82 lines
2.6 KiB
Bash
Executable File
82 lines
2.6 KiB
Bash
Executable File
#!/bin/bash
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# Example script to deltify 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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max_depth=
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[ "$1" == "-d" ] && max_depth="--max-depth=$2" && shift 2
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overlap=30
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max_behind="--max-behind=$overlap"
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function process_list() {
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if [ "$list" ]; then
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echo "Processing $curr_file"
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echo "$list" | xargs git-mkdelta $max_depth $max_behind -v
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fi
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}
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rev_list=""
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curr_file=""
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git-rev-list HEAD |
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while true; do
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# Let's batch revisions into groups of 1000 to give it a chance to
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# scale with repositories containing long revision lists. We also
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# overlap with the previous batch the size of mkdelta's look behind
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# value in order to account for the processing discontinuity.
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rev_list="$(echo -e -n "$rev_list" | tail --lines=$overlap)"
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for i in $(seq 1000); do
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read rev || break
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rev_list="$rev_list$rev\n"
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done
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echo -e -n "$rev_list" |
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git-diff-tree -r -t --stdin |
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awk '/^:/ { if ($5 == "M") printf "%s %s\n%s %s\n", $4, $6, $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="$sha1"
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fi
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done
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[ "$rev" ] || break
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done
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process_list
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curr_file="root directory"
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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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