/*
* This file is part of the Heritrix web crawler (crawler.archive.org).
*
* Licensed to the Internet Archive (IA) by one or more individual
* contributors.
*
* The IA licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.archive.crawler.frontier;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Pattern;
import javax.management.openmbean.CompositeData;
import javax.management.openmbean.CompositeDataSupport;
import javax.management.openmbean.OpenDataException;
import org.apache.commons.collections.Closure;
import org.archive.bdb.KryoBinding;
import org.archive.modules.CrawlURI;
import org.archive.util.ArchiveUtils;
import com.google.common.base.Charsets;
import com.sleepycat.bind.EntryBinding;
import com.sleepycat.bind.serial.StoredClassCatalog;
import com.sleepycat.je.Cursor;
import com.sleepycat.je.Database;
import com.sleepycat.je.DatabaseEntry;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.OperationStatus;
import com.sleepycat.util.RuntimeExceptionWrapper;
/**
* A BerkeleyDB-database-backed structure for holding ordered
* groupings of CrawlURIs. Reading the groupings from specific
* per-grouping (per-classKey/per-Host) starting points allows
* this to act as a collection of independent queues.
*
* <p>For how the bdb keys are made, see {@link #calculateInsertKey(CrawlURI)}.
*
* <p>TODO: refactor, improve naming.
*
* @author gojomo
*/
public class BdbMultipleWorkQueues {
private static final long serialVersionUID = 1L;
private static final Logger LOGGER =
Logger.getLogger(BdbMultipleWorkQueues.class.getName());
/** Database holding all pending URIs, grouped in virtual queues
* 数据库保存所有带处理的URI，分组在虚拟的队列
* */
private Database pendingUrisDB = null;
/** Supporting bdb serialization of CrawlURIs */
private EntryBinding<CrawlURI> crawlUriBinding;
/**
* Create the multi queue in the given environment.
*
* @param env bdb environment to use
* @param classCatalog Class catalog to use.
* @param recycle True if we are to reuse db content if any.
* @throws DatabaseException
*/
public BdbMultipleWorkQueues(Database db,
StoredClassCatalog classCatalog)
throws DatabaseException {
this.pendingUrisDB = db;
crawlUriBinding =
new KryoBinding<CrawlURI>(CrawlURI.class);
// new RecyclingSerialBinding<CrawlURI>(classCatalog, CrawlURI.class);
// new BenchmarkingBinding<CrawlURI>(new EntryBinding[] {
// new KryoBinding<CrawlURI>(CrawlURI.class,true),
// new KryoBinding<CrawlURI>(CrawlURI.class,false),
// new RecyclingSerialBinding<CrawlURI>(classCatalog, CrawlURI.class),
// });
}
/**
* Delete all CrawlURIs matching the given expression.
* JE的记录包含两部分,key键值和value数据值，
* 这两个值都是通过DatabaseEntry对象封装起来，
* 所以说如果要使用记录，则你必须创建两个DatabaseEntry对象，
* 一个是用来做为key，另外一个是做为value.
* @param match
* @param queue
* @param headKey
* @return count of deleted items
* @throws DatabaseException
* @throws DatabaseException
*/
public long deleteMatchingFromQueue(String match, String queue,
DatabaseEntry headKey) throws DatabaseException {
long deletedCount = 0;//定义删除数量
Pattern pattern = Pattern.compile(match);//得到匹配模式
DatabaseEntry key = headKey;//从头key开始搜索
DatabaseEntry value = new DatabaseEntry();//存放搜索到的数据
Cursor cursor = null;//定义游标，游标一定要在使用后关闭
try {
cursor = pendingUrisDB.openCursor(null, null);//获取游标
OperationStatus result = cursor.getSearchKeyRange(headKey,
value, null);//从第一个key开始的所有结果都要遍历
while (result == OperationStatus.SUCCESS) {//如果找到了记录
if(value.getData().length>0) {//获取数据都是byte[]数据，可以转换为JAVA对象，对象必须可以序列化
CrawlURI curi = (CrawlURI) crawlUriBinding
.entryToObject(value);
if (!curi.getClassKey().equals(queue)) {//进一步确认找到的是否是在指定队列中，每个队列有一个classkey，如果不在指定的队列中了对跳出循环
// rolled into next queue; finished with this queue
break;
}
if (pattern.matcher(curi.toString()).matches()) {//判断URL是否匹配正则
cursor.delete();//匹配就删除记录
deletedCount++;//删除个数增加
}
}
result = cursor.getNext(key, value, null);
}
} finally {
if (cursor != null) {
cursor.close();
}
}
return deletedCount;
}
/**
* @param m marker or null to start with first entry
* @param maxMatches
* @return list of matches starting from marker position
* @throws DatabaseException
*/
public CompositeData getFrom(
String m,
int maxMatches,
Pattern pattern,
boolean verbose)
throws DatabaseException {
int matches = 0;
int tries = 0;
ArrayList<String> results = new ArrayList<String>(maxMatches);
DatabaseEntry key;
if (m == null) {
key = getFirstKey();
} else {
byte[] marker = m.getBytes(); // = FrontierJMXTypes.fromString(m);
