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99 lines
3.1 KiB
99 lines
3.1 KiB
// CachedFileReader.java
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// ---------------------
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// (C) 2009 by Michael Peter Christen; mc@yacy.net
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// first published 09.09.2009 on http://yacy.net
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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.io;
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import java.io.File;
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import java.io.FileNotFoundException;
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import java.io.IOException;
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import java.io.RandomAccessFile;
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import net.yacy.cora.util.ConcurrentLog;
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import net.yacy.kelondro.util.MemoryControl;
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public final class CachedFileReader extends AbstractReader implements Reader {
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private final RandomAccessFile RAFile;
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private byte[] cache;
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private final int cachelen;
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public CachedFileReader(final File file) throws IOException, FileNotFoundException {
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this.name = file.getName();
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this.file = file;
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this.RAFile = new RandomAccessFile(this.file, "r");
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if (MemoryControl.available() / 10L > this.RAFile.length() && this.RAFile.length() < Integer.MAX_VALUE) {
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this.cache = new byte[(int) this.RAFile.length()];
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this.RAFile.seek(0);
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this.RAFile.readFully(this.cache);
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} else {
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this.cache = null;
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}
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this.cachelen = 0;
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}
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@Override
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public final synchronized long available() throws IOException {
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return this.length() - RAFile.getFilePointer();
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}
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@Override
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public final synchronized long length() throws IOException {
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return this.RAFile.length();
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}
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@Override
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public final synchronized void readFully(final byte[] b, final int off, int len) throws IOException {
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long seek = RAFile.getFilePointer();
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if (cache != null && cachelen - seek >= len) {
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// read from cache
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System.arraycopy(cache, (int) (seek), b, off, len);
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RAFile.seek(seek + len);
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return;
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}
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// cannot use the cache
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RAFile.readFully(b, off, len);
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return;
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}
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@Override
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public final synchronized void seek(final long pos) throws IOException {
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RAFile.seek(pos);
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}
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@Override
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public final synchronized void close() {
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if (RAFile != null) try {
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try{RAFile.getChannel().close();} catch (final IOException e) {}
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RAFile.close();
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} catch (final IOException e) {
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ConcurrentLog.logException(e);
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}
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this.cache = null;
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}
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@Override
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protected void finalize() throws Throwable {
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this.close();
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super.finalize();
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}
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}
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