java.lang.Object
org.eclipse.jgit.internal.storage.file.GC

public class GC extends Object
A garbage collector for git FileRepository. Instances of this class are not thread-safe. Don't use the same instance from multiple threads. This class started as a copy of DfsGarbageCollector from Shawn O. Pearce adapted to FileRepositories.
  • Field Details

    • LOG

      private static final org.slf4j.Logger LOG
    • PRUNE_EXPIRE_DEFAULT

      private static final String PRUNE_EXPIRE_DEFAULT
      See Also:
    • PRUNE_PACK_EXPIRE_DEFAULT

      private static final String PRUNE_PACK_EXPIRE_DEFAULT
      See Also:
    • PATTERN_LOOSE_OBJECT

      private static final Pattern PATTERN_LOOSE_OBJECT
    • PACK_EXT

      private static final String PACK_EXT
    • BITMAP_EXT

      private static final String BITMAP_EXT
    • INDEX_EXT

      private static final String INDEX_EXT
    • KEEP_EXT

      private static final String KEEP_EXT
    • DEFAULT_AUTOPACKLIMIT

      private static final int DEFAULT_AUTOPACKLIMIT
      See Also:
    • DEFAULT_AUTOLIMIT

      private static final int DEFAULT_AUTOLIMIT
      See Also:
    • executor

      private static volatile ExecutorService executor
    • repo

      private final FileRepository repo
    • pm

      private ProgressMonitor pm
    • expireAgeMillis

      private long expireAgeMillis
    • expire

      private Date expire
    • packExpireAgeMillis

      private long packExpireAgeMillis
    • packExpire

      private Date packExpire
    • pconfig

      private PackConfig pconfig
    • lastPackedRefs

      private Collection<Ref> lastPackedRefs
      the refs which existed during the last call to repack(). This is needed during prune(Set) where we can optimize by looking at the difference between the current refs and the refs which existed during last repack().
    • lastRepackTime

      private long lastRepackTime
      Holds the starting time of the last repack() execution. This is needed in prune() to inspect only those reflog entries which have been added since last repack().
    • automatic

      private boolean automatic
      Whether gc should do automatic housekeeping
    • background

      private boolean background
      Whether to run gc in a background thread
  • Constructor Details

    • GC

      public GC(FileRepository repo)
      Creates a new garbage collector with default values. An expirationTime of two weeks and null as progress monitor will be used.
      Parameters:
      repo - the repo to work on
  • Method Details

    • setExecutor

      public static void setExecutor(ExecutorService e)
      Set the executor for running auto-gc in the background. If no executor is set JGit's own WorkQueue will be used.
      Parameters:
      e - the executor to be used for running auto-gc
    • gc

      public Collection<Pack> gc() throws IOException, ParseException
      Runs a garbage collector on a FileRepository. It will
      • pack loose references into packed-refs
      • repack all reachable objects into new pack files and delete the old pack files
      • prune all loose objects which are now reachable by packs
      If setAuto(boolean) was set to true gc will first check whether any housekeeping is required; if not, it exits without performing any work. If setBackground(boolean) was set to true collectGarbage will start the gc in the background, and then return immediately. In this case, errors will not be reported except in gc.log.
      Returns:
      the collection of Pack's which are newly created
      Throws:
      IOException
      ParseException - If the configuration parameter "gc.pruneexpire" couldn't be parsed
    • executor

      private ExecutorService executor()
    • doGc

      private Collection<Pack> doGc() throws IOException, ParseException
      Throws:
      IOException
      ParseException
    • loosen

      private void loosen(ObjectDirectoryInserter inserter, ObjectReader reader, Pack pack, HashSet<ObjectId> existing) throws IOException
      Loosen objects in a pack file which are not also in the newly-created pack files.
      Parameters:
      inserter -
      reader -
      pack -
      existing -
      Throws:
      IOException
    • deleteOldPacks

      private void deleteOldPacks(Collection<Pack> oldPacks, Collection<Pack> newPacks) throws ParseException, IOException
      Delete old pack files. What is 'old' is defined by specifying a set of old pack files and a set of new pack files. Each pack file contained in old pack files but not contained in new pack files will be deleted. If preserveOldPacks is set, keep a copy of the pack file in the preserve directory. If an expirationDate is set then pack files which are younger than the expirationDate will not be deleted nor preserved.

      If we're not immediately expiring loose objects, loosen any objects in the old pack files which aren't in the new pack files.

