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