// kelondroMHashMap.java
// -----------------------
// part of YaCy
// (C) by Michael Peter Christen; mc@yacy.net
// first published on http://www.anomic.de
// Frankfurt, Germany, 2005
// Created 08.12.2005
//
// 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 de.anomic.kelondro;
import java.util.Iterator;
public class kelondroMHashMap {
int keylen;
int valuelen;
int reclen, count;
byte[] mem;
private final byte[] emptykey;
public kelondroMHashMap(final int valuelen) {
// initializes a hash map with integer access key
this(4, valuelen);
}
public kelondroMHashMap(final int keylen, final int valuelen) {
this.keylen = keylen;
this.valuelen = valuelen;
this.reclen = keylen + valuelen;
this.mem = new byte[1 * reclen];
this.count = 0;
this.emptykey = new byte[keylen];
for (int i = 0; i < keylen; i++) emptykey[i] = 0;
for (int i = 0; i < (mem.length / reclen); i++) System.arraycopy(emptykey, 0, mem, i * reclen, keylen);
}
private boolean equals(final int posKeyInMem, final byte[] otherkey) {
assert (otherkey.length == keylen);
int pos = posKeyInMem * reclen;
int i = 0;
while (i < keylen) if (mem[pos++] != otherkey[i++]) return false;
return true;
}
private int rehashtry() {
return 1 + mem.length / 2;
}
private int capacity() {
return mem.length / reclen;
}
private static int hashkey(final byte[] key, final int capacity) {
int h = 0;
for (int i = 0; i < key.length; i++) h = h * 15 + (0xff & key[i]);
//System.out.println("hash code of key " + new String(key) + " is " + h);
return h % capacity;
}
private static int rehash(int previousKey, final int capacity) {
if (previousKey == 0) previousKey = capacity;
return previousKey - 1;
}
public int size() {
return count;
}
private int findExisting(final byte[] key) {
// returns an index position if found; -1 otherwise
int hash = hashkey(key, capacity());
//System.out.println("first guess for key " + new String(key) + ": " + hash + "( capacity is " + capacity() + " )");
int testcount = 0;
while (testcount++ < rehashtry()) {
if (mem[hash * reclen] == 0) return -1;
if (equals(hash, key)) return hash;
hash = rehash(hash, capacity());
}
return -1;
}
private int findSpace(final byte[] key) {
// returns an new index position which is empty
// if there is no space left -1 is returned
int hash = hashkey(key, capacity());
int testcount = 0;
while (testcount++ < rehashtry()) {
if (mem[hash * reclen] == 0) return hash;
hash = rehash(hash, capacity());
}
return -1;
}
private static int findSpace(final byte[] m, final byte[] key, final int rl, final int trycount, final int capacity) {
// returns an new index position which is empty
// if there is no space left -1 is returned
int hash = hashkey(key, capacity);
int testcount = 0;
while (testcount++ < trycount) {
if (m[hash * rl] == 0) return hash;
hash = rehash(hash, capacity);
}
return -1;
}
private static byte[] toByteKey(int v) {
assert (v >= 0);
v = v | 0x80000000; // set bit in first byte
return new byte[]{(byte) ((v >>> 24) & 0xFF), (byte) ((v >>> 16) & 0xFF),
(byte) ((v >>> 8) & 0xFF), (byte) ((v >>> 0) & 0xFF)};
}
public void put(final int key, final byte[] value) {
put(toByteKey(key), value);
}
public void put(final byte[] key, final byte[] value) {
// inserts a new value or overwrites existing
// if the hash is full, a RuntimeException is thrown
// this method does not return the old value to avoid generation of objects
assert (key.length == keylen);
assert (value.length == valuelen);
int hash = findExisting(key);
if (hash < 0) {
// insert new entry
hash = findSpace(key);
if (hash < 0) {
// increase space of hashtable
// create temporary bigger hashtable and insert all
synchronized (mem) {
System.out.println("increasing space to " + mem.length * 2);
final int newspace = mem.length * 2;
final int newcapacity = capacity() * 2;
byte[] newmem = new byte[newspace];
final Iterator<entry> i = entries();
kelondroMHashMap.entry e;
