/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* You can obtain a copy of the license at
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* trunk/opends/resource/legal-notices/OpenDS.LICENSE
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* or https://OpenDS.dev.java.net/OpenDS.LICENSE.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at
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* trunk/opends/resource/legal-notices/OpenDS.LICENSE. If applicable,
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* add the following below this CDDL HEADER, with the fields enclosed
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* by brackets "[]" replaced with your own identifying information:
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* Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*
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*
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* Copyright 2008 Sun Microsystems, Inc.
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*/
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package org.opends.server.backends.jeb.importLDIF;
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import org.opends.server.types.Entry;
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import org.opends.server.backends.jeb.Index;
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import org.opends.server.backends.jeb.EntryID;
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import com.sleepycat.je.Transaction;
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import com.sleepycat.je.DatabaseException;
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import com.sleepycat.je.DatabaseEntry;
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import com.sleepycat.je.dbi.MemoryBudget;
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import static org.opends.server.loggers.ErrorLogger.logError;
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import org.opends.messages.Message;
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import static org.opends.messages.JebMessages.*;
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import java.util.*;
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/**
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* Manages a shared cache among worker threads that caches substring
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* key/value pairs to avoid DB cache access. Once the cache is above it's
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* memory usage limit, it will start slowly flushing keys (similar to the
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* JEB eviction process) until it is under the limit.
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*/
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public class BufferManager {
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//Memory usage counter.
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private long memoryUsage=0;
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//Memory limit.
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private long memoryLimit;
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//Next element in the cache to start flushing at during next flushAll cycle.
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private KeyHashElement nextElem;
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//Extra bytes to flushAll.
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private final int extraBytes = 1024 * 1024;
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//Counters for statistics, total is number of accesses, hit is number of
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//keys found in cache.
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private long total=0, hit=0;
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//Actual map used to buffer keys.
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private TreeMap<KeyHashElement, KeyHashElement> elementMap =
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new TreeMap<KeyHashElement, KeyHashElement>();
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//Overhead values determined from using JHAT. They appear to be the same
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//for both 32 and 64 bit machines. Close enough.
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private final static int TREEMAP_ENTRY_OVERHEAD = 29;
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private final static int KEY_ELEMENT_OVERHEAD = 32;
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/**
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* Create buffer manager instance.
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*
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* @param memoryLimit The memory limit.
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* @param importThreadCount The count of import worker threads.
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*/
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public BufferManager(long memoryLimit, int importThreadCount) {
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this.memoryLimit = memoryLimit;
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this.nextElem = null;
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}
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/**
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* Insert an entry ID into the buffer using the both the specified index and
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* entry to build a key set. Will flush the buffer if over the memory limit.
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*
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* @param index The index to use.
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* @param entry The entry used to build the key set.
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* @param entryID The entry ID to insert into the key set.
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* @param txn A transaction.
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* @throws DatabaseException If a problem happened during a flushAll cycle.
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*/
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void insert(Index index, Entry entry,
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EntryID entryID, Transaction txn)
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throws DatabaseException {
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Set<byte[]> keySet = new HashSet<byte[]>();
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index.indexer.indexEntry(txn, entry, keySet);
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synchronized(elementMap) {
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insertKeySet(keySet, index, entryID);
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//If over the memory limit and import hasn't completed
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//flush some keys from the cache to make room.
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if(memoryUsage > memoryLimit) {
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flushUntilUnderLimit();
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}
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}
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}
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/**
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* Special case for id2children and id2subtree.
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* Insert an entry ID into the buffer using the both the specified index and
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* entry to build a key set.
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* @param id2children The id2children index.
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* @param id2subtree The id2subtree index.
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* @param entry The entry to used to build the keyset.
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* @param entryID The entry ID to insert into the key set.
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* @param txn A transaction.
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* @throws DatabaseException If a problem happens formating the keyset.
