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This bundle is the core implementation of the Karaf features support.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.karaf.features.internal.region;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.function.ToIntFunction;
import org.apache.karaf.features.internal.resolver.ResolverUtil;
import org.osgi.framework.Version;
import org.osgi.framework.namespace.BundleNamespace;
import org.osgi.framework.namespace.IdentityNamespace;
import org.osgi.framework.namespace.PackageNamespace;
import org.osgi.framework.wiring.BundleCapability;
import org.osgi.resource.Capability;
import org.osgi.resource.Resource;
public class CandidateComparator implements Comparator {
private final ToIntFunction cost;
public CandidateComparator(ToIntFunction cost) {
this.cost = cost;
}
public int compare(Capability cap1, Capability cap2) {
int c = 0;
// Always prefer system bundle
if (cap1 instanceof BundleCapability && !(cap2 instanceof BundleCapability)) {
c = -1;
} else if (!(cap1 instanceof BundleCapability) && cap2 instanceof BundleCapability) {
c = 1;
}
// Always prefer mandatory resources
if (c == 0) {
int c1 = cost.applyAsInt(cap1.getResource());
int c2 = cost.applyAsInt(cap2.getResource());
c = Integer.compare(c1, c2);
}
// Compare revision capabilities.
if ((c == 0) && cap1.getNamespace().equals(BundleNamespace.BUNDLE_NAMESPACE)) {
c = compareNames(cap1, cap2, BundleNamespace.BUNDLE_NAMESPACE);
if (c == 0) {
c = compareVersions(cap1, cap2, BundleNamespace.CAPABILITY_BUNDLE_VERSION_ATTRIBUTE);
}
// Compare package capabilities.
} else if ((c == 0) && cap1.getNamespace().equals(PackageNamespace.PACKAGE_NAMESPACE)) {
c = compareNames(cap1, cap2, PackageNamespace.PACKAGE_NAMESPACE);
if (c == 0) {
c = compareVersions(cap1, cap2, PackageNamespace.CAPABILITY_VERSION_ATTRIBUTE);
// if same version, rather compare on the bundle version
if (c == 0) {
c = compareVersions(cap1, cap2, BundleNamespace.CAPABILITY_BUNDLE_VERSION_ATTRIBUTE);
}
}
// Compare feature capabilities
} else if ((c == 0) && cap1.getNamespace().equals(IdentityNamespace.IDENTITY_NAMESPACE)) {
c = compareNames(cap1, cap2, IdentityNamespace.IDENTITY_NAMESPACE);
if (c == 0) {
c = compareVersions(cap1, cap2, IdentityNamespace.CAPABILITY_VERSION_ATTRIBUTE);
}
}
if (c == 0) {
// We just want to have a deterministic heuristic
final Resource resource1 = cap1.getResource();
final Resource resource2 = cap2.getResource();
String n1 = ResolverUtil.getSymbolicName(resource1);
String n2 = ResolverUtil.getSymbolicName(resource2);
c = n1.compareTo(n2);
// Resources looks like identical, but it required by different features/subsystems/regions
// so use this difference for deterministic heuristic
if (c == 0) {
String o1 = ResolverUtil.getOwnerName(resource1);
String o2 = ResolverUtil.getOwnerName(resource2);
if (o1 != null && o2 != null) {
// In case the owners are the same but with different version, prefer the latest one
// TODO: this may not be fully correct, as we'd need to separate names/versions
// TODO: and do a real version comparison
c = - o1.compareTo(o2);
}
}
}
return c;
}
private int compareNames(Capability cap1, Capability cap2, String attribute) {
Object o1 = cap1.getAttributes().get(attribute);
Object o2 = cap2.getAttributes().get(attribute);
if (o1 instanceof List || o2 instanceof List) {
List l1 = o1 instanceof List ? (List) o1 : Collections.singletonList((String) o1);
List l2 = o2 instanceof List ? (List) o2 : Collections.singletonList((String) o2);
for (String s : l1) {
if (l2.contains(s)) {
return 0;
}
}
return l1.get(0).compareTo(l2.get(0));
} else {
return((String) o1).compareTo((String) o2);
}
}
private int compareVersions(Capability cap1, Capability cap2, String attribute) {
Version v1 = (!cap1.getAttributes().containsKey(attribute))
? Version.emptyVersion
: (Version) cap1.getAttributes().get(attribute);
Version v2 = (!cap2.getAttributes().containsKey(attribute))
? Version.emptyVersion
: (Version) cap2.getAttributes().get(attribute);
// Compare these in reverse order, since we want
// highest version to have priority.
return v2.compareTo(v1);
}
}