// Heap.java
// (C) 2008 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 09.07.2008 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// LICENSE
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package net.yacy.kelondro.blob;
import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
import net.yacy.cora.document.UTF8;
import net.yacy.kelondro.index.RowSpaceExceededException;
import net.yacy.kelondro.io.AbstractWriter;
import net.yacy.kelondro.logging.Log;
import net.yacy.kelondro.order.ByteOrder;
import net.yacy.kelondro.order.CloneableIterator;
import net.yacy.kelondro.order.NaturalOrder;
import net.yacy.kelondro.util.MemoryControl;
public final class Heap extends HeapModifier implements BLOB {
private SortedMap<byte[], byte[]> buffer; // a write buffer to limit IO to the file
private int buffersize; // bytes that are buffered in buffer
private final int buffermax; // maximum size of the buffer
/*
* This class implements a BLOB management based on a sequence of records in a random access file
* The data structure is:
* file :== record*
* record :== reclen key blob
* reclen :== <4 byte integer == length of key and blob>
* key :== <bytes as defined with keylen, if first byte is zero then record is empty>
* blob :== <bytes of length reclen - keylen>
* that means that each record has the size reclen+4
*
* The elements are organized in two data structures:
* index<kelondroBytesLongMap> : key/seek relation for used records
* free<ArrayList<Integer[]>> : list of {size, seek} pairs denoting space and position of free records
*
* Because the blob sizes are stored with integers, one entry may not exceed 2GB
*
* If a record is removed, it becomes a free record.
* New records are either appended to the end of the file or filled into a free record.
* A free record must either fit exactly to the size of the new record, or an old record is split
* into a filled and a new, smaller empty record.
*/
/**
* create a heap file: a arbitrary number of BLOBs, indexed by an access key
* The heap file will be indexed upon initialization.
* @param heapFile
* @param keylength
* @param ordering
* @throws IOException
*/
public Heap(
final File heapFile,
final int keylength,
final ByteOrder ordering,
int buffermax) throws IOException {
super(heapFile, keylength, ordering);
this.buffermax = buffermax;
this.buffer = new TreeMap<byte[], byte[]>(ordering);
this.buffersize = 0;
Log.logInfo("Heap", "initializing heap " + this.name());
/*
// DEBUG
Iterator<byte[]> i = index.keys(true, null);
//byte[] b;
int c = 0;
while (i.hasNext()) {
key = i.next();
System.out.println("*** DEBUG BLOBHeap " + this.name() + " KEY=" + UTF8.String(key));
//b = get(key);
//System.out.println("BLOB=" + UTF8.String(b));
//System.out.println();
c++;
if (c >= 20) break;
}
System.out.println("*** DEBUG - counted " + c + " BLOBs");
*/
}
/**
* the number of BLOBs in the heap
* @return the number of BLOBs in the heap
*/
@Override
public synchronized int size() {
return super.size() + ((this.buffer == null) ? 0 : this.buffer.size());
}
/**
* test if a key is in the heap file. This does not need any IO, because it uses only the ram index
* @param key
* @return true if the key exists, false otherwise
*/
@Override
public boolean containsKey(byte[] key) {
assert this.index != null;
key = normalizeKey(key);
synchronized (this) {
// check the buffer
assert this.buffer != null;
if (this.buffer != null) {
if (this.buffer.containsKey(key)) return true;
}
return super.containsKey(key);
}
}
/**
* add a BLOB to the heap: this adds the blob always to the end of the file
* @param key
* @param blob
* @throws IOException
* @throws RowSpaceExceededException
*/
private void add(byte[] key, final byte[] blob) throws IOException {
assert blob.length > 0;
