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526 lines
19 KiB
526 lines
19 KiB
// kelondroBLOBHeap.java
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// (C) 2008 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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// first published 09.07.2008 on http://yacy.net
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//
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// This is a part of YaCy, a peer-to-peer based web search engine
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//
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// $LastChangedDate: 2008-03-14 01:16:04 +0100 (Fr, 14 Mrz 2008) $
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// $LastChangedRevision$
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// $LastChangedBy$
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//
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// LICENSE
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package net.yacy.kelondro.blob;
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import java.io.File;
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import java.io.IOException;
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import java.util.HashMap;
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import java.util.Iterator;
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import java.util.Map;
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import net.yacy.kelondro.index.RowSpaceExceededException;
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import net.yacy.kelondro.io.AbstractWriter;
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import net.yacy.kelondro.logging.Log;
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import net.yacy.kelondro.order.ByteOrder;
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import net.yacy.kelondro.order.CloneableIterator;
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import net.yacy.kelondro.order.NaturalOrder;
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public final class Heap extends HeapModifier implements BLOB {
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private HashMap<String, byte[]> buffer; // a write buffer to limit IO to the file; attention: Maps cannot use byte[] as key
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private int buffersize; // bytes that are buffered in buffer
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private int buffermax; // maximum size of the buffer
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/*
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* This class implements a BLOB management based on a sequence of records in a random access file
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* The data structure is:
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* file :== record*
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* record :== reclen key blob
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* reclen :== <4 byte integer == length of key and blob>
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* key :== <bytes as defined with keylen, if first byte is zero then record is empty>
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* blob :== <bytes of length reclen - keylen>
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* that means that each record has the size reclen+4
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*
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* The elements are organized in two data structures:
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* index<kelondroBytesLongMap> : key/seek relation for used records
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* free<ArrayList<Integer[]>> : list of {size, seek} pairs denoting space and position of free records
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*
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* Because the blob sizes are stored with integers, one entry may not exceed 2GB
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*
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* If a record is removed, it becomes a free record.
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* New records are either appended to the end of the file or filled into a free record.
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* A free record must either fit exactly to the size of the new record, or an old record is splitted
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* into a filled and a new, smaller empty record.
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*/
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/**
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* create a heap file: a arbitrary number of BLOBs, indexed by an access key
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* The heap file will be indexed upon initialization.
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* @param heapFile
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* @param keylength
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* @param ordering
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* @throws IOException
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*/
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public Heap(
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final File heapFile,
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final int keylength,
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final ByteOrder ordering,
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int buffermax) throws IOException {
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super(heapFile, keylength, ordering);
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this.buffermax = buffermax;
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this.buffer = new HashMap<String, byte[]>();
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this.buffersize = 0;
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/*
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// DEBUG
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Iterator<byte[]> i = index.keys(true, null);
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//byte[] b;
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int c = 0;
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while (i.hasNext()) {
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key = i.next();
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System.out.println("*** DEBUG BLOBHeap " + this.name() + " KEY=" + new String(key));
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//b = get(key);
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//System.out.println("BLOB=" + new String(b));
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//System.out.println();
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c++;
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if (c >= 20) break;
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}
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System.out.println("*** DEBUG - counted " + c + " BLOBs");
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*/
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}
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/**
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* the number of BLOBs in the heap
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* @return the number of BLOBs in the heap
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*/
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@Override
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public synchronized int size() {
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return super.size() + ((this.buffer == null) ? 0 : this.buffer.size());
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}
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/**
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* test if a key is in the heap file. This does not need any IO, because it uses only the ram index
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* @param key
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* @return true if the key exists, false otherwise
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*/
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@Override
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public synchronized boolean has(final byte[] key) {
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assert index != null;
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assert this.keylength == key.length : this.keylength + "!=" + key.length;
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// check the buffer
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if (this.buffer.containsKey(new String(key))) return true;
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return super.has(key);
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}
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/**
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* add a BLOB to the heap: this adds the blob always to the end of the file
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* @param key
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* @param blob
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* @throws IOException
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* @throws RowSpaceExceededException
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*/
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private void add(final byte[] key, final byte[] blob) throws IOException, RowSpaceExceededException {
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assert blob.length > 0;
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assert key.length == this.keylength;
