# RuntimeData.java

    /*******************************************************************************
     * 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 org.jacoco.core.data.ExecutionData;
    import org.jacoco.core.data.ExecutionDataStore;
    import org.jacoco.core.data.IExecutionDataVisitor;
    import org.jacoco.core.data.ISessionInfoVisitor;
    import org.jacoco.core.data.SessionInfo;
    import org.jacoco.core.internal.instr.InstrSupport;
    import org.objectweb.asm.MethodVisitor;
    import org.objectweb.asm.Opcodes;

    /**
     * Container for runtime execution and meta data. All access to the runtime data
     * is thread safe.
     */
    public class RuntimeData {

    	/** store for execution data */
    	protected final ExecutionDataStore store;

    	private long startTimeStamp;

    	private String sessionId;

    	/**
    	 * Creates a new runtime.
    	 */
    	public RuntimeData() {
    		store = new ExecutionDataStore();
    		sessionId = "<none>";
    		startTimeStamp = System.currentTimeMillis();
    	}

    	/**
    	 * Sets a session identifier for this runtime. The identifier is used when
    	 * execution data is collected. If no identifier is explicitly set a
    	 * identifier is generated from the host name and a random number. This
    	 * method can be called at any time.
    	 *
    	 * @see #collect(IExecutionDataVisitor, ISessionInfoVisitor, boolean)
    	 * @param id
    	 *            new session identifier
    	 */
    	public void setSessionId(final String id) {
    		sessionId = id;
    	}

    	/**
    	 * Get the current a session identifier for this runtime.
    	 *
    	 * @see #setSessionId(String)
    	 * @return current session identifier
    	 */
    	public String getSessionId() {
    		return sessionId;
    	}

    	/**
    	 * Collects the current execution data and writes it to the given
    	 * {@link IExecutionDataVisitor} object.
    	 *
    	 * @param executionDataVisitor
    	 *            handler to write coverage data to
    	 * @param sessionInfoVisitor
    	 *            handler to write session information to
    	 * @param reset
    	 *            if <code>true</code> the current coverage information is also
    	 *            cleared
    	 */
    	public final void collect(final IExecutionDataVisitor executionDataVisitor,
    			final ISessionInfoVisitor sessionInfoVisitor, final boolean reset) {
    		synchronized (store) {
    			final SessionInfo info = new SessionInfo(sessionId, startTimeStamp,
    					System.currentTimeMillis());
    			sessionInfoVisitor.visitSessionInfo(info);
    			store.accept(executionDataVisitor);
    			if (reset) {
    				reset();
    			}
    		}
    	}

    	/**
    	 * Resets all coverage information.
    	 */
    	public final void reset() {
    		synchronized (store) {
    			store.reset();
    			startTimeStamp = System.currentTimeMillis();
    		}
    	}

    	/**
    	 * Returns the coverage data for the class with the given identifier. If
    	 * there is no data available under the given id a new entry is created.
    	 * This is a synchronized access to the underlying store.
    	 *
    	 * @param id
    	 *            class identifier
    	 * @param name
    	 *            VM name of the class
    	 * @param probecount
    	 *            probe data length
    	 * @return execution data
    	 */
    	public ExecutionData getExecutionData(final Long id, final String name,
    			final int probecount) {
    		synchronized (store) {
    			return store.get(id, name, probecount);
    		}
    	}

    	/**
    	 * Retrieves the execution probe array for a given class. The passed
    	 * {@link Object} array instance is used for parameters and the return value
    	 * as follows. Call parameters:
    	 *
    	 * <ul>
    	 * <li>args[0]: class id ({@link Long})
    	 * <li>args[1]: vm class name ({@link String})
    	 * <li>args[2]: probe count ({@link Integer})
    	 * </ul>
    	 *
    	 * Return value:
    	 *
    	 * <ul>
    	 * <li>args[0]: probe array (<code>boolean[]</code>)
    	 * </ul>
    	 *
    	 * @param args
    	 *            parameter array of length 3
    	 */
    	public void getProbes(final Object[] args) {
    		final Long classid = (Long) args[0];
    		final String name = (String) args[1];
    		final int probecount = ((Integer) args[2]).intValue();
    		args[0] = getExecutionData(classid, name, probecount).getProbes();
    	}

