ExecutionDataAccess.java
/*******************************************************************************
* Copyright (c) 2009, 2012 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.ExecutionDataStore;
import org.jacoco.core.internal.instr.InstrSupport;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
/**
* This class implements the access from instrumented classes to execution data
* storage in the runtime. Instead of directly referencing JaCoCo implementation
* classes the access is decoupled through a JRE API. This avoids dependencies
* from instrumented classes on JaCoCo APIs.
*
* The JRE interface method used is {@link Object#equals(Object)} where the
* passed argument is an {@link Object} array containing the class id (
* {@link Long}), the class vm name ({@link String}) and the probe count (
* {@link Integer}). After the method call the probe array instance is stored in
* the first slot of the {@link Object} array.
*/
class ExecutionDataAccess {
private final ExecutionDataStore store;
ExecutionDataAccess(final ExecutionDataStore store) {
this.store = store;
}
/**
* 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 getExecutionData(final Object[] args) {
final Long classid = (Long) args[0];
final String name = (String) args[1];
final int probecount = ((Integer) args[2]).intValue();
synchronized (store) {
args[0] = store.get(classid, name, probecount).getData();
}
}
/**
* Generates code that creates the argument array for the
* <code>getExecutionData()</code> 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 the runtime data access 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
* @param classname
* @param probecount
* @param mv
*/
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);
}
/**
* 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) {
getExecutionData((Object[]) args);
return false;
}
}