if ((blob == null) || (blob.length == 0)) return;
final int pos = (int) this.file.length();
try {
this.index.put(key, pos);
this.file.seek(pos);
this.file.writeInt(this.keylength + blob.length);
this.file.write(key);
this.file.write(blob, 0, blob.length);
} catch (RowSpaceExceededException e) {
throw new IOException(e.getMessage()); // should never occur;
}
}
/**
* flush the buffer completely
* this is like adding all elements of the buffer, but it needs only one IO access
* @throws IOException
* @throws RowSpaceExceededException
*/
public void flushBuffer() throws IOException {
assert this.buffer != null;
if (this.buffer == null) return;
// check size of buffer
Iterator<Map.Entry<byte[], byte[]>> i = this.buffer.entrySet().iterator();
int l = 0;
while (i.hasNext()) l += i.next().getValue().length;
assert l == this.buffersize;
int posBuffer = 0;
Map.Entry<byte[], byte[]> entry;
byte[] key, blob;
// simulate write: this whole code block is only here to test the assert at the end of the block; remove after testing
/*
i = this.buffer.entrySet().iterator();
while (i.hasNext()) {
entry = i.next();
key = normalizeKey(entry.getKey());
blob = entry.getValue();
posBuffer += 4 + this.keylength + blob.length;
}
assert l + (4 + this.keylength) * this.buffer.size() == posBuffer : "l = " + l + ", this.keylength = " + this.keylength + ", this.buffer.size() = " + this.buffer.size() + ", posBuffer = " + posBuffer;
*/
synchronized (this) {
super.deleteFingerprint();
}
// append all contents of the buffer into one byte[]
i = this.buffer.entrySet().iterator();
final long pos = this.file.length();
long posFile = pos;
posBuffer = 0;
byte[] ba = new byte[l + (4 + this.keylength) * this.buffer.size()];
byte[] b;
SortedMap<byte[], byte[]> nextBuffer = new TreeMap<byte[], byte[]>(this.ordering);
flush: while (i.hasNext()) {
entry = i.next();
key = normalizeKey(entry.getKey());
blob = entry.getValue();
try {
this.index.put(key, posFile);
} catch (RowSpaceExceededException e) {
nextBuffer.put(entry.getKey(), blob);
continue flush;
}
b = AbstractWriter.int2array(this.keylength + blob.length);
assert b.length == 4;
assert posBuffer + 4 < ba.length : "posBuffer = " + posBuffer + ", ba.length = " + ba.length;
System.arraycopy(b, 0, ba, posBuffer, 4);
assert posBuffer + 4 + key.length <= ba.length : "posBuffer = " + posBuffer + ", key.length = " + key.length + ", ba.length = " + ba.length;
System.arraycopy(key, 0, ba, posBuffer + 4, key.length);
assert posBuffer + 4 + key.length + blob.length <= ba.length : "posBuffer = " + posBuffer + ", key.length = " + key.length + ", blob.length = " + blob.length + ", ba.length = " + ba.length;
//System.out.println("*** DEBUG posFile=" + posFile + ",blob.length=" + blob.length + ",ba.length=" + ba.length + ",posBuffer=" + posBuffer + ",key.length=" + key.length);
//System.err.println("*** DEBUG posFile=" + posFile + ",blob.length=" + blob.length + ",ba.length=" + ba.length + ",posBuffer=" + posBuffer + ",key.length=" + key.length);
System.arraycopy(blob, 0, ba, posBuffer + 4 + this.keylength, blob.length); //java.lang.ArrayIndexOutOfBoundsException here
posFile += 4 + this.keylength + blob.length;
posBuffer += 4 + this.keylength + blob.length;
}
assert ba.length == posBuffer; // must fit exactly
this.file.seek(pos);
this.file.write(ba);
this.buffer.clear();
this.buffer.putAll(nextBuffer);
this.buffersize = 0;
}
/**
* read a blob from the heap
* @param key
* @return
* @throws IOException
*/
@Override
public byte[] get(byte[] key) throws IOException, RowSpaceExceededException {
key = normalizeKey(key);
synchronized (this) {
// check the buffer
assert this.buffer != null;
if (this.buffer != null) {
byte[] blob = this.buffer.get(key);
if (blob != null) return blob;
}
return super.get(key);
