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/* Copyright (C) 2003 Vladimir Roubtsov. All rights reserved.
*
* This program and the accompanying materials are made available under
* the terms of the Common Public License v1.0 which accompanies this distribution,
* and is available at http://www.eclipse.org/legal/cpl-v10.html
*
* $Id: InstrClassLoadHook.java,v 1.1.1.1 2004/05/09 16:57:44 vlad_r Exp $
*/
package com.vladium.emma.rt;
import java.io.IOException;
import com.vladium.jcd.cls.ClassDef;
import com.vladium.jcd.compiler.ClassWriter;
import com.vladium.jcd.parser.ClassDefParser;
import com.vladium.util.ByteArrayOStream;
import com.vladium.util.Descriptors;
import com.vladium.util.asserts.$assert;
import com.vladium.emma.filter.IInclExclFilter;
import com.vladium.emma.instr.InstrVisitor;
import com.vladium.emma.data.CoverageOptions;
import com.vladium.emma.data.IMetaData;
// ----------------------------------------------------------------------------
/**
* MT-safety ensured by the containing loader
*
* @author Vlad Roubtsov, (C) 2003
*/
public
final class InstrClassLoadHook implements IClassLoadHook
{
// public: ................................................................
/**
* @param filter [can be null]
*/
public InstrClassLoadHook (final IInclExclFilter filter, final IMetaData mdata)
{
if (mdata == null) throw new IllegalArgumentException ("null input: mdata");
m_filter = filter; // can be null
m_metadata = mdata;
// important to use the same options as the metadata may have been populated earlier:
final CoverageOptions options = mdata.getOptions ();
m_classDefProcessor = new InstrVisitor (options);
m_instrResult = new InstrVisitor.InstrResult ();
}
public boolean processClassDef (final String className,
final byte [] bytes, final int length,
ByteArrayOStream out)
throws IOException
{
if ($assert.ENABLED)
{
$assert.ASSERT (className != null, "className is null");
$assert.ASSERT (bytes != null, "bytes is null");
$assert.ASSERT (bytes != null, "out is null");
}
final IInclExclFilter filter = m_filter;
if ((filter == null) || filter.included (className))
{
final ClassDef clsDef = ClassDefParser.parseClass (bytes, length);
final String classVMName = Descriptors.javaNameToVMName (className);
final Object lock = m_metadata.lock ();
final boolean metadataExists;
synchronized (lock)
{
metadataExists = m_metadata.hasDescriptor (classVMName);
}
// since this is the first [and only] time the parent loader is
// loading the class in question, if metadata for 'className' exists
// it means it was created during the app runner's classpath scan --
// do not overwrite it (the class def should be the same)
// [this picture breaks down if the design changes so that the same
// metadata instance could be associated with more than one app loader]
m_classDefProcessor.process (clsDef, false, true, ! metadataExists, m_instrResult);
boolean useOurs = m_instrResult.m_instrumented;
if (m_instrResult.m_descriptor != null) // null means either the metadata existed already or the class is an interface
{
// try to update metadata [this supports the "no initial full cp
// scan mode" in the app runner and also ensures that we pick up
// any dynamically generated classes to support (hacky) apps that
// do dynamic source generation/compilation]:
synchronized (lock)
{
// do not force overwrites of existing descriptors to support
// correct handling of race conditions: if another thread
// updates the metadata first, discard our version of the class def
// [actually, this guard is redundant here because
// right now the hook can only have a single classloader parent
// and the parent's loadClass() is a critical section]
if (! m_metadata.add (m_instrResult.m_descriptor, false))
useOurs = false;
}
}
if (useOurs)
{
ClassWriter.writeClassTable (clsDef, out);
return true;
}
}
return false;
}
// protected: .............................................................
// package: ...............................................................
// private: ...............................................................
private final IInclExclFilter m_filter; // can be null [equivalent to no filtering]
private final IMetaData m_metadata; // never null
private final InstrVisitor m_classDefProcessor; // never null
private final InstrVisitor.InstrResult m_instrResult;
} // end of class
// ----------------------------------------------------------------------------
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