1 Star 0 Fork 16

胡李俊 / hydrogen-ssdb

加入 Gitee
与超过 1200万 开发者一起发现、参与优秀开源项目,私有仓库也完全免费 :)
免费加入
克隆/下载
贡献代码
同步代码
取消
提示: 由于 Git 不支持空文件夾,创建文件夹后会生成空的 .keep 文件
Loading...
README
Apache-2.0

996icu code style

hydrogen-ssdb

Java 编写的 SSDB 客户端

更新

注意:master 分支是正在开发中的分支,稳定版请使用对应的版本号分支。

  • 2019-03-27: 开发版本号更新到 V2.0.0-SNAPSHOT,项目最低要求 Java 8,并加入 Spring Boot 支持.
  • 2019-02-06: 版本号更新到 V1.1.1 修复了 multiGet() 方法在多服务器环境下返回错误结果的问题。
  • 2018-05-06: 修复了从节点恢复时没有被认作是从节点的问题。
  • 2018-02-25: 版本号更新到 V1.1.0,添加了 multiGet() 方法,修复了若干方法在多服务器负载均衡上的 BUG。
  • 2017-08-03: 修复了 Cluster 无法恢复的问题,版本号更新到 1.0.1。
  • 2017-06-13: 完成了最后一个基本特性的实现,版本号正式改为 1.0.0。

介绍

hydrogen-ssdb 是一个 Java 编写的 SSDB 客户端,支持多线程并发请求和多服务器的负载均衡(客户端分发请求)。

SSDB 是一个类似 Redis 的 NOSQL 数据库,兼容 Redis 协议,且支持多线程,内存占用小。

hydrogen-ssdb 是一个 SSDB 客户端,具有以下特性:

  1. 易于配置,易于使用;
  2. 支持 SSDB 主从集群与负载均衡;
  3. 当集群中的服务器 down 掉时,能自动识别并跳过该服务器。

【负载均衡的抽象和实现】

hydrogen-ssdb 将负载均衡抽象为Sharding类,该类负责决定一个请求应该发送给哪台 SSDB 服务器。

Sharding中,所有的服务器(Server)被归为多个集群(Cluster),Cluster 是负载均衡的顶层单位。每个 Cluster 包含多个 Server,一个 Server 可以是主服务器,也可以是从服务器(这个必须与 SSDB 实际的主从配置严格一致),但 Cluster 中必须要有主服务器。

hydrogen-ssdb 缺省实现了基于一致性哈希环的负载均衡方式。如果这种方式不适合您的实际情况,您可以自己实现Sharding的子类,然后通过SsdbClient的构造方法传入。下面是一个如何使用自定义Sharding的例子,假设你已经实现了自定义的MySharding类:

MySharding mySharding = ...  // 自定义 Sharding
SsdbClient client = new SsdbClient(mySharding);

下面介绍 hydrogen-ssdb 缺省实现的负载均衡的原理。

【基于一致性哈希环的负载均衡】

【对某些命令的处理】

在多服务器环境下,某些命令会发送给所有的 cluster,然后收集结果,例如 scan() 方法;

还有些命令仅仅在单服务器下执行,例如 multiGet() 方法,当在多服务器下时,它不会执行 multi_get 命令,而是对每个 key 依次调用 get 方法,然后收集结果。

【对单点故障的处理】

在负载均衡当中,每个节点都负责整个一致性哈希环中的一部分(称为哈希段)。当负载均衡当中出现单点故障时,故障节点对应的哈希段将无法执行存取操作,于是有两种处理方式:

  1. 故障节点前面的节点自动接管该哈希段。这种方式适用于将 SSDB 用于缓存,因为缓存丢失是可以重新填充的;
  2. 保留哈希段的故障状态,直到故障节点恢复。这种方式适用于将 SSDB 用于数据库,这样能严格保证一个 key 会保存在对应的节点中。

hydrogen-ssdb 缺省情况下使用第一种方式来处理。如果需要修改,可以以下面的方式:

ConsistentHashSharding sharding = (ConsistentHashSharding)ssdbClient.getSharding();
sharding.setSpofStrategy(SPOFStrategy.PreserveKeySpaceStrategy);

