83 lines
2.4 KiB
Java
83 lines
2.4 KiB
Java
package it.cavallium.strangedb.database.blocks;
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import it.cavallium.strangedb.database.IBlocksMetadata;
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import java.io.IOException;
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import java.nio.ByteBuffer;
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import java.nio.channels.AsynchronousFileChannel;
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import java.nio.file.Path;
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import java.nio.file.StandardOpenOption;
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import java.util.concurrent.ExecutionException;
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import java.util.concurrent.Future;
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public class DatabaseBlocksMetadata implements IBlocksMetadata {
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public static final BlockInfo ERROR_BLOCK_INFO = new BlockInfo(-2, 0);
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private final AsynchronousFileChannel metaFileChannel;
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private final int BLOCK_META_BYTES_COUNT = Long.BYTES + Integer.BYTES;
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private final DatabaseBlocksMetadataCache cache;
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private long firstFreeBlock;
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public DatabaseBlocksMetadata(Path metaFile) throws IOException {
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metaFileChannel = AsynchronousFileChannel.open(metaFile, StandardOpenOption.READ, StandardOpenOption.WRITE);
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firstFreeBlock = metaFileChannel.size() / BLOCK_META_BYTES_COUNT;
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this.cache = new DatabaseBlocksMetadataCache(this::writeBlockToDisk);
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}
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@Override
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public BlockInfo getBlockInfo(long blockId) throws IOException {
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if (blockId == EMPTY_BLOCK_ID) {
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return EMPTY_BLOCK_INFO;
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}
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BlockInfo blockInfo;
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if ((blockInfo = cache.get(blockId)) != ERROR_BLOCK_INFO) {
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return blockInfo;
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}
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ByteBuffer buffer = ByteBuffer.allocate(BLOCK_META_BYTES_COUNT);
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try {
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metaFileChannel.read(buffer, blockId * BLOCK_META_BYTES_COUNT).get();
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} catch (InterruptedException e) {
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throw new IOException(e);
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} catch (ExecutionException e) {
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throw new IOException(e.getCause());
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}
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buffer.flip();
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long index = buffer.getLong();
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int size = buffer.getInt();
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blockInfo = new BlockInfo(index, size);
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cache.put(blockId, blockInfo);
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return blockInfo;
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}
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@Override
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public long newBlock(long index, int size) throws IOException {
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if (size == 0) {
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return EMPTY_BLOCK_ID;
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}
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long newBlockId = firstFreeBlock++;
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BlockInfo blockInfo = new BlockInfo(index, size);
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cache.put(newBlockId, blockInfo);
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return newBlockId;
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}
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@Override
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public void close() throws IOException {
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cache.close();
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metaFileChannel.close();
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}
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private Future<Integer> writeBlockToDisk(long blockId, long index, int size) {
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ByteBuffer data = ByteBuffer.allocate(BLOCK_META_BYTES_COUNT);
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data.putLong(index);
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data.putInt(size);
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data.flip();
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return metaFileChannel.write(data, blockId * BLOCK_META_BYTES_COUNT);
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}
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@Override
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public long getTotalBlocksCount() {
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return firstFreeBlock;
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}
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}
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