def main(argv):
o = options.Options(optspec)
opt, flags, extra = o.parse_bytes(argv[1:])
if extra:
o.fatal("no arguments expected")
git.check_repo_or_die()
with git.PackIdxList(git.repo(b'objects/pack'),
ignore_midx=opt.ignore_midx) as mi:
def do_predict(ix, out):
total = len(ix)
maxdiff = 0
for count,i in enumerate(ix):
prefix = struct.unpack('!Q', i[:8])[0]
expected = prefix * total // (1 << 64)
diff = count - expected
maxdiff = max(maxdiff, abs(diff))
out.write(b'%d of %d (%.3f%%) '
% (maxdiff, len(ix), maxdiff * 100.0 / len(ix)))
out.flush()
assert(count+1 == len(ix))
sys.stdout.flush()
out = byte_stream(sys.stdout)
if opt.predict:
if opt.ignore_midx:
for pack in mi.packs:
do_predict(pack, out)
else:
do_predict(mi, out)
else:
# default mode: find longest matching prefix
last = b'\0'*20
longmatch = 0
for i in mi:
if i == last:
continue
#assert(str(i) >= last)
pm = _helpers.bitmatch(last, i)
longmatch = max(longmatch, pm)
last = i
out.write(b'%d\n' % longmatch)
log('%d matching prefix bits\n' % longmatch)
doublings = math.log(len(mi), 2)
bpd = longmatch / doublings
log('%.2f bits per doubling\n' % bpd)
remain = 160 - longmatch
rdoublings = remain / bpd
log('%d bits (%.2f doublings) remaining\n' % (remain, rdoublings))
larger = 2**rdoublings
log('%g times larger is possible\n' % larger)
perperson = larger/POPULATION_OF_EARTH
log('\nEveryone on earth could have %d data sets like yours, all in one\n'
'repository, and we would expect 1 object collision.\n'
% int(perperson))
if opt.predict:
if opt.ignore_midx:
for pack in mi.packs:
do_predict(pack)
else:
do_predict(mi)
else:
# default mode: find longest matching prefix
last = '\0' * 20
longmatch = 0
for i in mi:
if i == last:
continue
#assert(str(i) >= last)
pm = _helpers.bitmatch(last, i)
longmatch = max(longmatch, pm)
last = i
print(longmatch)
log('%d matching prefix bits\n' % longmatch)
doublings = math.log(len(mi), 2)
bpd = longmatch / doublings
log('%.2f bits per doubling\n' % bpd)
remain = 160 - longmatch
rdoublings = remain / bpd
log('%d bits (%.2f doublings) remaining\n' % (remain, rdoublings))
larger = 2**rdoublings
log('%g times larger is possible\n' % larger)
perperson = larger / POPULATION_OF_EARTH
log('\nEveryone on earth could have %d data sets like yours, all in one\n'
'repository, and we would expect 1 object collision.\n' %
if opt.predict:
if opt.ignore_midx:
for pack in mi.packs:
do_predict(pack)
else:
do_predict(mi)
else:
# default mode: find longest matching prefix
last = '\0'*20
longmatch = 0
for i in mi:
if i == last:
continue
#assert(str(i) >= last)
pm = _helpers.bitmatch(last, i)
longmatch = max(longmatch, pm)
last = i
print longmatch
log('%d matching prefix bits\n' % longmatch)
doublings = math.log(len(mi), 2)
bpd = longmatch / doublings
log('%.2f bits per doubling\n' % bpd)
remain = 160 - longmatch
rdoublings = remain / bpd
log('%d bits (%.2f doublings) remaining\n' % (remain, rdoublings))
larger = 2**rdoublings
log('%g times larger is possible\n' % larger)
perperson = larger/POPULATION_OF_EARTH
log('\nEveryone on earth could have %d data sets like yours, all in one\n'
'repository, and we would expect 1 object collision.\n'