new job to aggressively fetch the most up to date routerInfo from peers by, er, asking them for it

disabled by default (enable through router.config 'netDb.shouldHarvest=true').
useful if you want to harvest the published router stats, since otherwise you could have data from a few hours back

router/java/src/net/i2p/router/networkdb/kademlia/HarvesterJob.java

+package net.i2p.router.networkdb.kademlia;
+
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+
+import net.i2p.data.Hash;
+import net.i2p.data.RouterInfo;
+import net.i2p.data.i2np.DatabaseLookupMessage;
+import net.i2p.util.Log;
+import net.i2p.router.JobImpl;
+import net.i2p.router.RouterContext;
+import net.i2p.router.message.SendMessageDirectJob;
+
+/**
+ * Simple job to try to keep our peer references up to date by aggressively
+ * requerying them every few minutes.  This isn't useful for normal operation,
+ * but instead helps with gathering operational data on the network - while old
+ * RouterInfo refs are sufficient for functionality, newer ones let us harvest
+ * the published peer statistics much more frequently.  By default this job 
+ * is disabled (it runs but doesn't do anything), but if the router config 
+ * option 'netDb.shouldHarvest' is set to 'true', then every minute it'll ask 
+ * the 5 oldest peers to send their latest info (unless the info is less than
+ * 30 minutes old).
+ *
+ */
+class HarvesterJob extends JobImpl {
+    private Log _log;
+    private KademliaNetworkDatabaseFacade _facade;
+    
+    /** rerun every minute */
+    private static final long REQUEUE_DELAY = 60*1000;
+    /** if the routerInfo is more than 30 minutes old, refresh */
+    private static final long MIN_UPDATE_FREQUENCY = 30*60*1000;
+    /** don't try to update more than 5 peers during each run */
+    private static final int MAX_PER_RUN = 5;
+    /** background job, who cares */
+    private static final int PRIORITY = 100;
+    
+    private static final String PROP_ENABLED = "netDb.shouldHarvest";
+    
+    public HarvesterJob(RouterContext context, KademliaNetworkDatabaseFacade facade) {
+        super(context);
+        _facade = facade;
+        _log = context.logManager().getLog(HarvesterJob.class);
+    }
+    
+    public String getName() { return "Harvest the netDb"; }
+    public void runJob() {
+        if (shouldHarvest()) {
+            List peers = selectPeersToUpdate();
+            for (int i = 0; i < peers.size(); i++) {
+                Hash peer= (Hash)peers.get(i);
+                harvest(peer);
+            }
+        }
+        requeue(REQUEUE_DELAY);
+    }
+    
+    private boolean shouldHarvest() {
+        String should = getContext().getProperty(PROP_ENABLED, "false");
+        return ( (should != null) && ("true".equals(should)) );
+    }
+    
+    /**
+     * Retrieve a list of hashes for peers we want to update
+     *
+     */
+    private List selectPeersToUpdate() { 
+        Map routersByAge = new TreeMap();
+        Set peers = _facade.getAllRouters();
+        long now = getContext().clock().now();
+        for (Iterator iter = peers.iterator(); iter.hasNext(); ) {
+            Hash peer = (Hash)iter.next();
+            RouterInfo info = _facade.lookupRouterInfoLocally(peer);
+            if (info != null) {
+                long when = info.getPublished();
+                if (when + MIN_UPDATE_FREQUENCY > now)
+                    continue;
+                while (routersByAge.containsKey(new Long(when)))
+                    when++;
+               routersByAge.put(new Long(when), info.getIdentity().getHash());
+            }
+        }
+        
+        // ok now we have the known peers sorted by date (oldest first),
+        // ignoring peers that are new, so lets grab the oldest MAX_PER_RUN
+        // entries
+        List rv = new ArrayList(); 
+        for (Iterator iter = routersByAge.values().iterator(); iter.hasNext(); ) {
+            Hash peer = (Hash)iter.next();
+            rv.add(peer);
+            if (rv.size() >= MAX_PER_RUN)
+                break;
+        }
+        return rv;
+    }
+    
+    /**
+     * Fire off a a message to query the peer directly.  We need to do this at
+     * a lower level than usual (aka SearchJob) because search would find the 
+     * data we already have.
+     *
+     */
+    private void harvest(Hash peer) {
+        long now = getContext().clock().now();
+        DatabaseLookupMessage msg = new DatabaseLookupMessage(getContext());
+        msg.setFrom(getContext().routerHash());
+        msg.setMessageExpiration(new Date(10*1000+now));
+        msg.setSearchKey(peer);
+        msg.setReplyTunnel(null);
+        SendMessageDirectJob job = new SendMessageDirectJob(getContext(), msg, peer, 10*1000, PRIORITY);
+        getContext().jobQueue().addJob(job);
+    }
+}

router/java/src/net/i2p/router/networkdb/kademlia/KademliaNetworkDatabaseFacade.java

@@ -57,6 +57,7 @@ public class KademliaNetworkDatabaseFacade extends NetworkDatabaseFacade {
     /** Clock independent time of when we started up */
     private long _started;
     private StartExplorersJob _exploreJob;
+    private HarvesterJob _harvestJob;
     /** when was the last time an exploration found something new? */
     private long _lastExploreNew;
     private PeerSelector _peerSelector;
@@ -235,9 +236,14 @@ public class KademliaNetworkDatabaseFacade extends NetworkDatabaseFacade {
             _context.jobQueue().addJob(new DataRepublishingSelectorJob(_context, this));
             // fill the search queue with random keys in buckets that are too small
             _context.jobQueue().addJob(new ExploreKeySelectorJob(_context, this));
-            _exploreJob = new StartExplorersJob(_context, this);
+            if (_exploreJob == null)
+                _exploreJob = new StartExplorersJob(_context, this);
             // fire off a group of searches from the explore pool
             _context.jobQueue().addJob(_exploreJob);
+            // if configured to do so, periodically try to get newer routerInfo stats
+            if (_harvestJob == null)
+                _harvestJob = new HarvesterJob(_context, this);
+            _context.jobQueue().addJob(_harvestJob);
         } else {
             _log.warn("Operating in quiet mode - not exploring or pushing data proactively, simply reactively");
             _log.warn("This should NOT be used in production");