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	/*
	* Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package sun.jvmstat.perfdata.monitor.v1_0;

	import sun.jvmstat.monitor.*;
	import sun.jvmstat.perfdata.monitor.*;
	import java.nio.*;

	/**
	* Class representing the 1.0 version of the HotSpot PerfData instrumentation
	* buffer header.
	* <p>
	* The PerfDataBufferPrologue2_0 class supports parsing of the version
	* specific portions of the PerfDataPrologue C structure:
	* <pre>
	* typedef struct {
	* ... // handled by superclass
	* jint used; // number of PerfData memory bytes used
	* jint overflow; // number of bytes of overflow
	* jlong mod_time_stamp; // time stamp of the last structural modification
	* } PerfDataPrologue
	* </pre>
	*
	* @author Brian Doherty
	* @since 1.5
	*/
	public class PerfDataBufferPrologue extends AbstractPerfDataBufferPrologue {

	private static final int SUPPORTED_MAJOR_VERSION = 1;
	private static final int SUPPORTED_MINOR_VERSION = 0;

	/*
	* the following constants must match the field offsets and sizes
	* in the PerfDataPrologue structure in perfMemory.hpp
	*/
	final static int PERFDATA_PROLOG_USED_OFFSET=8;
	final static int PERFDATA_PROLOG_USED_SIZE=4; // sizeof(int)
	final static int PERFDATA_PROLOG_OVERFLOW_OFFSET=12;
	final static int PERFDATA_PROLOG_OVERFLOW_SIZE=4; // sizeof(int)
	final static int PERFDATA_PROLOG_MODTIMESTAMP_OFFSET=16;
	final static int PERFDATA_PROLOG_MODTIMESTAMP_SIZE=8; // sizeof(long)
	final static int PERFDATA_PROLOG_SIZE=24; // sizeof(struct PerfDataProlog)

	// counter names for prologue psuedo counters
	final static String PERFDATA_BUFFER_SIZE_NAME = "sun.perfdata.size";
	final static String PERFDATA_BUFFER_USED_NAME = "sun.perfdata.used";
	final static String PERFDATA_OVERFLOW_NAME = "sun.perfdata.overflow";
	final static String PERFDATA_MODTIMESTAMP_NAME = "sun.perfdata.timestamp";

	/**
	* Create an instance of PerfDataBufferPrologue from the given
	* ByteBuffer object.
	*
	* @param byteBuffer the buffer containing the binary header data
	*/
	public PerfDataBufferPrologue(ByteBuffer byteBuffer)
	throws MonitorException {
	super(byteBuffer);
	assert ((getMajorVersion() == 1) && (getMinorVersion() == 0));
	}

	/**
	* {@inheritDoc}
	*/
	public boolean supportsAccessible() {
	return false;
	}

	/**
	* {@inheritDoc}
	*/
	public boolean isAccessible() {
	return true;
	}

	/**
	* Get the utilization of the instrumentation memory buffer.
	*
	* @return int - the utilization of the buffer
	*/
	public int getUsed() {
	byteBuffer.position(PERFDATA_PROLOG_USED_OFFSET);
	return byteBuffer.getInt();
	}

	/**
	* Get the size of the instrumentation memory buffer.
	*
	* @return int - the size of the buffer
	*/
	public int getBufferSize() {
	return byteBuffer.capacity();
	}

	/**
	* Get the buffer overflow amount. This value is non-zero if the
	* HotSpot JVM has overflowed the instrumentation memory buffer.
	* The target JVM can be restarted with -XX:PerfDataMemSize=X to
	* create a larger memory buffer.
	*
	* @return int - the size of the buffer
	*/
	public int getOverflow() {
	byteBuffer.position(PERFDATA_PROLOG_OVERFLOW_OFFSET);
	return byteBuffer.getInt();
	}

	/**
	* Get the time of last modification for the instrumentation
	* memory buffer. This method returns the time, as ticks since the
	* start of the target JVM, of the last structural modification to
	* the instrumentation buffer. Structural modifications correspond to
	* the addition or deletion of instrumentation objects. Updates to
	* counter values are not structural modifications.
	*/
	public long getModificationTimeStamp() {
	byteBuffer.position(PERFDATA_PROLOG_MODTIMESTAMP_OFFSET);
	return byteBuffer.getLong();
	}

	/**
	* {@inheritDoc}
	*/
	public int getSize() {
	return PERFDATA_PROLOG_SIZE; // sizeof(struct PerfDataProlog)
	}

	/**
	* Return an IntBuffer that accesses the used value. This is used
	* to create a Monitor object for this value.
	*
	* @return IntBuffer - a ByteBuffer that accesses the used value
	* in the instrumentation buffer header.
	* @see #getUsed()
	*/
	public IntBuffer usedBuffer() {
	byteBuffer.position(PERFDATA_PROLOG_USED_OFFSET);
	IntBuffer ib = byteBuffer.asIntBuffer();
	ib.limit(1);
	return ib;
	}

	/**
	* Return an IntBuffer that accesses the size value. This is used
	* to create a Monitor object for this value.
	*
	* @return IntBuffer - a ByteBuffer that accesses the size value
	* in the instrumentation buffer header.
	* @see #getBufferSize()
	*/
	public IntBuffer sizeBuffer() {
	IntBuffer ib = IntBuffer.allocate(1);
	ib.put(byteBuffer.capacity());
	return ib;
	}

	/**
	* Return an IntBuffer that accesses the overflow value. This is used
	* to create a Monitor object for this value.
	*
	* @return IntBuffer - a ByteBuffer that accesses the overflow value
	* in the instrumentation buffer header.
	* @see #getOverflow()
	*/
	public IntBuffer overflowBuffer() {
	byteBuffer.position(PERFDATA_PROLOG_OVERFLOW_OFFSET);
	IntBuffer ib = byteBuffer.asIntBuffer();
	ib.limit(1);
	return ib;
	}

	/**
	* Return an LongBuffer that accesses the modification timestamp value.
	* This is used* to create a Monitor object for this value.
	*
	* @return LongBuffer - a ByteBuffer that accesses the modification time
	* stamp value in the instrumentation buffer header.
	* @see #getModificationTimeStamp()
	*/
	public LongBuffer modificationTimeStampBuffer() {
	byteBuffer.position(PERFDATA_PROLOG_MODTIMESTAMP_OFFSET);
	LongBuffer lb = byteBuffer.asLongBuffer();
	lb.limit(1);
	return lb;
	}
	}

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