Linus

   1 #!/bin/sh
   2 # How much of the very original version from Linus survive?
   3
   4 _x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
   5 _x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
   6
   7 initial=$(git rev-parse --verify e83c5163316f89bfbde7d9ab23ca2e25604af290) &&
   8 this=$(git rev-parse --verify ${1-HEAD}^0) || exit
   9
  10 tmp="/var/tmp/Linus.$$"
  11 trap 'rm -f "$tmp".*' 0
  12
  13 # We blame each file in the initial revision pretending as if it is a
  14 # direct descendant of the given version, and also pretend that the
  15 # latter is a root commit.  This way, lines in the initial revision
  16 # that survived to the other version can be identified (they will be
  17 # attributed to the other version).
  18 graft="$tmp.graft" &&
  19 {
  20         echo "$initial $this"
  21         echo "$this"
  22 } >"$graft" || exit
  23
  24 opts='-C -C -C -w'
  25
  26 show () {
  27         s=$1 t=$2 n=$3
  28         p=$(($s * 100 / $t))
  29         c=$(($s * 10000 / $t - $p * 100))
  30         printf "%12d %12d %s (%d.%02d%%)\n" $s $t $n $p $c
  31 }
  32
  33 git ls-tree -r "$initial" |
  34 while read mode type sha1 name
  35 do
  36         git blame $opts --porcelain -S "$graft" "$initial" -- "$name" |
  37         sed -ne "s/^\($_x40\) .*/\1/p" |
  38         sort |
  39         uniq -c | {
  40                 # There are only two commits in the fake history, so
  41                 # there will be at most two output from the above.
  42                 read cnt1 commit1
  43                 read cnt2 commit2
  44                 if test -z "$commit2"
  45                 then
  46                         cnt2=0
  47                 fi
  48                 if test "$initial" != "$commit1"
  49                 then
  50                         cnt_surviving=$cnt1
  51                 else
  52                         cnt_surviving=$cnt2
  53                 fi
  54                 cnt_total=$(( $cnt1 + $cnt2 ))
  55                 echo "$cnt_surviving $cnt_total $name"
  56         }
  57 done | {
  58         total=0
  59         surviving=0
  60         printf "%12s %12s %s (survival%%)\n" surviving original path
  61         while read s t n
  62         do
  63                 total=$(( $total + $t )) surviving=$(( $surviving + $s ))
  64                 # printf "%12d %12d %s\n" $s $t $n
  65                 show $s $t $n
  66         done
  67         # printf "%12d %12d %s\n" $surviving $total Total
  68         show $surviving $total Total
  69 }