      Parameters:
      oldPacks -
      newPacks -
      Throws:
      ParseException
      IOException
    • removeOldPack

      private void removeOldPack(PackFile packFile, int deleteOptions) throws IOException
      Deletes old pack file, unless 'preserve-oldpacks' is set, in which case it moves the pack file to the preserved directory
      Parameters:
      packFile -
      deleteOptions -
      Throws:
      IOException
    • prunePreserved

      private void prunePreserved()
      Delete the preserved directory including all pack files within
    • prunePack

      private void prunePack(PackFile packFile)
      Delete files associated with a single pack file. First try to delete the ".pack" file because on some platforms the ".pack" file may be locked and can't be deleted. In such a case it is better to detect this early and give up on deleting files for this packfile. Otherwise we may delete the ".index" file and when failing to delete the ".pack" file we are left with a ".pack" file without a ".index" file.
      Parameters:
      packFile -
    • prunePacked

      public void prunePacked() throws IOException
      Like "git prune-packed" this method tries to prune all loose objects which can be found in packs. If certain objects can't be pruned (e.g. because the filesystem delete operation fails) this is silently ignored.
      Throws:
      IOException
    • prune

      public void prune(Set<ObjectId> objectsToKeep) throws IOException, ParseException
      Like "git prune" this method tries to prune all loose objects which are unreferenced. If certain objects can't be pruned (e.g. because the filesystem delete operation fails) this is silently ignored.
      Parameters:
      objectsToKeep - a set of objects which should explicitly not be pruned
      Throws:
      IOException
      ParseException - If the configuration parameter "gc.pruneexpire" couldn't be parsed
    • getExpireDate

      private long getExpireDate() throws ParseException
      Throws:
      ParseException
    • getPruneExpireStr

      private String getPruneExpireStr()
    • getPackExpireDate

      private long getPackExpireDate() throws ParseException
      Throws:
      ParseException
    • removeReferenced

      private void removeReferenced(Map<ObjectId,File> id2File, ObjectWalk w) throws MissingObjectException, IncorrectObjectTypeException, IOException
      Remove all entries from a map which key is the id of an object referenced by the given ObjectWalk
      Parameters:
      id2File -
      w -
      Throws:
      MissingObjectException
      IncorrectObjectTypeException
      IOException
    • equals

      private static boolean equals(Ref r1, Ref r2)
    • packRefs

      public void packRefs() throws IOException
      Pack ref storage. For a RefDirectory database, this packs all non-symbolic, loose refs into packed-refs. For Reftable, all of the data is compacted into a single table.
      Throws:
      IOException
    • repack

      public Collection<Pack> repack() throws IOException
      Packs all objects which reachable from any of the heads into one pack file. Additionally all objects which are not reachable from any head but which are reachable from any of the other refs (e.g. tags), special refs (e.g. FETCH_HEAD) or index are packed into a separate pack file. Objects included in pack files which have a .keep file associated are never repacked. All old pack files which existed before are deleted.
      Returns:
      a collection of the newly created pack files
      Throws:
      IOException - when during reading of refs, index, packfiles, objects, reflog-entries or during writing to the packfiles IOException occurs
    • isHead

      private static boolean isHead(Ref ref)
    • isTag

      private static boolean isTag(Ref ref)
    • deleteEmptyRefsFolders

      private void deleteEmptyRefsFolders() throws IOException
      Throws:
      IOException
    • canBeSafelyDeleted

      private boolean canBeSafelyDeleted(Path path, Instant threshold)
    • deleteDir

      private void deleteDir(Path dir)
    • isDirectory

      private boolean isDirectory(Path p)
    • delete

      private void delete(Path d)
    • deleteOrphans

      private void deleteOrphans()
      Deletes orphans

      A file is considered an orphan if it is either a "bitmap" or an index file, and its corresponding pack file is missing in the list.

    • deleteTempPacksIdx

      private void deleteTempPacksIdx()
    • listRefLogObjects

      private Set<ObjectId> listRefLogObjects(Ref ref, long minTime) throws IOException
      Parameters:
      ref - the ref which log should be inspected
      minTime - only reflog entries not older then this time are processed
      Returns:
      the ObjectIds contained in the reflog
      Throws:
      IOException
    • getAllRefs

      private Collection<Ref> getAllRefs() throws IOException
      Returns a collection of all refs and additional refs. Additional refs which don't start with "refs/" are not returned because they should not save objects from being garbage collected. Examples for such references are ORIG_HEAD, MERGE_HEAD, FETCH_HEAD and CHERRY_PICK_HEAD.
      Returns:
      a collection of refs pointing to live objects.
      Throws:
      IOException
    • listNonHEADIndexObjects

