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202 lines
8.0 KiB
202 lines
8.0 KiB
// kelondroCachedRA.java
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// -----------------------
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// part of The Kelondro Database
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// (C) by Michael Peter Christen; mc@anomic.de
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// first published on http://www.anomic.de
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// Frankfurt, Germany, 2004, 2005
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// last major change: 06.10.2004
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// this file was previously named kelondroBufferedRA
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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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//
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// Using this software in any meaning (reading, learning, copying, compiling,
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// running) means that you agree that the Author(s) is (are) not responsible
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// for cost, loss of data or any harm that may be caused directly or indirectly
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// by usage of this softare or this documentation. The usage of this software
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// is on your own risk. The installation and usage (starting/running) of this
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// software may allow other people or application to access your computer and
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// any attached devices and is highly dependent on the configuration of the
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// software which must be done by the user of the software; the author(s) is
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// (are) also not responsible for proper configuration and usage of the
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// software, even if provoked by documentation provided together with
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// the software.
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//
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// Any changes to this file according to the GPL as documented in the file
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// gpl.txt aside this file in the shipment you received can be done to the
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// lines that follows this copyright notice here, but changes must not be
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// done inside the copyright notive above. A re-distribution must contain
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// the intact and unchanged copyright notice.
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// Contributions and changes to the program code must be marked as such.
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package de.anomic.kelondro;
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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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public class kelondroCachedRA extends kelondroAbstractRA implements kelondroRA {
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protected kelondroRA ra;
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protected kelondroMScoreCluster cacheScore;
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protected HashMap cacheMemory;
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private int cacheMaxElements;
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private int cacheElementSize;
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private long seekpos;
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public kelondroCachedRA(kelondroRA ra, int cachesize, int elementsize) {
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this.ra = ra;
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this.name = ra.name();
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this.cacheMemory = new HashMap();
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this.cacheScore = new kelondroMScoreCluster();
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this.cacheElementSize = elementsize;
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this.cacheMaxElements = cachesize / cacheElementSize;
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this.seekpos = 0;
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}
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public long length() throws IOException {
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return ra.available();
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}
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public long available() throws IOException {
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synchronized (ra) {
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ra.seek(seekpos);
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return ra.available();
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}
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}
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private int cacheElementNumber(long address) {
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return (int) address / cacheElementSize;
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}
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private int cacheElementOffset(long address) {
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return (int) address % cacheElementSize;
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}
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private byte[] readCache(int cacheNr) throws IOException {
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Integer cacheNrI = new Integer(cacheNr);
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byte[] cache = (byte[]) cacheMemory.get(cacheNrI);
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if (cache == null) {
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if (cacheMemory.size() >= cacheMaxElements) {
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// delete elements in buffer if buffer too big
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Iterator it = cacheScore.scores(true);
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Integer element = (Integer) it.next();
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writeCache((byte[]) cacheMemory.get(element), element.intValue());
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cacheMemory.remove(element);
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int age = cacheScore.deleteScore(element);
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de.anomic.server.logging.serverLog.logFine("CACHE: " + name, "GC; age=" + ((((int) (0xFFFFFFFFL & System.currentTimeMillis())) - age) / 1000));
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}
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// add new element
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cache = new byte[cacheElementSize];
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//System.out.println("buffernr=" + bufferNr + ", elSize=" + bufferElementSize);
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ra.seek(cacheNr * cacheElementSize);
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ra.read(cache, 0, cacheElementSize);
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cacheMemory.put(cacheNrI, cache);
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}
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cacheScore.setScore(cacheNrI, (int) (0xFFFFFFFFL & System.currentTimeMillis()));
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return cache;
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}
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private void writeCache(byte[] cache, int cacheNr) throws IOException {
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if (cache == null) return;
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Integer cacheNrI = new Integer(cacheNr);
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ra.seek(cacheNr * cacheElementSize);
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ra.write(cache, 0, cacheElementSize);
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cacheScore.setScore(cacheNrI, (int) (0xFFFFFFFFL & System.currentTimeMillis()));
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}
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// pseudo-native method read
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public int read() throws IOException {
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int bn = cacheElementNumber(seekpos);
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int offset = cacheElementOffset(seekpos);
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seekpos++;
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return 0xFF & readCache(bn)[offset];
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}
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// pseudo-native method write
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public void write(int b) throws IOException {
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int bn = cacheElementNumber(seekpos);
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int offset = cacheElementOffset(seekpos);
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byte[] cache = readCache(bn);
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seekpos++;
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cache[offset] = (byte) b;
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//writeBuffer(buffer, bn);
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}
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public int read(byte[] b, int off, int len) throws IOException {
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int bn1 = cacheElementNumber(seekpos);
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int bn2 = cacheElementNumber(seekpos + len - 1);
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int offset = cacheElementOffset(seekpos);
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byte[] buffer = readCache(bn1);
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if (bn1 == bn2) {
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// simple case
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//System.out.println("C1: bn1=" + bn1 + ", offset=" + offset + ", off=" + off + ", len=" + len);
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System.arraycopy(buffer, offset, b, off, len);
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seekpos += len;
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return len;
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}
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// do recursively
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int thislen = cacheElementSize - offset;
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//System.out.println("C2: bn1=" + bn1 + ", bn2=" + bn2 +", offset=" + offset + ", off=" + off + ", len=" + len + ", thislen=" + thislen);
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System.arraycopy(buffer, offset, b, off, thislen);
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seekpos += thislen;
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return thislen + read(b, off + thislen, len - thislen);
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}
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public void write(byte[] b, int off, int len) throws IOException {
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int bn1 = cacheElementNumber(seekpos);
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int bn2 = cacheElementNumber(seekpos + len - 1);
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int offset = cacheElementOffset(seekpos);
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byte[] cache = readCache(bn1);
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if (bn1 == bn2) {
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// simple case
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System.arraycopy(b, off, cache, offset, len);
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seekpos += len;
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//writeBuffer(buffer, bn1);
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} else {
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// do recursively
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int thislen = cacheElementSize - offset;
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System.arraycopy(b, off, cache, offset, thislen);
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seekpos += thislen;
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//writeBuffer(buffer, bn1);
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write(b, off + thislen, len - thislen);
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}
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}
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public void seek(long pos) throws IOException {
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seekpos = pos;
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}
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public void close() throws IOException {
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// write all unwritten buffers
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if (cacheMemory == null) return;
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Iterator it = cacheScore.scores(true);
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while (it.hasNext()) {
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Integer element = (Integer) it.next();
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writeCache((byte[]) cacheMemory.get(element), element.intValue());
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cacheMemory.remove(element);
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}
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ra.close();
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cacheScore = null;
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cacheMemory = null;
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}
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public void finalize() {
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try {
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close();
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} catch (IOException e) {}
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}
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}
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