dump created by exportPath() into the Nix
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store. */
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virtual Path importPath(bool requireSignature, Source & source) = 0;
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/* Ensure that the output paths of the derivation are valid. If
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they are already valid, this is a no-op. Otherwise, validity
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can be reached in two ways. First, if the output paths is
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substitutable, then build the path that way. Second, the
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output paths can be created by running the builder, after
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recursively building any sub-derivations. */
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virtual void buildDerivations(const PathSet & drvPaths) = 0;
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/* Ensure that a path is valid. If it is not currently valid, it
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may be made valid by running a substitute (if defined for the
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path). */
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virtual void ensurePath(const Path & path) = 0;
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/* Add a store path as a temporary root of the garbage collector.
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The root disappears as soon as we exit. */
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virtual void addTempRoot(const Path & path) = 0;
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/* Add an indirect root, which is merely a symlink to `path' from
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/nix/var/nix/gcroots/auto/<hash of `path'>. `path' is supposed
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to be a symlink to a store path. The garbage collector will
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automatically remove the indirect root when it finds that
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`path' has disappeared. */
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virtual void addIndirectRoot(const Path & path) = 0;
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/* Acquire the global GC lock, then immediately release it. This
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function must be called after registering a new permanent root,
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but before exiting. Otherwise, it is possible that a running
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garbage collector doesn't see the new root and deletes the
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stuff we've just built. By acquiring the lock briefly, we
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ensure that either:
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- The collector is already running, and so we block until the
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collector is finished. The collector will know about our
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*temporary* locks, which should include whatever it is we
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want to register as a permanent lock.
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- The collector isn't running, or it's just started but hasn't
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acquired the GC lock yet. In that case we get and release
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the lock right away, then exit. The collector scans the
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permanent root and sees our's.
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In either case the permanent root is seen by the collector. */
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virtual void syncWithGC() = 0;
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/* Find the roots of the garbage collector. Each root is a pair
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(link, storepath) where `link' is the path of the symlink
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outside of the Nix store that point to `storePath'. */
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virtual Roots findRoots() = 0;
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/* Perform a garbage collection. */
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virtual void collectGarbage(const GCOptions & options, GCResults & results) = 0;
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};
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/* !!! These should be part of the store API, I guess. */
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/* Throw an exception if `path' is not directly in the Nix store. */
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void assertStorePath(const Path & path);
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bool isInStore(const Path & path);
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bool isStorePath(const Path & path);
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void checkStoreName(const string & name);
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/* Chop off the parts after the top-level store name, e.g.,
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/nix/store/abcd-foo/bar => /nix/store/abcd-foo. */
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Path toStorePath(const Path & path);
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/* Follow symlinks until we end up with a path in the Nix store. */
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Path followLinksToStore(const Path & path);
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/* Same as followLinksToStore(), but apply toStorePath() to the
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result. */
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Path followLinksToStorePath(const Path & path);
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/* Constructs a unique store path name. */
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Path makeStorePath(const string & type,
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const Hash & hash, const string & suffix);
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Path makeFixedOutputPath(bool recursive,
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string hashAlgo, Hash hash, string name);
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/* This is the preparatory part of addToStore() and addToStoreFixed();
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it computes the store path to which srcPath is to be copied.
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Returns the store path and the cryptographic hash of the
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contents of srcPath. */
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std::pair<Path, Hash> computeStorePathForPath(const Path & srcPath,
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bool fixed = false, bool recursive = false, string hashAlgo = "",
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PathFilter & filter = defaultPathFilter);
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/* Preparatory part of addTextToStore().
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!!! Computation of the path should take the references given to
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addTextToStore() into account, otherwise we have a (relatively
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minor) security hole: a caller can register a source file with
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bogus references. If there are too many references, the path may
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not be garbage collected when it has to be (not really a problem,
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the caller could create a root anyway), or it may be garbage
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collected when it shouldn't be (more serious).
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Hashing the references would solve this (bogus references would
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simply yield a different store path, so other users wouldn't be
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affected), but it has some backwards compatibility issues (the
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hashing scheme changes), so I'm not doing that for now. */
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Path computeStorePathForText(const string & suffix, const string & s,
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const PathSet & references);
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/* Remove the temporary roots file for this process. Any temporary
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root becomes garbage after this point unless it has been registered
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as a (permanent) root. */
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void removeTempRoots();
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/* Register a permanent GC root. */
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Path addPermRoot(const Path & storePath, const Path & gcRoot,
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bool indirect, bool allowOutsideRootsDir = false);
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/* Sort a set of paths topologically under the references relation.
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If p refers to q, then p follows q in this list. */
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Paths topoSortPaths(const PathSet & paths);
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/* For now, there is a single global store API object, but we'll
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purify that in the future. */
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extern boost::shared_ptr<StoreAPI> store;
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/* Factory method: open the Nix database, either through the local or
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remote implementation. */
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boost::shared_ptr<StoreAPI> openStore();
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/* Display a set of paths in human-readable form (i.e., between quotes
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and separated by commas). */
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string showPaths(const PathSet & paths);
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string makeValidityRegistration(const PathSet & paths,
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bool showDerivers, bool showHash);
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struct ValidPathInfo
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{
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Path path;
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Path deriver;
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Hash hash;
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PathSet references;
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time_t registrationTime;
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ValidPathInfo() : registrationTime(0) { }
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};
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typedef list<ValidPathInfo> ValidPathInfos;
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ValidPathInfo decodeValidPathInfo(std::istream & str,
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bool hashGiven = false);
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}
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#endif /* !__STOREAPI_H */
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