key = new DatabaseEntry(marker);
}
DatabaseEntry value = new DatabaseEntry();
Cursor cursor = null;
OperationStatus result = null;
try {
cursor = pendingUrisDB.openCursor(null,null);
result = cursor.getSearchKey(key, value, null);
while(matches < maxMatches && result == OperationStatus.SUCCESS) {
if(value.getData().length>0) {
CrawlURI curi = (CrawlURI) crawlUriBinding.entryToObject(value);
if(pattern.matcher(curi.toString()).matches()) {
if (verbose) {
results.add("[" + curi.getClassKey() + "] "
+ curi.shortReportLine());
} else {
results.add(curi.toString());
}
matches++;
}
tries++;
}
result = cursor.getNext(key,value,null);
}
} finally {
if (cursor !=null) {
cursor.close();
}
}
if(result != OperationStatus.SUCCESS) {
// end of scan
m = null;
} else {
m = new String(key.getData()); // = FrontierJMXTypes.toString(key.getData());
}
String[] arr = results.toArray(new String[results.size()]);
CompositeData cd;
try {
cd = new CompositeDataSupport(
/*FrontierJMXTypes.URI_LIST_DATA*/ null,
new String[] { "list", "marker" },
new Object[] { arr, m });
} catch (OpenDataException e) {
throw new IllegalStateException(e);
}
return cd;
}
/**
* @return the key to the first item in the database
* @throws DatabaseException
*/
protected DatabaseEntry getFirstKey() throws DatabaseException {
DatabaseEntry key = new DatabaseEntry();
DatabaseEntry value = new DatabaseEntry();
Cursor cursor = pendingUrisDB.openCursor(null,null);
OperationStatus status = cursor.getNext(key,value,null);
cursor.close();
if(status == OperationStatus.SUCCESS) {
return key;
}
return null;
}
/**
* Get the next nearest item after the given key. Relies on
* external discipline -- we'll look at the queues count of how many
* items it has -- to avoid asking for something from a
* range where there are no associated items --
* otherwise could get first item of next 'queue' by mistake.
*
* <p>TODO: hold within a queue's range
*
* @param headKey Key prefix that demarks the beginning of the range
* in <code>pendingUrisDB</code> we're interested in.
* @return CrawlURI.
* @throws DatabaseException
*/
public CrawlURI get(DatabaseEntry headKey)
throws DatabaseException {
DatabaseEntry result = new DatabaseEntry();
// From Linda Lee of sleepycat:
// "You want to check the status returned from Cursor.getSearchKeyRange
// to make sure that you have OperationStatus.SUCCESS. In that case,
// you have found a valid data record, and result.getData()
// (called by internally by the binding code, in this case) will be
// non-null. The other possible status return is
// OperationStatus.NOTFOUND, in which case no data record matched
// the criteria. "
OperationStatus status = getNextNearestItem(headKey, result);
CrawlURI retVal = null;
if (status != OperationStatus.SUCCESS) {
LOGGER.severe("See '1219854 NPE je-2.0 "
+ "entryToObject...'. OperationStatus "
+ " was not SUCCESS: "
+ status
+ ", headKey "
+ BdbWorkQueue.getPrefixClassKey(headKey.getData()));
return null;
}
try {
retVal = (CrawlURI)crawlUriBinding.entryToObject(result);
} catch (ClassCastException cce) {
Object obj = crawlUriBinding.entryToObject(result);
LOGGER.log(Level.SEVERE,
"see [#HER-1283]: deserialized " + obj.getClass()
+ " has ClassLoader "
+ obj.getClass().getClassLoader().getClass(),
cce);
return null;
} catch (RuntimeExceptionWrapper rw) {
LOGGER.log(
Level.SEVERE,
"expected object missing in queue " +
BdbWorkQueue.getPrefixClassKey(headKey.getData()),
rw);
return null;
}
retVal.setHolderKey(headKey);
return retVal;
}
protected OperationStatus getNextNearestItem(DatabaseEntry headKey,
DatabaseEntry result) throws DatabaseException {
Cursor cursor = null;
OperationStatus status;
try {
cursor = this.pendingUrisDB.openCursor(null, null);
// get cap; headKey at this point should always point to
// a queue-beginning cap entry (zero-length value)
status = cursor.getSearchKey(headKey, result, null);
if (status != OperationStatus.SUCCESS) {
LOGGER.severe("bdb queue cap missing: "
+ status.toString() + " " + new String(headKey.getData()));
return status;
}
if (result.getData().length > 0) {
LOGGER.severe("bdb queue has nonzero size: "
+ result.getData().length);
return OperationStatus.KEYEXIST;
}
// get next item (real first item of queue)
status = cursor.getNext(headKey,result,null);
} finally {
if(cursor!=null) {
cursor.close();
}
}
return status;
}
/**
* Put the given CrawlURI in at the appropriate place.