}
}
/**
* retrieve the size of the BLOB
* @param key
* @return the size of the BLOB or -1 if the BLOB does not exist
* @throws IOException
*/
@Override
public long length(byte[] key) throws IOException {
key = normalizeKey(key);
synchronized (this) {
// check the buffer
assert this.buffer != null;
if (this.buffer != null) {
byte[] blob = this.buffer.get(key);
if (blob != null) return blob.length;
}
return super.length(key);
}
}
/**
* clears the content of the database
* @throws IOException
*/
@Override
public synchronized void clear() throws IOException {
Log.logInfo("Heap", "clearing heap " + this.name());
assert this.buffer != null;
if (this.buffer == null) this.buffer = new TreeMap<byte[], byte[]>(this.ordering);
this.buffer.clear();
this.buffersize = 0;
super.clear();
}
/**
* close the BLOB table
*/
@Override
public synchronized void close(final boolean writeIDX) {
Log.logInfo("Heap", "closing heap " + this.name());
if (this.file != null && this.buffer != null) {
try {
flushBuffer();
} catch (IOException e) {
Log.logException(e);
}
}
this.buffer = null;
super.close(writeIDX);
assert this.file == null;
}
@Override
public synchronized void close() {
this.close(true);
}
@Override
public void finalize() {
this.close();
}
public int getBuffermax() {
return this.buffermax;
}
/**
* write a whole byte array as BLOB to the table
* @param key the primary key
* @param b
* @throws IOException
* @throws RowSpaceExceededException
* @throws RowSpaceExceededException
*/
@Override
public void insert(byte[] key, final byte[] b) throws IOException {
key = normalizeKey(key);
// we do not write records of length 0 into the BLOB
if (b.length == 0) return;
synchronized (this) {
// first remove the old entry (removes from buffer and file)
// TODO: this can be enhanced!
this.delete(key);
// then look if we can use a free entry
try {
if (putToGap(key, b)) return;
} catch (RowSpaceExceededException e) {} // too less space can be ignored, we have a second try
assert this.buffer != null;
// if there is not enough space in the buffer, flush all
if (this.buffersize + b.length > this.buffermax || MemoryControl.shortStatus()) {
// this is too big. Flush everything
super.shrinkWithGapsAtEnd();
flushBuffer();
if (b.length > this.buffermax) {
this.add(key, b);
} else {
if (this.buffer != null) {
this.buffer.put(key, b);
this.buffersize += b.length;
}
}
return;
}
// add entry to buffer
if (this.buffer != null) {
this.buffer.put(key, b);
this.buffersize += b.length;
}
}
}
private boolean putToGap(byte[] key, final byte[] b) throws IOException, RowSpaceExceededException {
// we do not write records of length 0 into the BLOB
if (b.length == 0) return true;
// then look if we can use a free entry
if (this.free.isEmpty()) return false;
// find the largest entry
long lseek = -1;
int lsize = 0;
final int reclen = b.length + this.keylength;
Map.Entry<Long, Integer> entry;
Iterator<Map.Entry<Long, Integer>> i = this.free.entrySet().iterator();
int acount = 0, bcount = 0;
while (i.hasNext()) {
entry = i.next();
if (entry.getValue().intValue() == reclen) {
// we found an entry that has exactly the size that we need!
// we use that entry and stop looking for a larger entry
// add the entry to the index
this.index.put(key, entry.getKey());
// write to file
this.file.seek(entry.getKey().longValue());
final int reclenf = this.file.readInt();
assert reclenf == reclen;
this.file.write(key);
if (this.keylength > key.length) {
for (int j = 0; j < this.keylength - key.length; j++) this.file.write(HeapWriter.ZERO);
}
this.file.write(b);
// remove the entry from the free list
i.remove();
//System.out.println("*** DEBUG BLOB: replaced-fit record at " + entry.seek + ", reclen=" + reclen + ", key=" + UTF8.String(key));
// finished!
