Java tutorial
/* * 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.*; /** * <p>The {@link CodeProvider} uses int[] to store counters.</p> * <p/> * <p>This implementation is not fully thread-safe, but significantly (10-100x) then {@link AtomicArrayCodeProvider}.</p> * <p/> * <p>What does it mean 'not fully thead-safe' ? * <ul> * <li>Using this provider will never cause throwing any exception because of concurrency problems</li> * <li>A code coverage results acquired using this code-provider will be exactly the same as using thread-safe provider)</li> * * <li>There could happen small (experiments showed around 1-3%) in value of specific counters because of race-condition.</li> * </ul> * </p> * <p/> * <p> * The reason of the race condition is fact that instruction: __cobertura_counters[counter_id]++ is translated into * sequence of operations: <ol> * <li>get value of __cobertura_counters[counter_id]</li> * <li>increment value</li> * <li>store value into __cobertura_counters[counter_id]</li> * </ol> * 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. * </p> * * @author piotr.tabor@gmail.com */ 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(); } }