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*/
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void insert(Index id2children, Index id2subtree, Entry entry,
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EntryID entryID, Transaction txn) throws DatabaseException {
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Set<byte[]> childKeySet = new HashSet<byte[]>();
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id2children.indexer.indexEntry(txn, entry, childKeySet);
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Set<byte[]> subKeySet = new HashSet<byte[]>();
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id2subtree.indexer.indexEntry(txn, entry, subKeySet);
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synchronized(elementMap) {
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insertKeySet(childKeySet, id2children, entryID);
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insertKeySet(subKeySet, id2subtree, entryID);
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}
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}
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/**
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* Insert a keySet into the element map using the provided index and entry ID.
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* @param keySet The key set to add to the map.
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* @param index The index that eventually will contain the entry IDs.
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* @param entryID The entry ID to add to the entry ID set.
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*/
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private void insertKeySet(Set<byte[]> keySet, Index index, EntryID entryID) {
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int entryLimit = index.getIndexEntryLimit();
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for(byte[] key : keySet) {
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KeyHashElement elem = new KeyHashElement(key, index, entryID);
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total++;
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if(!elementMap.containsKey(elem)) {
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elementMap.put(elem, elem);
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memoryUsage += TREEMAP_ENTRY_OVERHEAD + elem.getMemorySize();
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} else {
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KeyHashElement curElem = elementMap.get(elem);
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if(curElem.isDefined() || index.getMaintainCount()) {
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int oldSize = curElem.getMemorySize();
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curElem.addEntryID(entryID, entryLimit);
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int newSize = curElem.getMemorySize();
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//Might have moved from defined to undefined.
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memoryUsage += (newSize - oldSize);
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hit++;
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}
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}
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}
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}
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/**
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* Flush the buffer to DB until the buffer is under the memory limit.
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*
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* @throws DatabaseException If a problem happens during an index insert.
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*/
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private void flushUntilUnderLimit() throws DatabaseException {
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Iterator<KeyHashElement> iter;
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if(nextElem == null) {
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iter = elementMap.keySet().iterator();
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} else {
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iter = elementMap.tailMap(nextElem).keySet().iterator();
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}
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while((memoryUsage + extraBytes) > memoryLimit) {
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if(iter.hasNext()) {
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KeyHashElement curElem = iter.next();
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//Never flush undefined elements.
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if(curElem.isDefined()) {
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int oldSize = curElem.getMemorySize();
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Index index = curElem.getIndex();
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index.insert(null, new DatabaseEntry(curElem.getKey()),
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curElem.getIDSet());
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if(curElem.isDefined()) {
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memoryUsage -= TREEMAP_ENTRY_OVERHEAD + curElem.getMemorySize();
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iter.remove();
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} else {
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//Went undefined don't remove the element, just substract the
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//memory size difference.
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memoryUsage -= (oldSize - curElem.getMemorySize());
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}
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}
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} else {
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//Wrapped around, start at the first element.
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nextElem = elementMap.firstKey();
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iter = elementMap.keySet().iterator();
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}
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}
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//Start at this element next flushAll cycle.
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nextElem = iter.next();
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}
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/**
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* Called from main thread to prepare for final buffer flush at end of
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* ldif load.
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*/
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void prepareFlush() {
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Message msg =
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NOTE_JEB_IMPORT_LDIF_BUFFER_FLUSH.get(elementMap.size(), total, hit);
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logError(msg);
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}
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/**
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* Writes all of the buffer elements to DB. The specific id is used to
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* share the buffer among the worker threads so this function can be
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* multi-threaded.
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*
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* @throws DatabaseException If an error occurred during the insert.
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*/
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void flushAll() throws DatabaseException {
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TreeSet<KeyHashElement> tSet =
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new TreeSet<KeyHashElement>(elementMap.keySet());
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for (KeyHashElement curElem : tSet) {
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Index index = curElem.getIndex();
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index.insert(null, new DatabaseEntry(curElem.getKey()),
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curElem.getIDSet());
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}
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}
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/**
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* Class used to represent an element in the buffer.
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*/
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class KeyHashElement implements Comparable {
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//Bytes representing the key.
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private byte[] key;
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//Hash code returned from the System.identityHashCode method on the index
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//object.
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private int indexHashCode;
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//Index related to the element.
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private Index index;
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//The set of IDs related to the key.
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private ImportIDSet importIDSet;
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//Used to speed up lookup.
