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57 commits

Author SHA1 Message Date
Nelson Elhage 18879bc526 pack-objects documentation: Fix --honor-pack-keep as well.
Signed-off-by: Nelson Elhage <nelhage@mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-02-24 19:10:22 -08:00
Junio C Hamano 3909f14f62 pack-objects documentation: reword "objects that appear in the standard input"
These were written back when we always read objects from the standard
input.  These days --revs and its friends can feed only the start and
end points and have the command internally enumerate the objects.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-02-24 15:41:27 -08:00
Nelson Elhage 21da426214 Documentation: pack-objects: Clarify --local's semantics.
The current documentation suggests that --local also ignores any
objects in local packs, which is incorrect. Change the language to be
clearer and more parallel to the other options that ignore objects.

While we're at it, fix a trivial error in --incremental's
documentation.

Signed-off-by: Nelson Elhage <nelhage@mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-02-20 09:24:19 -08:00
Stephen Boyd 738820a913 Documentation: describe --thin more accurately
The description for --thin was misleading and downright wrong. Correct
it with some inspiration from the description of index-pack's --fix-thin
and some background information from Nicolas Pitre <nico@fluxnic.net>.

Signed-off-by: Stephen Boyd <bebarino@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-02-18 17:13:18 -08:00
Jeff King cc1b8d8bc6 docs: don't talk about $GIT_DIR/refs/ everywhere
It is misleading to say that we pull refs from $GIT_DIR/refs/*, because we
may also consult the packed refs mechanism. These days we tend to treat
the "refs hierarchy" as more of an abstract namespace that happens to be
represented as $GIT_DIR/refs. At best, this is a minor inaccuracy, but at
worst it can confuse users who then look in $GIT_DIR/refs and find that it
is missing some of the refs they expected to see.

This patch drops most uses of "$GIT_DIR/refs/*", changing them into just
"refs/*", under the assumption that users can handle the concept of an
abstract refs namespace. There are a few things to note:

  - most cases just dropped the $GIT_DIR/ portion. But for cases where
    that left _just_ the word "refs", I changed it to "refs/" to help
    indicate that it was a hierarchy.  I didn't do the same for longer
    paths (e.g., "refs/heads" remained, instead of becoming
    "refs/heads/").

  - in some cases, no change was made, as the text was explicitly about
    unpacked refs (e.g., the discussion in git-pack-refs).

  - In some cases it made sense instead to note the existence of packed
    refs (e.g., in check-ref-format and rev-parse).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-02-17 21:40:09 -08:00
Nicolas Pitre 07cf0f2407 make --max-pack-size argument to 'git pack-object' count in bytes
The value passed to --max-pack-size used to count in MiB which was
inconsistent with the corresponding configuration variable as well as
other command arguments which are defined to count in bytes with an
optional unit suffix.  This brings --max-pack-size in line with the
rest of Git.

Also, in order not to cause havoc with people used to the previous
megabyte scale, and because this is a sane thing to do anyway, a
minimum size of 1 MiB is enforced to avoid an explosion of pack files.

Adjust and extend test suite accordingly.

Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-02-03 20:39:56 -08:00
Thomas Rast 0b444cdb19 Documentation: spell 'git cmd' without dash throughout
The documentation was quite inconsistent when spelling 'git cmd' if it
only refers to the program, not to some specific invocation syntax:
both 'git-cmd' and 'git cmd' spellings exist.

The current trend goes towards dashless forms, and there is precedent
in 647ac70 (git-svn.txt: stop using dash-form of commands.,
2009-07-07) to actively eliminate the dashed variants.

Replace 'git-cmd' with 'git cmd' throughout, except where git-shell,
git-cvsserver, git-upload-pack, git-receive-pack, and
git-upload-archive are concerned, because those really live in the
$PATH.
2010-01-10 13:01:28 +01:00
Nicolas Pitre 4f36627518 pack-objects: split implications of --all-progress from progress activation
Currently the --all-progress flag is used to use force progress display
during the writing object phase even if output goes to stdout which is
primarily the case during a push operation.  This has the unfortunate
side effect of forcing progress display even if stderr is not a
terminal.

Let's introduce the --all-progress-implied argument which has the same
intent except for actually forcing the activation of any progress
display.  With this, progress display will be automatically inhibited
whenever stderr is not a terminal, or full progress display will be
included otherwise.  This should let people use 'git push' within a cron
job without filling their logs with useless percentage displays.

Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
Tested-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-11-23 21:33:09 -08:00
Johannes Schindelin 7f3140cd23 git repack: keep commits hidden by a graft
When you have grafts that pretend that a given commit has different
parents than the ones recorded in the commit object, it is dangerous
to let 'git repack' remove those hidden parents, as you can easily
remove the graft and end up with a broken repository.

So let's play it safe and keep those parent objects and everything
that is reachable by them, in addition to the grafted parents.

As this behavior can only be triggered by git pack-objects, and as that
command handles duplicate parents gracefully, we do not bother to cull
duplicated parents that may result by using both true and grafted
parents.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-07-24 09:10:16 -07:00
Brandon Casey daae062595 pack-objects: extend --local to mean ignore non-local loose objects too
With this patch, --local means pack only local objects that are not already
packed.

Additionally, this fixes t7700 testing whether loose objects in an alternate
object database are repacked.

Signed-off-by: Brandon Casey <drafnel@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-11-12 10:29:22 -08:00
Brandon Casey e96fb9b8f9 pack-objects: new option --honor-pack-keep
This adds a new option to pack-objects which will cause it to ignore an
object which appears in a local pack which has a .keep file, even if it
was specified for packing.

This option will be used by the porcelain repack.

Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-11-12 10:28:10 -08:00
Jonathan Nieder ba020ef5eb manpages: italicize git command names (which were in teletype font)
The names of git commands are not meant to be entered at the
commandline; they are just names. So we render them in italics,
as is usual for command names in manpages.

Using

	doit () {
	  perl -e 'for (<>) { s/\`(git-[^\`.]*)\`/'\''\1'\''/g; print }'
	}
	for i in git*.txt config.txt diff*.txt blame*.txt fetch*.txt i18n.txt \
	        merge*.txt pretty*.txt pull*.txt rev*.txt urls*.txt
	do
	  doit <"$i" >"$i+" && mv "$i+" "$i"
	done
	git diff

.

Signed-off-by: Jonathan Nieder <jrnieder@uchicago.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-07-05 11:24:40 -07:00
Jonathan Nieder 483bc4f045 Documentation formatting and cleanup
Following what appears to be the predominant style, format
names of commands and commandlines both as `teletype text`.

While we're at it, add articles ("a" and "the") in some
places, italicize the name of the command in the manual page
synopsis line, and add a comma or two where it seems appropriate.

Signed-off-by: Jonathan Nieder <jrnieder@uchicago.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-07-01 17:20:16 -07:00
Jonathan Nieder b1889c36d8 Documentation: be consistent about "git-" versus "git "
Since the git-* commands are not installed in $(bindir), using
"git-command <parameters>" in examples in the documentation is
not a good idea. On the other hand, it is nice to be able to
refer to each command using one hyphenated word. (There is no
escaping it, anyway: man page names cannot have spaces in them.)

This patch retains the dash in naming an operation, command,
program, process, or action. Complete command lines that can
be entered at a shell (i.e., without options omitted) are
made to use the dashless form.

The changes consist only of replacing some spaces with hyphens
and vice versa. After a "s/ /-/g", the unpatched and patched
versions are identical.

Signed-off-by: Jonathan Nieder <jrnieder@uchicago.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-07-01 17:20:15 -07:00
Stephan Beyer 3240240ff4 Docs: Use "-l::\n--long\n" format in OPTIONS sections
The OPTIONS section of a documentation file contains a list
of the options a git command accepts.

Currently there are several variants to describe the case that
different options (almost) do the same in the OPTIONS section.

Some are:

 -f, --foo::
 -f|--foo::
 -f | --foo::

But AsciiDoc has the special form:

 -f::
 --foo::

This patch applies this form to the documentation of the whole git suite,
and removes useless em-dash prevention, so \--foo becomes --foo.

Signed-off-by: Stephan Beyer <s-beyer@gmx.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-06-08 13:46:38 -07:00
Christian Couder 9e1f0a85c6 documentation: move git(7) to git(1)
As the "git" man page describes the "git" command at the end-user
level, it seems better to move it to man section 1.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-06-06 11:18:28 -07:00
Junio C Hamano 56ae8df5c7 Manual subsection to refer to other pages is SEE ALSO
Consistently say so in all caps as it is customary to do so.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-28 16:59:40 -07:00
Peter Eriksen ba1333fec3 git-pack-objects.txt: Make wording slightly less ambiguous
It is a bit confusing on first read, that

        "The packed archive format (.pack) is designed
        to be unpackable..."

