1<?php
2
3/**
4 * Copyright 2017 DataStax, Inc.
5 *
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19namespace Cassandra\RetryPolicy;
20
21/**
22 * A retry policy that will downgrade the consistency of a request in
23 * an attempt to save a request in cases where there is any chance of success. A
24 * write request will succeed if there is at least a single copy persisted and a
25 * read request will succeed if there is some data available even if it increases
26 * the risk of reading stale data. This policy will retry in the same scenarios as
27 * the default policy, and it will also retry in the following case:
28 *
29 * * On a read timeout, if some replicas responded but is lower than
30 *   required by the current consistency level then retry with a lower
31 *   consistency level
32 * * On a write timeout, Retry unlogged batches at a lower consistency level
33 *   if at least one replica responded. For single queries and batch if any
34 *   replicas responded then consider the request successful and swallow the
35 *   error.
36 * * On unavailable, retry at a lower consistency if at lease one replica
37 *   responded.
38 *
39 * Important: This policy may attempt to retry requests with a lower
40 * consistency level. Using this policy can break consistency guarantees.
41 */
42final class DowngradingConsistency implements \Cassandra\RetryPolicy {
43
44}
45