Updating selfpopulatingcache example
Note that these classes are marked Note that this is cut down from the real one but only to remove features such as auto-configuration.
The use-case that fails occasionally for me runs like this.
It also supports use with the popular Hibernate Object/Relational tool and caching with the Java EE Servlet. The rest of the documentation can be explored for a deeper understanding. This means that application code which accesses the system-of-record (SOR) should consult the cache first, and if the cache contains the data, then return the data directly from the cache, bypassing the SOR.
Otherwise, the application code must fetch the data from the system-of-record, store the data in the cache, and then return it.
In general, keeping an eye on cache hits and miss will tell you a lot about the cache effectiveness.
A low hit-to-miss ratio, for example, means that the cache is not that good.
The pattern delegates SOR reading and writing activies to the cache, so that application code is absolved of this responsibility.
To implement the cache-as-sor pattern, use a combination of the following read and write patterns: .
The cache knows how to populate itself, after expiration it would again use the method to retrieve the new values, so the second problem of expiration would be solved.
I recently had to sit down and figure out exactly how it works, and thought I’d take a moment to write it up. Because open source development is more about individuals than organisations, Wotif staff members don’t really have much to do with ehcache development. You can monitor cache hits and misses in detail by turning the logging for the up.
it was initially written at Wotif, to overcome problems with the Jakarta JCS project. Since it was originally released, ehcache has grown somewhat and has a modest direct following. If you regularly see the same set of objects going in and out of the cache, you know you need a larger cache to be truly effective.
In this part of the article about caching we’ll discuss using Eh Cache for a different purpose other than as Hibernate second level cache.
Before working with Eh Cahe, I used a static variable for a cache.
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If the element is null, other reads will block until an element with the same key is put into the cache.