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# Copyright 2018 the V8 project authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
from . import base
# Alphabet size determines the hashing radix. Choosing a prime number prevents
# clustering of the hashes.
HASHING_ALPHABET_SIZE = 2 ** 7 -1
def radix_hash(capacity, key):
h = 0
for character in key:
h = (h * HASHING_ALPHABET_SIZE + ord(character)) % capacity
return h
class ShardProc(base.TestProcFilter):
@staticmethod
def create(options):
myid, count = options.shard_info
if count == 1:
return None
return ShardProc(myid, count)
"""Processor distributing tests between shards.
It hashes the unique test identifiers uses the hash to shard tests.
"""
def __init__(self, myid, shards_count):
"""
Args:
myid: id of the shard within [0; shards_count - 1]
shards_count: number of shards
"""
super(ShardProc, self).__init__()
assert myid >= 0 and myid < shards_count
self._myid = myid
self._shards_count = shards_count
def _filter(self, test):
return self._myid != radix_hash(self._shards_count, test.procid)
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