/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
**********************************************************************************************************************/
package eu.stratosphere.nephele.services.memorymanager.spi;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import eu.stratosphere.core.memory.MemorySegment;
import eu.stratosphere.nephele.services.memorymanager.MemoryAllocationException;
import eu.stratosphere.nephele.services.memorymanager.MemoryManager;
import eu.stratosphere.nephele.template.AbstractInvokable;
public class DefaultMemoryManager implements MemoryManager {
/**
* The default memory page size. Currently set to 32 KiBytes.
*/
public static final int DEFAULT_PAGE_SIZE = 32 * 1024;
/**
* The minimal memory page size. Currently set to 4 KiBytes.
*/
public static final int MIN_PAGE_SIZE = 4 * 1024;
/**
* The Log.
*/
private static final Log LOG = LogFactory.getLog(DefaultMemoryManager.class);
// --------------------------------------------------------------------------------------------
private final Object lock = new Object(); // The lock used on the shared structures.
private final ArrayDeque<byte[]> freeSegments; // the free memory segments
private final HashMap<AbstractInvokable, Set<DefaultMemorySegment>> allocatedSegments;
private final long roundingMask; // mask used to round down sizes to multiples of the page size
private final int pageSize; // the page size, in bytes
private final int pageSizeBits; // the number of bits that the power-of-two page size corresponds to
private final int totalNumPages; // The initial total size, for verification.
private boolean isShutDown; // flag whether the close() has already been invoked.
// ------------------------------------------------------------------------
// Constructors / Destructors
// ------------------------------------------------------------------------
/**
* Creates a memory manager with the given capacity, using the default page size.
*
* @param memorySize The total size of the memory to be managed by this memory manager.
*/
public DefaultMemoryManager(long memorySize) {
this(memorySize, DEFAULT_PAGE_SIZE);
}
/**
* Creates a memory manager with the given capacity and given page size.
*
* @param memorySize The total size of the memory to be managed by this memory manager.
* @param pageSize The size of the pages handed out by the memory manager.
*/
public DefaultMemoryManager(long memorySize, int pageSize) {
// sanity checks
if (memorySize <= 0) {
throw new IllegalArgumentException("Size of total memory must be positive.");
}
if (pageSize < MIN_PAGE_SIZE) {
throw new IllegalArgumentException("The page size must be at least " + MIN_PAGE_SIZE + " bytes.");
}
if ((pageSize & (pageSize - 1)) != 0) {
// not a power of two
throw new IllegalArgumentException("The given page size is not a power of two.");
}
// assign page size and bit utilities
this.pageSize = pageSize;
this.roundingMask = ~((long) (pageSize - 1));
int log = 0;
while ((pageSize = pageSize >>> 1) != 0) {
log++;
}
this.pageSizeBits = log;
this.totalNumPages = getNumPages(memorySize);
if (this.totalNumPages < 1) {
throw new IllegalArgumentException("The given amount of memory amounted to less than one page.");
}
// initialize the free segments and allocated segments tracking structures
this.freeSegments = new ArrayDeque<byte[]>(this.totalNumPages);
this.allocatedSegments = new HashMap<AbstractInvokable, Set<DefaultMemorySegment>>();
// add the full chunks
for (int i = 0; i < this.totalNumPages; i++) {
// allocate memory of the specified size
this.freeSegments.add(new byte[this.pageSize]);
}
}
@Override
public void shutdown() {
// -------------------- BEGIN CRITICAL SECTION -------------------
synchronized (this.lock)
{
if (!this.isShutDown) {
if (LOG.isDebugEnabled()) {
LOG.debug("Shutting down MemoryManager instance " + toString());
}
// mark as shutdown and release memory
this.isShutDown = true;
this.freeSegments.clear();
// go over all allocated segments and release them
for (Set<DefaultMemorySegment> segments : this.allocatedSegments.values()) {
for (DefaultMemorySegment seg : segments) {
seg.destroy();
}
}
}
}
// -------------------- END CRITICAL SECTION -------------------
}
public boolean verifyEmpty() {
synchronized (this.lock) {
return this.freeSegments.size() == this.totalNumPages;
}
}
// ------------------------------------------------------------------------
// MemoryManager interface implementation
// ------------------------------------------------------------------------
@Override
public List<MemorySegment> allocatePages(AbstractInvokable owner, int numPages) throws MemoryAllocationException {
final ArrayList<MemorySegment> segs = new ArrayList<MemorySegment>(numPages);
allocatePages(owner, segs, numPages);
return segs;
}
@Override
public void allocatePages(AbstractInvokable owner, List<MemorySegment> target, int numPages)
throws MemoryAllocationException
{
// sanity check
if (owner == null) {
throw new IllegalAccessError("The memory owner must not be null.");
}
// reserve array space, if applicable
if (target instanceof ArrayList) {
((ArrayList<MemorySegment>) target).ensureCapacity(numPages);
}
// -------------------- BEGIN CRITICAL SECTION -------------------
synchronized (this.lock)
{
