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// httpCache.java
// -----------------------
// part of YaCy
// (C) by Michael Peter Christen; mc@yacy.net
// first published on http://www.anomic.de
// Frankfurt, Germany, 2004
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// 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
/*
Class documentation:
This class has two purposes:
1. provide a object that carries path and header information
that shall be used as objects within a scheduler's stack
2. static methods for a cache control and cache aging
the class shall also be used to do a cache-cleaning and index creation
*/
package net.yacy.crawler.data;
import java.io.File;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.atomic.AtomicLong;
import net.yacy.cora.document.encoding.ASCII;
import net.yacy.cora.document.id.DigestURL;
import net.yacy.cora.order.Base64Order;
import net.yacy.cora.protocol.ResponseHeader;
import net.yacy.cora.storage.HandleSet;
import net.yacy.cora.util.ConcurrentLog;
import net.yacy.cora.util.SpaceExceededException;
import net.yacy.kelondro.blob.ArrayStack;
import net.yacy.kelondro.blob.Compressor;
import net.yacy.kelondro.blob.MapHeap;
import net.yacy.kelondro.data.word.Word;
import net.yacy.kelondro.index.RowHandleSet;
public final class Cache {
/** Default size in bytes of the backend buffer (buffered bytes before writing to the the file system) */
protected static final int DEFAULT_BACKEND_BUFFER_SIZE = 1024 * 1024 * 2;
/** Default size in bytes of the compressor buffer (buffered bytes before compressing and sending to the backend ) */
protected static final int DEFAULT_COMPRESSOR_BUFFER_SIZE = 6 * 1024 * 1024;
/** Default size in bytes of the response header data base buffer (buffered bytes before writing to the file system) */
protected static final int DEFAULT_RESPONSE_HEADER_BUFFER_SIZE = 2048;
private static final String RESPONSE_HEADER_DB_NAME = "responseHeader.heap";
private static final String FILE_DB_NAME = "file.array";
private static MapHeap responseHeaderDB = null;
private static Compressor fileDB = null;
private static ArrayStack fileDBunbuffered = null;
private static volatile long maxCacheSize = Long.MAX_VALUE;
/** Total number of requests for cached response since last start/initialization or cache clear */
private static AtomicLong totalRequests = new AtomicLong(0);
/** Total number of cache hits since last start/initialization or cache clear */
private static AtomicLong hits = new AtomicLong(0);
private static File cachePath = null;
private static String prefix;
public static final ConcurrentLog log = new ConcurrentLog("HTCACHE");
/**
* @param htCachePath folder path for the cache
* @param peerSalt peer identifier
* @param cacheSizeMax maximum cache size in bytes
* @param lockTimeout maximum time (in milliseconds) to acquire a synchronization lock on store() and getContent()
* @param compressionLevel the compression level : supported values ranging from 0 - no compression, to 9 - best compression
*/
public static void init(final File htCachePath, final String peerSalt, final long cacheSizeMax, final long lockTimeout, final int compressionLevel) {
cachePath = htCachePath;
maxCacheSize = cacheSizeMax;
prefix = peerSalt;
totalRequests.set(0);
hits.set(0);
// set/make cache path
if (!htCachePath.exists()) {
htCachePath.mkdirs();
}
// open the response header database
final File dbfile = new File(cachePath, RESPONSE_HEADER_DB_NAME);
try {
responseHeaderDB = new MapHeap(dbfile, Word.commonHashLength, Base64Order.enhancedCoder, DEFAULT_RESPONSE_HEADER_BUFFER_SIZE, 100, ' ');
} catch (final IOException e) {
ConcurrentLog.logException(e);
// try a healing
if (dbfile.exists()) {
dbfile.delete();
try {
responseHeaderDB = new MapHeap(dbfile, Word.commonHashLength, Base64Order.enhancedCoder, DEFAULT_RESPONSE_HEADER_BUFFER_SIZE, 100, ' ');
} catch (final IOException ee) {
ConcurrentLog.logException(e);
}
}
}
// open the cache file
try {
fileDBunbuffered = new ArrayStack(new File(cachePath, FILE_DB_NAME), prefix, Base64Order.enhancedCoder, 12, DEFAULT_BACKEND_BUFFER_SIZE, false, true);
fileDBunbuffered.setMaxSize(maxCacheSize);
fileDB = new Compressor(fileDBunbuffered, DEFAULT_COMPRESSOR_BUFFER_SIZE, lockTimeout, compressionLevel);
} catch (final IOException e) {
ConcurrentLog.logException(e);
// try a healing
if (cachePath.exists()) {
cachePath.delete();
try {
fileDBunbuffered = new ArrayStack(new File(cachePath, FILE_DB_NAME), prefix, Base64Order.enhancedCoder, 12, DEFAULT_BACKEND_BUFFER_SIZE, false, true);
fileDBunbuffered.setMaxSize(maxCacheSize);
fileDB = new Compressor(fileDBunbuffered, DEFAULT_COMPRESSOR_BUFFER_SIZE, lockTimeout, compressionLevel);
} catch (final IOException ee) {
ConcurrentLog.logException(e);
}
}
}
ConcurrentLog.info("Cache", "initialized cache database responseHeaderDB.size() = " + (responseHeaderDB == null ? "NULL" : responseHeaderDB.size()) + ", fileDB.size() = " + (fileDB == null ? "NULL" : fileDB.size()));
// clean up the responseHeaderDB which cannot be cleaned the same way as the cache files.
