/*
* 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 CodeProvider
uses int[] to store counters.
This implementation is not fully thread-safe, but significantly (10-100x) then 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: piotr.tabor@gmail.com
/**
* <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
/**
* 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();
}
}