def _DistributionToBackendFormat(dist):
"""Convert an object size distribution to the format needed by the backend.
Args:
dist: a distribution, given as a dictionary mapping size to
frequency. Size will be a string with a quantity and a
unit. Frequency will be a percentage, including a '%'
character. dist may also be a string, in which case it represents
a single object size which applies to 100% of objects.
Returns:
A dictionary giving an object size distribution. Sizes will be
integers representing bytes. Frequencies will be floating-point
numbers in [0,100], representing percentages.
Raises:
ValueError if dist is not a valid distribution.
"""
if isinstance(dist, dict):
val = {
flag_util.StringToBytes(size):
flag_util.StringToRawPercent(frequency)
for size, frequency in dist.iteritems()
}
else:
# We allow compact notation for point distributions. For instance,
# '1KB' is an abbreviation for '{1KB: 100%}'.
val = {flag_util.StringToBytes(dist): 100.0}
# I'm requiring exact addition to 100, which can always be satisfied
# with integer percentages. If we want to allow general decimal
# percentages, all we have to do is replace this equality check with
# approximate equality.
if sum(val.itervalues()) != 100.0:
raise ValueError("Frequencies in %s don't add to 100%%!" % dist)
return val
def testPercentAbove100(self):
with self.assertRaises(ValueError):
flag_util.StringToRawPercent('112%')
def testNegativePercent(self):
with self.assertRaises(ValueError):
flag_util.StringToRawPercent('-12%')
def testNoPercentSign(self):
with self.assertRaises(ValueError):
flag_util.StringToRawPercent('100')
def testOneCharacterString(self):
with self.assertRaises(ValueError):
flag_util.StringToRawPercent('%')
def testNullString(self):
with self.assertRaises(ValueError):
flag_util.StringToRawPercent('')
def testValidPct(self):
self.assertEquals(flag_util.StringToRawPercent('50.5%'),
50.5)
