123 lines
2.9 KiB
Java
123 lines
2.9 KiB
Java
package org.warp.jcwdb;
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import it.unimi.dsi.fastutil.longs.Long2IntMap;
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import it.unimi.dsi.fastutil.longs.Long2IntRBTreeMap;
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import it.unimi.dsi.fastutil.objects.ObjectBidirectionalIterator;
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import java.io.IOException;
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import java.nio.channels.SeekableByteChannel;
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public class FileAllocator implements AutoCloseable {
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private static final int MAXIMUM_UNALLOCATED_ENTRIES = 500000;
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private final SeekableByteChannel dataFileChannel;
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private volatile long fileSize;
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private volatile boolean closed;
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private final Object closeLock = new Object();
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private final Object allocateLock = new Object();
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/**
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* index -> free space size
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*/
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private final Long2IntRBTreeMap freeBytes = new Long2IntRBTreeMap((a, b) -> (int) (a - b));
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public FileAllocator(SeekableByteChannel dataFileChannel) throws IOException {
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this.dataFileChannel = dataFileChannel;
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this.fileSize = this.dataFileChannel.size();
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}
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/**
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* TODO: not implemented
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*
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* @param size
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* @return offset
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*/
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public long allocate(int size) {
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checkClosed();
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synchronized (allocateLock) {
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long offset = allocateIntoUnusedParts(size);
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if (offset == -1) {
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return allocateToEnd(size);
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} else {
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return offset;
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}
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}
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}
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private long allocateIntoUnusedParts(int size) {
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ObjectBidirectionalIterator<Long2IntMap.Entry> it = freeBytes.long2IntEntrySet().iterator();
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long holeOffset = -1;
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int holeSize = 0;
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while (it.hasNext()) {
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Long2IntMap.Entry entry = it.next();
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int currentHoleSize = entry.getIntValue();
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if (currentHoleSize < size) {
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freeBytes.remove(holeOffset);
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if (holeSize > size) {
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freeBytes.put(holeOffset + size, holeSize - size);
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}
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break;
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}
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holeOffset = entry.getLongKey();
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holeSize = currentHoleSize;
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}
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return holeOffset;
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}
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private long allocateToEnd(int size) {
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long allocatedOffset = fileSize;
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fileSize += size;
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return allocatedOffset;
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}
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public void close() throws IOException {
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if (closed) {
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return;
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}
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synchronized (closeLock) {
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if (closed) {
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return;
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}
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closed = true;
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}
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}
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/**
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* Frees the unused bytes
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*
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* @param startPosition
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* @param length
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*/
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public void markFree(long startPosition, int length) {
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checkClosed();
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if (freeBytes.containsKey(startPosition + length)) {
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int secondLength = freeBytes.remove(startPosition + length);
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freeBytes.put(startPosition, length + secondLength);
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} else {
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boolean addedToList = false;
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for (Long2IntMap.Entry entry : freeBytes.long2IntEntrySet()) {
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if (entry.getLongKey() + entry.getIntValue() == startPosition) {
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freeBytes.put(entry.getLongKey(), entry.getIntValue() + length);
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addedToList = true;
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break;
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}
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}
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if (!addedToList) {
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freeBytes.put(startPosition, length);
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}
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}
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if (freeBytes.size() > MAXIMUM_UNALLOCATED_ENTRIES) {
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freeBytes.remove(freeBytes.lastLongKey());
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}
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}
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private void checkClosed() {
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if (closed) {
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throw new RuntimeException("Index Manager is closed.");
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}
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}
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}
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