Signed-off-by: Peter Eriksen <s022018@student.dtu.dk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-04-05 16:51:16 -07:00
Shawn O. Pearce f0a24aa56e git-pack-objects: Automatically pack annotated tags if object was packed
The new option "--include-tag" allows the caller to request that
any annotated tag be included into the packfile if the object the tag
references was also included as part of the packfile.

This option can be useful on the server side of a native git transport,
where the server knows what commits it is including into a packfile to
update the client.  If new annotated tags have been introduced then we
can also include them in the packfile, saving the client from needing
to request them through a second connection.

This change only introduces the backend option and provides a test.
Protocol extensions to make this useful in fetch-pack/upload-pack
are still necessary to activate the logic during transport.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-03-04 23:28:14 -08:00
Andreas Ericsson 833e3df171 pack-objects: Add runtime detection of online CPU's
Packing objects can be done in parallell nowadays, but it's
only done if the config option pack.threads is set to a value
above 1. Because of that, the code-path used is often not the
most optimal one.

This patch adds a routine to detect the number of online CPU's
at runtime (online_cpus()). When pack.threads (or --threads=) is
given a value of 0, the number of threads is set to the number of
online CPU's. This feature is also documented.

As per Nicolas Pitre's recommendations, the default is still to
run pack-objects single-threaded unless explicitly activated,
either by configuration or by command line parameter.

The routine online_cpus() is a rework of "numcpus.c", written by
one Philip Willoughby <pgw99@doc.ic.ac.uk>. numcpus.c is in the
public domain and can presently be downloaded from
http://csgsoft.doc.ic.ac.uk/numcpus/

Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-02-23 12:00:32 -08:00
Johannes Schindelin 2b84b5a874 Introduce the config variable pack.packSizeLimit
"git pack-objects" has the option --max-pack-size to limit the file
size of the packs to a certain amount of bytes.  On platforms where
the pack file size is limited by filesystem constraints, it is easy
to forget this option, and this option does not exist for "git gc"
to begin with.

So introduce a config variable to set the default maximum, but make
this overrideable by the command line.

Suggested by Tor Arvid Lund.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-02-09 23:41:34 -08:00
Dan McGee 5162e69732 Documentation: rename gitlink macro to linkgit
Between AsciiDoc 8.2.2 and 8.2.3, the following change was made to the stock
Asciidoc configuration:

@@ -149,7 +153,10 @@
 # Inline macros.
 # Backslash prefix required for escape processing.
 # (?s) re flag for line spanning.
-(?su)[\\]?(?P<name>\w(\w|-)*?):(?P<target>\S*?)(\[(?P<attrlist>.*?)\])=
+
+# Explicit so they can be nested.
+(?su)[\\]?(?P<name>(http|https|ftp|file|mailto|callto|image|link)):(?P<target>\S*?)(\[(?P<attrlist>.*?)\])=
+
 # Anchor: [[[id]]]. Bibliographic anchor.
 (?su)[\\]?\[\[\[(?P<attrlist>[\w][\w-]*?)\]\]\]=anchor3
 # Anchor: [[id,xreflabel]]

This default regex now matches explicit values, and unfortunately in this
case gitlink was being matched by just 'link', causing the wrong inline
macro template to be applied. By renaming the macro, we can avoid being
matched by the wrong regex.

Signed-off-by: Dan McGee <dpmcgee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-06 18:41:44 -08:00
Junio C Hamano 4f337e2466 Merge branch 'maint'
* maint:
  git-svn: don't attempt to spawn pager if we don't want one
  Supplant the "while case ... break ;; esac" idiom
  User Manual: add a chapter for submodules
  user-manual: don't assume refs are stored under .git/refs
  Detect exec bit in more cases.
  Conjugate "search" correctly in the git-prune-packed man page.
  Move the paragraph specifying where the .idx and .pack files should be
  Documentation/git-lost-found.txt: drop unnecessarily duplicated name.
2007-09-23 17:13:55 -07:00
Matt Kraai 1e6ab5de4f Move the paragraph specifying where the .idx and .pack files should be
Signed-off-by: Matt Kraai <kraai@ftbfs.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-21 12:54:11 -07:00
Junio C Hamano d225ae59c9 Merge branch 'np/delta'
* np/delta:
  builtin-pack-objects.c: avoid bogus gcc warnings
  threaded delta search: proper locking for cache accounting
  threaded delta search: add pack.threads config variable
  fix threaded delta search locking
  threaded delta search: specify number of threads at run time
  threaded delta search: better chunck split point
  threaded delta search: refine work allocation
  basic threaded delta search
  rearrange delta search progress reporting
  localize window memory usage accounting
  straighten the list of objects to deltify
2007-09-14 22:33:28 -07:00
Nicolas Pitre 05cc2ffc57 fix doc for --compression argument to pack-objects
Remove obsolete details (core.legacyheaders is always true now).

