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179 lines
7.3 KiB
179 lines
7.3 KiB
// CachedFileWriter.java
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// ---------------------------------
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// part of The Kelondro Database
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// (C) by Michael Peter Christen; mc@yacy.net
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// first published on http://yacy.net
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// Frankfurt, Germany, 2004-2008s
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//
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// $LastChangedDate$
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// $LastChangedRevision$
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// $LastChangedBy$
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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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public final class CachedFileWriter extends AbstractWriter implements Writer {
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private RandomAccessFile RAFile;
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private byte[] cache;
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private long cachestart;
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private int cachelen;
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public CachedFileWriter(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, "rw");
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this.cache = new byte[32768];
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this.cachestart = 0;
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this.cachelen = 0;
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}
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@Override
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public final synchronized long length() throws IOException {
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this.checkReopen();
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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 setLength(long length) throws IOException {
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this.checkReopen();
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this.cachelen = 0;
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this.RAFile.setLength(length);
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}
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@Override
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public final synchronized long available() throws IOException {
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this.checkReopen();
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return this.length() - this.RAFile.getFilePointer();
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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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this.checkReopen();
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final long seek = this.RAFile.getFilePointer();
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if (this.cache != null && this.cachestart <= seek && this.cachelen - seek + this.cachestart >= len) {
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// read from cache
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//System.out.println("*** DEBUG FileRA " + this.file.getName() + ": CACHE HIT at " + seek);
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System.arraycopy(this.cache, (int) (seek - this.cachestart), b, off, len);
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this.RAFile.seek(seek + len);
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return;
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}
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if (this.cache == null || this.cache.length < len) {
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// cannot fill cache here
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this.RAFile.readFully(b, off, len);
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return;
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}
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// we fill the cache here
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final long available = this.RAFile.length() - seek;
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if (available == -seek) return; // we don't know how this happens but we just silently ignore it by now TODO:fixme
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//System.out.println("*** available = " + available);
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if (available < len) throw new IOException("EOF in " + this.file.getName() + ", available = " + available + ", requested = " + len + ", this.RAFile.length() = " + this.RAFile.length() + ", seek = " + seek);
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if (this.cachestart + this.cachelen == seek && this.cache.length - this.cachelen >= len) {
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this.RAFile.readFully(this.cache, this.cachelen, len);
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//System.out.println("*** DEBUG FileRA " + this.file.getName() + ": append fill " + len + " bytes");
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System.arraycopy(this.cache, this.cachelen, b, off, len);
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this.cachelen += len;
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} else {
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// fill the cache as much as possible
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final int m = (int) Math.min(available, this.cache.length);
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this.RAFile.readFully(this.cache, 0, m);
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this.cachestart = seek;
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this.cachelen = m;
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if (m != len) this.RAFile.seek(seek + len);
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//System.out.println("*** DEBUG FileRA " + this.file.getName() + ": replace fill " + len + " bytes");
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System.arraycopy(this.cache, 0, b, off, len);
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}
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}
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@Override
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public final synchronized void write(final byte[] b, final int off, final int len) throws IOException {
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this.checkReopen();
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//assert len > 0;
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// write to file
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if (this.cache.length > 512) {
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// the large cache is only useful during an initialization phase
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final byte[] newcache = new byte[512];
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System.arraycopy(this.cache, 0, newcache, 0, newcache.length);
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this.cache = newcache;
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if (this.cachelen > this.cache.length) this.cachelen = this.cache.length;
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}
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final long seekpos = this.RAFile.getFilePointer();
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if (this.cachelen + len <= this.cache.length && this.cachestart + this.cachelen == seekpos) {
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// append to cache
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System.arraycopy(b, off, this.cache, this.cachelen, len);
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//System.out.println("*** DEBUG FileRA " + this.file.getName() + ": write append " + len + " bytes");
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this.cachelen += len;
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} else if (len <= this.cache.length) {
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// copy to cache
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System.arraycopy(b, off, this.cache, 0, len);
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//System.out.println("*** DEBUG FileRA " + this.file.getName() + ": write copy " + len + " bytes");
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this.cachelen = len;
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this.cachestart = seekpos;
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} else {
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// delete cache
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this.cachelen = 0;
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}
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this.RAFile.write(b, off, len);
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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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this.checkReopen();
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this.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 (this.RAFile != null) try {
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try{this.RAFile.getChannel().close();} catch (final IOException e) {}
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//System.out.println("***DEBUG*** closed file " + this.file + ", FD is " + ((RAFile.getFD().valid()) ? "VALID" : "VOID") + ", channel is " + ((RAFile.getChannel().isOpen()) ? "OPEN" : "CLOSE"));
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this.RAFile.close();
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//System.out.println("***DEBUG*** closed file " + this.file + ", FD is " + ((RAFile.getFD().valid()) ? "VALID" : "VOID") + ", channel is " + ((RAFile.getChannel().isOpen()) ? "OPEN" : "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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this.RAFile = null;
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}
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private final void checkReopen() {
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if (this.RAFile != null) return;
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// re-open the file
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try {
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this.RAFile = new RandomAccessFile(this.file, "rw");
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} catch (final FileNotFoundException e) {
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ConcurrentLog.logException(e);
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}
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this.cache = new byte[8192];
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this.cachestart = 0;
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this.cachelen = 0;
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}
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@Override
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protected final void finalize() throws Throwable {
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this.close();
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}
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}
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