*
* @param curi
* @throws DatabaseException
*/
public void put(CrawlURI curi, boolean overwriteIfPresent)
throws DatabaseException {
DatabaseEntry insertKey = (DatabaseEntry)curi.getHolderKey();
if (insertKey == null) {
insertKey = calculateInsertKey(curi);
curi.setHolderKey(insertKey);
}
DatabaseEntry value = new DatabaseEntry();
crawlUriBinding.objectToEntry(curi, value);
// Output tally on avg. size if level is FINE or greater.
if (LOGGER.isLoggable(Level.FINE)) {
tallyAverageEntrySize(curi, value);
}
OperationStatus status;
if(overwriteIfPresent) {
status = pendingUrisDB.put(null, insertKey, value);
} else {
status = pendingUrisDB.putNoOverwrite(null, insertKey, value);
}
if (status!=OperationStatus.SUCCESS) {
LOGGER.log(Level.SEVERE,"URI enqueueing failed; "+status+ " "+curi, new RuntimeException());
}
}
private long entryCount = 0;
private long entrySizeSum = 0;
private int largestEntry = 0;
/**
* Log average size of database entry.
* @param curi CrawlURI this entry is for.
* @param value Database entry value.
*/
private synchronized void tallyAverageEntrySize(CrawlURI curi,
DatabaseEntry value) {
entryCount++;
int length = value.getData().length;
entrySizeSum += length;
int avg = (int) (entrySizeSum/entryCount);
if(entryCount % 1000 == 0) {
LOGGER.fine("Average entry size at "+entryCount+": "+avg);
}
if (length>largestEntry) {
largestEntry = length;
LOGGER.fine("Largest entry: "+length+" "+curi);
if(length>(2*avg)) {
LOGGER.fine("excessive?");
}
}
}
/**
* Calculate the 'origin' key for a virtual queue of items
* with the given classKey. This origin key will be a
* prefix of the keys for all items in the queue.
*
* @param classKey String key to derive origin byte key from
* @return a byte array key
*/
static byte[] calculateOriginKey(String classKey) {
byte[] classKeyBytes = null;
int len = 0;
try {
classKeyBytes = classKey.getBytes("UTF-8");
len = classKeyBytes.length;
} catch (UnsupportedEncodingException e) {
// should be impossible; all JVMs must support UTF-8
e.printStackTrace();
}
byte[] keyData = new byte[len+1];
System.arraycopy(classKeyBytes,0,keyData,0,len);
keyData[len]=0;
return keyData;
}
/**
* Calculate the insertKey that places a CrawlURI in the
* desired spot. First bytes are always classKey (usu. host)
* based -- ensuring grouping by host -- terminated by a zero
* byte. Then 8 bytes of data ensuring desired ordering
* within that 'queue' are used. The first byte of these 8 is
* priority -- allowing 'immediate' and 'soon' items to
* sort above regular. Next 1 byte is 'precedence'. Last 6 bytes
* are ordinal serial number, ensuring earlier-discovered
* URIs sort before later.