if (this.isShutDown) {
throw new IllegalStateException("Memory manager has been shut down.");
}
if (numPages > this.freeSegments.size()) {
throw new MemoryAllocationException("Could not allocate " + numPages + " pages. Only " +
this.freeSegments.size() + " pages are remaining.");
}
Set<DefaultMemorySegment> segmentsForOwner = this.allocatedSegments.get(owner);
if (segmentsForOwner == null) {
segmentsForOwner = new HashSet<DefaultMemorySegment>(4 * numPages / 3 + 1);
this.allocatedSegments.put(owner, segmentsForOwner);
}
for (int i = numPages; i > 0; i--) {
byte[] buffer = this.freeSegments.poll();
final DefaultMemorySegment segment = new DefaultMemorySegment(owner, buffer);
target.add(segment);
segmentsForOwner.add(segment);
}
}
// -------------------- END CRITICAL SECTION -------------------
}
// ------------------------------------------------------------------------
@Override
public void release(MemorySegment segment) {
// check if segment is null or has already been freed
if (segment == null || segment.isFreed() || !(segment instanceof DefaultMemorySegment)) {
return;
}
final DefaultMemorySegment defSeg = (DefaultMemorySegment) segment;
final AbstractInvokable owner = defSeg.owner;
// -------------------- BEGIN CRITICAL SECTION -------------------
synchronized (this.lock)
{
if (this.isShutDown) {
throw new IllegalStateException("Memory manager has been shut down.");
}
// remove the reference in the map for the owner
try {
Set<DefaultMemorySegment> segsForOwner = this.allocatedSegments.get(owner);
if (segsForOwner != null) {
segsForOwner.remove(defSeg);
if (segsForOwner.isEmpty()) {
this.allocatedSegments.remove(owner);
}
}
}
catch (Throwable t) {
LOG.error("Error removing book-keeping reference to allocated memory segment.", t);
}
finally {
// release the memory in any case
byte[] buffer = defSeg.destroy();
this.freeSegments.add(buffer);
}
}
// -------------------- END CRITICAL SECTION -------------------
}
@Override
public <T extends MemorySegment> void release(Collection<T> segments) {
// sanity checks
if (segments == null) {
return;
}
// -------------------- BEGIN CRITICAL SECTION -------------------
synchronized (this.lock)
{
if (this.isShutDown) {
throw new IllegalStateException("Memory manager has been shut down.");
}
final Iterator<T> segmentsIterator = segments.iterator();
AbstractInvokable lastOwner = null;
Set<DefaultMemorySegment> segsForOwner = null;
// go over all segments
while (segmentsIterator.hasNext()) {
final MemorySegment seg = segmentsIterator.next();
if (seg.isFreed()) {
continue;
}
final DefaultMemorySegment defSeg = (DefaultMemorySegment) seg;
final AbstractInvokable owner = defSeg.owner;
try {
// get the list of segments by this owner only if it is a different owner than for
// the previous one (or it is the first segment)
if (lastOwner != owner) {
lastOwner = owner;
segsForOwner = this.allocatedSegments.get(owner);
}
// remove the segment from the list
if (segsForOwner != null) {
segsForOwner.remove(defSeg);
if (segsForOwner.isEmpty()) {
this.allocatedSegments.remove(owner);
}
}
}
catch (Throwable t) {
LOG.error("Error removing book-keeping reference to allocated memory segment.", t);
}
finally {
// release the memory in any case
byte[] buffer = defSeg.destroy();
this.freeSegments.add(buffer);
}
}
segments.clear();
}
// -------------------- END CRITICAL SECTION -------------------
}
@Override
public void releaseAll(AbstractInvokable owner) {
// -------------------- BEGIN CRITICAL SECTION -------------------
synchronized (this.lock)
{
if (this.isShutDown) {
throw new IllegalStateException("Memory manager has been shut down.");
}
// get all segments
final Set<DefaultMemorySegment> segments = this.allocatedSegments.remove(owner);
// all segments may have been freed previously individually
if (segments == null || segments.isEmpty()) {
return;
}
// free each segment
for (DefaultMemorySegment seg : segments) {
final byte[] buffer = seg.destroy();
this.freeSegments.add(buffer);
}
segments.clear();
}
// -------------------- END CRITICAL SECTION -------------------
}
// ------------------------------------------------------------------------
@Override
public int getPageSize() {
return this.pageSize;
}
@Override
public int computeNumberOfPages(long numBytes) {
return getNumPages(numBytes);
}
@Override
public long roundDownToPageSizeMultiple(long numBytes) {
return numBytes & this.roundingMask;
}
// ------------------------------------------------------------------------
private final int getNumPages(long numBytes) {
if (numBytes < 0) {
throw new IllegalArgumentException("The number of bytes to allocate must not be negative.");
}
final long numPages = numBytes >>> this.pageSizeBits;
if (numPages <= Integer.MAX_VALUE) {
return (int) numPages;
} else {
throw new IllegalArgumentException("The given number of bytes correstponds to more than MAX_INT pages.");
}
}
// ------------------------------------------------------------------------
private static final class DefaultMemorySegment extends MemorySegment {
private AbstractInvokable owner;
DefaultMemorySegment(AbstractInvokable owner, byte[] memory) {
super(memory);
this.owner = owner;
}
byte[] destroy() {
final byte[] buffer = this.memory;
this.memory = null;
this.wrapper = null;
return buffer;
}
}
}