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-09 23:58:56 -07:00
Nicolas Pitre 367f4a4343 threaded delta search: specify number of threads at run time
This adds a --threads=<n> parameter to 'git pack-objects' with
documentation.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-09 22:26:06 -07:00
Brian Downing e93b15cd74 Add documentation for --window-memory, pack.windowMemory
Signed-off-by: Brian Downing <bdowning@lavos.net>
Acked-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-07-12 14:32:35 -07:00
Junio C Hamano a6080a0a44 War on whitespace
This uses "git-apply --whitespace=strip" to fix whitespace errors that have
crept in to our source files over time.  There are a few files that need
to have trailing whitespaces (most notably, test vectors).  The results
still passes the test, and build result in Documentation/ area is unchanged.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-06-07 00:04:01 -07:00
Dana L. How 6b94b1a09a git-repack --max-pack-size: add option parsing to enable feature
Add --max-pack-size parsing and usage messages.
Upgrade git-repack.sh to handle multiple packfile names,
and build packfiles in GIT_OBJECT_DIRECTORY not GIT_DIR.
Update documentation.

Signed-off-by: Dana L. How <danahow@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-20 21:55:26 -07:00
Dana How 960ccca680 Custom compression levels for objects and packs
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: Dana L. How <danahow@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-10 15:23:09 -07:00
Nicolas Pitre fa736f72b0 allow for undeltified objects not to be reused
Currently non deltified object data is always reused when possible.
This means that any change to core.compression has no effect on those
objects as they don't get recompressed when repacking them.

Let's add a --no-reuse-object flag to git-repack in order to force
recompression of all objects when desired.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-10 15:22:33 -07:00
Theodore Ts'o 618e613a70 Increase pack.depth default to 50
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-08 22:47:17 -07:00
Theodore Ts'o 842aaf9323 Add pack.depth option to git-pack-objects.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-08 22:47:17 -07:00
Nicolas Pitre be18c1fe12 document --index-version for index-pack and pack-objects
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-04-19 20:38:00 -07:00
Nicolas Pitre 231f240b63 git-pack-objects progress flag documentation and cleanup
This adds documentation for --progress and --all-progress, remove a
duplicate --progress handling and make usage string more readable.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-11-07 16:05:37 -08:00
Nicolas Pitre fa438a2eb1 make git-push a bit more verbose
Currently git-push displays progress status for the local packing of
objects to send, but nothing once it starts to push it over the
connection.  Having progress status in that later case is especially
nice when pushing lots of objects over a slow network link.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-11-01 15:13:10 -08:00
Junio C Hamano 7854e526ff Merge branch 'maint'
* maint:
  pack-objects doesn't create random pack names
  link_temp_to_file: don't leave the path truncated on adjust_shared_perm failure
2006-11-01 15:09:55 -08:00
Nicolas Pitre e23ed9a8b4 pack-objects doesn't create random pack names
Documentation for pack-objects seems to be out of date in this regard.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-11-01 15:09:39 -08:00
Junio C Hamano 05eb811aa1 Merge branch 'np/pack'
* np/pack:
  add the capability for index-pack to read from a stream
  index-pack: compare only the first 20-bytes of the key.
  git-repack: repo.usedeltabaseoffset
  pack-objects: document --delta-base-offset option
  allow delta data reuse even if base object is a preferred base
  zap a debug remnant
  let the GIT native protocol use offsets to delta base when possible
  make pack data reuse compatible with both delta types
  make git-pack-objects able to create deltas with offset to base
  teach git-index-pack about deltas with offset to base
  teach git-unpack-objects about deltas with offset to base
  introduce delta objects with offset to base
2006-10-22 22:51:42 -07:00
Junio C Hamano 63fba759bc pack-objects: document --delta-base-offset option
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-10-10 01:06:20 -07:00
Dennis Stosberg 3df196716e Add default values for --window and --depth to the docs
Currently, you actually have to read the source to find out the
default values. While at it, fix two typos and suggest that these
options actually take a parameter in git-pack-objects.txt.