    	/**
    	 * In violation of the regular semantic of {@link Object#equals(Object)}
    	 * this implementation is used as the interface to the execution data store.
    	 *
    	 * @param args
    	 *            the arguments as an {@link Object} array
    	 * @return has no meaning
    	 */
    	@Override
    	public boolean equals(final Object args) {
    		if (args instanceof Object[]) {
    			getProbes((Object[]) args);
    		}
    		return super.equals(args);
    	}

    	/**
    	 * Generates code that creates the argument array for the
    	 * {@link #getProbes(Object[])} method. The array instance is left on the
    	 * operand stack. The generated code requires a stack size of 5.
    	 *
    	 * @param classid
    	 *            class identifier
    	 * @param classname
    	 *            VM class name
    	 * @param probecount
    	 *            probe count for this class
    	 * @param mv
    	 *            visitor to emit generated code
    	 */
    	public static void generateArgumentArray(final long classid,
    			final String classname, final int probecount, final MethodVisitor mv) {
    		mv.visitInsn(Opcodes.ICONST_3);
    		mv.visitTypeInsn(Opcodes.ANEWARRAY, "java/lang/Object");

    		// Class Id:
    		mv.visitInsn(Opcodes.DUP);
    		mv.visitInsn(Opcodes.ICONST_0);
    		mv.visitLdcInsn(Long.valueOf(classid));
    		mv.visitMethodInsn(Opcodes.INVOKESTATIC, "java/lang/Long", "valueOf",
    				"(J)Ljava/lang/Long;");
    		mv.visitInsn(Opcodes.AASTORE);

    		// Class Name:
    		mv.visitInsn(Opcodes.DUP);
    		mv.visitInsn(Opcodes.ICONST_1);
    		mv.visitLdcInsn(classname);
    		mv.visitInsn(Opcodes.AASTORE);

    		// Probe Count:
    		mv.visitInsn(Opcodes.DUP);
    		mv.visitInsn(Opcodes.ICONST_2);
    		InstrSupport.push(mv, probecount);
    		mv.visitMethodInsn(Opcodes.INVOKESTATIC, "java/lang/Integer",
    				"valueOf", "(I)Ljava/lang/Integer;");
    		mv.visitInsn(Opcodes.AASTORE);
    	}

    	/**
    	 * Generates the code that calls a {@link RuntimeData} instance through the
    	 * JRE API method {@link Object#equals(Object)}. The code pops a
    	 * {@link Object} instance from the stack and pushes the probe array of type
    	 * <code>boolean[]</code> on the operand stack. The generated code requires
    	 * a stack size of 6.
    	 *
    	 * @param classid
    	 *            class identifier
    	 * @param classname
    	 *            VM class name
    	 * @param probecount
    	 *            probe count for this class
    	 * @param mv
    	 *            visitor to emit generated code
    	 */
    	public static void generateAccessCall(final long classid,
    			final String classname, final int probecount, final MethodVisitor mv) {
    		// stack[0]: Ljava/lang/Object;

    		generateArgumentArray(classid, classname, probecount, mv);

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

    		mv.visitInsn(Opcodes.DUP_X1);

    		// stack[2]: [Ljava/lang/Object;
    		// stack[1]: Ljava/lang/Object;
    		// stack[0]: [Ljava/lang/Object;

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

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

    		mv.visitInsn(Opcodes.ICONST_0);
    		mv.visitInsn(Opcodes.AALOAD);

    		// stack[0]: [Z

    		mv.visitTypeInsn(Opcodes.CHECKCAST, InstrSupport.DATAFIELD_DESC);
    	}

    }