[PATCH] script to display a distribution of longest common hash prefixes
From: Nicolas Pitre <hidden>
Date: 2016-06-15 22:43:20
Subsystem:
the rest · Maintainer:
Linus Torvalds
This script was originally posted on the git mailing list by
Randal L. Schwartz [off-list ref].
Signed-off-by: Nicolas Pitre <redacted>
---
diff --git a/contrib/stats/git-common-hash b/contrib/stats/git-common-hash
new file mode 100755
index 0000000..e27fd08
--- /dev/null
+++ b/contrib/stats/git-common-hash@@ -0,0 +1,26 @@ +#!/bin/sh + +# This script displays the distribution of longest common hash prefixes. +# This can be used to determine the minimum prefix length to use +# for object names to be unique. + +git rev-list --objects --all | sort | perl -lne ' + substr($_, 40) = ""; + # uncomment next line for a distribution of bits instead of hex chars + # $_ = unpack("B*",pack("H*",$_)); + if (defined $p) { + ($p ^ $_) =~ /^(\0*)/; + $common = length $1; + if (defined $pcommon) { + $count[$pcommon > $common ? $pcommon : $common]++; + } else { + $count[$common]++; # first item + } + } + $p = $_; + $pcommon = $common; + END { + $count[$common]++; # last item + print "$_: $count[$_]" for 0..$#count; + } +'