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assert this.keylength == key.length : this.keylength + "!=" + key.length;
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if ((blob == null) || (blob.length == 0)) return;
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final int pos = (int) file.length();
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index.put(key, pos);
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file.seek(pos);
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file.writeInt(key.length + blob.length);
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file.write(key);
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file.write(blob, 0, blob.length);
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}
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/**
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* flush the buffer completely
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* this is like adding all elements of the buffer, but it needs only one IO access
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* @throws IOException
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* @throws RowSpaceExceededException
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*/
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private void flushBuffer() throws IOException, RowSpaceExceededException {
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// check size of buffer
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Iterator<Map.Entry<String, byte[]>> i = this.buffer.entrySet().iterator();
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int l = 0;
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while (i.hasNext()) l += i.next().getValue().length;
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assert l == this.buffersize;
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// simulate write: this whole code block is only here to test the assert at the end of the block; remove after testing
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i = this.buffer.entrySet().iterator();
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int posBuffer = 0;
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Map.Entry<String, byte[]> entry;
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byte[] key, blob;
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while (i.hasNext()) {
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entry = i.next();
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key = entry.getKey().getBytes();
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assert key.length == this.keylength : "key.length = " + key.length + ", this.keylength = " + this.keylength;
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blob = entry.getValue();
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posBuffer += 4 + key.length + blob.length;
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}
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assert l + (4 + this.keylength) * this.buffer.size() == posBuffer : "l = " + l + ", this.keylength = " + this.keylength + ", this.buffer.size() = " + this.buffer.size() + ", posBuffer = " + posBuffer;
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// append all contents of the buffer into one byte[]
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i = this.buffer.entrySet().iterator();
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final long pos = file.length();
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long posFile = pos;
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posBuffer = 0;
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byte[] ba = new byte[l + (4 + this.keylength) * this.buffer.size()];
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byte[] b;
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while (i.hasNext()) {
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entry = i.next();
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key = entry.getKey().getBytes();
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assert key.length == this.keylength : "key.length = " + key.length + ", this.keylength = " + this.keylength;
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blob = entry.getValue();
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index.put(key, posFile);
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b = AbstractWriter.int2array(key.length + blob.length);
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assert b.length == 4;
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assert posBuffer + 4 < ba.length : "posBuffer = " + posBuffer + ", ba.length = " + ba.length;
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System.arraycopy(b, 0, ba, posBuffer, 4);
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assert posBuffer + 4 + key.length <= ba.length : "posBuffer = " + posBuffer + ", key.length = " + key.length + ", ba.length = " + ba.length;
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System.arraycopy(key, 0, ba, posBuffer + 4, key.length);
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assert posBuffer + 4 + key.length + blob.length <= ba.length : "posBuffer = " + posBuffer + ", key.length = " + key.length + ", blob.length = " + blob.length + ", ba.length = " + ba.length;
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//System.out.println("*** DEBUG posFile=" + posFile + ",blob.length=" + blob.length + ",ba.length=" + ba.length + ",posBuffer=" + posBuffer + ",key.length=" + key.length);
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//System.err.println("*** DEBUG posFile=" + posFile + ",blob.length=" + blob.length + ",ba.length=" + ba.length + ",posBuffer=" + posBuffer + ",key.length=" + key.length);
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System.arraycopy(blob, 0, ba, posBuffer + 4 + this.keylength, blob.length); //java.lang.ArrayIndexOutOfBoundsException here
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posFile += 4 + key.length + blob.length;
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posBuffer += 4 + key.length + blob.length;
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}
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assert ba.length == posBuffer; // must fit exactly
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this.file.seek(pos);
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this.file.write(ba);
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this.buffer.clear();
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this.buffersize = 0;
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}
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/**
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* read a blob from the heap
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* @param key
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* @return
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* @throws IOException
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*/
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@Override
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public synchronized byte[] get(final byte[] key) throws IOException {
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assert this.keylength == key.length : this.keylength + "!=" + key.length;
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// check the buffer
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byte[] blob = this.buffer.get(new String(key));
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if (blob != null) return blob;
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return super.get(key);
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}
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/**
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* retrieve the size of the BLOB
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* @param key
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* @return the size of the BLOB or -1 if the BLOB does not exist
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* @throws IOException
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*/
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@Override
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public synchronized long length(final byte[] key) throws IOException {
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assert this.keylength == key.length : this.keylength + "!=" + key.length;
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// check the buffer
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byte[] blob = this.buffer.get(new String(key));
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if (blob != null) return blob.length;
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return super.length(key);
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}
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/**
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* clears the content of the database
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* @throws IOException
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*/
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@Override
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public synchronized void clear() throws IOException {
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this.buffer.clear();
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this.buffersize = 0;
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super.clear();
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}
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/**
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* close the BLOB table
