[infinispan-issues] [JBoss JIRA] (ISPN-3847) Improve resilience of ModuleLifecycle loading

Improve resilience of ModuleLifecycle loading --------------------------------------------- Key: ISPN-3847 URL: https://issues.jboss.org/browse/ISPN-3847 Project: Infinispan Issue Type: Enhancement Components: Core API Affects Versions: 6.0.1.Final Reporter: Paul Ferraro Assignee: Mircea Markus Currently, org.infinispan.util.ModuleProperties.resolveModuleLifecycles(...) uses a ServiceLoader to directly load ModuleLifecycle instances. However, if a jar exists on the classpath containing a META-INF/services/org.infinispan.lifecycle.ModuleLifecycle file, but the class name contained within cannot be loaded, due to, for example, a dependency jar being missing, then the whole resolveModuleLifecycles(...) method chokes due to a ServiceConfigurationError. For example, if infinispan-query is on the classpath, but hibernate-search is not, Infinispan is unusable. I can see 2 ways to fix this: 1. Use the iterator directly instead of the enhanced for-loop, and catch and handle the SCE: e.g. {code:java} Iterator<ModuleLifecycle> lifecycles = ServiceLoader.load(ModuleLifecycle.class, classLoader); while (lifecycles.hasNext()) { try { ModuleLifecycle lifecycle = lifecycles.next(); // This can throw SCE result.add(lifecycle); } catch (ServiceConfigurationError e) { // Log error } } {code} 2. Introduce a ModuleLifecycleProvider abstraction - that won't throw an SCE. The ServiceLoader spec actually recommends this: "The provider class is typically not the entire provider itself but rather a proxy which contains enough information to decide whether the provider is able to satisfy a particular request together with code that can create the actual provider on demand." In the end, this would look something like: {code:java} for (ModuleLifecycleFactory factory: ServiceLoader.load(ModuleLifecycleFactory.class, classLoader)) { if (factory.isEnabled()) { // returns true if create method will not throw SCE ModuleLifecycle lifecycle = factory.createModuleLifecycle(); result.add(lifecycle); } } {code}