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private int keyHashCode;
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/**
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* Create instance of an element for the specified key and index, the add
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* the specified entry ID to the ID set.
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*
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* @param key The key.
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* @param index The index.
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* @param entryID The entry ID to start off with.
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*/
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public KeyHashElement(byte[] key, Index index, EntryID entryID) {
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this.key = key;
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this.index = index;
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//Use the integer set for right now. This is good up to 2G number of
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//entries. There is also a LongImportSet, but it currently isn't used.
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this.importIDSet = new IntegerImportIDSet(entryID);
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//Used if there when there are conflicts if two or more indexes have
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//the same key.
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this.indexHashCode = System.identityHashCode(index);
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this.keyHashCode = Arrays.hashCode(key);
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}
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/**
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* Add an entry ID to the set.
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*
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* @param entryID The entry ID to add.
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* @param entryLimit The entry limit
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*/
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void addEntryID(EntryID entryID, int entryLimit) {
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importIDSet.addEntryID(entryID, entryLimit, index.getMaintainCount());
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}
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/**
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* Return the index.
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*
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* @return The index.
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*/
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Index getIndex(){
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return index;
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}
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/**
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* Return the key.
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*
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* @return The key.
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*/
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byte[] getKey() {
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return key;
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}
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/**
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* Return value of the key hash code.
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*
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* @return The key hash code value.
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*/
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int getKeyHashCode() {
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return keyHashCode;
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}
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/**
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* Return the ID set.
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* @return The import ID set.
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*/
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ImportIDSet getIDSet() {
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return importIDSet;
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}
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/**
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* Return if the ID set is defined or not.
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*
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* @return <CODE>True</CODE> if the ID set is defined.
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*/
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boolean isDefined() {
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return importIDSet.isDefined();
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}
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/**
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* Compare the bytes of two keys. The is slow, only use if the hashcode
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* had a collision.
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*
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* @param a Key a.
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* @param b Key b.
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* @return 0 if the keys are equal, -1 if key a is less than key b, 1 if
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* key a is greater than key b.
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*/
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private int compare(byte[] a, byte[] b) {
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int i;
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for (i = 0; i < a.length && i < b.length; i++) {
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if (a[i] > b[i]) {
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return 1;
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}
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else if (a[i] < b[i]) {
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return -1;
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}
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}
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if (a.length == b.length) {
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return 0;
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}
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if (a.length > b.length){
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return 1;
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}
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else {
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return -1;
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}
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}
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/**
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* Compare two element keys. First check the precomputed hashCode. If
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* the hashCodes are equal, do a second byte per byte comparision in case
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* there was a collision.
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*
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* @param elem The element to compare.
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* @return 0 if the keys are equal, -1 if key a is less than key b, 1 if
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* key a is greater than key b.
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*/
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private int compare(KeyHashElement elem) {
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if(keyHashCode == elem.getKeyHashCode()) {
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return compare(key, elem.key);
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} else {
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if(keyHashCode < elem.getKeyHashCode()) {
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return -1;
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} else {
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return 1;
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}
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}
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}
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/**
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* Compare the specified object to the current object. If the keys are
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* equal, then the indexHashCode value is used as a tie-breaker.
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*
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* @param o The object representing a KeyHashElement.
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* @return 0 if the objects are equal, -1 if the current object is less
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* than the specified object, 1 otherwise.
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*/
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public int compareTo(Object o) {
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if (o == null) {
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throw new NullPointerException();
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}
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KeyHashElement inElem = (KeyHashElement) o;
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// int keyCompare = compare(key, inElem.key);
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int keyCompare = compare(inElem);
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if(keyCompare == 0) {
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if(indexHashCode == inElem.indexHashCode) {
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return 0;
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} else if(indexHashCode < inElem.indexHashCode) {
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return -1;
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} else {
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return 1;
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}
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} else {
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return keyCompare;
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}
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}
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/**
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* Return the current total memory size of the element.
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* @return The memory size estimate of a KeyHashElement.
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*/
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int getMemorySize() {
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return KEY_ELEMENT_OVERHEAD +
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MemoryBudget.byteArraySize(key.length) +
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importIDSet.getMemorySize();
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}
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}
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}
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