Signed-off-by: Dennis Stosberg <dennis@stosberg.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-10-06 02:53:39 -07:00
Junio C Hamano 4321134cd8 pack-objects: document --revs, --unpacked and --all.
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-09-12 22:59:15 -07:00
Fredrik Kuivinen 7bd7f2804d Remove trailing dot after short description
Signed-off-by: Fredrik Kuivinen <freku045@student.liu.se>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-03-09 11:44:11 -08:00
Jeff Muizelaar 46444f514b cosmetics: change from 'See-Also' to 'See Also'
Changes the documentation that uses 'See-Also' to the more common
'See Also' form.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-03-05 00:57:37 -08:00
Junio C Hamano ca5381d43e pack-objects: finishing touches.
This introduces --no-reuse-delta option to disable reusing of
existing delta, which is a large part of the optimization
introduced by this series.  This may become necessary if
repeated repacking makes delta chain too long.  With this, the
output of the command becomes identical to that of the older
implementation.  But the performance suffers greatly.

It still allows reusing non-deltified representations; there is
no point uncompressing and recompressing the whole text.

It also adds a couple more statistics output, while squelching
it under -q flag, which the last round forgot to do.

  $ time old-git-pack-objects --stdout >/dev/null <RL
  Generating pack...
  Done counting 184141 objects.
  Packing 184141 objects....................
  real    12m8.530s       user    11m1.450s       sys     0m57.920s
  $ time git-pack-objects --stdout >/dev/null <RL
  Generating pack...
  Done counting 184141 objects.
  Packing 184141 objects.....................
  Total 184141, written 184141 (delta 138297), reused 178833 (delta 134081)
  real    0m59.549s       user    0m56.670s       sys     0m2.400s
  $ time git-pack-objects --stdout --no-reuse-delta >/dev/null <RL
  Generating pack...
  Done counting 184141 objects.
  Packing 184141 objects.....................
  Total 184141, written 184141 (delta 134833), reused 47904 (delta 0)
  real    11m13.830s      user    9m45.240s       sys     0m44.330s

There is one remaining issue when --no-reuse-delta option is not
used.  It can create delta chains that are deeper than specified.

    A<--B<--C<--D   E   F   G

Suppose we have a delta chain A to D (A is stored in full either
in a pack or as a loose object. B is depth1 delta relative to A,
C is depth2 delta relative to B...) with loose objects E, F, G.
And we are going to pack all of them.

B, C and D are left as delta against A, B and C respectively.
So A, E, F, and G are examined for deltification, and let's say
we decided to keep E expanded, and store the rest as deltas like
this:

    E<--F<--G<--A

Oops.  We ended up making D a bit too deep, didn't we?  B, C and
D form a chain on top of A!

This is because we did not know what the final depth of A would
be, when we checked objects and decided to keep the existing
delta.  Unfortunately, deferring the decision until just before
the deltification is not an option.  To be able to make B, C,
and D candidates for deltification with the rest, we need to
know the type and final unexpanded size of them, but the major
part of the optimization comes from the fact that we do not read
the delta data to do so -- getting the final size is quite an
expensive operation.

To prevent this from happening, we should keep A from being
deltified.  But how would we tell that, cheaply?

To do this most precisely, after check_object() runs, each
object that is used as the base object of some existing delta
needs to be marked with the maximum depth of the objects we
decided to keep deltified (in this case, D is depth 3 relative
to A, so if no other delta chain that is longer than 3 based on
A exists, mark A with 3).  Then when attempting to deltify A, we
would take that number into account to see if the final delta
chain that leads to D becomes too deep.

However, this is a bit cumbersome to compute, so we would cheat
and reduce the maximum depth for A arbitrarily to depth/4 in
this implementation.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-17 02:11:38 -08:00
Junio C Hamano 89438677ab Documentation: spell.
Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-29 01:32:56 -08:00
Nikolai Weibull 63ae26f87a Document the --non-empty command-line option to git-pack-objects.
This provides (minimal) documentation for the --non-empty command-line
option to the pack-objects command.

Signed-off-by: Nikolai Weibull <nikolai@bitwi.se>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-08 15:50:13 -08:00
Junio C Hamano 12ea5bea58 Update git-pack-objects documentation.
Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-10-30 17:28:03 -08:00
Christian Meder 72e9340cfd Convert usage of GIT and Git into git
Convert usage of GIT and Git into git.

Signed-off-by: Christian Meder <chris@absolutegiganten.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-10-10 16:01:31 -07:00