      private Set<ObjectId> listNonHEADIndexObjects() throws CorruptObjectException, IOException
      Return a list of those objects in the index which differ from whats in HEAD
      Returns:
      a set of ObjectIds of changed objects in the index
      Throws:
      IOException
      CorruptObjectException
      NoWorkTreeException
    • writePack

      private Pack writePack(@NonNull Set<? extends ObjectId> want, @NonNull Set<? extends ObjectId> have, @NonNull Set<ObjectId> tags, Set<ObjectId> tagTargets, List<ObjectIdSet> excludeObjects) throws IOException
      Throws:
      IOException
    • checkCancelled

      private void checkCancelled() throws CancelledException
      Throws:
      CancelledException
    • getStatistics

      public GC.RepoStatistics getStatistics() throws IOException
      Returns information about objects and pack files for a FileRepository.
      Returns:
      information about objects and pack files for a FileRepository
      Throws:
      IOException
    • setProgressMonitor

      public GC setProgressMonitor(ProgressMonitor pm)
      Set the progress monitor used for garbage collection methods.
      Parameters:
      pm - a ProgressMonitor object.
      Returns:
      this
    • setExpireAgeMillis

      public void setExpireAgeMillis(long expireAgeMillis)
      During gc() or prune() each unreferenced, loose object which has been created or modified in the last expireAgeMillis milliseconds will not be pruned. Only older objects may be pruned. If set to 0 then every object is a candidate for pruning.
      Parameters:
      expireAgeMillis - minimal age of objects to be pruned in milliseconds.
    • setPackExpireAgeMillis

      public void setPackExpireAgeMillis(long packExpireAgeMillis)
      During gc() or prune() packfiles which are created or modified in the last packExpireAgeMillis milliseconds will not be deleted. Only older packfiles may be deleted. If set to 0 then every packfile is a candidate for deletion.
      Parameters:
      packExpireAgeMillis - minimal age of packfiles to be deleted in milliseconds.
    • setPackConfig

      public void setPackConfig(@NonNull PackConfig pconfig)
      Set the PackConfig used when (re-)writing packfiles. This allows to influence how packs are written and to implement something similar to "git gc --aggressive"
      Parameters:
      pconfig - the PackConfig used when writing packs
    • setExpire

      public void setExpire(Date expire)
      During gc() or prune() each unreferenced, loose object which has been created or modified after or at expire will not be pruned. Only older objects may be pruned. If set to null then every object is a candidate for pruning.
      Parameters:
      expire - instant in time which defines object expiration objects with modification time before this instant are expired objects with modification time newer or equal to this instant are not expired
    • setPackExpire

      public void setPackExpire(Date packExpire)
      During gc() or prune() packfiles which are created or modified after or at packExpire will not be deleted. Only older packfiles may be deleted. If set to null then every packfile is a candidate for deletion.
      Parameters:
      packExpire - instant in time which defines packfile expiration
    • setAuto

      public void setAuto(boolean auto)
      Set the gc --auto option. With this option, gc checks whether any housekeeping is required; if not, it exits without performing any work. Some JGit commands run gc --auto after performing operations that could create many loose objects.

      Housekeeping is required if there are too many loose objects or too many packs in the repository. If the number of loose objects exceeds the value of the gc.auto option JGit GC consolidates all existing packs into a single pack (equivalent to -A option), whereas git-core would combine all loose objects into a single pack using repack -d -l. Setting the value of gc.auto to 0 disables automatic packing of loose objects.

      If the number of packs exceeds the value of gc.autoPackLimit, then existing packs (except those marked with a .keep file) are consolidated into a single pack by using the -A option of repack. Setting gc.autoPackLimit to 0 disables automatic consolidation of packs.

      Like git the following jgit commands run auto gc:

      • fetch
      • merge
      • rebase
      • receive-pack
      The auto gc for receive-pack can be suppressed by setting the config option receive.autogc = false
      Parameters:
      auto - defines whether gc should do automatic housekeeping
    • setBackground

      void setBackground(boolean background)
      Parameters:
      background - whether to run the gc in a background thread.
    • needGc

      private boolean needGc()
    • addRepackAllOption

      private void addRepackAllOption()
    • tooManyPacks

      boolean tooManyPacks()
      Returns:
      true if number of packs > gc.autopacklimit (default 50)
    • tooManyLooseObjects

      boolean tooManyLooseObjects()
      Quickly estimate number of loose objects, SHA1 is distributed evenly so counting objects in one directory (bucket 17) is sufficient
      Returns:
      true if number of loose objects > gc.auto (default 6700)
    • getLooseObjectLimit

      private int getLooseObjectLimit()