// SearchEventCache.java
// (C) 2005 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 10.10.2005 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// LICENSE
//
// 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
package net.yacy.search.query;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.SortedSet;
import net.yacy.cora.util.ConcurrentLog;
import net.yacy.data.WorkTables;
import net.yacy.kelondro.util.MemoryControl;
import net.yacy.peers.SeedDB;
import net.yacy.repository.LoaderDispatcher;
import net.yacy.search.Switchboard;
import net.yacy.search.SwitchboardConstants;
public class SearchEventCache {
private volatile static LinkedHashMap<String, SearchEvent> lastEvents = new LinkedHashMap<String, SearchEvent>(); // a cache for objects from this class: re-use old search requests
private static final long eventLifetimeBigMem = 600000; // the time an event will stay in the cache when available memory is high, 10 Minutes
private static final long eventLifetimeMediumMem = 60000; // the time an event will stay in the cache when available memory is medium, 1 Minute
private static final long eventLifetimeShortMem = 10000; // the time an event will stay in the cache when memory is low, 10 seconds
private static final long memlimitHigh = 600 * 1024 * 1024; // 400 MB
private static final long memlimitMedium = 200 * 1024 * 1024; // 100 MB
public volatile static String lastEventID = "";
public static long cacheInsert = 0, cacheHit = 0, cacheMiss = 0, cacheDelete = 0;
public static int size() {
return lastEvents.size();
}
protected static void put(final String eventID, final SearchEvent event) {
if (MemoryControl.shortStatus()) cleanupEvents(false);
lastEventID = eventID;
synchronized (lastEvents) {
final SearchEvent oldEvent = lastEvents.put(eventID, event);
if (oldEvent == null) cacheInsert++;
}
}
public static boolean delete(final String urlhash) {
synchronized (lastEvents) {
for (final SearchEvent event: lastEvents.values()) {
if (event.delete(urlhash)) return true;
}
}
return false;
}
public static void cleanupEvents(boolean all) {
// remove old events in the event cache
if (MemoryControl.shortStatus()) all = true;
// the less memory is there, the less time is acceptable for elements in the cache
final long memx = MemoryControl.available();
final long acceptTime = memx > memlimitHigh ? eventLifetimeBigMem : memx > memlimitMedium ? eventLifetimeMediumMem : eventLifetimeShortMem;
Map.Entry<String, SearchEvent> eventEntry;
synchronized (lastEvents) {
final Iterator<Map.Entry<String, SearchEvent>> i = lastEvents.entrySet().iterator();
SearchEvent event;
while (i.hasNext()) {
eventEntry = i.next();
event = eventEntry.getValue();
if (event == null) continue;
if (all || event.getEventTime() + acceptTime < System.currentTimeMillis()) {
event.cleanup();
i.remove();
cacheDelete++;
}
}
}
}
public static void cleanupEvents(int maxsize) {
// remove old events in the event cache
if (MemoryControl.shortStatus()) {cleanupEvents(true); return;}
Map.Entry<String, SearchEvent> eventEntry;
synchronized (lastEvents) {
final Iterator<Map.Entry<String, SearchEvent>> i = lastEvents.entrySet().iterator(); // iterates in order of entry
int dc = lastEvents.size() - maxsize;
if (dc <= 0) return;
SearchEvent event;
while (i.hasNext()) {
eventEntry = i.next();
event = eventEntry.getValue();
if (event == null) continue;
event.cleanup();
i.remove();
cacheDelete++;
dc--;
if (dc <= 0) break;
}
}
}
public static SearchEvent getEvent(final String eventID) {
SearchEvent event = lastEvents.get(eventID);
if (event == null) {
synchronized (lastEvents) {
event = lastEvents.get(eventID);
if (event == null) cacheMiss++; else cacheHit++;
}
cacheMiss++;
} else {
cacheHit++;
}
return event;
}
public static SearchEvent getEvent(
final QueryParams query,
final SeedDB peers,
final WorkTables workTables,
final SortedSet<byte[]> preselectedPeerHashes,
final boolean generateAbstracts,
final LoaderDispatcher loader,
final int remote_maxcount,
final long remote_maxtime) {
if (MemoryControl.shortStatus()) cleanupEvents(true);
final String id = query.id(false);
SearchEvent event = getEvent(id);
if (Switchboard.getSwitchboard() != null && !Switchboard.getSwitchboard().crawlQueues.noticeURL.isEmpty() && event != null && System.currentTimeMillis() - event.getEventTime() > 60000) {
// if a local crawl is ongoing, don't use the result from the cache to use possibly more results that come from the current crawl
// to prevent that this happens during a person switches between the different result pages, a re-search happens no more than
// once a minute
synchronized (lastEvents) {
lastEvents.remove(id);
}
cacheDelete++;
event = null;
} else {
if (event != null) {
//re-new the event time for this event, so it is not deleted next time too early
event.resetEventTime();
// replace the current result offset
event.query.offset = query.offset;
event.query.itemsPerPage = query.itemsPerPage;
}
}
if (event == null) {
// check if there are too many other searches alive now
synchronized (lastEvents) {
ConcurrentLog.info("SearchEventCache", "getEvent: " + lastEvents.size() + " in cache");
}
// start a new event
Switchboard sb = Switchboard.getSwitchboard();
final boolean delete = sb == null || Switchboard.getSwitchboard().getConfigBool(SwitchboardConstants.SEARCH_VERIFY_DELETE, true);
final boolean addToLocalIdx = sb == null || Switchboard.getSwitchboard().getConfigBool(SwitchboardConstants.REMOTESEARCH_RESULT_STORE, true);
event = new SearchEvent(query, peers, workTables, preselectedPeerHashes, generateAbstracts, loader, remote_maxcount, remote_maxtime, delete, addToLocalIdx);
MemoryControl.request(100 * 1024 * 1024, false); // this may trigger a short memory status which causes a reducing of cache space of other threads
}
return event;
}
}