net.sourceforge.cobertura.instrument.pass3.FastArrayCodeProvider Maven / Gradle / Ivy

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Cobertura is a free Java tool that calculates the percentage of code accessed by tests. It can be used to identify which parts of your Java program are lacking test coverage. It is based on jcoverage.
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/*
 * Cobertura - http://cobertura.sourceforge.net/
 *
 * Copyright (C) 2011 Piotr Tabor
 *
 * Note: This file is dual licensed under the GPL and the Apache
 * Source License (so that it can be used from both the main
 * Cobertura classes and the ant tasks).
 *
 * Cobertura is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License,
 * or (at your option) any later version.
 *
 * Cobertura is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Cobertura; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 */

package net.sourceforge.cobertura.instrument.pass3;

import org.objectweb.asm.*;

/**
 * The {@link CodeProvider} uses int[] to store counters.
 * 
 * 
This implementation is not fully thread-safe, but significantly (10-100x) then {@link AtomicArrayCodeProvider}.
 * 
 * 
What does it mean 'not fully thead-safe' ?
 * 

 * Using this provider will never cause throwing any exception because of concurrency problems
 * A code coverage results acquired using this code-provider will be exactly the same as using thread-safe provider) *
 * There could happen small (experiments showed around 1-3%) in value of specific counters because of race-condition.
 * 
 * 
 * 
 * 

 * The reason of the race condition is fact that instruction: __cobertura_counters[counter_id]++ is translated into
 * sequence of operations: 

 * get value of __cobertura_counters[counter_id]
 * increment value
 * store value into __cobertura_counters[counter_id]
 * 
 * This mean that in case of race condition we can miss some increments. But if a counter was hit at least once, we
 * are sure that we will increment the counter at least one. For code coverage results fact of being hit is crucial.
 * 
 *
 * @author [email protected]
 */
public class FastArrayCodeProvider extends AbstractCodeProvider
		implements
			CodeProvider {

	/**
	 * Type of the generated field, that is used to store counters
	 */
	static final String COBERTURA_COUNTERS_FIELD_TYPE = "[I";

	public void generateCodeThatIncrementsCoberturaCounterFromInternalVariable(
			MethodVisitor nextMethodVisitor, int lastJumpIdVariableIndex,
			String className) {
		/*cobertura_counters[value('lastJumpIdVariableIndex')]++;*/
		/*cobertura_counters.*/
		nextMethodVisitor.visitFieldInsn(Opcodes.GETSTATIC, className,
				COBERTURA_COUNTERS_FIELD_NAME, COBERTURA_COUNTERS_FIELD_TYPE);
		/*index:*/
		nextMethodVisitor.visitVarInsn(Opcodes.ILOAD, lastJumpIdVariableIndex);
		nextMethodVisitor.visitInsn(Opcodes.DUP2);
		nextMethodVisitor.visitInsn(Opcodes.IALOAD);
		nextMethodVisitor.visitLdcInsn(1);
		nextMethodVisitor.visitInsn(Opcodes.IADD);
		nextMethodVisitor.visitInsn(Opcodes.IASTORE);
	}

	public void generateCodeThatIncrementsCoberturaCounter(
			MethodVisitor nextMethodVisitor, Integer counterId, String className) {
		/*cobertura_counters[value('lastJumpIdVariableIndex')]++;*/
		/*cobertura_counters.*/
		nextMethodVisitor.visitFieldInsn(Opcodes.GETSTATIC, className,
				COBERTURA_COUNTERS_FIELD_NAME, COBERTURA_COUNTERS_FIELD_TYPE);
		/*index:*/
		nextMethodVisitor.visitLdcInsn((int) counterId);
		nextMethodVisitor.visitInsn(Opcodes.DUP2);
		nextMethodVisitor.visitInsn(Opcodes.IALOAD);
		nextMethodVisitor.visitLdcInsn(1);
		nextMethodVisitor.visitInsn(Opcodes.IADD);
		nextMethodVisitor.visitInsn(Opcodes.IASTORE);
	}

	public void generateCountersField(ClassVisitor cv) {
		/*final tooks 270ms, no-modifier 310ms, volatile 500ms*/
		FieldVisitor fv = cv.visitField(Opcodes.ACC_STATIC | Opcodes.ACC_PUBLIC
				| Opcodes.ACC_FINAL | Opcodes.ACC_TRANSIENT,
				COBERTURA_COUNTERS_FIELD_NAME, COBERTURA_COUNTERS_FIELD_TYPE,
				null, null);
		fv.visitEnd();
	}

	//	static int x[];
	//	
	//	static void abc() {
	//		if (x == null) {
	//			x = new int[5];
	//		}
	//	}

	public void generateCINITmethod(MethodVisitor mv, String className,
			int counters_cnt) {
		mv.visitFieldInsn(Opcodes.GETSTATIC, className,
				COBERTURA_COUNTERS_FIELD_NAME, COBERTURA_COUNTERS_FIELD_TYPE);
		Label l1 = new Label();
		mv.visitJumpInsn(Opcodes.IFNONNULL, l1);
		mv.visitLdcInsn(counters_cnt);
		mv.visitIntInsn(Opcodes.NEWARRAY, Opcodes.T_INT);
		mv.visitFieldInsn(Opcodes.PUTSTATIC, className,
				COBERTURA_COUNTERS_FIELD_NAME, COBERTURA_COUNTERS_FIELD_TYPE);
		generateRegisterClass(mv, className);
		mv.visitLabel(l1);
	}

	public void generateCoberturaGetAndResetCountersMethod(ClassVisitor cv,
			String className) {
		MethodVisitor mv = cv.visitMethod(Opcodes.ACC_PUBLIC
				| Opcodes.ACC_STATIC,
				COBERTURA_GET_AND_RESET_COUNTERS_METHOD_NAME, "()[I", null,
				null);
		mv.visitCode();
		/*cobertura_counters.*/
		mv.visitFieldInsn(Opcodes.GETSTATIC, className,
				COBERTURA_COUNTERS_FIELD_NAME, COBERTURA_COUNTERS_FIELD_TYPE);
		mv.visitVarInsn(Opcodes.ASTORE, 0);
		/*cobertura_counters.*/
		mv.visitFieldInsn(Opcodes.GETSTATIC, className,
				COBERTURA_COUNTERS_FIELD_NAME, COBERTURA_COUNTERS_FIELD_TYPE);
		mv.visitInsn(Opcodes.ARRAYLENGTH);

		mv.visitIntInsn(Opcodes.NEWARRAY, Opcodes.T_INT);
		mv.visitFieldInsn(Opcodes.PUTSTATIC, className,
				COBERTURA_COUNTERS_FIELD_NAME, COBERTURA_COUNTERS_FIELD_TYPE);
		mv.visitVarInsn(Opcodes.ALOAD, 0);
		mv.visitInsn(Opcodes.ARETURN);
		mv.visitMaxs(0, 0);//will be recalculated by writer
		mv.visitEnd();
	}

}