tjwatson commented on code in PR #552: URL: https://github.com/apache/felix-dev/pull/552#discussion_r3907938699
########## framework/src/main/java/org/apache/felix/framework/PlurlURLHandlers.java: ########## @@ -0,0 +1,124 @@ +/* + * 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.felix.framework; + +import java.io.IOException; +import java.net.ContentHandler; +import java.net.URLStreamHandler; + +import org.apache.felix.framework.plurl.Plurl; +import org.apache.felix.framework.plurl.PlurlContentHandlerFactory; +import org.apache.felix.framework.plurl.PlurlStreamHandlerFactory; + +/** + * <p> + * PROTOTYPE (FELIX-6759): adapts Felix' {@link URLHandlers} onto the plurl + * multiplexing URL factories. + * </p> + * <p> + * {@code URLHandlers} currently claims the JVM-wide {@code java.net.URL} stream + * handler factory by reflectively swapping a private static field + * ({@code SecureAction.swapStaticFieldIfNotClass}). Obtaining a + * {@code MethodHandles.Lookup} trusted enough to do that is the sole reason the + * framework still uses {@code sun.misc.Unsafe}, and it means whichever framework + * installs itself last wins the singleton - so Felix and Equinox cannot coexist in + * one JVM without clobbering each other. + * </p> + * <p> + * Plurl instead installs one cooperative router through the supported + * {@code URL.setURLStreamHandlerFactory} API and lets any number of parties + * register with it. Each registered factory answers {@link #shouldHandle(Class)} + * to say whether a given calling class belongs to it; plurl walks the call stack + * and routes accordingly. That maps directly onto what + * {@link URLHandlers#getFrameworkFromContext()} already does. + * </p> + * <p> + * See {@code org/apache/felix/framework/plurl/README.md} for the provenance of the + * vendored plurl sources and the <b>unresolved licensing question</b> that currently + * blocks this approach. + * </p> + */ +class PlurlURLHandlers implements PlurlStreamHandlerFactory, PlurlContentHandlerFactory +{ + private final URLHandlers m_delegate; + + PlurlURLHandlers(URLHandlers delegate) + { + m_delegate = delegate; + } + + /** + * Registers this framework's handlers with the plurl router, installing the + * router first if nobody has yet. + */ + static PlurlURLHandlers install(URLHandlers delegate) throws IOException + { + PlurlURLHandlers handlers = new PlurlURLHandlers(delegate); + Plurl.add((PlurlStreamHandlerFactory) handlers); + Plurl.add((PlurlContentHandlerFactory) handlers); + return handlers; + } + + /** + * Unregisters this framework's handlers, leaving the router in place for any + * other framework instance still using it. + */ + void uninstall() throws IOException + { + Plurl.remove((PlurlStreamHandlerFactory) this); + Plurl.remove((PlurlContentHandlerFactory) this); + } + + /** + * Tells plurl whether the given calling class belongs to this framework. + * <p> + * This replaces the call stack walking URLHandlers does today: rather than + * inspecting the stack itself to work out which framework owns the caller, the + * router asks each registered factory about a single candidate class. + */ + @Override + public boolean shouldHandle(Class<?> clazz) + { + if (clazz == null) + { + return false; + } + ClassLoader loader = clazz.getClassLoader(); + if (loader == null) + { + return false; + } + String name = loader.getClass().getName(); + return name.startsWith("org.apache.felix.framework.BundleWiringImpl$BundleClassLoader") + || name.startsWith("org.apache.felix.framework.ModuleImpl$ModuleClassLoader") + || name.equals("org.apache.felix.framework.searchpolicy.ContentClassLoader"); Review Comment: For Equinox I do an additional check to make sure the class loader is for a bundle that is actually installed in this framework instance. I assume you would want the same thing here. Otherwise one felix framework may handle lookups for a bundle resolved in another felix framework instance. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