int mempos;
while (i.hasNext()) {
e = i.next();
hash = findSpace(newmem, e.key, reclen, newspace, newcapacity);
mempos = hash * reclen;
System.arraycopy(e.key, 0, newmem, mempos, keylen);
System.arraycopy(e.value, 0, newmem, mempos + keylen, valuelen);
}
// finally insert new value
hash = findSpace(newmem, key, reclen, newspace, newcapacity);
mempos = hash * reclen;
System.arraycopy(key, 0, newmem, mempos, keylen);
System.arraycopy(value, 0, newmem, mempos + keylen, valuelen);
// move newmem to mem
mem = newmem;
}
} else {
// there is enough space
//System.out.println("put " + new String(key) + " into cell " + hash);
final int mempos = hash * reclen;
System.arraycopy(key, 0, mem, mempos, keylen);
System.arraycopy(value, 0, mem, mempos + keylen, valuelen);
}
count++;
} else {
// overwrite old entry
final int mempos = hash * reclen;
System.arraycopy(key, 0, mem, mempos, keylen);
System.arraycopy(value, 0, mem, mempos + keylen, valuelen);
}
}
public byte[] get(final int key) {
return get(toByteKey(key));
}
public byte[] get(final byte[] key) {
assert (key.length == keylen);
final int hash = findExisting(key);
//System.out.println("get " + new String(key) + " from cell " + hash);
if (hash < 0) {
return null;
}
// read old entry
final byte[] value = new byte[valuelen];
System.arraycopy(mem, hash * reclen + keylen, value, 0, valuelen);
return value;
}
public void remove(final int key) {
remove(toByteKey(key));
}
public void remove(final byte[] key) {
assert (key.length == keylen);
System.out.println("REMOVE!");
final int hash = findExisting(key);
if (hash >= 0) {
// overwrite old key
System.arraycopy(emptykey, 0, mem, hash * reclen, keylen);
count--;
}
}
Iterator<entry> entries() {
return new entryIterator();
}
public class entryIterator implements Iterator<entry> {
int hashkey;
public entryIterator() {
hashkey = anyhashpos(0);
}
public boolean hasNext() {
return hashkey >= 0;
}
public entry next() {
final int i = hashkey;
hashkey = anyhashpos(hashkey + 1);
return new entry(i);
}
public void remove() {
mem[hashkey * reclen] = 0;
}
}
public void removeany() {
//System.out.println("CALLED REMOVEANY");
int start = 0;
while (start < capacity()) {
if (mem[start * reclen] != 0) {
System.arraycopy(emptykey,0, mem, start * reclen, keylen);
count--;
return;
}
start++;
}
return;
}
protected int anyhashpos(int start) {
while (start < capacity()) {
if (mem[start * reclen] != 0) return start;
start++;
}
return -1;
}
public byte[] anykey() {
int hash = 0;
int mempos;
while (hash < capacity()) {
mempos = hash * reclen;
if (mem[mempos] != 0) {
final byte[] key = new byte[keylen];
System.arraycopy(mem, mempos, key, 0, keylen);
return key;
}
hash++;
}
return null;
}
public class entry {
public byte[] key, value;
public entry(final int index) {
this.key = new byte[keylen];
this.value = new byte[valuelen];
final int mempos = index * (reclen);
System.arraycopy(mem, mempos, key, 0, keylen);
System.arraycopy(mem, mempos + keylen, value, 0, valuelen);
}
public entry(final byte[] key, final byte[] value) {
this.key = key;
this.value = value;
}
}
public static void main(final String[] args) {
final long start = System.currentTimeMillis();
final kelondroMHashMap map = new kelondroMHashMap(4);
for (int i = 0; i < 100; i++) map.put(3333 + i, ("" + (1000 + i)).getBytes());
final Iterator<entry> i = map.entries();
kelondroMHashMap.entry e;
System.out.println("Enumeration of elements: count=" + map.size());
int c = 0;
while (i.hasNext()) {
e = i.next();
System.out.println("key=" + new String(e.key) + ", value=" + new String(e.value) + ", retrieved=" + new String(map.get(e.key)));
c++;
}
System.out.println("c = " + c + "; re-catch:");
for (int j = 0; j < 100; j++) {
System.out.println("key=" + j + ", retrieved=" + new String(map.get(3333 + j)));
}
System.out.println("runtime = " + (System.currentTimeMillis() - start));
}
}