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*/
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@Override
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public synchronized void close(final boolean writeIDX) {
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if (file != null && buffer != null) {
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try {
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flushBuffer();
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} catch (IOException e) {
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Log.logException(e);
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} catch (RowSpaceExceededException e) {
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Log.logException(e);
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}
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}
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this.buffer = null;
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super.close(writeIDX);
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assert file == null;
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}
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@Override
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public synchronized void close() {
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this.close(true);
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}
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@Override
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public void finalize() {
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this.close();
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}
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/**
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* write a whole byte array as BLOB to the table
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* @param key the primary key
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* @param b
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* @throws IOException
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* @throws RowSpaceExceededException
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*/
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@Override
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public synchronized void put(final byte[] key, final byte[] b) throws IOException, RowSpaceExceededException {
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assert this.keylength == key.length : this.keylength + "!=" + key.length;
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// we do not write records of length 0 into the BLOB
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if (b.length == 0) return;
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// first remove the old entry (removes from buffer and file)
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// TODO: this can be enhanced!
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this.remove(key);
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// then look if we can use a free entry
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if (putToGap(key, b)) return;
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// if there is not enough space in the buffer, flush all
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if (this.buffersize + b.length > buffermax) {
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// this is too big. Flush everything
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super.shrinkWithGapsAtEnd();
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flushBuffer();
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if (b.length > buffermax) {
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this.add(key, b);
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} else {
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this.buffer.put(new String(key), b);
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this.buffersize += b.length;
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}
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return;
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}
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// add entry to buffer
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this.buffer.put(new String(key), b);
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this.buffersize += b.length;
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}
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private boolean putToGap(final byte[] key, final byte[] b) throws IOException, RowSpaceExceededException {
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assert this.keylength == key.length : this.keylength + "!=" + key.length;
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// we do not write records of length 0 into the BLOB
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if (b.length == 0) return true;
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// then look if we can use a free entry
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if (this.free.isEmpty()) return false;
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// find the largest entry
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long lseek = -1;
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int lsize = 0;
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final int reclen = b.length + this.keylength;
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Map.Entry<Long, Integer> entry;
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Iterator<Map.Entry<Long, Integer>> i = this.free.entrySet().iterator();
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while (i.hasNext()) {
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entry = i.next();
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if (entry.getValue().intValue() == reclen) {
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// we found an entry that has exactly the size that we need!
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// we use that entry and stop looking for a larger entry
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// add the entry to the index
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this.index.put(key, entry.getKey());
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// write to file
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file.seek(entry.getKey().longValue());
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final int reclenf = file.readInt();
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assert reclenf == reclen;
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file.write(key);
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file.write(b);
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// remove the entry from the free list
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i.remove();
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//System.out.println("*** DEBUG BLOB: replaced-fit record at " + entry.seek + ", reclen=" + reclen + ", key=" + new String(key));
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// finished!
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return true;
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}
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// look for the biggest size
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if (entry.getValue() > lsize) {
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lseek = entry.getKey();
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lsize = entry.getValue();
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}
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}
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// check if the found entry is large enough
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if (lsize > reclen + 4) {
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// split the free entry into two new entries
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// if would be sufficient if lsize = reclen + 4, but this would mean to create
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// an empty entry with zero next bytes for BLOB and key, which is not very good for the
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// data structure in the file
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// write the new entry
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file.seek(lseek);
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file.writeInt(reclen);
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file.write(key);
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file.write(b);
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// add the index to the new entry
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index.put(key, lseek);
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// define the new empty entry
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final int newfreereclen = lsize - reclen - 4;
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assert newfreereclen > 0;
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file.writeInt(newfreereclen);
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// remove the old free entry
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this.free.remove(lseek);
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// add a new free entry
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this.free.put(lseek + 4 + reclen, newfreereclen);
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//System.out.println("*** DEBUG BLOB: replaced-split record at " + lseek + ", reclen=" + reclen + ", new reclen=" + newfreereclen + ", key=" + new String(key));
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// finished!
