contrib/stats/git-common-hash

   1 #!/bin/sh
   2
   3 # This script displays the distribution of longest common hash prefixes.
   4 # This can be used to determine the minimum prefix length to use
   5 # for object names to be unique.
   6
   7 git rev-list --objects --all | sort | perl -lne '
   8   substr($_, 40) = "";
   9   # uncomment next line for a distribution of bits instead of hex chars
  10   # $_ = unpack("B*",pack("H*",$_));
  11   if (defined $p) {
  12     ($p ^ $_) =~ /^(\0*)/;
  13     $common = length $1;
  14     if (defined $pcommon) {
  15       $count[$pcommon > $common ? $pcommon : $common]++;
  16     } else {
  17       $count[$common]++; # first item
  18     }
  19   }
  20   $p = $_;
  21   $pcommon = $common;
  22   END {
  23     $count[$common]++; # last item
  24     print "$_: $count[$_]" for 0..$#count;
  25   }
  26 '