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53d4b46085
Although it was described as such, git-mkdelta didn't really attempt to find the best delta against any previous object in the list, but was only able to create a delta against the preceeding object. This patch reworks the code to fix that limitation and hopefully makes it a bit clearer than before, including fixing the delta loop detection which was broken. This means that git-mkdelta sha1 sha2 sha3 sha4 sha5 sha6 will now create a sha2 delta against sha1, a sha3 delta against either sha2 or sha1 and keep the best one, a sha4 delta against either sha3, sha2 or sha1, etc. The --max-behind argument limits that search for the best delta to the specified number of previous objects in the list. If no limit is specified it is unlimited (note: it might run out of memory with long object lists). Also added a -q (quiet) switch so it is possible to have 3 levels of output: -q for nothing, -v for verbose, and if none of -q nor -v is specified then only actual changes on the object database are shown. Finally the git-deltafy-script has been updated accordingly, and some bugs fixed (thanks to Stephen C. Tweedie for spotting them). This version has been toroughly tested and I think it is ready for public consumption. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
67 lines
2.1 KiB
Bash
Executable file
67 lines
2.1 KiB
Bash
Executable file
#!/bin/bash
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# Example script to deltafy an entire GIT repository based on the commit list.
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# The most recent version of a file is the reference and previous versions
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# are made delta against the best earlier version available. And so on for
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# successive versions going back in time. This way the increasing delta
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# overhead is pushed towards older versions of any given file.
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#
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# The -d argument allows to provide a limit on the delta chain depth.
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# If 0 is passed then everything is undeltafied. Limiting the delta
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# depth is meaningful for subsequent access performance to old revisions.
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# A value of 16 might be a good compromize between performance and good
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# space saving. Current default is unbounded.
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#
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# The --max-behind=30 argument is passed to git-mkdelta so to keep
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# combinations and memory usage bounded a bit. If you have lots of memory
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# and CPU power you may remove it (or set to 0) to let git-mkdelta find the
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# best delta match regardless of the number of revisions for a given file.
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# You can also make the value smaller to make it faster and less
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# memory hungry. A value of 5 ought to still give pretty good results.
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# When set to 0 or ommitted then look behind is unbounded. Note that
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# git-mkdelta might die with a segmentation fault in that case if it
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# runs out of memory. Note that the GIT repository will still be consistent
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# even if git-mkdelta dies unexpectedly.
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set -e
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depth=
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[ "$1" == "-d" ] && depth="--max-depth=$2" && shift 2
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function process_list() {
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if [ "$list" ]; then
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echo "Processing $curr_file"
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echo "$head $list" | xargs git-mkdelta $depth --max-behind=30 -v
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fi
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}
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curr_file=""
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git-rev-list HEAD |
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git-diff-tree -r -t --stdin |
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awk '/^:/ { if ($5 == "M" || $5 == "N") print $4, $6;
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if ($5 == "M") print $3, $6 }' |
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LC_ALL=C sort -s -k 2 | uniq |
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while read sha1 file; do
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if [ "$file" == "$curr_file" ]; then
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list="$list $sha1"
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else
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process_list
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curr_file="$file"
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list=""
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head="$sha1"
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fi
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done
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process_list
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curr_file="root directory"
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head=""
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list="$(
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git-rev-list HEAD |
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while read commit; do
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git-cat-file commit $commit |
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sed -n 's/tree //p;Q'
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done
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)"
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process_list
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