【如何添加 Cluster】

对于一致性哈希环,每一个 Cluster 的哈希段都是固定的,所以每添加一个新的 Cluster,都只会给当前的其中 1 个 Cluster 减负,而不是给所有的 Cluster 减负。例如当前有 A、B、C 三个 Cluster,那么当添加一个 D 到 A 和 B 之间,形成 “A-D-B-C” 时,它只会分担 A 的一部分哈希段,B 和 C 的哈希段没有改变,也就是说 B 和 C 的负载没有变化。

ConsistentHashSharding 使用 key 的 MD5 签名的前四个字节作为 hash 值,以尽可能让所有的 key 均匀分布。

由此可知,在添加 Cluster 之前,你需要明确的了解每个 Cluster 当前的负载情况,找到负载最重的 Cluster,将新的 Cluster 加在它后面。

所以,ConsistentHashShardingaddCluster() 方法有两个参数,第一个是要添加的 Cluster,第二个是需要被分担负载的 Cluster。

项目依赖

hydrogen-ssdb 依赖于下面两个框架:

  • Apache commons-pool2 (对象池框架)
  • slf4j (日志框架)

使用方法

基本使用方法

SsdbClient client = new SsdbClient(host, port);
client.set("key", "value");
System.out.println(client.get("key"));   // output "value"
client.close();    // 应用结束时需要调用 close() 方法,也可以配置在 Spring 的 destroy-method 中

配置主从服务器

List<Server> servers = Arrays.asList(
        new Server("192.168.1.180", 8888, true),  // 主服务器
        new Server("192.168.1.180", 8889, false)  // 从服务器
);

SsdbClient client = SsdbClient.fromSingleCluster(servers);
client.set("name", "hydrogen-ssdb");    // 写入请求一定会发送给主服务器
System.out.println(client.get("name")); // 读取请求会随机发送给任意一台服务器

配置负载均衡

Sharding sharding = new ConsistentHashSharding(Arrays.asList(
        new Cluster(new Server("192.168.1.180", 8888), 100),  // 100 和 200 这两个参数指的是权重,
        new Cluster(new Server("192.168.1.180", 8889), 200)   // 权重越大的 Cluster 所保存的 key 越多。
));

SsdbClient ssdbClient = new SsdbClient(sharding);

Spring XML 配置

<!-- 单个 SSDB 服务器的配置,其他几个类似的构造方法在此略去 -->
<bean id="singleServerSsdbClient" class="com.hyd.ssdb.SsdbClient" destroy-method="close">
    <constructor-arg name="host" value="192.168.1.180"/>
    <constructor-arg name="port" value="8888"/>
</bean>

<!-- 自定义 Sharding -->
<bean id="custShardingClient" class="com.hyd.ssdb.SsdbClient" destroy-method="close">
    <constructor-arg name="sharding">
        <bean class="com.hyd.ssdb.AjiaSharding"/>
    </constructor-arg>
</bean>

<!-- 多台 SSDB 主从服务器的配置 -->
<bean id="ssdbServer1" class="com.hyd.ssdb.conf.Server">
    <property name="host" value="192.168.1.180"/>
    <property name="port" value="8888"/>
    <property name="master" value="true"/>
</bean>
<bean id="ssdbServer2" class="com.hyd.ssdb.conf.Server">
    <property name="host" value="192.168.1.180"/>
    <property name="port" value="8889"/>
    <property name="master" value="false"/>
</bean>
<bean id="singleClusterSsdbClient" class="com.hyd.ssdb.SsdbClient"
      factory-method="fromSingleCluster" destroy-method="close">
    <constructor-arg name="servers">
        <list value-type="com.hyd.ssdb.conf.Server">
            <ref bean="ssdbServer1"/>
            <ref bean="ssdbServer2"/>
        </list>
    </constructor-arg>
</bean>

<!-- 多台 SSDB 负载均衡的配置(每个 Cluster 一台服务器) -->
<bean id="ssdbCluster1" class="com.hyd.ssdb.conf.Cluster" factory-method="fromSingleServer">
    <constructor-arg name="server" ref="ssdbServer1"/>
</bean>
<bean id="ssdbCluster2" class="com.hyd.ssdb.conf.Cluster" factory-method="fromSingleServer">
    <constructor-arg name="server" ref="ssdbServer2"/>
</bean>
<bean id="shardingSsdbClient" class="com.hyd.ssdb.SsdbClient"
      factory-method="fromClusters" destroy-method="close">
    <constructor-arg name="clusters">
        <list value-type="com.hyd.ssdb.conf.Cluster">
            <ref bean="ssdbCluster1"/>
            <ref bean="ssdbCluster2"/>
        </list>
    </constructor-arg>
</bean>

