97 lines
2.4 KiB
Java
97 lines
2.4 KiB
Java
package org.apache.jdbm;
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import java.io.*;
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import java.nio.ByteBuffer;
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/**
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* Storage which keeps all data in memory.
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* Data are lost after storage is closed.
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*/
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class StorageMemory implements Storage {
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private LongHashMap<byte[]> pages = new LongHashMap<byte[]>();
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private boolean transactionsDisabled;
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StorageMemory(boolean transactionsDisabled){
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this.transactionsDisabled = transactionsDisabled;
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}
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public ByteBuffer read(long pageNumber) throws IOException {
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byte[] data = pages.get(pageNumber);
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if (data == null) {
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//out of bounds, so just return empty data
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return ByteBuffer.wrap(PageFile.CLEAN_DATA).asReadOnlyBuffer();
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}else{
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ByteBuffer b = ByteBuffer.wrap(data);
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if(!transactionsDisabled)
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return b.asReadOnlyBuffer();
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else
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return b;
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}
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}
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public void write(long pageNumber, ByteBuffer data) throws IOException {
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if (data.capacity() != PAGE_SIZE) throw new IllegalArgumentException();
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byte[] b = pages.get(pageNumber);
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if(transactionsDisabled && data.hasArray() && data.array() == b){
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//already putted directly into array
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return;
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}
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if(b == null)
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b = new byte[PAGE_SIZE];
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data.position(0);
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data.get(b,0, PAGE_SIZE);
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pages.put(pageNumber,b);
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}
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public void sync() throws IOException {
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}
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public void forceClose() throws IOException {
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pages = null;
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}
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private ByteArrayOutputStream transLog;
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public DataInputStream readTransactionLog() {
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if (transLog == null)
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return null;
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DataInputStream ret = new DataInputStream(
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new ByteArrayInputStream(transLog.toByteArray()));
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//read stream header
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try {
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ret.readShort();
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} catch (IOException e) {
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throw new IOError(e);
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}
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return ret;
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}
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public void deleteTransactionLog() {
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transLog = null;
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}
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public DataOutputStream openTransactionLog() throws IOException {
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if (transLog == null)
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transLog = new ByteArrayOutputStream();
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return new DataOutputStream(transLog);
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}
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public void deleteAllFiles() throws IOException {
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}
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public boolean isReadonly() {
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return false;
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}
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}
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