*
* NOTE: Dangers here are:
* (1) priorities or precedences over 2^7 (signed byte comparison)
* (2) ordinals over 2^48
*
* Package access & static for testing purposes.
*
* @param curi
* @return a DatabaseEntry key for the CrawlURI
*/
static DatabaseEntry calculateInsertKey(CrawlURI curi) {
byte[] classKeyBytes = null;
int len = 0;
classKeyBytes = curi.getClassKey().getBytes(Charsets.UTF_8);
len = classKeyBytes.length;
byte[] keyData = new byte[len+9];
System.arraycopy(classKeyBytes,0,keyData,0,len);
keyData[len]=0;
long ordinalPlus = curi.getOrdinal() & 0x0000FFFFFFFFFFFFL;
ordinalPlus =
((long)curi.getSchedulingDirective() << 56) | ordinalPlus;
long precedence = Math.min(curi.getPrecedence(), 127);
ordinalPlus =
(((precedence) & 0xFFL) << 48) | ordinalPlus;
ArchiveUtils.longIntoByteArray(ordinalPlus, keyData, len+1);
return new DatabaseEntry(keyData);
}
static String insertKeyToString(DatabaseEntry holderKey) {
StringBuilder result = new StringBuilder();
byte[] data = holderKey.getData();
int p = findFirstZero(data);
result.append(new String(data, 0, p));
java.io.ByteArrayInputStream binp =
new java.io.ByteArrayInputStream(data, p + 1, data.length);
java.io.DataInputStream dinp = new java.io.DataInputStream(binp);
long l = 0;
try {
l = dinp.readLong();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
result.append(" blah=").append(l);
return result.toString();
}
private static int findFirstZero(byte[] b) {
for (int i = 0; i < b.length; i++) {
if (b[i] == 0) {
return i;
}
}
return -1;
}
/**
* Delete the given CrawlURI from persistent store. Requires
* the key under which it was stored be available.
*
* @param item
* @throws DatabaseException
*/
public void delete(CrawlURI item) throws DatabaseException {
OperationStatus status;
DatabaseEntry de = (DatabaseEntry)item.getHolderKey();
status = pendingUrisDB.delete(null, de);
if (status != OperationStatus.SUCCESS) {
LOGGER.severe("expected item not present: "
+ item
+ "("
+ (new BigInteger(((DatabaseEntry) item.getHolderKey())
.getData())).toString(16) + ")");
}
}
/**
* Method used by BdbFrontier during checkpointing.
* <p>The backing bdbje database has been marked deferred write so we save
* on writes to disk. Means no guarantees disk will have whats in memory
* unless a sync is called (Calling sync on the bdbje Environment is not
* sufficent).
* <p>Package access only because only Frontiers of this package would ever
* need access.
* @see <a href="http://www.sleepycat.com/jedocs/GettingStartedGuide/DB.html">Deferred Write Databases</a>
*/
void sync() {
if (this.pendingUrisDB == null) {
return;
}
try {
this.pendingUrisDB.sync();
} catch (DatabaseException e) {
e.printStackTrace();
}
}
/**
* clean up
*
*/
public void close() {
/* try {
this.pendingUrisDB.close();
} catch (DatabaseException e) {
e.printStackTrace();
} */
}
/**
* Add a dummy 'cap' entry at the given insertion key. Prevents
* 'seeks' to queue heads from holding lock on last item of
* 'preceding' queue. See:
* http://sourceforge.net/tracker/index.php?func=detail&aid=1262665&group_id=73833&atid=539102
*
* @param origin key at which to insert the cap
*/
public void addCap(byte[] origin) {
try {
pendingUrisDB.put(null, new DatabaseEntry(origin),
new DatabaseEntry(new byte[0]));
} catch (DatabaseException e) {
throw new RuntimeException(e);
}
}
/**
* Utility method to perform action for all pending CrawlURI instances.
* @param c Closure action to perform
* @throws DatabaseException
*/
protected void forAllPendingDo(Closure c) throws DatabaseException {
DatabaseEntry key = new DatabaseEntry();
DatabaseEntry value = new DatabaseEntry();
Cursor cursor = pendingUrisDB.openCursor(null, null);
while (cursor.getNext(key, value, null) == OperationStatus.SUCCESS) {
if (value.getData().length == 0) {
continue;
}
CrawlURI item = (CrawlURI) crawlUriBinding.entryToObject(value);
c.execute(item);
}
cursor.close();
}
}BDB 封装
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