// We do this as a concurrent job only once after start-up silently
if (responseHeaderDB.size() != fileDB.size()) {
ConcurrentLog.warn("Cache", "file and metadata size is not equal, starting a cleanup thread...");
Thread startupCleanup = new Thread("Cache startupCleanup") {
@Override
public void run() {
// enumerate the responseHeaderDB and find out all entries that are not inside the fileDBunbuffered
BlockingQueue<byte[]> q = responseHeaderDB.keyQueue(1000);
final HandleSet delkeys = new RowHandleSet(Word.commonHashLength, Base64Order.enhancedCoder, 1);
ConcurrentLog.info("Cache", "started cleanup thread to remove unused cache metadata");
try {
byte[] k;
while (((k = q.take()) != MapHeap.POISON_QUEUE_ENTRY)) {
if (!fileDB.containsKey(k)) try { delkeys.put(k); } catch (final SpaceExceededException e) { break; }
}
} catch (final InterruptedException e) {
} finally {
// delete the collected keys from the metadata
ConcurrentLog.info("Cache", "cleanup thread collected " + delkeys.size() + " unused metadata entries; now deleting them from the file...");
for (byte[] k: delkeys) {
try {
responseHeaderDB.delete(k);
} catch (final IOException e) {
}
}
}
ConcurrentLog.info("Cache", "running check to remove unused file cache data");
delkeys.clear();
for (byte[] k: fileDB) {
if (!responseHeaderDB.containsKey(k)) try { delkeys.put(k); } catch (final SpaceExceededException e) { break; }
}
ConcurrentLog.info("Cache", "cleanup thread collected " + delkeys.size() + " unused cache entries; now deleting them from the file...");
for (byte[] k: delkeys) {
try {
fileDB.delete(k);
} catch (final IOException e) {
}
}
ConcurrentLog.info("Cache", "terminated cleanup thread; responseHeaderDB.size() = " + responseHeaderDB.size() + ", fileDB.size() = " + fileDB.size());
}
};
startupCleanup.start();
}
}
public static void commit() {
fileDB.flushAll();
}
/**
* clear the cache
*/
public static void clear() {
responseHeaderDB.clear();
try {
fileDB.clear();
} catch (final IOException e) {
ConcurrentLog.logException(e);
}
try {
fileDBunbuffered.clear();
} catch (final IOException e) {
ConcurrentLog.logException(e);
}
/* Clear statistics */
totalRequests.set(0);
hits.set(0);
}
/**
* This method changes the HTCache size.<br>
* @param the new cache size in bytes
*/
public static void setMaxCacheSize(final long newCacheSize) {
maxCacheSize = newCacheSize;
fileDBunbuffered.setMaxSize(maxCacheSize);
}
/**
* Warning : even when the cache is empty,
* the actual cache size may not be zero because heap files still containing zeros after deletions
* @return the current actual cache size stored on disk
*/
public static long getActualCacheSize() {
return fileDBunbuffered.length();
}
/**
* @return the current actual number of cached documents stored on disk
*/
public static long getActualCacheDocCount() {
return fileDBunbuffered.size();
}
/**
* Set the new content compression level
* @param newCompressionLevel the new compression level. Supported values between 0 (no compression) and 9 (best compression)
*/
public static void setCompressionLevel(final int newCompressionLevel) {
fileDB.setCompressionLevel(newCompressionLevel);
}
/**
* Set the new synchronization lock timeout.
* @param lockTimeout the new synchronization lock timeout (in milliseconds).
