| # 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): |
| """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) |
