- remove superfluous entries in remote search tracker handles

- avoid concurrent access from same client
this is a fix for http://forum.yacy-websuche.de/viewtopic.php?p=20045#p20045

git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@6866 6c8d7289-2bf4-0310-a012-ef5d649a1542

htroot/yacy/search.java

@@ -146,6 +146,7 @@ public final class search {
         TreeSet<Long> trackerHandles = sb.remoteSearchTracker.get(client);
         if (trackerHandles == null) trackerHandles = new TreeSet<Long>();
         boolean block = false;
+        synchronized (trackerHandles) {
             if (trackerHandles.tailSet(Long.valueOf(System.currentTimeMillis() -   3000)).size() >  1) {
                 block = true;
             }
@@ -155,6 +156,7 @@ public final class search {
             if (trackerHandles.tailSet(Long.valueOf(System.currentTimeMillis() - 600000)).size() > 36) {
                 block = true;
             }
+        }
         if (block) {
             prop.put("links", "");
             prop.put("linkcount", "0");
@@ -386,10 +388,13 @@ public final class search {
         sb.remoteSearches.add(theQuery);
         
         // update the search tracker
-        trackerHandles.add(theQuery.handle);
+        synchronized (trackerHandles) {
+            trackerHandles.add(theQuery.handle); // thats the time when the handle was created
+            // we don't need too much entries in the list; remove superfluous
+            while (trackerHandles.size() > 36) if (!trackerHandles.remove(trackerHandles.first())) break;
+        }
         sb.remoteSearchTracker.put(client, trackerHandles);
         
-        
         // log
         yacyCore.log.logInfo("EXIT HASH SEARCH: " +
                 QueryParams.anonymizedQueryHashes(theQuery.queryHashes) + " - " + joincount + " links found, " +