使用注意

线程安全

SsdbClient 对象包含了对整个负载均衡的拓扑结构的处理,所以对于每一个由多个 SSDB 服务器组成的负载均衡架构,只需创建一个 SsdbClient 对象即可。另外 SsdbClient 是线程安全的,所以可以让任意多个线程访问。

误用导致内存占用过高

因为一个 SsdbClient 对象可能包含一个或多个连接池(每个连接池对应一个 SSDB 服务器),因此请不要创建大量的 SsdbClient 对象,这样完全没有必要,也会使得内存很容易被用光。

Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. "Licensor" shall mean the copyright owner or entity authorized by the copyright owner that is granting the License. "Legal Entity" shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, "control" means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity. "You" (or "Your") shall mean an individual or Legal Entity exercising permissions granted by this License. "Source" form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files. "Object" form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types. "Work" shall mean the work of authorship, whether in Source or Object form, made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below). "Derivative Works" shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship. For the purposes of this License, Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof. "Contribution" shall mean any work of authorship, including the original version of the Work and any modifications or additions to that Work or Derivative Works thereof, that is intentionally submitted to Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose of discussing and improving the Work, but excluding communication that is conspicuously marked or otherwise designated in writing by the copyright owner as "Not a Contribution." "Contributor" shall mean Licensor and any individual or Legal Entity on behalf of whom a Contribution has been received by Licensor and subsequently incorporated within the Work. 2. Grant of Copyright License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form. 3. Grant of Patent License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by combination of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed. 4. Redistribution. You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions: (a) You must give any other recipients of the Work or Derivative Works a copy of this License; and (b) You must cause any modified files to carry prominent notices stating that You changed the files; and (c) You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and (d) If the Work includes a "NOTICE" text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices contained within such NOTICE file, excluding those notices that do not pertain to any part of the Derivative Works, in at least one of the following places: within a NOTICE text file distributed as part of the Derivative Works; within the Source form or documentation, if provided along with the Derivative Works; or, within a display generated by the Derivative Works, if and wherever such third-party notices normally appear. The contents of the NOTICE file are for informational purposes only and do not modify the License. You may add Your own attribution notices within Derivative Works that You distribute, alongside or as an addendum to the NOTICE text from the Work, provided that such additional attribution notices cannot be construed as modifying the License. You may add Your own copyright statement to Your modifications and may provide additional or different license terms and conditions for use, reproduction, or distribution of Your modifications, or for any such Derivative Works as a whole, provided Your use, reproduction, and distribution of the Work otherwise complies with the conditions stated in this License. 5. Submission of Contributions. Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions. 6. Trademarks. This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor, except as required for reasonable and customary use in describing the origin of the Work and reproducing the content of the NOTICE file. 7. Disclaimer of Warranty. Unless required by applicable law or agreed to in writing, Licensor provides the Work (and each Contributor provides its Contributions) on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or redistributing the Work and assume any risks associated with Your exercise of permissions under this License. 8. Limitation of Liability. In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages. 9. Accepting Warranty or Additional Liability. While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may act only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability. END OF TERMS AND CONDITIONS APPENDIX: How to apply the Apache License to your work. To apply the Apache License to your work, attach the following boilerplate notice, with the fields enclosed by brackets "{}" replaced with your own identifying information. (Don't include the brackets!) The text should be enclosed in the appropriate comment syntax for the file format. We also recommend that a file or class name and description of purpose be included on the same "printed page" as the copyright notice for easier identification within third-party archives. Copyright {yyyy} {name of copyright owner} Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

简介

Java 编写的 SSDB 客户端,支持负载均衡 展开 收起
Java
Apache-2.0
取消

发行版

暂无发行版

贡献者

全部

近期动态

加载更多
不能加载更多了
Java
1
https://gitee.com/lijun.hu/hydrogen-ssdb.git
git@gitee.com:lijun.hu/hydrogen-ssdb.git
lijun.hu
hydrogen-ssdb
hydrogen-ssdb
master

搜索帮助