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return true;
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}
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// could not insert to gap
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return false;
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}
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/**
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* remove a BLOB
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* @param key the primary key
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* @throws IOException
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*/
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@Override
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public synchronized void remove(final byte[] key) throws IOException {
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assert this.keylength == key.length : this.keylength + "!=" + key.length;
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// check the buffer
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byte[] blob = this.buffer.remove(new String(key));
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if (blob != null) {
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this.buffersize -= blob.length;
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return;
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}
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super.remove(key);
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}
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/**
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* iterator over all keys
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* @param up
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* @param rotating
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* @return
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* @throws IOException
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*/
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@Override
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public synchronized CloneableIterator<byte[]> keys(final boolean up, final boolean rotating) throws IOException {
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try {
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this.flushBuffer();
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} catch (RowSpaceExceededException e) {
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Log.logException(e);
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}
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return super.keys(up, rotating);
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}
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/**
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* iterate over all keys
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* @param up
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* @param firstKey
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* @return
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* @throws IOException
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*/
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@Override
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public synchronized CloneableIterator<byte[]> keys(final boolean up, final byte[] firstKey) throws IOException {
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try {
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this.flushBuffer();
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} catch (RowSpaceExceededException e) {
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Log.logException(e);
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}
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return super.keys(up, firstKey);
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}
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@Override
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public synchronized long length() {
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return super.length() + this.buffersize;
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}
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public static void heaptest() {
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final File f = new File("/Users/admin/blobtest.heap");
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try {
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//f.delete();
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final Heap heap = new Heap(f, 12, NaturalOrder.naturalOrder, 1024 * 512);
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heap.put("aaaaaaaaaaaa".getBytes(), "eins zwei drei".getBytes());
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heap.put("aaaaaaaaaaab".getBytes(), "vier fuenf sechs".getBytes());
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heap.put("aaaaaaaaaaac".getBytes(), "sieben acht neun".getBytes());
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heap.put("aaaaaaaaaaad".getBytes(), "zehn elf zwoelf".getBytes());
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// iterate over keys
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Iterator<byte[]> i = heap.index.keys(true, null);
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while (i.hasNext()) {
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System.out.println("key_a: " + new String(i.next()));
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}
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i = heap.keys(true, false);
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while (i.hasNext()) {
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System.out.println("key_b: " + new String(i.next()));
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}
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heap.remove("aaaaaaaaaaab".getBytes());
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heap.remove("aaaaaaaaaaac".getBytes());
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heap.put("aaaaaaaaaaaX".getBytes(), "WXYZ".getBytes());
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heap.close(true);
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} catch (final IOException e) {
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Log.logException(e);
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} catch (RowSpaceExceededException e) {
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Log.logException(e);
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}
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}
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private static Map<String, String> map(final String a, final String b) {
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HashMap<String, String> m = new HashMap<String, String>();
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m.put(a, b);
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return m;
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}
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public static void maptest() {
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final File f = new File("/Users/admin/blobtest.heap");
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try {
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//f.delete();
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final MapView heap = new MapView(new Heap(f, 12, NaturalOrder.naturalOrder, 1024 * 512), 500, '_');
|
|
heap.put("aaaaaaaaaaaa", map("aaaaaaaaaaaa", "eins zwei drei"));
|
|
heap.put("aaaaaaaaaaab", map("aaaaaaaaaaab", "vier fuenf sechs"));
|
|
heap.put("aaaaaaaaaaac", map("aaaaaaaaaaac", "sieben acht neun"));
|
|
heap.put("aaaaaaaaaaad", map("aaaaaaaaaaad", "zehn elf zwoelf"));
|
|
heap.remove("aaaaaaaaaaab");
|
|
heap.remove("aaaaaaaaaaac");
|
|
heap.put("aaaaaaaaaaaX", map("aaaaaaaaaaad", "WXYZ"));
|
|
heap.close();
|
|
} catch (final IOException e) {
|
|
Log.logException(e);
|
|
} catch (RowSpaceExceededException e) {
|
|
Log.logException(e);
|
|
}
|
|
}
|
|
|
|
public static void main(final String[] args) {
|
|
//heaptest();
|
|
maptest();
|
|
}
|
|
|
|
}
|