Dynamic configuration in Ehcache v3+

Question

I want to use Ehcache dynamic configuration in version 3.

As seen in the doc here https://www.ehcache.org/documentation/2.8/configuration/configuration.html#ehcache.xsd

since Ehcache 2.0, certain cache configuration parameters can be modified dynamically at runtime

This is simply done in ehcache v2 by setting the <ehcache> element’s dynamicConfig attribute to “true” in the ehcache.xml configuration file.

Now I'd like to know how to do that in ecache v3, since there is no <ehcache> element in v3, so the dynamicConfig attribute is nowhere to be found in my v3 ehcache.xml file.

I cannot find it anywhere in the documentation or in SO.

This is my ehcache v3 xml file, but it seems neither <config> element nor <cache> element have some sort of dynamicConfig attribute that I need.

<config xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
    xmlns='http://www.ehcache.org/v3'
    xsi:schemaLocation="
            http://www.ehcache.org/v3 
            http://www.ehcache.org/schema/ehcache-core-3.7.xsd">


    <persistence directory="spring-boot-ehcache/cache" />
    <cache alias="categoriesCache">
    

        <expiry>
            <ttl unit="seconds">3000</ttl>
        </expiry>


        <listeners>
            <listener>
                <class>com.something.somethingv.jr.be.cache.CacheEventLogger
                </class>
                <event-firing-mode>ASYNCHRONOUS</event-firing-mode>
                <event-ordering-mode>UNORDERED</event-ordering-mode>
                <events-to-fire-on>CREATED</events-to-fire-on>
                <events-to-fire-on>EXPIRED</events-to-fire-on>
                <events-to-fire-on>EVICTED</events-to-fire-on>
            </listener>
        </listeners>


        <resources>
            <heap>1000</heap>
            <offheap unit="MB">10</offheap>
            <disk persistent="true" unit="MB">20</disk>
        </resources>
    </cache>



    <cache alias="autocompleteCache">
        <expiry>
            <ttl unit="seconds">3000</ttl>
        </expiry>


        <listeners>
            <listener>
                <class>com.something.somethingv.jr.be.cache.CacheEventLogger
                </class>
                <event-firing-mode>ASYNCHRONOUS</event-firing-mode>
                <event-ordering-mode>UNORDERED</event-ordering-mode>
                <events-to-fire-on>CREATED</events-to-fire-on>
                <events-to-fire-on>EXPIRED</events-to-fire-on>
                <events-to-fire-on>EVICTED</events-to-fire-on>
            </listener>
        </listeners>


        <resources>
            <heap>1000</heap>
            <offheap unit="MB">10</offheap>
            <disk persistent="true" unit="MB">20</disk>
        </resources>
    </cache>
    
</config>

So, how can I do it?

Answer 1

    private void modifyCacheSize(int newSize) {
    org.ehcache.config.ResourcePools rp = ResourcePoolsBuilder.newResourcePoolsBuilder().heap(newSize, EntryUnit.ENTRIES).build();

    javax.cache.Cache<Long, MyObject> cache = cacheManager.getCache(YOURCACHENAME);
    org.ehcache.jsr107.Eh107Configuration<Long, MyObject> configuration = cache.getConfiguration(org.ehcache.jsr107.Eh107Configuration.class);
    org.ehcache.config.CacheRuntimeConfiguration<Long, MyObject> rtc = configuration.unwrap(org.ehcache.config.CacheRuntimeConfiguration.class);
    
    rtc.updateResourcePools(rp);

    SizedResourcePool srp = rtc.getResourcePools().getPoolForResource(ResourceType.Core.HEAP);
    long size = srp.getSize();
    System.out.println(size);

This may not answer your question but this is the top search result for modifying a running cache in ehcache3. The documentation could be more help.

This code sample shows how to dynamically update the size of a heap resource pool in a running cache. The rtc variable exposes anything you can modify.

Hopefully this helps someone trying to do this.