return true;
}
acount++;
// look for the biggest size
if (entry.getValue().intValue() > lsize) {
lseek = entry.getKey();
lsize = entry.getValue();
bcount++;
if (acount > 100 || bcount > 10) break; // in case that we have really a lot break here
}
}
// check if the found entry is large enough
if (lsize > reclen + 4) {
// split the free entry into two new entries
// if would be sufficient if lsize = reclen + 4, but this would mean to create
// an empty entry with zero next bytes for BLOB and key, which is not very good for the
// data structure in the file
// write the new entry
this.file.seek(lseek);
this.file.writeInt(reclen);
this.file.write(key);
if (this.keylength > key.length) {
for (int j = 0; j < this.keylength - key.length; j++) this.file.write(HeapWriter.ZERO);
}
this.file.write(b);
// add the index to the new entry
this.index.put(key, lseek);
// define the new empty entry
final int newfreereclen = lsize - reclen - 4;
assert newfreereclen > 0;
this.file.writeInt(newfreereclen);
// remove the old free entry
this.free.remove(lseek);
// add a new free entry
this.free.put(lseek + 4 + reclen, newfreereclen);
//System.out.println("*** DEBUG BLOB: replaced-split record at " + lseek + ", reclen=" + reclen + ", new reclen=" + newfreereclen + ", key=" + UTF8.String(key));
// finished!
return true;
}
// could not insert to gap
return false;
}
/**
* remove a BLOB
* @param key the primary key
* @throws IOException
*/
@Override
public void delete(byte[] key) throws IOException {
key = normalizeKey(key);
synchronized (this) {
super.deleteFingerprint();
// check the buffer
assert this.buffer != null;
if (this.buffer != null) {
byte[] blob = this.buffer.remove(key);
if (blob != null) {
this.buffersize -= blob.length;
return;
}
}
super.delete(key);
}
}
/**
* iterator over all keys
* @param up
* @param rotating
* @return
* @throws IOException
*/
@Override
public synchronized CloneableIterator<byte[]> keys(final boolean up, final boolean rotating) throws IOException {
this.flushBuffer();
return super.keys(up, rotating);
}
/**
* iterate over all keys
* @param up
* @param firstKey
* @return
* @throws IOException
*/
@Override
public synchronized CloneableIterator<byte[]> keys(final boolean up, final byte[] firstKey) throws IOException {
this.flushBuffer();
return super.keys(up, firstKey);
}
@Override
public synchronized long length() {
return super.length() + this.buffersize;
}
public static void heaptest() {
final File f = new File("/Users/admin/blobtest.heap");
try {
//f.delete();
final Heap heap = new Heap(f, 12, NaturalOrder.naturalOrder, 1024 * 512);
heap.insert("aaaaaaaaaaaa".getBytes(), "eins zwei drei".getBytes());
heap.insert("aaaaaaaaaaab".getBytes(), "vier fuenf sechs".getBytes());
heap.insert("aaaaaaaaaaac".getBytes(), "sieben acht neun".getBytes());
heap.insert("aaaaaaaaaaad".getBytes(), "zehn elf zwoelf".getBytes());
// iterate over keys
Iterator<byte[]> i = heap.index.keys(true, null);
while (i.hasNext()) {
System.out.println("key_a: " + UTF8.String(i.next()));
}
i = heap.keys(true, false);
while (i.hasNext()) {
System.out.println("key_b: " + UTF8.String(i.next()));
}
heap.delete("aaaaaaaaaaab".getBytes());
heap.delete("aaaaaaaaaaac".getBytes());
heap.insert("aaaaaaaaaaaX".getBytes(), "WXYZ".getBytes());
heap.close(true);
} catch (final IOException e) {
Log.logException(e);
}
}
private static Map<String, String> map(final String a, final String b) {
Map<String, String> m = new HashMap<String, String>();
m.put(a, b);
return m;
}
public static void maptest() {
final File f = new File("/Users/admin/blobtest.heap");
try {
//f.delete();
final MapHeap heap = new MapHeap(f, 12, NaturalOrder.naturalOrder, 1024 * 512, 500, '_');
heap.insert("aaaaaaaaaaaa".getBytes(), map("aaaaaaaaaaaa", "eins zwei drei"));
heap.insert("aaaaaaaaaaab".getBytes(), map("aaaaaaaaaaab", "vier fuenf sechs"));
heap.insert("aaaaaaaaaaac".getBytes(), map("aaaaaaaaaaac", "sieben acht neun"));
heap.insert("aaaaaaaaaaad".getBytes(), map("aaaaaaaaaaad", "zehn elf zwoelf"));
heap.delete("aaaaaaaaaaab".getBytes());
heap.delete("aaaaaaaaaaac".getBytes());
heap.insert("aaaaaaaaaaaX".getBytes(), 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();
}
}