1. 05 Nov, 2007 1 commit
    • Nicolas Pitre's avatar
      make display of total transferred more accurate · 218558af
      Nicolas Pitre authored
      The throughput display needs a delay period before accounting and
      displaying anything.  Yet it might be called after some amount of data
      has already been transferred.  The display of total data is therefore
      accounted late and therefore smaller than the reality.
      
      Let's call display_throughput() with an absolute amount of transferred
      data instead of a relative number, and let the throughput code find the
      relative amount of data by itself as needed.  This way the displayed
      total is always exact.
      Signed-off-by: default avatarNicolas Pitre <nico@cam.org>
      Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
      218558af
  2. 30 Oct, 2007 1 commit
  3. 13 Jun, 2007 1 commit
  4. 10 May, 2007 1 commit
    • Dana How's avatar
      Custom compression levels for objects and packs · 960ccca6
      Dana How authored
      Add config variables pack.compression and core.loosecompression ,
      and switch --compression=level to pack-objects.
      
      Loose objects will be compressed using core.loosecompression if set,
      else core.compression if set, else Z_BEST_SPEED.
      Packed objects will be compressed using --compression=level if seen,
      else pack.compression if set, else core.compression if set,
      else Z_DEFAULT_COMPRESSION.  This is the "pack compression level".
      
      Loose objects added to a pack undeltified will be recompressed
      to the pack compression level if it is unequal to the current
      loose compression level by the preceding rules,  or if the loose
      object was written while core.legacyheaders = true.  Newly
      deltified loose objects are always compressed to the current
      pack compression level.
      
      Previously packed objects added to a pack are recompressed
      to the current pack compression level exactly when their
      deltification status changes,  since the previous pack data
      cannot be reused.
      
      In either case,  the --no-reuse-object switch from the first
      patch below will always force recompression to the current pack
      compression level,  instead of assuming the pack compression level
      hasn't changed and pack data can be reused when possible.
      
      This applies on top of the following patches from Nicolas Pitre:
      [PATCH] allow for undeltified objects not to be reused
      [PATCH] make "repack -f" imply "pack-objects --no-reuse-object"
      Signed-off-by: default avatarDana L. How <danahow@gmail.com>
      Signed-off-by: default avatarJunio C Hamano <junkio@cox.net>
      960ccca6
  5. 10 Apr, 2007 1 commit
    • Nicolas Pitre's avatar
      compute a CRC32 for each object as stored in a pack · 78d1e84f
      Nicolas Pitre authored
      The most important optimization for performance when repacking is the
      ability to reuse data from a previous pack as is and bypass any delta
      or even SHA1 computation by simply copying the raw data from one pack
      to another directly.
      
      The problem with  this is that any data corruption within a copied object
      would go unnoticed and the new (repacked) pack would be self-consistent
      with its own checksum despite containing a corrupted object.  This is a
      real issue that already happened at least once in the past.
      
      In some attempt to prevent this, we validate the copied data by inflating
      it and making sure no error is signaled by zlib.  But this is still not
      perfect as a significant portion of a pack content is made of object
      headers and references to delta base objects which are not deflated and
      therefore not validated when repacking actually making the pack data reuse
      still not as safe as it could be.
      
      Of course a full SHA1 validation could be performed, but that implies
      full data inflating and delta replaying which is extremely costly, which
      cost the data reuse optimization was designed to avoid in the first place.
      
      So the best solution to this is simply to store a CRC32 of the raw pack
      data for each object in the pack index.  This way any object in a pack can
      be validated before being copied as is in another pack, including header
      and any other non deflated data.
      
      Why CRC32 instead of a faster checksum like Adler32?  Quoting Wikipedia:
      
         Jonathan Stone discovered in 2001 that Adler-32 has a weakness for very
         short messages. He wrote "Briefly, the problem is that, for very short
         packets, Adler32 is guaranteed to give poor coverage of the available
         bits. Don't take my word for it, ask Mark Adler. :-)" The problem is
         that sum A does not wrap for short messages. The maximum value of A for
         a 128-byte message is 32640, which is below the value 65521 used by the
         modulo operation. An extended explanation can be found in RFC 3309,
         which mandates the use of CRC32 instead of Adler-32 for SCTP, the
         Stream Control Transmission Protocol.
      
      In the context of a GIT pack, we have lots of small objects, especially
      deltas, which are likely to be quite small and in a size range for which
      Adler32 is dimed not to be sufficient.  Another advantage of CRC32 is the
      possibility for recovery from certain types of small corruptions like
      single bit errors which are the most probable type of corruptions.
      
      OK what this patch does is to compute the CRC32 of each object written to
      a pack within pack-objects.  It is not written to the index yet and it is
      obviously not validated when reusing pack data yet either.
      Signed-off-by: default avatarNicolas Pitre <nico@cam.org>
      Signed-off-by: default avatarJunio C Hamano <junkio@cox.net>
      78d1e84f
  6. 10 Aug, 2005 1 commit
    • Timo Sirainen's avatar
      [PATCH] -Werror fixes · 4ec99bf0
      Timo Sirainen authored
      GCC's format __attribute__ is good for checking errors, especially
      with -Wformat=2 parameter. This fixes most of the reported problems
      against 2005-08-09 snapshot.
      4ec99bf0
  7. 28 Jun, 2005 1 commit
  8. 27 Jun, 2005 2 commits
    • Linus Torvalds's avatar
      csum-file interface updates: return resulting SHA1 · e1808845
      Linus Torvalds authored
      Also, make the writing of the SHA1 as a end-header be conditional: not
      every user will necessarily want to write the SHA1 to the file itself,
      even though current users do (but we migh end up using the same helper
      functions for the object files themselves, that don't do this).
      
      This also makes the packed index file contain the SHA1 of the packed
      data file at the end (just before its own SHA1).  That way you can
      validate the pairing of the two if you want to.
      e1808845
    • Linus Torvalds's avatar
      git-pack-objects: write the pack files with a SHA1 csum · c38138cd
      Linus Torvalds authored
      We want to be able to check their integrity later, and putting the
      sha1-sum of the contents at the end is a good thing.  The writing
      routines are generic, so we could try to re-use them for the index file,
      instead of having the same logic duplicated.
      
      Update unpack-objects to know about the extra 20 bytes at the end
      of the index.
      c38138cd