第 5 章 集群的计数

要开始使用计数器，您需要在 Maven pom.xml 文件中添加依赖项：

<dependency>
  <groupId>org.infinispan</groupId>
  <artifactId>infinispan-clustered-counter</artifactId>
</dependency>

这些计数器可以通过本文档稍后详述的 CounterManager 接口配置 Data Grid 配置文件或按需。当 EmbeddedCacheManager 启动时，会在引导时在 Data Grid 配置文件中配置的计数器。这些计数器以百分比方式启动，它们可在所有集群的所有节点中可用。

<infinispan>
    <cache-container ...>
        <!-- To persist counters, you need to configure the global state. -->
        <global-state>
        <!-- Global state configuration goes here. -->
        </global-state>
        <!-- Cache configuration goes here. -->
         <counters xmlns="urn:infinispan:config:counters:13.0" num-owners="3" reliability="CONSISTENT">
             <strong-counter name="c1" initial-value="1" storage="PERSISTENT"/>
             <strong-counter name="c2" initial-value="2" storage="VOLATILE" lower-bound="0"/>
             <strong-counter name="c3" initial-value="3" storage="PERSISTENT" upper-bound="5"/>
             <strong-counter name="c4" initial-value="4" storage="VOLATILE" lower-bound="0" upper-bound="10"/>
             <strong-counter name="c5" initial-value="0" upper-bound="100" lifespan="60000"/>
             <weak-counter name="c6" initial-value="5" storage="PERSISTENT" concurrency-level="1"/>
         </counters>
    </cache-container>
</infinispan>

或者以编程方式，在 GlobalConfigurationBuilder 中：

GlobalConfigurationBuilder globalConfigurationBuilder = ...;
CounterManagerConfigurationBuilder builder = globalConfigurationBuilder.addModule(CounterManagerConfigurationBuilder.class);
builder.numOwner(3).reliability(Reliability.CONSISTENT);
builder.addStrongCounter().name("c1").initialValue(1).storage(Storage.PERSISTENT);
builder.addStrongCounter().name("c2").initialValue(2).lowerBound(0).storage(Storage.VOLATILE);
builder.addStrongCounter().name("c3").initialValue(3).upperBound(5).storage(Storage.PERSISTENT);
builder.addStrongCounter().name("c4").initialValue(4).lowerBound(0).upperBound(10).storage(Storage.VOLATILE);
builder.addStrongCounter().name("c5").initialValue(0).upperBound(100).lifespan(60000);
builder.addWeakCounter().name("c6").initialValue(5).concurrencyLevel(1).storage(Storage.PERSISTENT);

另一方面，可以在 Embeded CacheManager 初始化后随时配置计数器。

CounterManager manager = ...;
manager.defineCounter("c1", CounterConfiguration.builder(CounterType.UNBOUNDED_STRONG).initialValue(1).storage(Storage.PERSISTENT).build());
manager.defineCounter("c2", CounterConfiguration.builder(CounterType.BOUNDED_STRONG).initialValue(2).lowerBound(0).storage(Storage.VOLATILE).build());
manager.defineCounter("c3", CounterConfiguration.builder(CounterType.BOUNDED_STRONG).initialValue(3).upperBound(5).storage(Storage.PERSISTENT).build());
manager.defineCounter("c4", CounterConfiguration.builder(CounterType.BOUNDED_STRONG).initialValue(4).lowerBound(0).upperBound(10).storage(Storage.VOLATILE).build());
manager.defineCounter("c4", CounterConfiguration.builder(CounterType.BOUNDED_STRONG).initialValue(0).upperBound(100).lifespan(60000).build());
manager.defineCounter("c6", CounterConfiguration.builder(CounterType.WEAK).initialValue(5).concurrencyLevel(1).storage(Storage.PERSISTENT).build());

如果计数器配置成功或为 false，则方法 defineCounter （） 将返回 true。但是，如果配置无效，则方法会抛出 CounterConfigurationException。要找出是否已定义了计数器，请使用方法 isDefined （）。

CounterManager manager = ...
if (!manager.isDefined("someCounter")) {
    manager.define("someCounter", ...);
}