Hello. So I now have what appears to be a working implementation of resource registration and resolution via the Extender pattern.
Basically: A resource resolver service watches bundles with a BundleTracker as they reach the RESOLVED state. It examines each bundle and if that bundle has metadata that allows it to participate in resource handling, the resources and packages exported by the bundle are recorded. The service itself is trivial: https://github.com/io7m/callisto/blob/feature/interfaces-sketch-00/com.io7m.callisto.resources.main/src/main/java/com/io7m/callisto/resources/main/CoResourceResolver.java The service inserts bundles into a resource model, and removes bundles from the model when they're uninstalled. The bulk of the code of the model implements scanning of bundle headers and wires, and implementing the logic to traverse wires to look up resources: https://github.com/io7m/callisto/blob/feature/interfaces-sketch-00/com.io7m.callisto.resources.main/src/main/java/com/io7m/callisto/resources/main/CoResourceModel.java As I've said, this all appears to work properly. I have quite extensive unit tests that cover close to 100% of the code, and the semantics seem to be sane. The problem: I don't know if there are race conditions. If I install a bundle B that contains both resources and code, the BundleTracker will register those resources when the bundle reaches the RESOLVED state. I can (I think) assume that code in B (such as bundle activators or immediate declarative services) will only execute when the bundle reaches the ACTIVE state, and therefore I believe that I can assume that the bundle tracker resource registration code for the bundle will happen before (in the concurrent happens-before sense) the activator or services start executing. However, if some bundle C makes calls into code in B, and B tries to resolve one of its own resources... Do I have any guarantees that the resource resolution code in the BundleTracker will have completed before code in bundle B has any opportunity to call the resolver service? I feel like I don't have that guarantee... Is there any way to get it? M
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