ReferenceConfig Cache

The instance of ReferenceConfig is heavy. It encapsulates the connection to the registry and the connection to the provider, so it need to be cached. Otherwise, repeatedly generating ReferenceConfig may cause performance problems , memory and connection leaks. This problem is easy to ignored when programming in API mode.

Therefore, since 2.4.0, dubbo provides a simple utility ReferenceConfigCache for caching instances of ReferenceConfig.

Use as follows：

ReferenceConfig<XxxService> reference = new ReferenceConfig<XxxService>();
reference.setInterface(XxxService.class);
reference.setVersion("1.0.0");
......
ReferenceConfigCache cache = ReferenceConfigCache.getCache();
// cache.get will cache the instance of Reference ，and call ReferenceConfig.get method to start ReferenceConfig
XxxService xxxService = cache.get(reference);
// Note: Cache will hold ReferenceConfig, do not call destroy method of ReferenceConfig outside. If you do this, it will invalidate ReferenceConfig in Cache!
// Use xxxService instance
xxxService.sayHello();

Destroy ReferenceConfig in the Cache, it also remove ReferenceConfig and release the corresponding resources。

ReferenceConfigCache cache = ReferenceConfigCache.getCache();
cache.destroy(reference);

By default ,ReferenceConfigCache caches one ReferenceConfig for the same service Group, interface, version. The key of ReferenceConfigCache is from the group of service Group, interface, and the version.

You can modify the strategy. Define an instance of KeyGenerator, pass it as parameter of getCache method. Refer to ReferenceConfigCache for information。

KeyGenerator keyGenerator = new ...
ReferenceConfigCache cache = ReferenceConfigCache.getCache(keyGenerator );

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