org.eclipse.osgi.framework.internal.core
Class CoreResolverHookFactory

java.lang.Object
  org.eclipse.osgi.framework.internal.core.CoreResolverHookFactory

All Implemented Interfaces:

ResolverHookFactory

public class CoreResolverHookFactory
extends Object
implements ResolverHookFactory

This class encapsulates the delegation to ResolverHooks that are registered with the service registry. This way the resolver implementation only has to call out to a single hook which does all the necessary service registry lookups. This class is not thread safe and expects external synchronization.

Constructor Summary

CoreResolverHookFactory(BundleContextImpl context, ServiceRegistry registry)

Method Summary

ResolverHook

begin(Collection<BundleRevision> triggers) This method is called by the framework each time a resolve process begins to obtain a resolver hook instance.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CoreResolverHookFactory

public CoreResolverHookFactory(BundleContextImpl context,
                               ServiceRegistry registry)

Method Detail

begin

public ResolverHook begin(Collection<BundleRevision> triggers)

Description copied from interface: ResolverHookFactory

This method is called by the framework each time a resolve process begins to obtain a resolver hook instance. This resolver hook instance will be used for the duration of the resolve process. At the end of the resolve process the method ResolverHook.end() must be called by the framework and the framework must not hold any references of the resolver hook instance.

The triggers represent the collection of bundles which triggered the resolve process. This collection may be empty if the triggers cannot be determined by the framework. In most cases the triggers can easily be determined. Calling certain methods on bundle when a bundle is in the INSTALLED state will cause the framework to begin a resolve process in order to resolve the bundle. The following methods will start a resolve process in this case:

• start
• loadClass
• findEntries
• getResource
• getResources

In such cases the collection will contain the single bundle which the framework is trying to resolve. Other cases will cause multiple bundles to be included in the trigger bundles collection. When resolveBundles is called the collection of triggers must include all the current bundle revisions for bundles passed to resolveBundles which are in the INSTALLED state.

When FrameworkWiring.refreshBundles(Collection, org.osgi.framework.FrameworkListener...) is called the collection of triggers is determined with the following steps:

• If the collection of bundles passed is null then FrameworkWiring.getRemovalPendingBundles() is called to get the initial collection of bundles.
• The equivalent of calling FrameworkWiring.getDependencyClosure(Collection) is called with the initial collection of bundles to get the dependency closure collection of the bundles being refreshed.
• Remove any non-active bundles from the dependency closure collection.
• For each bundle remaining in the dependency closure collection get the current bundle revision and add it to the collection of triggers.

As described above, a resolve process is typically initiated as a result of calling API that causes the framework to attempt to resolve one or more bundles. The framework is free to start a resolve process at any time for reasons other than calls to framework API. For example, a resolve process may be used by the framework for diagnostic purposes and result in no bundles actually becoming resolved at the end of the process. Resolver hook implementations must be prepared for resolve processes that are initiated for other reasons besides calls to framework API.

Specified by:

begin in interface ResolverHookFactory

Parameters:

triggers - an unmodifiable collection of bundles which triggered the resolve process. This collection may be empty if the collection of trigger bundles cannot be determined.

Returns:

a resolver hook instance to be used for the duration of the resolve process. A null value may be returned which indicates this resolver hook factory abstains from the resolve process.