*/
public static void setLockTimeout(final long lockTimeout) {
fileDB.setLockTimeout(lockTimeout);
}
/**
* close the databases
*/
public static void close() {
responseHeaderDB.close();
fileDB.close(true);
}
public static void store(final DigestURL url, final ResponseHeader responseHeader, final byte[] file) throws IOException {
if (maxCacheSize == 0) return;
if (responseHeader == null) throw new IOException("Cache.store of url " + url.toNormalform(false) + " not possible: responseHeader == null");
if (responseHeader.getXRobotsTag().contains("noarchive")) return; // don't cache, see http://noarchive.net/
if (file == null) throw new IOException("Cache.store of url " + url.toNormalform(false) + " not possible: file == null");
log.info("storing content of url " + url.toNormalform(false) + ", " + file.length + " bytes");
// store the file
try {
fileDB.insert(url.hash(), file);
} catch (final UnsupportedEncodingException e) {
throw new IOException("Cache.store: cannot write to fileDB (1): " + e.getMessage());
} catch (final IOException e) {
throw new IOException("Cache.store: cannot write to fileDB (2): " + e.getMessage());
}
// store the response header into the header database
final HashMap<String, String> hm = new HashMap<String, String>();
hm.putAll(responseHeader);
hm.put("@@URL", url.toNormalform(true));
try {
responseHeaderDB.insert(url.hash(), hm);
} catch (final Exception e) {
fileDB.delete(url.hash());
throw new IOException("Cache.store: cannot write to headerDB: " + e.getMessage());
}
if (log.isFine()) log.fine("stored in cache: " + url.toNormalform(true));
}
/**
* check if the responseHeaderDB and the fileDB has an entry for the given url
* @param url the url of the resource
* @return true if the content of the url is in the cache, false otherwise
*/
public static boolean has(final byte[] urlhash) {
totalRequests.incrementAndGet();
boolean headerExists;
boolean fileExists;
//synchronized (responseHeaderDB) {
headerExists = responseHeaderDB.containsKey(urlhash);
fileExists = fileDB.containsKey(urlhash);
//}
if (headerExists && fileExists) {
hits.incrementAndGet();
return true;
}
if (!headerExists && !fileExists) return false;
// if not both is there then we do a clean-up
if (headerExists) try {
log.warn("header but not content of urlhash " + ASCII.String(urlhash) + " in cache; cleaned up");
responseHeaderDB.delete(urlhash);
} catch (final IOException e) {}
if (fileExists) try {
//log.logWarning("content but not header of url " + url.toString() + " in cache; cleaned up");
fileDB.delete(urlhash);
} catch (final IOException e) {}
return false;
}
/**
* Returns an object containing metadata about a cached resource
* @param url the {@link URL} of the resource
* @return an {@link IResourceInfo info object}
* @throws <b>IllegalAccessException</b> if the {@link SecurityManager} doesn't allow instantiation
* of the info object with the given protocol
* @throws <b>UnsupportedProtocolException</b> if the protocol is not supported and therefore the
* info object couldn't be created
*/
public static ResponseHeader getResponseHeader(final byte[] hash) {
totalRequests.incrementAndGet();
// loading data from database
Map<String, String> hdb = null;
try {
hdb = responseHeaderDB.get(hash);
} catch (final IOException e) {
return null;
} catch (final SpaceExceededException e) {
return null;
}
if (hdb == null) {
return null;
}
hits.incrementAndGet();
return new ResponseHeader(hdb);
}
/**
* Returns the content of a cached resource as byte[]
* @param url the requested resource
* @return the resource content as byte[]. If no data
* is available or the cached file is not readable, <code>null</code>
* is returned.
*/
public static byte[] getContent(final byte[] hash) {
totalRequests.incrementAndGet();
// load the url as resource from the cache
try {
final byte[] b = fileDB.get(hash);
if (b == null) {
return null;
}
hits.incrementAndGet();
return b;
} catch (final UnsupportedEncodingException e) {
ConcurrentLog.logException(e);
return null;
} catch (final IOException e) {
ConcurrentLog.logException(e);
return null;
} catch (final SpaceExceededException e) {
ConcurrentLog.logException(e);
return null;
} catch (final OutOfMemoryError e) {
ConcurrentLog.logException(e);
return null;
}
}
public static boolean hasContent(final byte[] hash) {
totalRequests.incrementAndGet();
// load the url as resource from the cache
try {
boolean result = fileDB.containsKey(hash);
if(result) {
hits.incrementAndGet();
}
return result;
} catch (final OutOfMemoryError e) {
ConcurrentLog.logException(e);
return false;
}
}
/**
* removed response header and cached content from the database
* @param url
* @throws IOException
*/
public static void delete(final byte[] hash) throws IOException {
responseHeaderDB.delete(hash);
fileDB.delete(hash);
}
/**
* @return the total number of requests for cache content since last start/initialization or cache clear
*/
public static long getTotalRequests() {
return totalRequests.get();
}
/**
* @return the total number of cache hits (cached response found) since last start/initialization or cache clear
*/
public static long getHits() {
return hits.get();
}
/**
* @return the hit rate (proportion of hits over total requests)
*/
public static double getHitRate() {
final long total = totalRequests.get();
return total > 0 ? ((Cache.getHits() / ((double) total))) : 0.0 ;
}
}
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