org.jacoco.core.runtime.URLStreamHandlerRuntime.java Source code

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Here is the source code for org.jacoco.core.runtime.URLStreamHandlerRuntime.java

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/*******************************************************************************
 * Copyright (c) 2009, 2013 Mountainminds GmbH & Co. KG and Contributors
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Marc R. Hoffmann - initial API and implementation
 *    
 *******************************************************************************/
package org.jacoco.core.runtime;

import java.io.IOException;
import java.lang.reflect.Field;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;
import java.util.Map;

import org.jacoco.core.internal.instr.InstrSupport;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

/**
 * This {@link IRuntime} implementation registers a special
 * {@link URLStreamHandler} to process coverage data. The handler is not
 * actually used for opening a URL, but to get access to the runtime object.
 */
public class URLStreamHandlerRuntime extends AbstractRuntime {

    private static final String PROTOCOLPREFIX = "jacoco-";

    private final String protocol;

    private Map<String, URLStreamHandler> handlers;

    /**
     * Creates a new runtime.
     */
    public URLStreamHandlerRuntime() {
        super();
        protocol = PROTOCOLPREFIX + Integer.toHexString(hashCode());
    }

    @Override
    public void startup(final RuntimeData data) throws Exception {
        super.startup(data);
        handlers = getHandlersReference();
        handlers.put(protocol, handler);
    }

    private Map<String, URLStreamHandler> getHandlersReference() throws Exception {
        final Field field = URL.class.getDeclaredField("handlers");
        field.setAccessible(true);
        @SuppressWarnings("unchecked")
        final Map<String, URLStreamHandler> map = (Map<String, URLStreamHandler>) field.get(null);
        return map;
    }

    public void shutdown() {
        handlers.remove(protocol);
    }

    public int generateDataAccessor(final long classid, final String classname, final int probecount,
            final MethodVisitor mv) {

        // The data accessor performs the following steps:
        //
        // final URL url = new URL(protocol, null, "");
        // final URLConnection connection = url.openConnection();
        // final Object[] args = new Object[3];
        // args[0] = Long.valueOf(classid);
        // args[1] = classname;
        // args[2] = Integer.valueOf(probecount);
        // connection.equals(args);
        // final byte[] probedata = (byte[]) args[0];

        RuntimeData.generateArgumentArray(classid, classname, probecount, mv);
        mv.visitInsn(Opcodes.DUP);

        // Stack[1]: [Ljava/lang/Object;
        // Stack[0]: [Ljava/lang/Object;

        mv.visitTypeInsn(Opcodes.NEW, "java/net/URL");
        mv.visitInsn(Opcodes.DUP);
        mv.visitLdcInsn(protocol);
        mv.visitInsn(Opcodes.ACONST_NULL);
        mv.visitLdcInsn("");
        mv.visitMethodInsn(Opcodes.INVOKESPECIAL, "java/net/URL", "<init>",
                "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)V");

        // Stack[2]: [Ljava/net/URL;
        // Stack[1]: [Ljava/lang/Object;
        // Stack[0]: [Ljava/lang/Object;

        mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/net/URL", "openConnection", "()Ljava/net/URLConnection;");

        // Stack[2]: [Ljava/net/URLConnection;
        // Stack[1]: [Ljava/lang/Object;
        // Stack[0]: [Ljava/lang/Object;

        mv.visitInsn(Opcodes.SWAP);

        // Stack[2]: [Ljava/lang/Object;
        // Stack[1]: [Ljava/net/URLConnection;
        // Stack[0]: [Ljava/lang/Object;

        mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Object", "equals", "(Ljava/lang/Object;)Z");

        // Stack[1]: Z;
        // Stack[0]: [Ljava/lang/Object;

        mv.visitInsn(Opcodes.POP);

        // Stack[0]: [Ljava/lang/Object;

        mv.visitInsn(Opcodes.ICONST_0);
        mv.visitInsn(Opcodes.AALOAD);
        mv.visitTypeInsn(Opcodes.CHECKCAST, InstrSupport.DATAFIELD_DESC);

        return 7;
    }

    private final URLStreamHandler handler = new URLStreamHandler() {
        @Override
        protected URLConnection openConnection(final URL u) throws IOException {
            return connection;
        }
    };

    private final URLConnection connection = new URLConnection(null) {
        @Override
        public void connect() throws IOException {
            throw new AssertionError();
        }

        @Override
        public boolean equals(final Object obj) {
            return data.equals(obj);
        }
    };

}