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![Nicolas Pitre](/assets/img/avatar_default.png)
Commit ccc1297226
changed the behavior
of 'git repack -A' so unreachable objects are stored as loose objects.
However it did so in a naive and inn efficient way by making packs
about to be deleted inaccessible and feeding their content through
'git unpack-objects'. While this works, there are major flaws with
this approach:
- It is unacceptably sloooooooooooooow.
In the Linux kernel repository with no actual unreachable objects,
doing 'git repack -A -d' before:
real 2m33.220s
user 2m21.675s
sys 0m3.510s
And with this change:
real 0m36.849s
user 0m24.365s
sys 0m1.950s
For reference, here's the timing for 'git repack -a -d':
real 0m35.816s
user 0m22.571s
sys 0m2.011s
This is explained by the fact that 'git unpack-objects' was used to
unpack _every_ objects even if (almost) 100% of them were thrown away.
- There is a black out period.
Between the removal of the .idx file for the redundant pack and the
completion of its unpacking, the unreachable objects become completely
unaccessible. This is not a big issue as we're talking about unreachable
objects, but some consistency is always good.
- There is no way to easily set a sensible mtime for the newly created
unreachable loose objects.
So, while having a command called "pack-objects" to perform object
unpacking looks really odd, this is probably the best compromize to be
able to solve the above issues in an efficient way.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
145 lines
3.4 KiB
Bash
Executable file
145 lines
3.4 KiB
Bash
Executable file
#!/bin/sh
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#
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# Copyright (c) 2005 Linus Torvalds
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#
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OPTIONS_KEEPDASHDASH=
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OPTIONS_SPEC="\
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git-repack [options]
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--
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a pack everything in a single pack
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A same as -a, and turn unreachable objects loose
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d remove redundant packs, and run git-prune-packed
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f pass --no-reuse-delta to git-pack-objects
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q,quiet be quiet
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l pass --local to git-pack-objects
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Packing constraints
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window= size of the window used for delta compression
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window-memory= same as the above, but limit memory size instead of entries count
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depth= limits the maximum delta depth
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max-pack-size= maximum size of each packfile
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"
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SUBDIRECTORY_OK='Yes'
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. git-sh-setup
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no_update_info= all_into_one= remove_redundant= unpack_unreachable=
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local= quiet= no_reuse= extra=
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while test $# != 0
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do
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case "$1" in
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-n) no_update_info=t ;;
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-a) all_into_one=t ;;
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-A) all_into_one=t
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unpack_unreachable=--unpack-unreachable ;;
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-d) remove_redundant=t ;;
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-q) quiet=-q ;;
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-f) no_reuse=--no-reuse-object ;;
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-l) local=--local ;;
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--max-pack-size|--window|--window-memory|--depth)
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extra="$extra $1=$2"; shift ;;
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--) shift; break;;
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*) usage ;;
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esac
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shift
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done
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# Later we will default repack.UseDeltaBaseOffset to true
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default_dbo=false
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case "`git config --bool repack.usedeltabaseoffset ||
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echo $default_dbo`" in
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true)
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extra="$extra --delta-base-offset" ;;
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esac
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PACKDIR="$GIT_OBJECT_DIRECTORY/pack"
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PACKTMP="$GIT_OBJECT_DIRECTORY/.tmp-$$-pack"
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rm -f "$PACKTMP"-*
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trap 'rm -f "$PACKTMP"-*' 0 1 2 3 15
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# There will be more repacking strategies to come...
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case ",$all_into_one," in
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,,)
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args='--unpacked --incremental'
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;;
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,t,)
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if [ -d "$PACKDIR" ]; then
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for e in `cd "$PACKDIR" && find . -type f -name '*.pack' \
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| sed -e 's/^\.\///' -e 's/\.pack$//'`
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do
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if [ -e "$PACKDIR/$e.keep" ]; then
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: keep
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else
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args="$args --unpacked=$e.pack"
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existing="$existing $e"
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fi
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done
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fi
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if test -z "$args"
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then
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args='--unpacked --incremental'
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elif test -n "$unpack_unreachable"
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then
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args="$args $unpack_unreachable"
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fi
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;;
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esac
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args="$args $local $quiet $no_reuse$extra"
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names=$(git pack-objects --non-empty --all --reflog $args </dev/null "$PACKTMP") ||
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exit 1
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if [ -z "$names" ]; then
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if test -z "$quiet"; then
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echo Nothing new to pack.
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fi
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fi
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for name in $names ; do
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fullbases="$fullbases pack-$name"
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chmod a-w "$PACKTMP-$name.pack"
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chmod a-w "$PACKTMP-$name.idx"
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mkdir -p "$PACKDIR" || exit
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for sfx in pack idx
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do
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if test -f "$PACKDIR/pack-$name.$sfx"
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then
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mv -f "$PACKDIR/pack-$name.$sfx" \
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"$PACKDIR/old-pack-$name.$sfx"
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fi
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done &&
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mv -f "$PACKTMP-$name.pack" "$PACKDIR/pack-$name.pack" &&
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mv -f "$PACKTMP-$name.idx" "$PACKDIR/pack-$name.idx" &&
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test -f "$PACKDIR/pack-$name.pack" &&
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test -f "$PACKDIR/pack-$name.idx" || {
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echo >&2 "Couldn't replace the existing pack with updated one."
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echo >&2 "The original set of packs have been saved as"
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echo >&2 "old-pack-$name.{pack,idx} in $PACKDIR."
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exit 1
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}
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rm -f "$PACKDIR/old-pack-$name.pack" "$PACKDIR/old-pack-$name.idx"
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done
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if test "$remove_redundant" = t
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then
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# We know $existing are all redundant.
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if [ -n "$existing" ]
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then
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sync
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( cd "$PACKDIR" &&
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for e in $existing
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do
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case " $fullbases " in
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*" $e "*) ;;
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*) rm -f "$e.pack" "$e.idx" "$e.keep" ;;
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esac
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done
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)
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fi
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git prune-packed $quiet
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fi
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case "$no_update_info" in
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t) : ;;
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*) git-update-server-info ;;
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esac
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